Stop sharing requirement_unit_state_ereq().

[freeciv.git] / client / helpdata.c

/***********************************************************************
 Freeciv - Copyright (C) 1996 - A Kjeldberg, L Gregersen, P Unold
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
***********************************************************************/

/***********************************************************************
 This module is for generic handling of help data, independent
 of gui considerations.
***********************************************************************/

#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif

#include <stdio.h>
#include <string.h>

/* utility */
#include "astring.h"
#include "bitvector.h"
#include "fciconv.h"
#include "fcintl.h"
#include "log.h"
#include "mem.h"
#include "registry.h"
#include "string_vector.h"
#include "support.h"

/* common */
#include "effects.h"
#include "game.h"
#include "government.h"
#include "map.h"
#include "movement.h"
#include "multipliers.h"
#include "reqtext.h"
#include "research.h"
#include "specialist.h"
#include "tilespec.h"
#include "unit.h"
#include "version.h"

/* client */
#include "client_main.h"
#include "climisc.h"
#include "gui_main_g.h" /* client_string */

#include "helpdata.h"

/* helper macro for easy conversion from snprintf and cat_snprintf */
#define CATLSTR(_b, _s, _t) fc_strlcat(_b, _t, _s)

/* This must be in same order as enum in helpdlg_g.h */
static const char * const help_type_names[] = {
  "(Any)", "(Text)", "Units", "Improvements", "Wonders",
  "Techs", "Terrain", "Extras", "Goods", "Specialists", "Governments",
  "Ruleset", "Tileset", "Nations", "Multipliers", NULL
};

/*define MAX_LAST (MAX(MAX(MAX(A_LAST,B_LAST),U_LAST),terrain_count()))*/

#define SPECLIST_TAG help
#define SPECLIST_TYPE struct help_item
#include "speclist.h"

#define help_list_iterate(helplist, phelp) \
    TYPED_LIST_ITERATE(struct help_item, helplist, phelp)
#define help_list_iterate_end  LIST_ITERATE_END

static const struct help_list_link *help_nodes_iterator;
static struct help_list *help_nodes;
static bool help_nodes_init = FALSE;
/* helpnodes_init is not quite the same as booted in boot_help_texts();
   latter can be 0 even after call, eg if couldn't find helpdata.txt.
*/

/****************************************************************
  Initialize.
*****************************************************************/
void helpdata_init(void)
{
  help_nodes = help_list_new();
}

/****************************************************************
  Clean up.
*****************************************************************/
void helpdata_done(void)
{
  help_list_destroy(help_nodes);
}

/****************************************************************
  Make sure help_nodes is initialised.
  Should call this just about everywhere which uses help_nodes,
  to be careful...  or at least where called by external
  (non-static) functions.
*****************************************************************/
static void check_help_nodes_init(void)
{
  if (!help_nodes_init) {
    help_nodes_init = TRUE;    /* before help_iter_start to avoid recursion! */
    help_iter_start();
  }
}

/****************************************************************
  Free all allocations associated with help_nodes.
*****************************************************************/
void free_help_texts(void)
{
  check_help_nodes_init();
  help_list_iterate(help_nodes, ptmp) {
    free(ptmp->topic);
    free(ptmp->text);
    free(ptmp);
  } help_list_iterate_end;
  help_list_clear(help_nodes);
}

/****************************************************************************
  Returns whether we should show help for this nation.
****************************************************************************/
static bool show_help_for_nation(const struct nation_type *pnation)
{
  return client_nation_is_in_current_set(pnation);
}

/****************************************************************************
  Insert fixed-width table describing veteran system.
  If only one veteran level, inserts 'nolevels' if non-NULL.
  Otherwise, insert 'intro' then a table.
****************************************************************************/
static bool insert_veteran_help(char *outbuf, size_t outlen,
                                const struct veteran_system *veteran,
                                const char *intro, const char *nolevels)
{
  /* game.veteran can be NULL in pregame; if so, keep quiet about
   * veteran levels */
  if (!veteran) {
    return FALSE;
  }

  fc_assert_ret_val(veteran->levels >= 1, FALSE);

  if (veteran->levels == 1) {
    /* Only a single veteran level. Don't bother to name it. */
    if (nolevels) {
      CATLSTR(outbuf, outlen, nolevels);
      return TRUE;
    } else {
      return FALSE;
    }
  } else {
    int i;
    fc_assert_ret_val(veteran->definitions != NULL, FALSE);
    if (intro) {
      CATLSTR(outbuf, outlen, intro);
      CATLSTR(outbuf, outlen, "\n\n");
    }
    /* raise_chance and work_raise_chance don't get to the client, so we
     * can't report them */
    CATLSTR(outbuf, outlen,
            /* TRANS: Header for fixed-width veteran level table.
             * TRANS: Translators cannot change column widths :(
             * TRANS: "Level name" left-justified, other two right-justified */
            _("Veteran level      Power factor   Move bonus\n"));
    CATLSTR(outbuf, outlen,
            /* TRANS: Part of header for veteran level table. */
            _("--------------------------------------------"));
    for (i = 0; i < veteran->levels; i++) {
      const struct veteran_level *level = &veteran->definitions[i];
      const char *name = name_translation_get(&level->name);
      /* Use get_internal_string_length() for correct alignment with
       * multibyte character encodings */
      cat_snprintf(outbuf, outlen,
          "\n%s%*s %4d%% %12s",
          name, MAX(0, 25 - (int)get_internal_string_length(name)), "",
          level->power_fact,
          /* e.g. "-    ", "+ 1/3", "+ 1    ", "+ 2 2/3" */
          move_points_text_full(level->move_bonus, TRUE, "+ ", "-", TRUE));
    }
    return TRUE;
  }
}

/****************************************************************************
  Insert generated text for the helpdata "name".
  Returns TRUE if anything was added.
****************************************************************************/
static bool insert_generated_text(char *outbuf, size_t outlen, const char *name)
{
  if (!game.client.ruleset_init) {
    return FALSE;
  }

  if (0 == strcmp(name, "TerrainAlterations")) {
    int clean_pollution_time = -1, clean_fallout_time = -1;
    bool terrain_independent_extras = FALSE;

    CATLSTR(outbuf, outlen,
            /* TRANS: Header for fixed-width terrain alteration table.
             * TRANS: Translators cannot change column widths :( */
            _("Terrain       Irrigation       Mining           Transform\n"));
    CATLSTR(outbuf, outlen,
            "----------------------------------------------------------------\n");
    terrain_type_iterate(pterrain) {
      if (0 != strlen(terrain_rule_name(pterrain))) {
        char irrigation_time[4], mining_time[4], transform_time[4];
        const char *terrain, *irrigation_result,
                   *mining_result,*transform_result;
        struct universal for_terr = { .kind = VUT_TERRAIN, .value = { .terrain = pterrain }};

        fc_snprintf(irrigation_time, sizeof(irrigation_time),
                    "%d", pterrain->irrigation_time);
        fc_snprintf(mining_time, sizeof(mining_time),
                    "%d", pterrain->mining_time);
        fc_snprintf(transform_time, sizeof(transform_time),
                    "%d", pterrain->transform_time);
        terrain = terrain_name_translation(pterrain);
        irrigation_result = 
          (pterrain->irrigation_result == pterrain
           || pterrain->irrigation_result == T_NONE
           || effect_cumulative_max(EFT_IRRIG_TF_POSSIBLE, &for_terr) <= 0) ? ""
          : terrain_name_translation(pterrain->irrigation_result);
        mining_result =
          (pterrain->mining_result == pterrain
           || pterrain->mining_result == T_NONE
           || effect_cumulative_max(EFT_MINING_TF_POSSIBLE, &for_terr) <= 0) ? ""
          : terrain_name_translation(pterrain->mining_result);
        transform_result =
          (pterrain->transform_result == pterrain
           || pterrain->transform_result == T_NONE
           || effect_cumulative_max(EFT_TRANSFORM_POSSIBLE, &for_terr) <= 0) ? ""
          : terrain_name_translation(pterrain->transform_result);
        /* Use get_internal_string_length() for correct alignment with
         * multibyte character encodings */
        cat_snprintf(outbuf, outlen,
            "%s%*s %3s %s%*s %3s %s%*s %3s %s\n",
            terrain,
            MAX(0, 12 - (int)get_internal_string_length(terrain)), "",
            (pterrain->irrigation_result == T_NONE) ? "-" : irrigation_time,
            irrigation_result,
            MAX(0, 12 - (int)get_internal_string_length(irrigation_result)), "",
            (pterrain->mining_result == T_NONE) ? "-" : mining_time,
            mining_result,
            MAX(0, 12 - (int)get_internal_string_length(mining_result)), "",
            (pterrain->transform_result == T_NONE) ? "-" : transform_time,
            transform_result);

        if (clean_pollution_time != 0) {
          if (clean_pollution_time < 0) {
            clean_pollution_time = pterrain->clean_pollution_time;
          } else {
            if (clean_pollution_time != pterrain->clean_pollution_time) {
              clean_pollution_time = 0; /* give up */
            }
          }
        }
        if (clean_fallout_time != 0) {
          if (clean_fallout_time < 0) {
            clean_fallout_time = pterrain->clean_fallout_time;
          } else {
            if (clean_fallout_time != pterrain->clean_fallout_time) {
              clean_fallout_time = 0; /* give up */
            }
          }
        }
      }
    } terrain_type_iterate_end;

    extra_type_by_cause_iterate(EC_BASE, pextra) {
      if (pextra->buildable && pextra->build_time > 0) {
        terrain_independent_extras = TRUE;
        break;
      }
    } extra_type_by_cause_iterate_end;
    if (!terrain_independent_extras) {
      extra_type_by_cause_iterate(EC_ROAD, pextra) {
        if (pextra->buildable && pextra->build_time > 0) {
          terrain_independent_extras = TRUE;
          break;
        }
      } extra_type_by_cause_iterate_end;
    }

    if (clean_pollution_time > 0 || clean_fallout_time > 0
        || terrain_independent_extras) {
      CATLSTR(outbuf, outlen, "\n");
      CATLSTR(outbuf, outlen,
              _("Time taken for the following activities is independent of "
                "terrain:\n"));
      CATLSTR(outbuf, outlen, "\n");
      CATLSTR(outbuf, outlen,
              /* TRANS: Header for fixed-width terrain alteration table.
               * TRANS: Translators cannot change column widths :( */
              _("Activity            Time\n"));
      CATLSTR(outbuf, outlen,
              "---------------------------");
      if (clean_pollution_time > 0)
        cat_snprintf(outbuf, outlen,
                     _("\nClean pollution    %3d"), clean_pollution_time);
      if (clean_fallout_time > 0)
        cat_snprintf(outbuf, outlen,
                     _("\nClean fallout      %3d"), clean_fallout_time);
      extra_type_by_cause_iterate(EC_ROAD, pextra) {
        if (pextra->buildable && pextra->build_time > 0) {
          const char *rname = extra_name_translation(pextra);

          cat_snprintf(outbuf, outlen,
                       "\n%s%*s %3d",
                       rname,
                       MAX(0, 18 - (int)get_internal_string_length(rname)), "",
                       pextra->build_time);
        }
      } extra_type_by_cause_iterate_end;
      extra_type_by_cause_iterate(EC_BASE, pextra) {
        if (pextra->buildable && pextra->build_time > 0) {
          const char *bname = extra_name_translation(pextra);

          cat_snprintf(outbuf, outlen,
                       "\n%s%*s %3d",
                       bname,
                       MAX(0, 18 - (int)get_internal_string_length(bname)), "",
                       pextra->build_time);
        }
      } extra_type_by_cause_iterate_end;
    }
    return TRUE;
  } else if (0 == strcmp(name, "VeteranLevels")) {
    return insert_veteran_help(outbuf, outlen, game.veteran,
        _("In this ruleset, the following veteran levels are defined:"),
        _("This ruleset has no default veteran levels defined."));
  } else if (0 == strcmp(name, "FreecivVersion")) {
    const char *ver = freeciv_name_version();

    cat_snprintf(outbuf, outlen,
                 /* TRANS: First %s is version string, e.g.,
                  * "Freeciv version 2.3.0-beta1 (beta version)" (translated).
                  * Second %s is client_string, e.g., "gui-gtk-2.0". */
                 _("This is %s, %s client."), ver, client_string);
    insert_client_build_info(outbuf, outlen);

    return TRUE;
  } else if (0 == strcmp(name, "DefaultMetaserver")) {
    cat_snprintf(outbuf, outlen, "  %s", FREECIV_META_URL);

    return TRUE;
  }
  log_error("Unknown directive '$%s' in help", name);
  return FALSE;
}

/****************************************************************************
  Append text to 'buf' if the given requirements list 'subjreqs' contains
  'psource', implying that ability to build the subject 'subjstr' is
  affected by 'psource'.
  'strs' is an array of (possibly i18n-qualified) format strings covering
  the various cases where additional requirements apply.
****************************************************************************/
static void insert_allows_single(struct universal *psource,
                                 struct requirement_vector *psubjreqs,
                                 const char *subjstr,
                                 const char *const *strs,
                                 char *buf, size_t bufsz) {
  struct strvec *coreqs = strvec_new();
  struct strvec *conoreqs = strvec_new();
  struct astring coreqstr = ASTRING_INIT;
  struct astring conoreqstr = ASTRING_INIT;
  char buf2[bufsz];

  /* FIXME: show other data like range and survives. */

  requirement_vector_iterate(psubjreqs, req) {
    if (!req->quiet && are_universals_equal(psource, &req->source)) {
      if (req->present) {
        /* psource enables the subject, but other sources may
         * also be required (or required to be absent). */
        requirement_vector_iterate(psubjreqs, coreq) {
          if (!coreq->quiet && !are_universals_equal(psource, &coreq->source)) {
            universal_name_translation(&coreq->source, buf2, sizeof(buf2));
            strvec_append(coreq->present ? coreqs : conoreqs, buf2);
          }
        } requirement_vector_iterate_end;

        if (0 < strvec_size(coreqs)) {
          if (0 < strvec_size(conoreqs)) {
            cat_snprintf(buf, bufsz,
                         Q_(strs[0]), /* "Allows %s (with %s but no %s)." */
                         subjstr,
                         strvec_to_and_list(coreqs, &coreqstr),
                         strvec_to_or_list(conoreqs, &conoreqstr));
          } else {
            cat_snprintf(buf, bufsz,
                         Q_(strs[1]), /* "Allows %s (with %s)." */
                         subjstr,
                         strvec_to_and_list(coreqs, &coreqstr));
          }
        } else {
          if (0 < strvec_size(conoreqs)) {
            cat_snprintf(buf, bufsz,
                         Q_(strs[2]), /* "Allows %s (absent %s)." */
                         subjstr,
                         strvec_to_and_list(conoreqs, &conoreqstr));
          } else {
            cat_snprintf(buf, bufsz,
                         Q_(strs[3]), /* "Allows %s." */
                         subjstr);
          }
        }
      } else {
        /* psource can, on its own, prevent the subject. */
        cat_snprintf(buf, bufsz,
                     Q_(strs[4]), /* "Prevents %s." */
                     subjstr);
      }
      cat_snprintf(buf, bufsz, "\n");
    }
  } requirement_vector_iterate_end;

  strvec_destroy(coreqs);
  strvec_destroy(conoreqs);
  astr_free(&coreqstr);
  astr_free(&conoreqstr);
}

/****************************************************************************
  Generate text for what this requirement source allows.  Something like

    "Allows Communism (with University).\n"
    "Allows Mfg. Plant (with Factory).\n"
    "Allows Library (absent Fundamentalism).\n"
    "Prevents Harbor.\n"

  This should be called to generate helptext for every possible source
  type.  Note this doesn't handle effects but rather requirements to
  create/maintain things (currently only building/government reqs).

