playout_moggy_choose(): Factor out fillboard_check()

[pachi.git] / playout / moggy.c

/* Playout policy by stochastically applying a fixed set of decision
 * rules in given order - modelled after the intelligent playouts
 * in the Mogo engine. */

#include <assert.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

#define DEBUG
#include "board.h"
#include "debug.h"
#include "joseki/base.h"
#include "mq.h"
#include "pattern3.h"
#include "playout.h"
#include "playout/moggy.h"
#include "random.h"
#include "tactics.h"
#include "uct/prior.h"

#define PLDEBUGL(n) DEBUGL_(p->debug_level, n)

/* Whether to avoid capturing/atariing doomed groups (this is big
 * performance hit and may reduce playouts balance; it does increase
 * the strength, but not quite proportionally to the performance). */
//#define NO_DOOMED_GROUPS


/* Note that the context can be shared by multiple threads! */

struct moggy_policy {
        bool ladders, ladderassess, borderladders, assess_local;
        unsigned int lcapturerate, atarirate, capturerate, patternrate, korate, josekirate;
        unsigned int selfatarirate, alwaysccaprate;
        unsigned int fillboardtries;
        int koage;
        /* Whether to look for patterns around second-to-last move. */
        bool pattern2;
        /* Whether, when self-atari attempt is detected, to play the other
         * group's liberty if that is non-self-atari. */
        bool selfatari_other;

        struct joseki_dict *jdict;
        struct pattern3s patterns;
};


struct group_state {
        enum {
                G_ATARI,
                G_2LIB, /* Unused. */
                G_SAFE /* Unused. */
        } status:2;

        /* Below, we keep track of each trait for each |color_to_play */
        int capturable_ready:2; // is @capturable meaningful?
        int capturable:2;

        int can_countercapture_ready:2;
        int can_countercapture:2;
};

/* Cache of evaluation of various board features. */
struct board_state {
        int bsize2;