  NB: This function overwrites any existing buffer contents by writing the
  generated text to the start of the given 'buf' pointer (i.e. it does
  NOT append like cat_snprintf).
****************************************************************************/
static void insert_allows(struct universal *psource,
                          char *buf, size_t bufsz)
{
  buf[0] = '\0';

  governments_iterate(pgov) {
    static const char *const govstrs[] = {
      /* TRANS: First %s is a government name. */
      N_("?gov:* Allows %s (with %s but no %s)."),
      /* TRANS: First %s is a government name. */
      N_("?gov:* Allows %s (with %s)."),
      /* TRANS: First %s is a government name. */
      N_("?gov:* Allows %s (absent %s)."),
      /* TRANS: %s is a government name. */
      N_("?gov:* Allows %s."),
      /* TRANS: %s is a government name. */
      N_("?gov:* Prevents %s.")
    };
    insert_allows_single(psource, &pgov->reqs,
                         government_name_translation(pgov), govstrs,
                         buf, bufsz);
  } governments_iterate_end;

  improvement_iterate(pimprove) {
    static const char *const imprstrs[] = {
      /* TRANS: First %s is a building name. */
      N_("?improvement:* Allows %s (with %s but no %s)."),
      /* TRANS: First %s is a building name. */
      N_("?improvement:* Allows %s (with %s)."),
      /* TRANS: First %s is a building name. */
      N_("?improvement:* Allows %s (absent %s)."),
      /* TRANS: %s is a building name. */
      N_("?improvement:* Allows %s."),
      /* TRANS: %s is a building name. */
      N_("?improvement:* Prevents %s.")
    };
    insert_allows_single(psource, &pimprove->reqs,
                         improvement_name_translation(pimprove), imprstrs,
                         buf, bufsz);
  } improvement_iterate_end;
}

/****************************************************************
  Allocate and initialize new help item
*****************************************************************/
static struct help_item *new_help_item(int type)
{
  struct help_item *pitem;
  
  pitem = fc_malloc(sizeof(struct help_item));
  pitem->topic = NULL;
  pitem->text = NULL;
  pitem->type = type;
  return pitem;
}

/****************************************************************
 for help_list_sort(); sort by topic via compare_strings()
 (sort topics with more leading spaces after those with fewer)
*****************************************************************/
static int help_item_compar(const struct help_item *const *ppa,
                            const struct help_item *const *ppb)
{
  const struct help_item *ha, *hb;
  char *ta, *tb;
  ha = *ppa;
  hb = *ppb;
  for (ta = ha->topic, tb = hb->topic; *ta != '\0' && *tb != '\0'; ta++, tb++) {
    if (*ta != ' ') {
      if (*tb == ' ') return -1;
      break;
    } else if (*tb != ' ') {
      if (*ta == ' ') return 1;
      break;
    }
  }
  return compare_strings(ta, tb);
}

/****************************************************************
  pplayer may be NULL.
*****************************************************************/
void boot_help_texts(void)
{
  static bool booted = FALSE;

  struct section_file *sf;
  const char *filename;
  struct help_item *pitem;
  int i;
  struct section_list *sec;
  const char **paras;
  size_t npara;
  char long_buffer[64000]; /* HACK: this may be overrun. */

  check_help_nodes_init();

  /* need to do something like this or bad things happen */
  popdown_help_dialog();

  if (!booted) {
    log_verbose("Booting help texts");
  } else {
    /* free memory allocated last time booted */
    free_help_texts();
    log_verbose("Rebooting help texts");
  }

  filename = fileinfoname(get_data_dirs(), "helpdata.txt");
  if (!filename) {
    log_error("Did not read help texts");
    return;
  }
  /* after following call filename may be clobbered; use sf->filename instead */
  if (!(sf = secfile_load(filename, FALSE))) {
    /* this is now unlikely to happen */
    log_error("failed reading help-texts from '%s':\n%s", filename,
              secfile_error());
    return;
  }

  sec = secfile_sections_by_name_prefix(sf, "help_");

  if (NULL != sec) {
    section_list_iterate(sec, psection) {
      char help_text_buffer[MAX_LEN_PACKET];
      const char *sec_name = section_name(psection);
      const char *gen_str = secfile_lookup_str(sf, "%s.generate", sec_name);

      if (gen_str) {
        enum help_page_type current_type = HELP_ANY;
        int level = strspn(gen_str, " ");

        gen_str += level;

        for (i = 2; help_type_names[i]; i++) {
          if (strcmp(gen_str, help_type_names[i]) == 0) {
            current_type = i;
            break;
          }
        }
        if (current_type == HELP_ANY) {
          log_error("bad help-generate category \"%s\"", gen_str);
          continue;
        }

        if (!booted) {
          if (current_type == HELP_EXTRA) {
            size_t ncats;

            /* Avoid warnings about entries unused on this round,
             * when the entries in question are valid once help system has been booted */
            (void) secfile_lookup_str_vec(sf, &ncats,
                                          "%s.categories", sec_name);
          }
          continue; /* on initial boot data tables are empty */
        }

        {
          /* Note these should really fill in pitem->text from auto-gen
             data instead of doing it later on the fly, but I don't want
             to change that now.  --dwp
          */
          char name[2048];
          struct help_list *category_nodes = help_list_new();

          switch (current_type) {
          case HELP_UNIT:
            unit_type_iterate(punittype) {
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          utype_name_translation(punittype));
              pitem->topic = fc_strdup(name);
              pitem->text = fc_strdup("");
              help_list_append(category_nodes, pitem);
            } unit_type_iterate_end;
            break;
          case HELP_TECH:
            advance_index_iterate(A_FIRST, advi) {
              if (valid_advance_by_number(advi)) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            advance_name_translation(advance_by_number(advi)));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } advance_index_iterate_end;
            break;
          case HELP_TERRAIN:
            terrain_type_iterate(pterrain) {
              if (0 != strlen(terrain_rule_name(pterrain))) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            terrain_name_translation(pterrain));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } terrain_type_iterate_end;
            break;
          case HELP_EXTRA:
            {
              const char **cats;
              size_t ncats;
              cats = secfile_lookup_str_vec(sf, &ncats,
                                            "%s.categories", sec_name);
              extra_type_iterate(pextra) {
                /* If categories not specified, don't filter */
                if (cats) {
                  bool include = FALSE;
                  const char *cat = extra_category_name(pextra->category);
                  int ci;

                  for (ci = 0; ci < ncats; ci++) {
                    if (fc_strcasecmp(cats[ci], cat) == 0) {
                      include = TRUE;
                      break;
                    }
                  }
                  if (!include) {
                    continue;
                  }
                }
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            extra_name_translation(pextra));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              } extra_type_iterate_end;
              FC_FREE(cats);
            }
            break;
          case HELP_GOODS:
            goods_type_iterate(pgood) {
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          goods_name_translation(pgood));
              pitem->topic = fc_strdup(name);
              pitem->text = fc_strdup("");
              help_list_append(category_nodes, pitem);
            } goods_type_iterate_end;
            break;
          case HELP_SPECIALIST:
            specialist_type_iterate(sp) {
              struct specialist *pspec = specialist_by_number(sp);

              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          specialist_plural_translation(pspec));
              pitem->topic = fc_strdup(name);
              pitem->text = fc_strdup("");
              help_list_append(category_nodes, pitem);
            } specialist_type_iterate_end;
            break;
          case HELP_GOVERNMENT:
            governments_iterate(gov) {
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          government_name_translation(gov));
              pitem->topic = fc_strdup(name);
              pitem->text = fc_strdup("");
              help_list_append(category_nodes, pitem);
            } governments_iterate_end;
            break;
          case HELP_IMPROVEMENT:
            improvement_iterate(pimprove) {
              if (valid_improvement(pimprove) && !is_great_wonder(pimprove)) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            improvement_name_translation(pimprove));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } improvement_iterate_end;
            break;
          case HELP_WONDER:
            improvement_iterate(pimprove) {
              if (valid_improvement(pimprove) && is_great_wonder(pimprove)) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            improvement_name_translation(pimprove));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } improvement_iterate_end;
            break;
          case HELP_RULESET:
            {
              int desc_len;
              int len;

              pitem = new_help_item(HELP_RULESET);
              /*           pitem->topic = fc_strdup(_(game.control.name)); */
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          Q_(HELP_RULESET_ITEM));
              pitem->topic = fc_strdup(name);
              if (game.ruleset_description != NULL) {
                desc_len = strlen("\n\n") + strlen(game.ruleset_description);
              } else {
                desc_len = 0;
              }
              if (game.ruleset_summary != NULL) {
                if (game.control.version[0] != '\0') {
                  len = strlen(_(game.control.name))
                    + strlen(" ")
                    + strlen(game.control.version)
                    + strlen("\n\n")
                    + strlen(_(game.ruleset_summary))
                    + 1;

                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(game.control.name), game.control.version,
                              _(game.ruleset_summary));
                } else {
                  len = strlen(_(game.control.name))
                    + strlen("\n\n")
                    + strlen(_(game.ruleset_summary))
                    + 1;

                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(game.control.name), _(game.ruleset_summary));
                }
              } else {
                const char *nodesc = _("Current ruleset contains no summary.");

                if (game.control.version[0] != '\0') {
                  len = strlen(_(game.control.name))
                    + strlen(" ")
                    + strlen(game.control.version)
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;

                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(game.control.name), game.control.version,
                              nodesc);
                } else {
                  len = strlen(_(game.control.name))
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;

                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(game.control.name),
                              nodesc);
                }
              }
              if (game.ruleset_description != NULL) {
                fc_strlcat(pitem->text, "\n\n", len + desc_len);
                fc_strlcat(pitem->text, game.ruleset_description, len + desc_len);
              }
              help_list_append(help_nodes, pitem);
            }
            break;
          case HELP_TILESET:
            {
              int desc_len;
              int len;
              const char *ts_name = tileset_name_get(tileset);
              const char *version = tileset_version(tileset);
              const char *summary = tileset_summary(tileset);
              const char *description = tileset_description(tileset);

              pitem = new_help_item(HELP_TILESET);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          Q_(HELP_TILESET_ITEM));
              pitem->topic = fc_strdup(name);
              if (description != NULL) {
                desc_len = strlen("\n\n") + strlen(description);
              } else {
                desc_len = 0;
              }
              if (summary != NULL) {
                if (version[0] != '\0') {
                  len = strlen(_(ts_name))
                    + strlen(" ")
                    + strlen(version)
                    + strlen("\n\n")
                    + strlen(_(summary))
                    + 1;

                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(ts_name), version, _(summary));
                } else {
                  len = strlen(_(ts_name))
                    + strlen("\n\n")
                    + strlen(_(summary))
                    + 1;

                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(ts_name), _(summary));
                }
              } else {
                const char *nodesc = _("Current tileset contains no summary.");

                if (version[0] != '\0') {
                  len = strlen(_(ts_name))
                    + strlen(" ")
                    + strlen(version)
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;

                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(ts_name), version,
                              nodesc);
                } else {
                  len = strlen(_(ts_name))
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;

                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(ts_name),
                              nodesc);
                }
              }
              if (description != NULL) {
                fc_strlcat(pitem->text, "\n\n", len + desc_len);
                fc_strlcat(pitem->text, description, len + desc_len);
              }
              help_list_append(help_nodes, pitem);
            }
            break;
          case HELP_NATIONS:
            nations_iterate(pnation) {
              if (client_state() < C_S_RUNNING
                  || show_help_for_nation(pnation)) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            nation_plural_translation(pnation));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } nations_iterate_end;
            break;
          case HELP_MULTIPLIER:
            multipliers_iterate(pmul) {
              help_text_buffer[0] = '\0';
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          name_translation_get(&pmul->name));
              pitem->topic = fc_strdup(name);
              if (pmul->helptext) {
                const char *sep = "";
                strvec_iterate(pmul->helptext, text) {
                  cat_snprintf(help_text_buffer, sizeof(help_text_buffer),
                               "%s%s", sep, text);
                  sep = "\n\n";
                } strvec_iterate_end;
              }
              pitem->text = fc_strdup(help_text_buffer);
              help_list_append(help_nodes, pitem);
            } multipliers_iterate_end;
            break;
          default:
            log_error("Bad current_type: %d.", current_type);
            break;
          }
          help_list_sort(category_nodes, help_item_compar);
          help_list_iterate(category_nodes, ptmp) {
            help_list_append(help_nodes, ptmp);
          } help_list_iterate_end;
          help_list_destroy(category_nodes);
          continue;
        }
      }
      
      /* It wasn't a "generate" node: */
      
      pitem = new_help_item(HELP_TEXT);
      pitem->topic = fc_strdup(Q_(secfile_lookup_str(sf, "%s.name",
                                                     sec_name)));

      paras = secfile_lookup_str_vec(sf, &npara, "%s.text", sec_name);

      long_buffer[0] = '\0';
      for (i = 0; i < npara; i++) {
        bool inserted;
        const char *para = paras[i];

        if (strncmp(para, "$", 1) == 0) {
          inserted =
            insert_generated_text(long_buffer, sizeof(long_buffer), para+1);
        } else {
          sz_strlcat(long_buffer, _(para));
          inserted = TRUE;
        }
        if (inserted && i != npara - 1) {
          sz_strlcat(long_buffer, "\n\n");
        }
      }
      free(paras);
      paras = NULL;
      pitem->text=fc_strdup(long_buffer);
      help_list_append(help_nodes, pitem);
    } section_list_iterate_end;

    section_list_destroy(sec);
  }

  secfile_check_unused(sf);
  secfile_destroy(sf);
  booted = TRUE;
  log_verbose("Booted help texts ok");
}

/****************************************************************
  The following few functions are essentially wrappers for the
  help_nodes help_list.  This allows us to avoid exporting the
  help_list, and instead only access it through a controlled
  interface.
*****************************************************************/

/****************************************************************
  Number of help items.
*****************************************************************/
int num_help_items(void)
{
  check_help_nodes_init();
  return help_list_size(help_nodes);
}

/****************************************************************
  Return pointer to given help_item.
  Returns NULL for 1 past end.
  Returns NULL and prints error message for other out-of bounds.
*****************************************************************/
const struct help_item *get_help_item(int pos)
{
  int size;
  
  check_help_nodes_init();
  size = help_list_size(help_nodes);
  if (pos < 0 || pos > size) {
    log_error("Bad index %d to get_help_item (size %d)", pos, size);
    return NULL;
  }
  if (pos == size) {
    return NULL;
  }
  return help_list_get(help_nodes, pos);
}

/****************************************************************
  Find help item by name and type.
  Returns help item, and sets (*pos) to position in list.
  If no item, returns pointer to static internal item with
  some faked data, and sets (*pos) to -1.
*****************************************************************/
const struct help_item*
get_help_item_spec(const char *name, enum help_page_type htype, int *pos)
{
  int idx;
  const struct help_item *pitem = NULL;
  static struct help_item vitem; /* v = virtual */
  static char vtopic[128];
  static char vtext[256];

  check_help_nodes_init();
  idx = 0;
  help_list_iterate(help_nodes, ptmp) {
    char *p = ptmp->topic;

    while (*p == ' ') {
      p++;
    }
    if (strcmp(name, p) == 0 && (htype == HELP_ANY || htype == ptmp->type)) {
      pitem = ptmp;
      break;
    }
    idx++;
  }
  help_list_iterate_end;
  
  if (!pitem) {
    idx = -1;
    vitem.topic = vtopic;
    sz_strlcpy(vtopic, name);
    vitem.text = vtext;
    if (htype == HELP_ANY || htype == HELP_TEXT) {
      fc_snprintf(vtext, sizeof(vtext),
                  _("Sorry, no help topic for %s.\n"), vitem.topic);
      vitem.type = HELP_TEXT;
    } else {
      fc_snprintf(vtext, sizeof(vtext),
                  _("Sorry, no help topic for %s.\n"
                    "This page was auto-generated.\n\n"),
                  vitem.topic);
      vitem.type = htype;
    }
    pitem = &vitem;
  }
  *pos = idx;
  return pitem;
}

/****************************************************************
  Start iterating through help items;
  that is, reset iterator to start position.
  (Could iterate using get_help_item(), but that would be
  less efficient due to scanning to find pos.)
*****************************************************************/
void help_iter_start(void)
{
  check_help_nodes_init();
  help_nodes_iterator = help_list_head(help_nodes);
}

/****************************************************************
  Returns next help item; after help_iter_start(), this is
  the first item.  At end, returns NULL.
*****************************************************************/
const struct help_item *help_iter_next(void)
{
  const struct help_item *pitem;
  
  check_help_nodes_init();
  pitem = help_list_link_data(help_nodes_iterator);
  if (pitem) {
    help_nodes_iterator = help_list_link_next(help_nodes_iterator);
  }

  return pitem;
}


/****************************************************************
  FIXME:
  Also, in principle these could be auto-generated once, inserted
  into pitem->text, and then don't need to keep re-generating them.
  Only thing to be careful of would be changeable data, but don't
  have that here (for ruleset change or spacerace change must
  re-boot helptexts anyway).  Eg, genuinely dynamic information
  which could be useful would be if help system said which wonders
  have been built (or are being built and by who/where?)
*****************************************************************/

/**************************************************************************
  Write dynamic text for buildings (including wonders).  This includes
  the ruleset helptext as well as any automatically generated text.

  pplayer may be NULL.
  user_text, if non-NULL, will be appended to the text.
**************************************************************************/
char *helptext_building(char *buf, size_t bufsz, struct player *pplayer,
                        const char *user_text, struct impr_type *pimprove)
{
  bool reqs = FALSE;
  struct universal source = {
    .kind = VUT_IMPROVEMENT,
    .value = {.building = pimprove}
  };

  fc_assert_ret_val(NULL != buf && 0 < bufsz, NULL);
  buf[0] = '\0';

  if (NULL == pimprove) {
    return buf;
  }

  if (NULL != pimprove->helptext) {
    strvec_iterate(pimprove->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }

  /* Add requirement text for improvement itself */
  requirement_vector_iterate(&pimprove->reqs, preq) {
    if (req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT)) {
      reqs = TRUE;
    }
  } requirement_vector_iterate_end;
  if (reqs) {
    fc_strlcat(buf, "\n", bufsz);
  }

  requirement_vector_iterate(&pimprove->obsolete_by, pobs) {
    if (VUT_ADVANCE == pobs->source.kind && pobs->present) {
      cat_snprintf(buf, bufsz,
                   _("* The discovery of %s will make %s obsolete.\n"),
                   advance_name_translation(pobs->source.value.advance),
                   improvement_name_translation(pimprove));
    }
    if (VUT_IMPROVEMENT == pobs->source.kind && pobs->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: both %s are improvement names */
                   _("* The presence of %s in the city will make %s "
                     "obsolete.\n"),
                     improvement_name_translation(pobs->source.value.building),
                     improvement_name_translation(pimprove));
    }
  } requirement_vector_iterate_end;

  if (is_small_wonder(pimprove)) {
    cat_snprintf(buf, bufsz,
                 _("* A 'small wonder': at most one of your cities may "
                   "possess this improvement.\n"));
  }
  /* (Great wonders are in their own help section explaining their
   * uniqueness, so we don't mention it here.) */

  if (building_has_effect(pimprove, EFT_ENABLE_NUKE)
      && num_role_units(action_id_get_role(ACTION_NUKE)) > 0) {
    struct unit_type *u = get_role_unit(action_id_get_role(ACTION_NUKE), 0);

    cat_snprintf(buf, bufsz,
                 /* TRANS: 'Allows all players with knowledge of atomic
                  * power to build nuclear units.' */
                 _("* Allows all players with knowledge of %s "
                   "to build %s units.\n"),
                 advance_name_translation(u->require_advance),
                 utype_name_translation(u));
  }

  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf));

  unit_type_iterate(u) {
    if (u->need_improvement == pimprove) {
      if (A_NEVER != u->require_advance) {
        cat_snprintf(buf, bufsz, _("* Allows %s (with %s).\n"),
                     utype_name_translation(u),
                     advance_name_translation(u->require_advance));
      } else {
        cat_snprintf(buf, bufsz, _("* Allows %s.\n"),
                     utype_name_translation(u));
      }
    }
  } unit_type_iterate_end;

  {
    int i;

    for (i = 0; i < MAX_NUM_BUILDING_LIST; i++) {
      Impr_type_id n = game.rgame.global_init_buildings[i];
      if (n == B_LAST) {
        break;
      } else if (improvement_by_number(n) == pimprove) {
        cat_snprintf(buf, bufsz,
                     _("* All players start with this improvement in their "
                       "first city.\n"));
        break;
      }
    }
  }

  /* Assume no-one will set the same building in both global and nation
   * init_buildings... */
  nations_iterate(pnation) {
    int i;

    /* Avoid mentioning nations not in current set. */
    if (!show_help_for_nation(pnation)) {
      continue;
    }
    for (i = 0; i < MAX_NUM_BUILDING_LIST; i++) {
      Impr_type_id n = pnation->init_buildings[i];
      if (n == B_LAST) {
        break;
      } else if (improvement_by_number(n) == pimprove) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a nation plural */
                     _("* The %s start with this improvement in their "
                       "first city.\n"), nation_plural_translation(pnation));
        break;
      }
    }
  } nations_iterate_end;

  if (improvement_has_flag(pimprove, IF_SAVE_SMALL_WONDER)) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: don't translate 'savepalace' */
                 _("* If you lose the city containing this improvement, "
                   "it will be rebuilt for free in another of your cities "
                   "(if the 'savepalace' server setting is enabled).\n"));
  }

  if (user_text && user_text[0] != '\0') {
    cat_snprintf(buf, bufsz, "\n\n%s", user_text);
  }
  return buf;
}

/****************************************************************
  Is unit type ever able to build an extra
*****************************************************************/
static bool help_is_extra_buildable(struct extra_type *pextra,
                                    struct unit_type *ptype)
{
  if (!pextra->buildable) {
    return FALSE;
  }

  return are_reqs_active(NULL, NULL, NULL, NULL, NULL,
                         NULL, ptype, NULL, NULL, NULL, &pextra->reqs,
                         RPT_POSSIBLE);
}

/****************************************************************
  Is unit type ever able to clean out an extra
*****************************************************************/
static bool help_is_extra_cleanable(struct extra_type *pextra,
                                    struct unit_type *ptype)
{
  return are_reqs_active(NULL, NULL, NULL, NULL, NULL,
                         NULL, ptype, NULL, NULL, NULL, &pextra->rmreqs,
                         RPT_POSSIBLE);
}

/****************************************************************
  Append misc dynamic text for units.
  Transport capacity, unit flags, fuel.

  pplayer may be NULL.
*****************************************************************/
char *helptext_unit(char *buf, size_t bufsz, struct player *pplayer,
                    const char *user_text, struct unit_type *utype)
{
  bool has_vet_levels;
  int flagid;
  struct unit_class *pclass;
  int fuel;

  fc_assert_ret_val(NULL != buf && 0 < bufsz && NULL != user_text, NULL);

  if (!utype) {
    log_error("Unknown unit!");
    fc_strlcpy(buf, user_text, bufsz);
    return buf;
  }

  has_vet_levels = utype_veteran_levels(utype) > 1;

  buf[0] = '\0';

  pclass = utype_class(utype);
  cat_snprintf(buf, bufsz,
               _("* Belongs to %s unit class."),
               uclass_name_translation(pclass));
  if (NULL != pclass->helptext) {
    strvec_iterate(pclass->helptext, text) {
      cat_snprintf(buf, bufsz, "\n%s\n", _(text));
    } strvec_iterate_end;
  } else {
    CATLSTR(buf, bufsz, "\n");
  }
  if (uclass_has_flag(pclass, UCF_CAN_OCCUPY_CITY)
      && !utype_has_flag(utype, UTYF_CIVILIAN)) {
    CATLSTR(buf, bufsz, _("  * Can occupy empty enemy cities.\n"));
  }
  if (!uclass_has_flag(pclass, UCF_TERRAIN_SPEED)) {
    CATLSTR(buf, bufsz, _("  * Speed is not affected by terrain.\n"));
  }
  if (!uclass_has_flag(pclass, UCF_TERRAIN_DEFENSE)) {
    CATLSTR(buf, bufsz, _("  * Does not get defense bonuses from terrain.\n"));
  }
  if (!uclass_has_flag(pclass, UCF_ZOC)) {
    CATLSTR(buf, bufsz, _("  * Not subject to zones of control.\n"));
  } else if (!utype_has_flag(utype, UTYF_IGZOC)) {
    CATLSTR(buf, bufsz, _("  * Subject to zones of control.\n"));
  }
  if (uclass_has_flag(pclass, UCF_DAMAGE_SLOWS)) {
    CATLSTR(buf, bufsz, _("  * Slowed down while damaged.\n"));
  }
  if (uclass_has_flag(pclass, UCF_MISSILE)) {
    CATLSTR(buf, bufsz, _("  * Gets used up in making an attack.\n"));
  }
  if (uclass_has_flag(pclass, UCF_CAN_FORTIFY)
      && !utype_has_flag(utype, UTYF_CANT_FORTIFY)) {
    if (utype->defense_strength > 0) {
      CATLSTR(buf, bufsz,
              /* xgettext:no-c-format */
              _("  * Gets a 50% defensive bonus while in cities.\n"));
      CATLSTR(buf, bufsz,
              /* xgettext:no-c-format */
              _("  * May fortify, granting a 50% defensive bonus when not in "
                "a city.\n"));
    } else {
      CATLSTR(buf, bufsz,
              _("  * May fortify to stay put.\n"));
    }
  }
  if (uclass_has_flag(pclass, UCF_UNREACHABLE)) {
    CATLSTR(buf, bufsz,
            _("  * Is unreachable. Most units cannot attack this one.\n"));
  }
  if (uclass_has_flag(pclass, UCF_CAN_PILLAGE)) {
    CATLSTR(buf, bufsz,
            _("  * Can pillage tile improvements.\n"));
  }
  if (uclass_has_flag(pclass, UCF_DOESNT_OCCUPY_TILE)
      && !utype_has_flag(utype, UTYF_CIVILIAN)) {
    CATLSTR(buf, bufsz,
            _("  * Doesn't prevent enemy cities from working the tile it's on.\n"));
  }
  if (can_attack_non_native(utype)) {
    CATLSTR(buf, bufsz,
            _("  * Can attack units on non-native tiles.\n"));
  }
  for (flagid = UCF_USER_FLAG_1; flagid <= UCF_LAST_USER_FLAG; flagid++) {
    if (uclass_has_flag(pclass, flagid)) {
      const char *helptxt = unit_class_flag_helptxt(flagid);

      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, Q_("?bullet:  * "));
        CATLSTR(buf, bufsz, _(helptxt));
        CATLSTR(buf, bufsz, "\n");
      }
    }
  }

  /* The unit's combat bonuses. Won't mention that another unit type has a
   * combat bonus against this unit type. Doesn't handle complex cases like
   * when a unit type has multiple combat bonuses of the same kind. */
  combat_bonus_list_iterate(utype->bonuses, cbonus) {
    const char *against[utype_count()];
    int targets = 0;

    if (cbonus->quiet) {
      /* Handled in the help text of the ruleset. */
      continue;
    }

    /* Find the unit types of the bonus targets. */
    unit_type_iterate(utype2) {
      if (utype_has_flag(utype2, cbonus->flag)) {
        against[targets++] = utype_name_translation(utype2);
      }
    } unit_type_iterate_end;

    if (targets > 0) {
      struct astring list = ASTRING_INIT;

      switch (cbonus->type) {
      case CBONUS_DEFENSE_MULTIPLIER:
        cat_snprintf(buf, bufsz,
                     /* TRANS: multipied by ... or-list of unit types */
                     _("* %dx defense bonus if attacked by %s.\n"),
                     cbonus->value + 1,
                     astr_build_or_list(&list, against, targets));
        break;
      case CBONUS_DEFENSE_DIVIDER:
        cat_snprintf(buf, bufsz,
                     /* TRANS: defense divider ... or-list of unit types */
                     _("* reduces target's defense to 1 / %d when "
                       "attacking %s.\n"),
                     cbonus->value + 1,
                     astr_build_or_list(&list, against, targets));
        break;
      case CBONUS_FIREPOWER1:
        cat_snprintf(buf, bufsz,
                     /* TRANS: or-list of unit types */
                     _("* reduces target's fire power to 1 when "
                       "attacking %s.\n"),
                     astr_build_and_list(&list, against, targets));
        break;
      }

      astr_free(&list);
    }
  } combat_bonus_list_iterate_end;

  if (utype->need_improvement) {
    cat_snprintf(buf, bufsz,
                 _("* Can only be built if there is %s in the city.\n"),
                 improvement_name_translation(utype->need_improvement));
  }

  if (utype->need_government) {
    cat_snprintf(buf, bufsz,
                 _("* Can only be built with %s as government.\n"),
                 government_name_translation(utype->need_government));
  }

  if (utype_has_flag(utype, UTYF_CANESCAPE)) {
    CATLSTR(buf, bufsz, _("* Can escape once stack defender is lost.\n"));
  }
  if (utype_has_flag(utype, UTYF_CANKILLESCAPING)) {
    CATLSTR(buf, bufsz, _("* Can pursue escaping units and kill them.\n"));
  }

  if (utype_has_flag(utype, UTYF_NOBUILD)) {
    CATLSTR(buf, bufsz, _("* May not be built in cities.\n"));
  }
  if (utype_has_flag(utype, UTYF_BARBARIAN_ONLY)) {
    CATLSTR(buf, bufsz, _("* Only barbarians may build this.\n"));
  }
  if (utype_has_flag(utype, UTYF_NEWCITY_GAMES_ONLY)) {
    CATLSTR(buf, bufsz, _("* Can only be built in games where new cities "
                          "are allowed.\n"));
    if (game.scenario.prevent_new_cities) {
      CATLSTR(buf, bufsz, _("  - New cities are not allowed in the current "
                            "game.\n"));
    } else {
      CATLSTR(buf, bufsz, _("  - New cities are allowed in the current "
                            "game.\n"));
    }
  }
  nations_iterate(pnation) {
    int i, count = 0;

    /* Avoid mentioning nations not in current set. */
    if (!show_help_for_nation(pnation)) {
      continue;
    }
    for (i = 0; i < MAX_NUM_UNIT_LIST; i++) {
      if (!pnation->init_units[i]) {
        break;
      } else if (pnation->init_units[i] == utype) {
        count++;
      }
    }
    if (count > 0) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a nation plural */
                   PL_("* The %s start the game with %d of these units.\n",
                       "* The %s start the game with %d of these units.\n",
                       count),
                   nation_plural_translation(pnation), count);
    }
  } nations_iterate_end;
  {
    const char *types[utype_count()];
    int i = 0;
    unit_type_iterate(utype2) {
      if (utype2->converted_to == utype) {
        types[i++] = utype_name_translation(utype2);
      }
    } unit_type_iterate_end;
    if (i > 0) {
      struct astring list = ASTRING_INIT;
      astr_build_or_list(&list, types, i);
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a list of unit types separated by "or". */
                   _("* May be obtained by conversion of %s.\n"),
                   astr_str(&list));
      astr_free(&list);
    }
  }
  if (NULL != utype->converted_to) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: %s is a unit type. "MP" = movement points. */
                 PL_("* May be converted into %s (takes %d MP).\n",
                     "* May be converted into %s (takes %d MP).\n",
                     utype->convert_time),
                 utype_name_translation(utype->converted_to),
                 utype->convert_time);
  }
  if (utype_has_flag(utype, UTYF_NOHOME)) {
    CATLSTR(buf, bufsz, _("* Never has a home city.\n"));
  }
  if (utype_has_flag(utype, UTYF_GAMELOSS)) {
    CATLSTR(buf, bufsz, _("* Losing this unit will lose you the game!\n"));
  }
  if (utype_has_flag(utype, UTYF_UNIQUE)) {
    CATLSTR(buf, bufsz,
            _("* Each player may only have one of this type of unit.\n"));
  }
  for (flagid = UTYF_USER_FLAG_1 ; flagid <= UTYF_LAST_USER_FLAG; flagid++) {
    if (utype_has_flag(utype, flagid)) {
      const char *helptxt = unit_type_flag_helptxt(flagid);

      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, Q_("?bullet:* "));
        CATLSTR(buf, bufsz, _(helptxt));
        CATLSTR(buf, bufsz, "\n");
      }
    }
  }
  if (utype->pop_cost > 0) {
    cat_snprintf(buf, bufsz,
                 PL_("* Costs %d population to build.\n",
                     "* Costs %d population to build.\n", utype->pop_cost),
                 utype->pop_cost);
  }
  if (0 < utype->transport_capacity) {
    const char *classes[uclass_count()];
    int i = 0;
    struct astring list = ASTRING_INIT;

    unit_class_iterate(uclass) {
      if (can_unit_type_transport(utype, uclass)) {
        classes[i++] = uclass_name_translation(uclass);
      }
    } unit_class_iterate_end;
    astr_build_or_list(&list, classes, i);

    cat_snprintf(buf, bufsz,
                 /* TRANS: %s is a list of unit classes separated by "or". */
                 PL_("* Can carry and refuel %d %s unit.\n",
                     "* Can carry and refuel up to %d %s units.\n",
                     utype->transport_capacity),
                 utype->transport_capacity, astr_str(&list));
    astr_free(&list);
    if (uclass_has_flag(utype_class(utype), UCF_UNREACHABLE)) {
      /* Document restrictions on when units can load/unload */
      bool has_restricted_load = FALSE, has_unrestricted_load = FALSE,
           has_restricted_unload = FALSE, has_unrestricted_unload = FALSE;
      unit_type_iterate(pcargo) {
        if (can_unit_type_transport(utype, utype_class(pcargo))) {
          if (utype_can_freely_load(pcargo, utype)) {
            has_unrestricted_load = TRUE;
          } else {
            has_restricted_load = TRUE;
          }
          if (utype_can_freely_unload(pcargo, utype)) {
            has_unrestricted_unload = TRUE;
          } else {
            has_restricted_unload = TRUE;
          }
        }
      } unit_type_iterate_end;
      if (has_restricted_load) {
        if (has_unrestricted_load) {
          /* At least one type of cargo can load onto us freely.
           * The specific exceptions will be documented in cargo help. */
          CATLSTR(buf, bufsz,
                  _("  * Some cargo cannot be loaded except in a city or a "
                    "base native to this transport.\n"));
        } else {
          /* No exceptions */
          CATLSTR(buf, bufsz,
                  _("  * Cargo cannot be loaded except in a city or a "
                    "base native to this transport.\n"));
        }
      } /* else, no restricted cargo exists; keep quiet */
      if (has_restricted_unload) {
        if (has_unrestricted_unload) {
          /* At least one type of cargo can unload from us freely. */
          CATLSTR(buf, bufsz,
                  _("  * Some cargo cannot be unloaded except in a city or a "
                    "base native to this transport.\n"));
        } else {
          /* No exceptions */
          CATLSTR(buf, bufsz,
                  _("  * Cargo cannot be unloaded except in a city or a "
                    "base native to this transport.\n"));
        }
      } /* else, no restricted cargo exists; keep quiet */
    }
  }
  if (utype_has_flag(utype, UTYF_COAST_STRICT)) {
    CATLSTR(buf, bufsz, _("* Must stay next to coast.\n"));
  }
  {
    /* Document exceptions to embark/disembark restrictions that we
     * have as cargo. */
    bv_unit_classes embarks, disembarks;
    BV_CLR_ALL(embarks);
    BV_CLR_ALL(disembarks);
    /* Determine which of our transport classes have restrictions in the first
     * place (that is, contain at least one transport which carries at least
     * one type of cargo which is restricted).
     * We'll suppress output for classes not in this set, since this cargo
     * type is not behaving exceptionally in such cases. */
    unit_type_iterate(utrans) {
      const Unit_Class_id trans_class = uclass_index(utype_class(utrans));
      /* Don't waste time repeating checks on classes we've already checked,
       * or weren't under consideration in the first place */
      if (!BV_ISSET(embarks, trans_class)
          && BV_ISSET(utype->embarks, trans_class)) {
        unit_type_iterate(other_cargo) {
          if (can_unit_type_transport(utrans, utype_class(other_cargo))
              && !utype_can_freely_load(other_cargo, utrans)) {
            /* At least one load restriction in transport class, which
             * we aren't subject to */
            BV_SET(embarks, trans_class);
          }
        } unit_type_iterate_end; /* cargo */
      }
      if (!BV_ISSET(disembarks, trans_class)
          && BV_ISSET(utype->disembarks, trans_class)) {
        unit_type_iterate(other_cargo) {
          if (can_unit_type_transport(utrans, utype_class(other_cargo))
              && !utype_can_freely_unload(other_cargo, utrans)) {
            /* At least one load restriction in transport class, which
             * we aren't subject to */
            BV_SET(disembarks, trans_class);
          }
        } unit_type_iterate_end; /* cargo */
      }
    } unit_class_iterate_end; /* transports */

    if (BV_ISSET_ANY(embarks)) {
      /* Build list of embark exceptions */
      const char *eclasses[uclass_count()];
      int i = 0;
      struct astring elist = ASTRING_INIT;

      unit_class_iterate(uclass) {
        if (BV_ISSET(embarks, uclass_index(uclass))) {
          eclasses[i++] = uclass_name_translation(uclass);
        }
      } unit_class_iterate_end;
      astr_build_or_list(&elist, eclasses, i);
      if (BV_ARE_EQUAL(embarks, disembarks)) {
        /* A common case: the list of disembark exceptions is identical */
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of unit classes separated
                      * by "or". */
                     _("* May load onto and unload from %s transports even "
                       "when underway.\n"),
                     astr_str(&elist));
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of unit classes separated
                      * by "or". */
                     _("* May load onto %s transports even when underway.\n"),
                     astr_str(&elist));
      }
      astr_free(&elist);
    }
    if (BV_ISSET_ANY(disembarks) && !BV_ARE_EQUAL(embarks, disembarks)) {
      /* Build list of disembark exceptions (if different from embarking) */
      const char *dclasses[uclass_count()];
      int i = 0;
      struct astring dlist = ASTRING_INIT;

      unit_class_iterate(uclass) {
        if (BV_ISSET(disembarks, uclass_index(uclass))) {
          dclasses[i++] = uclass_name_translation(uclass);
        }
      } unit_class_iterate_end;
      astr_build_or_list(&dlist, dclasses, i);
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a list of unit classes separated
                    * by "or". */
                   _("* May unload from %s transports even when underway.\n"),
                   astr_str(&dlist));
      astr_free(&dlist);
    }
  }
  if (utype_has_flag(utype, UTYF_SETTLERS)) {
    struct universal for_utype = { .kind = VUT_UTYPE, .value = { .utype = utype }};
    struct astring extras_and = ASTRING_INIT;
    struct strvec *extras_vec = strvec_new();

    /* Roads, rail, mines, irrigation. */
    extra_type_by_cause_iterate(EC_ROAD, pextra) {
      if (help_is_extra_buildable(pextra, utype)) {
        strvec_append(extras_vec, extra_name_translation(pextra));
      }
    } extra_type_by_cause_iterate_end;
    if (strvec_size(extras_vec) > 0) {
      strvec_to_and_list(extras_vec, &extras_and);
      /* TRANS: %s is list of extra types separated by ',' and 'and' */
      cat_snprintf(buf, bufsz, _("* Can build %s on tiles.\n"),
                   astr_str(&extras_and));
      strvec_clear(extras_vec);
    }

    if (effect_cumulative_max(EFT_MINING_POSSIBLE, &for_utype) > 0) {
      extra_type_by_cause_iterate(EC_MINE, pextra) {
        if (help_is_extra_buildable(pextra, utype)) {
          strvec_append(extras_vec, extra_name_translation(pextra));
        }
      } extra_type_by_cause_iterate_end;

      if (strvec_size(extras_vec) > 0) {
        strvec_to_and_list(extras_vec, &extras_and);
        cat_snprintf(buf, bufsz, _("* Can build %s on tiles.\n"),
                     astr_str(&extras_and));
        strvec_clear(extras_vec);
      }
    }
    if (effect_cumulative_max(EFT_MINING_TF_POSSIBLE, &for_utype) > 0) {
      CATLSTR(buf, bufsz, _("* Can convert terrain to another type by "
                            "mining.\n"));
    }

    if (effect_cumulative_max(EFT_IRRIG_POSSIBLE, &for_utype) > 0) {
      extra_type_by_cause_iterate(EC_IRRIGATION, pextra) {
        if (help_is_extra_buildable(pextra, utype)) {
          strvec_append(extras_vec, extra_name_translation(pextra));
        }
      } extra_type_by_cause_iterate_end;

      if (strvec_size(extras_vec) > 0) {
        strvec_to_and_list(extras_vec, &extras_and);
        cat_snprintf(buf, bufsz, _("* Can build %s on tiles.\n"),
                     astr_str(&extras_and));
        strvec_clear(extras_vec);
      }
    }
    if (effect_cumulative_max(EFT_IRRIG_TF_POSSIBLE, &for_utype) > 0) {
      CATLSTR(buf, bufsz, _("* Can convert terrain to another type by "
                            "irrigation.\n"));
    }
    if (effect_cumulative_max(EFT_TRANSFORM_POSSIBLE, &for_utype) > 0) {
      CATLSTR(buf, bufsz, _("* Can transform terrain to another type.\n"));
    }

    extra_type_by_cause_iterate(EC_BASE, pextra) {
      if (help_is_extra_buildable(pextra, utype)) {
        strvec_append(extras_vec, extra_name_translation(pextra));
      }
    } extra_type_by_cause_iterate_end;

    if (strvec_size(extras_vec) > 0) {
      strvec_to_and_list(extras_vec, &extras_and);
      cat_snprintf(buf, bufsz, _("* Can build %s on tiles.\n"),
                   astr_str(&extras_and));
      strvec_clear(extras_vec);
    }

    /* Pollution, fallout. */
    extra_type_by_rmcause_iterate(ERM_CLEANPOLLUTION, pextra) {
      if (help_is_extra_cleanable(pextra, utype)) {
        strvec_append(extras_vec, extra_name_translation(pextra));
     }
    } extra_type_by_rmcause_iterate_end;

    if (strvec_size(extras_vec) > 0) {
      strvec_to_and_list(extras_vec, &extras_and);
      /* TRANS: list of extras separated by "and" */
      cat_snprintf(buf, bufsz, _("* Can clean %s from tiles.\n"),
                   astr_str(&extras_and));
      strvec_clear(extras_vec);
    }
    
    extra_type_by_rmcause_iterate(ERM_CLEANFALLOUT, pextra) {
      if (help_is_extra_cleanable(pextra, utype)) {
        strvec_append(extras_vec, extra_name_translation(pextra));
      }
    } extra_type_by_rmcause_iterate_end;

    if (strvec_size(extras_vec) > 0) {
      strvec_to_and_list(extras_vec, &extras_and);
      /* TRANS: list of extras separated by "and" */
      cat_snprintf(buf, bufsz, _("* Can clean %s from tiles.\n"),
                   astr_str(&extras_and));
      strvec_clear(extras_vec);
    }

    strvec_destroy(extras_vec);
  }

  if (utype_has_flag(utype, UTYF_SPY)) {
    CATLSTR(buf, bufsz, _("* Performs better diplomatic actions.\n"));
  }
  if (utype_has_flag(utype, UTYF_DIPLOMAT)
      || utype_has_flag(utype, UTYF_SUPERSPY)) {
    CATLSTR(buf, bufsz, _("* Defends cities against diplomatic actions.\n"));
  }
  if (utype_has_flag(utype, UTYF_SUPERSPY)) {
    CATLSTR(buf, bufsz, _("* Will never lose a diplomat-versus-diplomat fight.\n"));
  }
  if (utype_has_flag(utype, UTYF_SPY)
      && utype_has_flag(utype, UTYF_SUPERSPY)) {
    CATLSTR(buf, bufsz, _("* Will always survive a spy mission.\n"));
  }
  if (utype_has_flag(utype, UTYF_PARTIAL_INVIS)) {
    CATLSTR(buf, bufsz,
            _("* Is invisible except when next to an enemy unit or city.\n"));
  }
  if (utype_has_flag(utype, UTYF_ONLY_NATIVE_ATTACK)) {
    CATLSTR(buf, bufsz,
            _("* Can only attack units on native tiles.\n"));
  }
  if (game.info.slow_invasions
      && utype_has_flag(utype, UTYF_BEACH_LANDER)) {
    /* BeachLander only matters when slow_invasions are enabled. */
    CATLSTR(buf, bufsz,
            _("* Won't lose all movement when moving from non-native "
              "terrain to native terrain.\n"));
  }
  if (!uclass_has_flag(utype_class(utype), UCF_MISSILE)
      && utype_has_flag(utype, UTYF_ONEATTACK)) {
    CATLSTR(buf, bufsz,
            _("* Making an attack ends this unit's turn.\n"));
  }
  if (utype_has_flag(utype, UTYF_CITYBUSTER)) {
    CATLSTR(buf, bufsz,
            _("* Gets double firepower when attacking cities.\n"));
  }
  if (utype_has_flag(utype, UTYF_IGTER)) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: "MP" = movement points. %s may have a 
                  * fractional part. */
                 _("* Ignores terrain effects (moving costs at most %s MP "
                   "per tile).\n"),
                 move_points_text(terrain_control.igter_cost, TRUE));
  }
  if (utype_has_flag(utype, UTYF_NOZOC)) {
    CATLSTR(buf, bufsz, _("* Never imposes a zone of control.\n"));
  } else {
    CATLSTR(buf, bufsz, _("* May impose a zone of control on its adjacent "
                          "tiles.\n"));
  }
  if (utype_has_flag(utype, UTYF_IGZOC)) {
    CATLSTR(buf, bufsz, _("* Not subject to zones of control imposed "
                          "by other units.\n"));
  }
  if (utype_has_flag(utype, UTYF_CIVILIAN)) {
    CATLSTR(buf, bufsz,
            _("* A non-military unit:\n"));
    CATLSTR(buf, bufsz,
            _("  * Cannot attack.\n"));
    CATLSTR(buf, bufsz,
            _("  * Doesn't impose martial law.\n"));
    CATLSTR(buf, bufsz,
            _("  * Can enter foreign territory regardless of peace treaty.\n"));
    CATLSTR(buf, bufsz,
            _("  * Doesn't prevent enemy cities from working the tile it's on.\n"));
  }
  if (utype_has_flag(utype, UTYF_FIELDUNIT)) {
    CATLSTR(buf, bufsz,
            _("* A field unit: one unhappiness applies even when non-aggressive.\n"));
  }
  if (utype_has_flag(utype, UTYF_SHIELD2GOLD)) {
    /* FIXME: the conversion shield => gold is activated if
     *        EFT_SHIELD2GOLD_FACTOR is not equal null; how to determine
     *        possible sources? */
    CATLSTR(buf, bufsz,
            _("* Under certain conditions the shield upkeep of this unit can "
              "be converted to gold upkeep.\n"));
  }

  unit_class_iterate(target) {
    if (uclass_has_flag(target, UCF_UNREACHABLE)
        && BV_ISSET(utype->targets, uclass_index(target))) {
      cat_snprintf(buf, bufsz,
                   _("* Can attack against %s units, which are usually not "
                     "reachable.\n"),
                   uclass_name_translation(target));
    }
  } unit_class_iterate_end;

  fuel = utype_fuel(utype);
  if (fuel > 0) {
    const char *types[utype_count()];
    int i = 0;

    unit_type_iterate(transport) {
      if (can_unit_type_transport(transport, utype_class(utype))) {
        types[i++] = utype_name_translation(transport);
      }
    } unit_type_iterate_end;

    if (0 == i) {
      if (utype_has_flag(utype, UTYF_COAST)) {
        if (fuel == 1) {
          cat_snprintf(buf, bufsz,
                       _("* Unit has to end each turn next to coast or"
                         " in a city or a base.\n"));
        } else {
          cat_snprintf(buf, bufsz,
                       /* Pluralization for the benefit of languages with
                        * duals etc */
                       /* TRANS: Never called for 'turns = 1' case */
                       PL_("* Unit has to be next to coast, in a city or a base"
                           " after %d turn.\n",
                           "* Unit has to be next to coast, in a city or a base"
                           " after %d turns.\n",
                           fuel),
                     fuel);
        }
      } else {
        cat_snprintf(buf, bufsz,
                     PL_("* Unit has to be in a city or a base"
                         " after %d turn.\n",
                         "* Unit has to be in a city or a base"
                         " after %d turns.\n",
                         fuel),
                     fuel);
      }
    } else {
      struct astring list = ASTRING_INIT;

      if (utype_has_flag(utype, UTYF_COAST)) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of unit types separated by "or" */
                     PL_("* Unit has to be next to coast, in a city, a base, or on a %s"
                         " after %d turn.\n",
                         "* Unit has to be next to coast, in a city, a base, or on a %s"
                         " after %d turns.\n",
                         fuel),
                     astr_build_or_list(&list, types, i), fuel);
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of unit types separated by "or" */
                     PL_("* Unit has to be in a city, a base, or on a %s"
                         " after %d turn.\n",
                         "* Unit has to be in a city, a base, or on a %s"
                         " after %d turns.\n",
                         fuel),
                     astr_build_or_list(&list, types, i), fuel);
      }
      astr_free(&list);
    }
  }
  action_iterate(act) {
    struct action *paction = action_by_number(act);

    if (action_by_number(act)->quiet) {
      /* The ruleset documents this action it self. */
      continue;
    }

    if (utype_can_do_action(utype, act)) {
      const char *target_adjective;
      const char *blockers[MAX_NUM_ACTIONS];
      int i = 0;

      /* Generic action information. */
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is the action's ruleset defined ui name */
                   _("* Can do the action \'%s\'.\n"),
                   action_id_name_translation(act));

      switch (action_id_get_target_kind(act)) {
      case ATK_SELF:
        /* No target. */
        break;
      default:
        if (!can_utype_do_act_if_tgt_diplrel(utype, act,
                                             DRO_FOREIGN, TRUE)) {
          /* TRANS: describes the target of an action. */
          target_adjective = _("domestic ");
        } else if (!can_utype_do_act_if_tgt_diplrel(utype, act,
                                                    DRO_FOREIGN, FALSE)) {
          /* TRANS: describes the target of an action. */
          target_adjective = _("foreign ");
        } else {
          /* Both foreign and domestic targets are acceptable. */
          target_adjective = "";
        }

        cat_snprintf(buf, bufsz,
                     /* TRANS: The first %s may be an adjective (that
                      * includes a space). The next is the name of its
                      * target kind. */
                     _("  * is done to %s%s.\n"),
                     target_adjective,
                     _(action_target_kind_name(
                         action_id_get_target_kind(act))));
      }

      if (action_id_get_target_kind(act) != ATK_SELF) {
        /* Distance to target is relevant. */

        /* FIXME: move paratroopers_range to the action and remove this
         * variable once actions are generalized. */
        int relative_max = action_has_result(paction, ACTION_PARADROP) ?
              MIN(paction->max_distance, utype->paratroopers_range) :
              paction->max_distance;

        if (paction->min_distance == relative_max) {
          /* Only one distance to target is acceptable */

          if (paction->min_distance == 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: distance between an actor unit and its
                          * target when performing a specific action. */
                         _("  * target must be at the same tile.\n"));
          } else {
          cat_snprintf(buf, bufsz,
                       /* TRANS: distance between an actor unit and its
                        * target when performing a specific action. */
                       PL_("  * target must be exactly %d tile away.\n",
                           "  * target must be exactly %d tiles away.\n",
                           paction->min_distance),
                       paction->min_distance);
          }
        } else if (relative_max == ACTION_DISTANCE_UNLIMITED) {
          /* No max distance */

          if (paction->min_distance == 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: distance between an actor unit and its
                          * target when performing a specific action. */
                         _("  * target can be anywhere.\n"));
          } else {
          cat_snprintf(buf, bufsz,
                       /* TRANS: distance between an actor unit and its
                        * target when performing a specific action. */
                       PL_("  * target must be at least %d tile away.\n",
                           "  * target must be at least %d tiles away.\n",
                           paction->min_distance),
                       paction->min_distance);
          }
        } else if (paction->min_distance == 0) {
          /* No min distance */

          cat_snprintf(buf, bufsz,
                       /* TRANS: distance between an actor unit and its
                        * target when performing a specific action. */
                       PL_("  * target can be max %d tile away.\n",
                           "  * target can be max %d tiles away.\n",
                           relative_max),
                       relative_max);
        } else {
          /* Full range. */

          cat_snprintf(buf, bufsz,
                       /* TRANS: distance between an actor unit and its
                        * target when performing a specific action. */
                       PL_("  * target must be between %d and %d tile away.\n",
                           "  * target must be between %d and %d tiles away.\n",
                           relative_max),
                       paction->min_distance, relative_max);
        }
      }

      /* Custom action specific information. */
      switch (act) {
      case ACTION_HELP_WONDER:
        cat_snprintf(buf, bufsz,
                     /* TRANS: the %d is the number of shields the unit can
                      * contribute. */
                     _("  * adds %d production.\n"),
                     utype_build_shield_cost(utype));
        break;
      case ACTION_FOUND_CITY:
        if (game.scenario.prevent_new_cities) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: is talking about an action. */
                       _("  * is disabled in the current game.\n"));
        }
        cat_snprintf(buf, bufsz,
                     /* TRANS: the %d is initial population. */
                     PL_("  * initial population: %d.\n",
                         "  * initial population: %d.\n",
                         utype->city_size),
                     utype->city_size);
        break;
      case ACTION_JOIN_CITY:
        cat_snprintf(buf, bufsz,
                     /* TRANS: the %d is population. */
                     PL_("  * max target size: %d.\n",
                         "  * max target size: %d.\n",
                         game.info.add_to_size_limit - utype_pop_value(utype)),
                     game.info.add_to_size_limit - utype_pop_value(utype));
        cat_snprintf(buf, bufsz,
                     /* TRANS: the %d is the population added. */
                     PL_("  * adds %d population.\n",
                         "  * adds %d population.\n",
                         utype_pop_value(utype)),
                     utype_pop_value(utype));
        break;
      case ACTION_BOMBARD:
        cat_snprintf(buf, bufsz,
                     /* TRANS: %d is bombard rate. */
                     _("  * %d per turn.\n"),
                     utype->bombard_rate);
        cat_snprintf(buf, bufsz,
                     /* TRANS: talking about bombard */
                     _("  * These attacks will only damage (never kill)"
                       " defenders, but damage all"
                       " defenders on a tile, and have no risk for the"
                       " attacker.\n"));
        break;
      default:
        /* No action specific details. */
        break;
      }

      action_iterate(blocker) {
        if (!utype_can_do_action(utype, blocker)) {
          /* Can't block since never legal. */
          continue;
        }

        if (action_id_would_be_blocked_by(act, blocker)) {
          char *quoted = fc_malloc(MAX_LEN_NAME);

          fc_snprintf(quoted, MAX_LEN_NAME,
                      /* TRANS: %s is an action that can block another. */
                      _("\'%s\'"), action_id_name_translation(blocker));
          blockers[i] = quoted;

          i++;
        }
      } action_iterate_end;

      if (i > 0) {
        struct astring blist = ASTRING_INIT;

        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of actions separated by "or". */
                     _("  * can't be done if %s is legal.\n"),
                     astr_build_or_list(&blist, blockers, i));

        astr_free(&blist);
      }
    }
  } action_iterate_end;
  action_iterate(act) {
    bool vulnerable;

    if (action_by_number(act)->quiet) {
      /* The ruleset documents this action it self. */
      continue;
    }

    /* Not relevant */
    if (action_id_get_target_kind(act) != ATK_UNIT
        && action_id_get_target_kind(act) != ATK_UNITS
        && action_id_get_target_kind(act) != ATK_SELF) {
      continue;
    }

    /* All units are immune to this since its not enabled */
    if (action_enabler_list_size(action_enablers_for_action(act)) == 0) {
      continue;
    }

    /* Must be immune in all cases */
    vulnerable = FALSE;
    action_enabler_list_iterate(action_enablers_for_action(act), enabler) {
      if (requirement_fulfilled_by_unit_type(utype,
                                             &(enabler->target_reqs))) {
        vulnerable = TRUE;
        break;
      }
    } action_enabler_list_iterate_end;

    if (!vulnerable) {
      cat_snprintf(buf, bufsz,
                   _("* Doing the action \'%s\' to this unit"
                     " is impossible.\n"),
                   action_id_name_translation(act));
    }
  } action_iterate_end;
  if (!has_vet_levels) {
    /* Only mention this if the game generally does have veteran levels. */
    if (game.veteran->levels > 1) {
      CATLSTR(buf, bufsz, _("* Will never achieve veteran status.\n"));
    }
  } else {
    /* Not useful currently: */
#if 0
    /* Some units can never become veteran through combat in practice. */
    bool veteran_through_combat =
      !((!utype_can_do_action(utype, ACTION_ATTACK)
         || uclass_has_flag(utype_class(utype), UCF_MISSILE))
        && utype->defense_strength == 0);
#endif
    /* FIXME: if we knew the raise chances on the client, we could be
     * more specific here about whether veteran status can be acquired
     * through combat/missions/work. Should also take into account
     * UTYF_NO_VETERAN when writing this text. (Gna patch #4794) */
    CATLSTR(buf, bufsz, _("* May acquire veteran status.\n"));
    if (utype_veteran_has_power_bonus(utype)) {
      if ((!utype_can_do_action(utype, ACTION_NUKE)
           && utype_can_do_action(utype, ACTION_ATTACK))
          || utype->defense_strength > 0) {
        CATLSTR(buf, bufsz,
                _("  * Veterans have increased strength in combat.\n"));
      }
      /* SUPERSPY always wins/escapes */
      if ((utype_has_flag(utype, UTYF_DIPLOMAT)
           || utype_has_flag(utype, UTYF_SPY))
          && !utype_has_flag(utype, UTYF_SUPERSPY)) {
        CATLSTR(buf, bufsz,
                _("  * Veterans have improved chances in diplomatic "
                  "contests.\n"));
        if (utype_has_flag(utype, UTYF_SPY)) {
          CATLSTR(buf, bufsz,
                  _("  * Veterans are more likely to survive missions.\n"));
        }
      }
      if (utype_has_flag(utype, UTYF_SETTLERS)) {
        CATLSTR(buf, bufsz,
                _("  * Veterans work faster.\n"));
      }
    }
  }
  if (strlen(buf) > 0) {
    CATLSTR(buf, bufsz, "\n");
  }
  if (has_vet_levels && utype->veteran) {
    /* The case where the unit has only a single veteran level has already
     * been handled above, so keep quiet here if that happens */
    if (insert_veteran_help(buf, bufsz, utype->veteran,
            _("This type of unit has its own veteran levels:"), NULL)) {
      CATLSTR(buf, bufsz, "\n\n");
    }
  }
  if (NULL != utype->helptext) {
    strvec_iterate(utype->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
  CATLSTR(buf, bufsz, user_text);
  return buf;
}

/****************************************************************************
  Append misc dynamic text for advance/technology.

  pplayer may be NULL.
****************************************************************************/
void helptext_advance(char *buf, size_t bufsz, struct player *pplayer,
                      const char *user_text, int i)
{
  struct astring astr = ASTRING_INIT;
  struct advance *vap = valid_advance_by_number(i);
  struct universal source = {
    .kind = VUT_ADVANCE,
    .value = {.advance = vap}
  };
  int flagid;

  fc_assert_ret(NULL != buf && 0 < bufsz && NULL != user_text);
  fc_strlcpy(buf, user_text, bufsz);

  if (NULL == vap) {
    log_error("Unknown tech %d.", i);
    return;
  }

  if (game.control.num_tech_classes > 0) {
    if (vap->tclass == NULL) {
      cat_snprintf(buf, bufsz, _("Belongs to the default tech class.\n\n"));
    } else {
      cat_snprintf(buf, bufsz, _("Belongs to tech class %s.\n\n"),
                   tech_class_name_translation(vap->tclass));
    }
  }

  if (NULL != pplayer) {
    const struct research *presearch = research_get(pplayer);

    if (research_invention_state(presearch, i) != TECH_KNOWN) {
      if (research_invention_state(presearch, i) == TECH_PREREQS_KNOWN) {
        int bulbs = research_total_bulbs_required(presearch, i, FALSE);

        cat_snprintf(buf, bufsz,
                     PL_("Starting now, researching %s would need %d bulb.",
                         "Starting now, researching %s would need %d bulbs.",
                         bulbs),
                     advance_name_translation(vap), bulbs);
      } else if (research_invention_reachable(presearch, i)) {
        /* Split string into two to allow localization of two pluralizations. */
        char buf2[MAX_LEN_MSG];
        int bulbs = research_goal_bulbs_required(presearch, i);

        fc_snprintf(buf2, ARRAY_SIZE(buf2),
                    /* TRANS: appended to another sentence. Preserve the
                     * leading space. */
                    PL_(" The whole project will require %d bulb to complete.",
                        " The whole project will require %d bulbs to complete.",
                        bulbs),
                    bulbs);
        cat_snprintf(buf, bufsz,
                     /* TRANS: last %s is a sentence pluralized separately. */
                     PL_("To reach %s you need to obtain %d other"
                         " technology first.%s",
                         "To reach %s you need to obtain %d other"
                         " technologies first.%s",
                         research_goal_unknown_techs(presearch, i) - 1),
                     advance_name_translation(vap),
                     research_goal_unknown_techs(presearch, i) - 1, buf2);
      } else {
        CATLSTR(buf, bufsz,
                _("You cannot research this technology."));
      }
      if (!techs_have_fixed_costs()
          && research_invention_reachable(presearch, i)) {
        CATLSTR(buf, bufsz,
                _(" This number may vary depending on what "
                  "other players research.\n"));
      } else {
        CATLSTR(buf, bufsz, "\n");
      }
    }

    CATLSTR(buf, bufsz, "\n");
  }

  if (requirement_vector_size(&vap->research_reqs) > 0) {
    CATLSTR(buf, bufsz, _("Requirements to research:\n"));
    requirement_vector_iterate(&vap->research_reqs, preq) {
      (void) req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT);
    } requirement_vector_iterate_end;
    CATLSTR(buf, bufsz, "\n");
  }

  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf));

  {
    int j;
    
    for (j = 0; j < MAX_NUM_TECH_LIST; j++) {
      if (game.rgame.global_init_techs[j] == A_LAST) {
        break;
      } else if (game.rgame.global_init_techs[j] == i) {
        CATLSTR(buf, bufsz,
                _("* All players start the game with knowledge of this "
                  "technology.\n"));
        break;
      }
    }
  }

  /* Assume no-one will set the same tech in both global and nation
   * init_tech... */
  nations_iterate(pnation) {
    int j;

    /* Avoid mentioning nations not in current set. */
    if (!show_help_for_nation(pnation)) {
      continue;
    }
    for (j = 0; j < MAX_NUM_TECH_LIST; j++) {
      if (pnation->init_techs[j] == A_LAST) {
        break;
      } else if (pnation->init_techs[j] == i) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a nation plural */
                     _("* The %s start the game with knowledge of this "
                       "technology.\n"), nation_plural_translation(pnation));
        break;
      }
    }
  } nations_iterate_end;

  if (advance_has_flag(i, TF_BONUS_TECH)) {
    cat_snprintf(buf, bufsz,
                 _("* The first player to research %s gets"
                   " an immediate advance.\n"),
                 advance_name_translation(vap));
  }

  for (flagid = TECH_USER_1 ; flagid <= TECH_USER_LAST; flagid++) {
    if (advance_has_flag(i, flagid)) {
      const char *helptxt = tech_flag_helptxt(flagid);

      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, Q_("?bullet:* "));
        CATLSTR(buf, bufsz, _(helptxt));
        CATLSTR(buf, bufsz, "\n");
      }
    }
  }

  /* FIXME: bases -- but there is no good way to find out which bases a tech
   * can enable currently, so we have to remain silent. */

  if (game.info.tech_upkeep_style != TECH_UPKEEP_NONE) {
    CATLSTR(buf, bufsz,
            _("* To preserve this technology for our nation some bulbs "
              "are needed each turn.\n"));
  }

  if (NULL != vap->helptext) {
    if (strlen(buf) > 0) {
      CATLSTR(buf, bufsz, "\n");
    }
    strvec_iterate(vap->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }

  astr_free(&astr);
}

/****************************************************************
  Append text for terrain.
*****************************************************************/
void helptext_terrain(char *buf, size_t bufsz, struct player *pplayer,
                      const char *user_text, struct terrain *pterrain)
{
  struct universal source = {
    .kind = VUT_TERRAIN,
    .value = {.terrain = pterrain}
  };
  int flagid;

  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';

  if (!pterrain) {
    log_error("Unknown terrain!");
    return;
  }

  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf));
  if (terrain_has_flag(pterrain, TER_NO_CITIES)) {
    CATLSTR(buf, bufsz,
            _("* You cannot build cities on this terrain."));
    CATLSTR(buf, bufsz, "\n");
  }
  if (pterrain->road_time == 0) {
    /* Can't build roads; only mention if ruleset has buildable roads */
    extra_type_by_cause_iterate(EC_ROAD, pextra) {
      if (pextra->buildable) {
        CATLSTR(buf, bufsz,
                _("* Paths cannot be built on this terrain."));
        CATLSTR(buf, bufsz, "\n");
        break;
      }
    } extra_type_by_cause_iterate_end;
  }
  if (pterrain->base_time == 0) {
    /* Can't build bases; only mention if ruleset has buildable bases */
    extra_type_by_cause_iterate(EC_BASE, pextra) {
      if (pextra->buildable) {
        CATLSTR(buf, bufsz,
                _("* Bases cannot be built on this terrain."));
        CATLSTR(buf, bufsz, "\n");
        break;
      }
    } extra_type_by_cause_iterate_end;
  }
  if (terrain_has_flag(pterrain, TER_UNSAFE_COAST)
      && terrain_type_terrain_class(pterrain) != TC_OCEAN) {
    CATLSTR(buf, bufsz,
            _("* The coastline of this terrain is unsafe."));
    CATLSTR(buf, bufsz, "\n");
  }
  {
    const char *classes[uclass_count()];
    int i = 0;

    unit_class_iterate(uclass) {
      if (is_native_to_class(uclass, pterrain, NULL)) {
        classes[i++] = uclass_name_translation(uclass);
      }
    } unit_class_iterate_end;

    if (0 < i) {
      struct astring list = ASTRING_INIT;

      /* TRANS: %s is a list of unit classes separated by "and". */
      cat_snprintf(buf, bufsz, _("* Can be traveled by %s units.\n"),
                   astr_build_and_list(&list, classes, i));
      astr_free(&list);
    }
  }
  if (terrain_has_flag(pterrain, TER_NO_ZOC)) {
    CATLSTR(buf, bufsz,
            _("* Units on this terrain neither impose zones of control "
              "nor are restricted by them.\n"));
  } else {
    CATLSTR(buf, bufsz,
            _("* Units on this terrain may impose a zone of control, or "
              "be restricted by one.\n"));
  }
  if (terrain_has_flag(pterrain, TER_NO_FORTIFY)) {
    CATLSTR(buf, bufsz,
            _("* No units can fortify on this terrain.\n"));
  } else {
    CATLSTR(buf, bufsz,
            _("* Units able to fortify may do so on this terrain.\n"));
  }
  for (flagid = TER_USER_1 ; flagid <= TER_USER_LAST; flagid++) {
    if (terrain_has_flag(pterrain, flagid)) {
      const char *helptxt = terrain_flag_helptxt(flagid);

      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, Q_("?bullet:* "));
        CATLSTR(buf, bufsz, _(helptxt));
        CATLSTR(buf, bufsz, "\n");
      }
    }
  }

  if (NULL != pterrain->helptext) {
    if (buf[0] != '\0') {
      CATLSTR(buf, bufsz, "\n");
    }
    strvec_iterate(pterrain->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
  if (user_text && user_text[0] != '\0') {
    CATLSTR(buf, bufsz, "\n\n");
    CATLSTR(buf, bufsz, user_text);
  }
}

/****************************************************************************
  Return a textual representation of the F/P/T bonus a road provides to a
  terrain if supplied, or the terrain-independent bonus if pterrain == NULL.
  e.g. "0/0/+1", "0/+50%/0", or for a complex road "+2/+1+50%/0".
  Returns a pointer to a static string, so caller should not free
  (or NULL if there is no effect at all).
****************************************************************************/
const char *helptext_road_bonus_str(const struct terrain *pterrain,
                                    const struct road_type *proad)
{
  static char str[64];
  bool has_effect = FALSE;

  str[0] = '\0';
  output_type_iterate(o) {
    switch (o) {
    case O_FOOD:
    case O_SHIELD:
    case O_TRADE:
      {
        int bonus = proad->tile_bonus[o];
        int incr = proad->tile_incr_const[o];

        if (pterrain) {
          incr +=
            proad->tile_incr[o] * pterrain->road_output_incr_pct[o] / 100;
        }
        if (str[0] != '\0') {
          CATLSTR(str, sizeof(str), "/");
        }
        if (incr == 0 && bonus == 0) {
          cat_snprintf(str, sizeof(str), "%d", incr);
        } else {
          has_effect = TRUE;
          if (incr != 0) {
            cat_snprintf(str, sizeof(str), "%+d", incr);
          }
          if (bonus != 0) {
            cat_snprintf(str, sizeof(str), "%+d%%", bonus);
          }
        }
      }
      break;
    default:
      /* FIXME: there's nothing actually stopping roads having gold, etc
       * bonuses */
      fc_assert(proad->tile_incr_const[o] == 0
                && proad->tile_incr[o] == 0
                && proad->tile_bonus[o] == 0);
      break;
    }
  } output_type_iterate_end;

  return has_effect ? str : NULL;
}

/****************************************************************************
  Append misc dynamic text for extras.
  Assumes build time and conflicts are handled in the GUI front-end.

  pplayer may be NULL.
****************************************************************************/
void helptext_extra(char *buf, size_t bufsz, struct player *pplayer,
                    const char *user_text, struct extra_type *pextra)
{
  struct base_type *pbase;
  struct road_type *proad;
  struct universal source = {
    .kind = VUT_EXTRA,
    .value = {.extra = pextra}
  };

  int flagid;

  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';

  if (!pextra) {
    log_error("Unknown extra!");
    return;
  }

  if (is_extra_caused_by(pextra, EC_BASE)) {
    pbase = pextra->data.base;
  } else {
    pbase = NULL;
  }

  if (is_extra_caused_by(pextra, EC_ROAD)) {
    proad = pextra->data.road;
  } else {
    proad = NULL;
  }

  if (pextra->helptext != NULL) {
    strvec_iterate(pextra->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }

  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf));

  if (is_extra_caused_by(pextra, EC_POLLUTION)) {
    CATLSTR(buf, bufsz,
            _("* May randomly appear around polluting city.\n"));
  }

  if (is_extra_caused_by(pextra, EC_FALLOUT)) {
    CATLSTR(buf, bufsz,
            _("* May randomly appear around nuclear blast.\n"));
  }

  if (is_extra_caused_by(pextra, EC_HUT)
      || (proad != NULL && road_has_flag(proad, RF_RIVER))) {
    CATLSTR(buf, bufsz,
            _("* Placed by map generator.\n"));
  }

  if (is_extra_caused_by(pextra, EC_APPEARANCE)) {
    CATLSTR(buf, bufsz,
            _("* May appear spontaneously.\n"));
  }

  if (pextra->eus == EUS_HIDDEN) {
    CATLSTR(buf, bufsz,
            _("* Units inside are hidden from non-allied players.\n"));
  }

  /* XXX Non-zero requirement vector is not a good test of whether
   * req_text_insert_nl() will give any output. */
  if (requirement_vector_size(&pextra->reqs) > 0) {
    if (pextra->buildable && is_extra_caused_by_worker_action(pextra)) {
      CATLSTR(buf, bufsz, _("Requirements to build:\n"));
    }
    requirement_vector_iterate(&pextra->reqs, preq) {
      (void) req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT);
    } requirement_vector_iterate_end;
    CATLSTR(buf, bufsz, "\n");
  }

  {
    const char *classes[uclass_count()];
    int i = 0;

    unit_class_iterate(uclass) {
      if (is_native_extra_to_uclass(pextra, uclass)) {
        classes[i++] = uclass_name_translation(uclass);
      }
    } unit_class_iterate_end;

    if (0 < i) {
      struct astring list = ASTRING_INIT;

      if (proad != NULL) {
        /* TRANS: %s is a list of unit classes separated by "and". */
        cat_snprintf(buf, bufsz, _("* Can be traveled by %s units.\n"),
                     astr_build_and_list(&list, classes, i));
      } else {
        /* TRANS: %s is a list of unit classes separated by "and". */
        cat_snprintf(buf, bufsz, _("* Native to %s units.\n"),
                     astr_build_and_list(&list, classes, i));
      }
      astr_free(&list);

      if (extra_has_flag(pextra, EF_NATIVE_TILE)) {
        CATLSTR(buf, bufsz,
                _("  * Such units can move onto this tile even if it would "
                  "not normally be suitable terrain.\n"));
      }
      if (pbase != NULL) {
        if (base_has_flag(pbase, BF_NOT_AGGRESSIVE)) {
          /* "3 tiles" is hardcoded in is_friendly_city_near() */
          CATLSTR(buf, bufsz,
                  _("  * Such units situated here are not considered aggressive "
                    "if this tile is within 3 tiles of a friendly city.\n"));
        }
        if (territory_claiming_base(pbase)) {
          CATLSTR(buf, bufsz,
                  _("  * Can be captured by such units if at war with the "
                    "nation that currently owns it.\n"));
        }
      }
      if (pextra->defense_bonus) {
        cat_snprintf(buf, bufsz,
                     _("  * Such units get a %d%% defense bonus on this "
                       "tile.\n"),
                     pextra->defense_bonus);
      }
    }
  }

  if (proad != NULL && road_provides_move_bonus(proad)) {
    if (proad->move_cost == 0) {
      CATLSTR(buf, bufsz, _("* Allows infinite movement.\n"));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "MP" = movement points. Second %s may have a
                    * fractional part. */
                   _("* Movement cost along %s is %s MP.\n"),
                   extra_name_translation(pextra),
                   move_points_text(proad->move_cost, TRUE));
    }
  }

  if (is_extra_removed_by(pextra, ERM_PILLAGE)) {
    CATLSTR(buf, bufsz,
            _("* Can be pillaged by units.\n"));
  }
  if (is_extra_removed_by(pextra, ERM_CLEANPOLLUTION) || is_extra_removed_by(pextra, ERM_CLEANFALLOUT)) {
    CATLSTR(buf, bufsz,
            _("* Can be cleaned by units.\n"));
  }
  if (game.info.killstack
      && extra_has_flag(pextra, EF_NO_STACK_DEATH)) {
    CATLSTR(buf, bufsz,
            _("* Defeat of one unit does not cause death of all other units "
              "on this tile.\n"));
  }
  if (pbase != NULL) {
    if (territory_claiming_base(pbase)) {
      CATLSTR(buf, bufsz,
              _("* Extends national borders of the building nation.\n"));
    }
    if (pbase->vision_main_sq >= 0) {
      CATLSTR(buf, bufsz,
              _("* Grants permanent vision of an area around the tile to "
                "its owner.\n"));
    }
    if (pbase->vision_invis_sq >= 0) {
      CATLSTR(buf, bufsz,
              _("* Allows the owner to see normally invisible units in an "
                "area around the tile.\n"));
    }
  }
  for (flagid = EF_USER_FLAG_1; flagid <= EF_LAST_USER_FLAG; flagid++) {
    if (extra_has_flag(pextra, flagid)) {
      const char *helptxt = extra_flag_helptxt(flagid);

      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, Q_("?bullet:* "));
        CATLSTR(buf, bufsz, _(helptxt));
        CATLSTR(buf, bufsz, "\n");
      }
    }
  }

  /* Table of terrain-specific attributes, if needed */
  if (proad != NULL || pbase != NULL) {
    bool road, do_time, do_bonus;

    road = (proad != NULL);
    /* Terrain-dependent build time? */
    do_time = pextra->buildable && pextra->build_time == 0;
    if (road) {
      /* Terrain-dependent output bonus? */
      do_bonus = FALSE;
      output_type_iterate(o) {
        if (proad->tile_incr[o] > 0) {
          do_bonus = TRUE;
          fc_assert(o == O_FOOD || o == O_SHIELD || o == O_TRADE);
        }
      } output_type_iterate_end;
    } else {
      /* Bases don't have output bonuses */
      do_bonus = FALSE;
    }

    if (do_time || do_bonus) {
      if (do_time && do_bonus) {
        CATLSTR(buf, bufsz,
                _("\nTime to build and output bonus depends on terrain:\n\n"));
        CATLSTR(buf, bufsz,
                /* TRANS: Header for fixed-width road properties table.
                 * TRANS: Translators cannot change column widths :( */
                _("Terrain       Time     Bonus F/P/T\n"
                  "----------------------------------\n"));
      } else if (do_time) {
        CATLSTR(buf, bufsz,
                _("\nTime to build depends on terrain:\n\n"));
        CATLSTR(buf, bufsz,
                /* TRANS: Header for fixed-width extra properties table.
                 * TRANS: Translators cannot change column widths :( */
                _("Terrain       Time\n"
                  "------------------\n"));
      } else {
        fc_assert(do_bonus);
        CATLSTR(buf, bufsz,
                /* TRANS: Header for fixed-width road properties table.
                 * TRANS: Translators cannot change column widths :( */
                _("\nYields an output bonus with some terrains:\n\n"));
        CATLSTR(buf, bufsz,
                _("Terrain       Bonus F/P/T\n"
                  "-------------------------\n"));;
      }
      terrain_type_iterate(t) {
        int turns = road ? terrain_extra_build_time(t, ACTIVITY_GEN_ROAD, pextra)
                           : terrain_extra_build_time(t, ACTIVITY_BASE, pextra);
        const char *bonus_text
          = road ? helptext_road_bonus_str(t, proad) : NULL;
        if (turns > 0 || bonus_text) {
          const char *terrain = terrain_name_translation(t);

          cat_snprintf(buf, bufsz,
                       "%s%*s ", terrain,
                       MAX(0, 12 - (int)get_internal_string_length(terrain)),
                       "");
          if (do_time) {
            if (turns > 0) {
              cat_snprintf(buf, bufsz, "%3d      ", turns);
            } else {
              CATLSTR(buf, bufsz, "  -      ");
            }
          }
          if (do_bonus) {
            fc_assert(proad != NULL);
            cat_snprintf(buf, bufsz, " %s", bonus_text ? bonus_text : "-");
          }
          CATLSTR(buf, bufsz, "\n");
        }
      } terrain_type_iterate_end;
    } /* else rely on client-specific display */
  }

  if (user_text && user_text[0] != '\0') {
    CATLSTR(buf, bufsz, "\n\n");
    CATLSTR(buf, bufsz, user_text);
  }
}

/****************************************************************************
  Append misc dynamic text for goods.
  Assumes effects are described in the help text.

  pplayer may be NULL.
****************************************************************************/
void helptext_goods(char *buf, size_t bufsz, struct player *pplayer,
                    const char *user_text, struct goods_type *pgood)
{
  bool reqs = FALSE;

  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';

  if (NULL != pgood->helptext) {
    strvec_iterate(pgood->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }

  cat_snprintf(buf, bufsz, _("Sending city enjoys %d%% income from the route.\n"),
               pgood->from_pct);
  cat_snprintf(buf, bufsz, _("Receiving city enjoys %d%% income from the route.\n\n"),
               pgood->to_pct);

  /* Requirements for this good. */
  requirement_vector_iterate(&pgood->reqs, preq) {
    if (req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT)) {
      reqs = TRUE;
    }
  } requirement_vector_iterate_end;
  if (reqs) {
    fc_strlcat(buf, "\n", bufsz);
  }

  CATLSTR(buf, bufsz, user_text);
}

/****************************************************************************
  Append misc dynamic text for specialists.
  Assumes effects are described in the help text.

  pplayer may be NULL.
****************************************************************************/
void helptext_specialist(char *buf, size_t bufsz, struct player *pplayer,
                         const char *user_text, struct specialist *pspec)
{
  bool reqs = FALSE;

  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';

  if (NULL != pspec->helptext) {
    strvec_iterate(pspec->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }

  /* Requirements for this specialist. */
  requirement_vector_iterate(&pspec->reqs, preq) {
    if (req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT)) {
      reqs = TRUE;
    }
  } requirement_vector_iterate_end;
  if (reqs) {
    fc_strlcat(buf, "\n", bufsz);
  }

  CATLSTR(buf, bufsz, user_text);
}

/****************************************************************
  Append text for government.

  pplayer may be NULL.

  TODO: Generalize the effects code for use elsewhere. Add
  other requirements.
*****************************************************************/
void helptext_government(char *buf, size_t bufsz, struct player *pplayer,
                         const char *user_text, struct government *gov)
{
  bool reqs = FALSE;
  struct universal source = {
    .kind = VUT_GOVERNMENT,
    .value = {.govern = gov}
  };

  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';

  if (NULL != gov->helptext) {
    strvec_iterate(gov->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }

  /* Add requirement text for government itself */
  requirement_vector_iterate(&gov->reqs, preq) {
    if (req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT)) {
      reqs = TRUE;
    }
  } requirement_vector_iterate_end;
  if (reqs) {
    fc_strlcat(buf, "\n", bufsz);
  }

  /* Effects */
  CATLSTR(buf, bufsz, _("Features:\n"));
  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf));
  effect_list_iterate(get_req_source_effects(&source), peffect) {
    Output_type_id output_type = O_LAST;
    struct unit_class *unitclass = NULL;
    struct unit_type *unittype = NULL;
    enum unit_type_flag_id unitflag = unit_type_flag_id_invalid();
    struct strvec *outputs = strvec_new();
    struct astring outputs_or = ASTRING_INIT;
    struct astring outputs_and = ASTRING_INIT;
    bool too_complex = FALSE;
    bool world_value_valid = TRUE;

    /* Grab output type, if there is one */
    requirement_vector_iterate(&peffect->reqs, preq) {
      /* Treat an effect with any negated requirements as too complex for
       * us to explain here.
       * Also don't try to explain an effect with any requirements explicitly
       * marked as 'quiet' by ruleset author. */
      if (!preq->present || preq->quiet) {
        too_complex = TRUE;
        continue;
      }
      switch (preq->source.kind) {
       case VUT_OTYPE:
         /* We should never have multiple outputtype requirements
          * in one list in the first place (it simply makes no sense,
          * output cannot be of multiple types)
          * Ruleset loading code should check against that. */
         fc_assert(output_type == O_LAST);
         output_type = preq->source.value.outputtype;
         strvec_append(outputs, get_output_name(output_type));
         break;
       case VUT_UCLASS:
         fc_assert(unitclass == NULL);
         unitclass = preq->source.value.uclass;
         /* FIXME: can't easily get world bonus for unit class */
         world_value_valid = FALSE;
         break;
       case VUT_UTYPE:
         fc_assert(unittype == NULL);
         unittype = preq->source.value.utype;
         break;
       case VUT_UTFLAG:
         if (!unit_type_flag_id_is_valid(unitflag)) {
           unitflag = preq->source.value.unitflag;
           /* FIXME: can't easily get world bonus for unit type flag */
           world_value_valid = FALSE;
         } else {
           /* Already have a unit flag requirement. More than one is too
            * complex for us to explain, so say nothing. */
           /* FIXME: we could handle this */
           too_complex = TRUE;
         }
         break;
       case VUT_GOVERNMENT:
         /* This is government we are generating helptext for.
          * ...or if not, it's ruleset bug that should never make it
          * this far. Fix ruleset loading code. */
         fc_assert(preq->source.value.govern == gov);
         break;
       default:
         too_complex = TRUE;
         world_value_valid = FALSE;
         break;
      };
    } requirement_vector_iterate_end;

    if (!too_complex) {
      /* Only list effects that don't have extra requirements too complex
       * for us to handle.
       * Anything more complicated will have to be documented by hand by the
       * ruleset author. */

      /* Guard condition for simple player-wide effects descriptions.
       * (FIXME: in many cases, e.g. EFT_MAKE_CONTENT, additional requirements
       * like unittype will be ignored for gameplay, but will affect our
       * help here.) */
      const bool playerwide
        = world_value_valid && !unittype && (output_type == O_LAST);
      /* In some cases we give absolute values (world bonus + gov bonus).
       * We assume the fact that there's an effect with a gov requirement
       * is sufficient reason to list it in that gov's help.
       * Guard accesses to these with 'playerwide' or 'world_value_valid'. */
      int world_value = -999, net_value = -999;
      if (world_value_valid) {
        /* Get government-independent world value of effect if the extra
         * requirements were simple enough. */
        struct output_type *potype =
          output_type != O_LAST ? get_output_type(output_type) : NULL;
        world_value = 
          get_target_bonus_effects(NULL, NULL, NULL, NULL, NULL, NULL,
                                   NULL, unittype, potype, NULL, NULL,
                                   peffect->type);
        net_value = peffect->value + world_value;
      }

      if (output_type == O_LAST) {
        /* There was no outputtype requirement. Effect is active for all
         * output types. Generate lists for that. */
        bool harvested_only = TRUE; /* Consider only output types from fields */

        if (peffect->type == EFT_UPKEEP_FACTOR
            || peffect->type == EFT_UNIT_UPKEEP_FREE_PER_CITY
            || peffect->type == EFT_OUTPUT_BONUS
            || peffect->type == EFT_OUTPUT_BONUS_2) {
          /* Effect can use or require any kind of output */
          harvested_only = FALSE;
        }

        output_type_iterate(ot) {
          struct output_type *pot = get_output_type(ot);

          if (!harvested_only || pot->harvested) {
            strvec_append(outputs, _(pot->name));
          }
        } output_type_iterate_end;
      }

      if (0 == strvec_size(outputs)) {
         /* TRANS: Empty output type list, should never happen. */
        astr_set(&outputs_or, "%s", Q_("?outputlist: Nothing "));
        astr_set(&outputs_and, "%s", Q_("?outputlist: Nothing "));
      } else {
        strvec_to_or_list(outputs, &outputs_or);
        strvec_to_and_list(outputs, &outputs_and);
      }

      switch (peffect->type) {
      case EFT_UNHAPPY_FACTOR:
        if (playerwide) {
          /* FIXME: EFT_MAKE_CONTENT_MIL_PER would cancel this out. We assume
           * no-one will set both, so we don't bother handling it. */
          cat_snprintf(buf, bufsz,
                       PL_("* Military units away from home and field units"
                           " will each cause %d citizen to become unhappy.\n",
                           "* Military units away from home and field units"
                           " will each cause %d citizens to become unhappy.\n",
                           net_value),
                       net_value);
        } /* else too complicated or silly ruleset */
        break;
      case EFT_ENEMY_CITIZEN_UNHAPPY_PCT:
        if (playerwide && net_value != world_value) {
          if (world_value > 0) {
            if (net_value > 0) {
              cat_snprintf(buf, bufsz,
                           _("* Unhappiness from foreign citizens due to "
                             "war with their home state is %d%% the usual "
                             "value.\n"),
                           (net_value * 100) / world_value);
            } else {
              CATLSTR(buf, bufsz,
                      _("* No unhappiness from foreign citizens even when "
                        "at war with their home state.\n"));
            }
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: not pluralised as gettext doesn't support
                          * fractional numbers, which this might be */
                         _("* Each foreign citizen causes %.2g unhappiness "
                           "in their city while you are at war with their "
                           "home state.\n"),
                         (double)net_value / 100);
          }
        }
        break;
      case EFT_MAKE_CONTENT_MIL:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("* Each of your cities will avoid %d unhappiness"
                           " caused by units.\n",
                           "* Each of your cities will avoid %d unhappiness"
                           " caused by units.\n",
                           peffect->value),
                       peffect->value);
        }
        break;
      case EFT_MAKE_CONTENT:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("* Each of your cities will avoid %d unhappiness,"
                           " not including that caused by aggression.\n",
                           "* Each of your cities will avoid %d unhappiness,"
                           " not including that caused by aggression.\n",
                           peffect->value),
                       peffect->value);
        }
        break;
      case EFT_FORCE_CONTENT:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("* Each of your cities will avoid %d unhappiness,"
                           " including that caused by aggression.\n",
                           "* Each of your cities will avoid %d unhappiness,"
                           " including that caused by aggression.\n",
                           peffect->value),
                       peffect->value);
        }
        break;
      case EFT_UPKEEP_FACTOR:
        if (world_value_valid && !unittype) {
          if (net_value == 0) {
            if (output_type != O_LAST) {
              cat_snprintf(buf, bufsz,
                           /* TRANS: %s is the output type, like 'shield'
                            * or 'gold'. */
                           _("* You pay no %s upkeep for your units.\n"),
                           astr_str(&outputs_or));
            } else {
              CATLSTR(buf, bufsz,
                      _("* You pay no upkeep for your units.\n"));
            }
          } else if (net_value != world_value) {
            double ratio = (double)net_value / world_value;
            if (output_type != O_LAST) {
              cat_snprintf(buf, bufsz,
                           /* TRANS: %s is the output type, like 'shield'
                            * or 'gold'. */
                           _("* You pay %.2g times normal %s upkeep for your "
                             "units.\n"),
                           ratio, astr_str(&outputs_and));
            } else {
              cat_snprintf(buf, bufsz,
                           _("* You pay %.2g times normal upkeep for your "
                             "units.\n"),
                           ratio);
            }
          } /* else this effect somehow has no effect; keep quiet */
        } /* else there was some extra condition making it complicated */
        break;
      case EFT_UNIT_UPKEEP_FREE_PER_CITY:
        if (!unittype) {
          if (output_type != O_LAST) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is the output type, like 'shield' or
                          * 'gold'; pluralised in %d but there is currently
                          * no way to control the singular/plural name of the
                          * output type; sorry */
                         PL_("* Each of your cities will avoid paying %d %s"
                             " upkeep for your units.\n",
                             "* Each of your cities will avoid paying %d %s"
                             " upkeep for your units.\n", peffect->value),
                         peffect->value, astr_str(&outputs_and));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: Amount is subtracted from upkeep cost
                          * for each upkeep type. */
                         PL_("* Each of your cities will avoid paying %d"
                             " upkeep for your units.\n",
                             "* Each of your cities will avoid paying %d"
                             " upkeep for your units.\n", peffect->value),
                         peffect->value);
          }
        } /* else too complicated */
        break;
      case EFT_CIVIL_WAR_CHANCE:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       _("* If you lose your capital,"
                         " the chance of civil war is %d%%.\n"),
                       net_value);
        }
        break;
      case EFT_EMPIRE_SIZE_BASE:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("* You can have %d city before an "
                           "additional unhappy citizen appears in each city "
                           "due to civilization size.\n",
                           "* You can have up to %d cities before an "
                           "additional unhappy citizen appears in each city "
                           "due to civilization size.\n", net_value),
                       net_value);
        }
        break;
      case EFT_EMPIRE_SIZE_STEP:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("* After the first unhappy citizen due to"
                           " civilization size, for each %d additional city"
                           " another unhappy citizen will appear.\n",
                           "* After the first unhappy citizen due to"
                           " civilization size, for each %d additional cities"
                           " another unhappy citizen will appear.\n",
                           net_value),
                       net_value);
        }
        break;
      case EFT_MAX_RATES:
        if (playerwide && game.info.changable_tax) {
          if (net_value < 100) {
            cat_snprintf(buf, bufsz,
                         _("* The maximum rate you can set for science,"
                            " gold, or luxuries is %d%%.\n"),
                         net_value);
          } else {
            CATLSTR(buf, bufsz,
                    _("* Has unlimited science/gold/luxuries rates.\n"));
          }
        }
        break;
      case EFT_MARTIAL_LAW_EACH:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("* Your units may impose martial law."
                           " Each military unit inside a city will force %d"
                           " unhappy citizen to become content.\n",
                           "* Your units may impose martial law."
                           " Each military unit inside a city will force %d"
                           " unhappy citizens to become content.\n",
                           peffect->value),
                       peffect->value);
        }
        break;
      case EFT_MARTIAL_LAW_MAX:
        if (playerwide && net_value < 100) {
          cat_snprintf(buf, bufsz,
                       PL_("* A maximum of %d unit in each city can enforce"
                           " martial law.\n",
                           "* A maximum of %d units in each city can enforce"
                           " martial law.\n",
                           net_value),
                       net_value);
        }
        break;
      case EFT_RAPTURE_GROW:
        if (playerwide && net_value > 0) {
          cat_snprintf(buf, bufsz,
                       _("* You may grow your cities by means of "
                         "celebrations."));
          if (game.info.celebratesize > 1) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: Preserve leading space. %d should always be
                          * 2 or greater. */
                         _(" (Cities below size %d cannot grow in this way.)"),
                         game.info.celebratesize);
          }
          cat_snprintf(buf, bufsz, "\n");
        }
        break;
      case EFT_REVOLUTION_UNHAPPINESS:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("* If a city is in disorder for more than %d turn "
                           "in a row, government will fall into anarchy.\n",
                           "* If a city is in disorder for more than %d turns "
                           "in a row, government will fall into anarchy.\n",
                           net_value),
                       net_value);
        }
        break;
      case EFT_HAS_SENATE:
        if (playerwide && net_value > 0) {
          CATLSTR(buf, bufsz,
                  _("* Has a senate that may prevent declaration of war.\n"));
        }
        break;
      case EFT_INSPIRE_PARTISANS:
        if (playerwide && net_value > 0) {
          CATLSTR(buf, bufsz,
                  _("* Allows partisans when cities are taken by the "
                    "enemy.\n"));
        }
        break;
      case EFT_HAPPINESS_TO_GOLD:
        if (playerwide && net_value > 0) {
          CATLSTR(buf, bufsz,
                  _("* Buildings that normally confer bonuses against"
                    " unhappiness will instead give gold.\n"));
        }
        break;
      case EFT_FANATICS:
        if (playerwide && net_value > 0) {
          struct strvec *fanatics = strvec_new();
          struct astring fanaticstr = ASTRING_INIT;

          unit_type_iterate(putype) {
            if (utype_has_flag(putype, UTYF_FANATIC)) {
              strvec_append(fanatics, utype_name_translation(putype));
            }
          } unit_type_iterate_end;
          cat_snprintf(buf, bufsz,
                       /* TRANS: %s is list of unit types separated by 'or' */
                       _("* Pays no upkeep for %s.\n"),
                       strvec_to_or_list(fanatics, &fanaticstr));
          strvec_destroy(fanatics);
          astr_free(&fanaticstr);
        }
        break;
      case EFT_NO_UNHAPPY:
        if (playerwide && net_value > 0) {
          CATLSTR(buf, bufsz, _("* Has no unhappy citizens.\n"));
        }
        break;
      case EFT_VETERAN_BUILD:
        {
          int conditions = 0;
          if (unitclass) {
            conditions++;
          }
          if (unittype) {
            conditions++;
          }
          if (unit_type_flag_id_is_valid(unitflag)) {
            conditions++;
          }
          if (conditions > 1) {
            /* More than one requirement on units, too complicated for us
             * to describe. */
            break;
          }
          if (unitclass) {
            /* FIXME: account for multiple veteran levels, or negative
             * values. This might lie for complicated rulesets! */
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a unit class */
                         Q_("?unitclass:* New %s units will be veteran.\n"),
                         uclass_name_translation(unitclass));
          } else if (unit_type_flag_id_is_valid(unitflag)) {
            /* FIXME: same problems as unitclass */
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a (translatable) unit type flag */
                         Q_("?unitflag:* New %s units will be veteran.\n"),
                         unit_type_flag_id_translated_name(unitflag));
          } else if (unittype != NULL) {
            if (world_value_valid && net_value > 0) {
              /* Here we can be specific about veteran level, and get
               * net value correct. */
              int maxlvl = utype_veteran_system(unittype)->levels - 1;
              const struct veteran_level *vlevel =
                utype_veteran_level(unittype, MIN(net_value, maxlvl));
              cat_snprintf(buf, bufsz,
                           /* TRANS: "* New Partisan units will have the rank
                            * of elite." */
                           Q_("?unittype:* New %s units will have the rank "
                              "of %s.\n"),
                           utype_name_translation(unittype),
                           name_translation_get(&vlevel->name));
            } /* else complicated */
          } else {
            /* No extra criteria. */
            /* FIXME: same problems as above */
            cat_snprintf(buf, bufsz,
                         _("* New units will be veteran.\n"));
          }
        }
        break;
      case EFT_OUTPUT_PENALTY_TILE:
        if (world_value_valid) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: %s is list of output types, with 'or';
                        * pluralised in %d but of course the output types
                        * can't be pluralised; sorry */
                       PL_("* Each worked tile that gives more than %d %s will"
                           " suffer a -1 penalty, unless the city working it"
                           " is celebrating.",
                           "* Each worked tile that gives more than %d %s will"
                           " suffer a -1 penalty, unless the city working it"
                           " is celebrating.", net_value),
                       net_value, astr_str(&outputs_or));
          if (game.info.celebratesize > 1) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: Preserve leading space. %d should always be
                          * 2 or greater. */
                         _(" (Cities below size %d will not celebrate.)"),
                         game.info.celebratesize);
          }
          cat_snprintf(buf, bufsz, "\n");
        }
        break;
      case EFT_OUTPUT_INC_TILE_CELEBRATE:
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is list of output types, with 'or' */
                     PL_("* Each worked tile with at least 1 %s will yield"
                         " %d more of it while the city working it is"
                         " celebrating.",
                         "* Each worked tile with at least 1 %s will yield"
                         " %d more of it while the city working it is"
                         " celebrating.", peffect->value),
                     astr_str(&outputs_or), peffect->value);
        if (game.info.celebratesize > 1) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: Preserve leading space. %d should always be
                        * 2 or greater. */
                       _(" (Cities below size %d will not celebrate.)"),
                       game.info.celebratesize);
        }
        cat_snprintf(buf, bufsz, "\n");
        break;
      case EFT_OUTPUT_INC_TILE:
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is list of output types, with 'or' */
                     PL_("* Each worked tile with at least 1 %s will yield"
                         " %d more of it.\n",
                         "* Each worked tile with at least 1 %s will yield"
                         " %d more of it.\n", peffect->value),
                     astr_str(&outputs_or), peffect->value);
        break;
      case EFT_OUTPUT_BONUS:
      case EFT_OUTPUT_BONUS_2:
        /* FIXME: makes most sense iff world_value == 0 */
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is list of output types, with 'and' */
                     _("* %s production is increased %d%%.\n"),
                     astr_str(&outputs_and), peffect->value);
        break;
      case EFT_OUTPUT_WASTE:
        if (world_value_valid) {
          if (net_value > 30) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("* %s production will suffer massive losses.\n"),
                         astr_str(&outputs_and));
          } else if (net_value >= 15) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("* %s production will suffer some losses.\n"),
                         astr_str(&outputs_and));
          } else if (net_value > 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("* %s production will suffer a small amount "
                           "of losses.\n"),
                         astr_str(&outputs_and));
          }
        }
        break;
      case EFT_HEALTH_PCT:
        if (playerwide) {
          if (peffect->value > 0) {
            CATLSTR(buf, bufsz, _("* Increases the chance of plague"
                                  " within your cities.\n"));
          } else if (peffect->value < 0) {
            CATLSTR(buf, bufsz, _("* Decreases the chance of plague"
                                  " within your cities.\n"));
          }
        }
        break;
      case EFT_OUTPUT_WASTE_BY_REL_DISTANCE:
        /* Semi-arbitrary scaling to get likely ruleset values in roughly
         * the same range as WASTE_BY_DISTANCE */
        /* FIXME: use different wording? */
        net_value = (net_value + 39) / 40; /* round up */
        /* fall through to: */
      case EFT_OUTPUT_WASTE_BY_DISTANCE:
        if (world_value_valid) {
          if (net_value >= 3) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("* %s losses will increase quickly"
                           " with distance from capital.\n"),
                         astr_str(&outputs_and));
          } else if (net_value == 2) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("* %s losses will increase"
                           " with distance from capital.\n"),
                         astr_str(&outputs_and));
          } else if (net_value > 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("* %s losses will increase slowly"
                           " with distance from capital.\n"),
                         astr_str(&outputs_and));
          }
        }
        break;
      case EFT_MIGRATION_PCT:
        if (playerwide) {
          if (peffect->value > 0) {
            CATLSTR(buf, bufsz, _("* Increases the chance of migration"
                                  " into your cities.\n"));
          } else if (peffect->value < 0) {
            CATLSTR(buf, bufsz, _("* Decreases the chance of migration"
                                  " into your cities.\n"));
          }
        }
        break;
      case EFT_BORDER_VISION:
        if (game.info.borders == BORDERS_ENABLED
            && playerwide && net_value > 0) {
          CATLSTR(buf, bufsz, _("* All tiles inside your borders are"
                                " monitored.\n"));
        }
        break;
      default:
        break;
      };
    }

    strvec_destroy(outputs);
    astr_free(&outputs_or);
    astr_free(&outputs_and);

  } effect_list_iterate_end;

  unit_type_iterate(utype) {
    if (utype->need_government == gov) {
      cat_snprintf(buf, bufsz,
                   _("* Allows you to build %s.\n"),
                   utype_name_translation(utype));
    }
  } unit_type_iterate_end;

  /* Action immunity */
  action_iterate(act) {
    if (action_by_number(act)->quiet) {
      /* The ruleset documents this action it self. */
      continue;
    }

    if (action_immune_government(gov, act)) {
      cat_snprintf(buf, bufsz,
                   _("* Makes it impossible to do the action \'%s\'"
                     " to your %s.\n"),
                   action_id_name_translation(act),
                   _(action_target_kind_name(
                       action_id_get_target_kind(act))));
    }
  } action_iterate_end;

  if (user_text && user_text[0] != '\0') {
    cat_snprintf(buf, bufsz, "\n%s", user_text);
  }
}

/****************************************************************
  Returns pointer to static string with eg: "1 shield, 1 unhappy"
*****************************************************************/
char *helptext_unit_upkeep_str(struct unit_type *utype)
{
  static char buf[128];
  int any = 0;

  if (!utype) {
    log_error("Unknown unit!");
    return "";
  }

  buf[0] = '\0';
  output_type_iterate(o) {
    if (utype->upkeep[o] > 0) {
      /* TRANS: "2 Food" or ", 1 Shield" */
      cat_snprintf(buf, sizeof(buf), _("%s%d %s"),
                   (any > 0 ? Q_("?blistmore:, ") : ""), utype->upkeep[o],
                   get_output_name(o));
      any++;
    }
  } output_type_iterate_end;
  if (utype->happy_cost > 0) {
    /* TRANS: "2 Unhappy" or ", 1 Unhappy" */
    cat_snprintf(buf, sizeof(buf), _("%s%d Unhappy"),
                 (any > 0 ? Q_("?blistmore:, ") : ""), utype->happy_cost);
    any++;
  }

  if (any == 0) {
    /* strcpy(buf, _("None")); */
    fc_snprintf(buf, sizeof(buf), "%d", 0);
  }
  return buf;
}

/****************************************************************************
  Returns nation legend and characteristics
****************************************************************************/
void helptext_nation(char *buf, size_t bufsz, struct nation_type *pnation,
                     const char *user_text)
{
  struct universal source = {
    .kind = VUT_NATION,
    .value = {.nation = pnation}
  };
  bool print_break = TRUE;
#define PRINT_BREAK() do { \
    if (print_break) { \
      if (buf[0] != '\0') { \
        CATLSTR(buf, bufsz, "\n\n"); \
      } \
      print_break = FALSE; \
    } \
  } while (FALSE)

  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';

  if (pnation->legend[0] != '\0') {
    /* Client side legend is stored already translated */
    cat_snprintf(buf, bufsz, "%s", pnation->legend);
  }

  if (pnation->init_government) {
    PRINT_BREAK();
    cat_snprintf(buf, bufsz,
                 _("Initial government is %s.\n"),
                 government_name_translation(pnation->init_government));
  }
  if (pnation->init_techs[0] != A_LAST) {
    const char *tech_names[MAX_NUM_TECH_LIST];
    int i;
    struct astring list = ASTRING_INIT;

    for (i = 0; i < MAX_NUM_TECH_LIST; i++) {
      if (pnation->init_techs[i] == A_LAST) {
        break;
      }
      tech_names[i] =
        advance_name_translation(advance_by_number(pnation->init_techs[i]));
    }
    astr_build_and_list(&list, tech_names, i);
    PRINT_BREAK();
    if (game.rgame.global_init_techs[0] != A_LAST) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of techs */
                   _("Starts with knowledge of %s in addition to the standard "
                     "starting technologies.\n"), astr_str(&list));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of techs */
                   _("Starts with knowledge of %s.\n"), astr_str(&list));
    }
    astr_free(&list);
  }
  if (pnation->init_units[0]) {
    const struct unit_type *utypes[MAX_NUM_UNIT_LIST];
    int count[MAX_NUM_UNIT_LIST];
    int i, j, n = 0, total = 0;

    /* Count how many of each type there is. */
    for (i = 0; i < MAX_NUM_UNIT_LIST; i++) {
      if (!pnation->init_units[i]) {
        break;
      }
      for (j = 0; j < n; j++) {
        if (pnation->init_units[i] == utypes[j]) {
          count[j]++;
          total++;
          break;
        }
      }
      if (j == n) {
        utypes[n] = pnation->init_units[i];
        count[n] = 1;
        total++;
        n++;
      }
    }
    {
      /* Construct the list of unit types and counts. */
      struct astring utype_names[MAX_NUM_UNIT_LIST];
      struct astring list = ASTRING_INIT;

      for (i = 0; i < n; i++) {
        astr_init(&utype_names[i]);
        if (count[i] > 1) {
          /* TRANS: a unit type followed by a count. For instance,
           * "Fighter (2)" means two Fighters. Count is never 1. 
           * Used in a list. */
          astr_set(&utype_names[i], _("%s (%d)"),
                   utype_name_translation(utypes[i]), count[i]);
        } else {
          astr_set(&utype_names[i], "%s", utype_name_translation(utypes[i]));
        }
      }
      {
        const char *utype_name_strs[MAX_NUM_UNIT_LIST];

        for (i = 0; i < n; i++) {
          utype_name_strs[i] = astr_str(&utype_names[i]);
        }
        astr_build_and_list(&list, utype_name_strs, n);
      }
      for (i = 0; i < n; i++) {
        astr_free(&utype_names[i]);
      }
      PRINT_BREAK();
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of unit types
                    * possibly with counts. Plurality is in total number of
                    * units represented. */
                   PL_("Starts with the following additional unit: %s.\n",
                       "Starts with the following additional units: %s.\n",
                      total), astr_str(&list));
      astr_free(&list);
    }
  }
  if (pnation->init_buildings[0] != B_LAST) {
    const char *impr_names[MAX_NUM_BUILDING_LIST];
    int i;
    struct astring list = ASTRING_INIT;

    for (i = 0; i < MAX_NUM_BUILDING_LIST; i++) {
      if (pnation->init_buildings[i] == B_LAST) {
        break;
      }
      impr_names[i] =
        improvement_name_translation(
          improvement_by_number(pnation->init_buildings[i]));
    }
    astr_build_and_list(&list, impr_names, i);
    PRINT_BREAK();
    if (game.rgame.global_init_buildings[0] != B_LAST) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of improvements */
                   _("First city will get %s for free in addition to the "
                     "standard improvements.\n"), astr_str(&list));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of improvements */
                   _("First city will get %s for free.\n"), astr_str(&list));
    }
    astr_free(&list);
  }

  if (buf[0] != '\0') {
    CATLSTR(buf, bufsz, "\n");
  }
  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf));

  if (user_text && user_text[0] != '\0') {
    if (buf[0] != '\0') {
      CATLSTR(buf, bufsz, "\n");
    }
    CATLSTR(buf, bufsz, user_text);
  }
#undef PRINT_BREAK
}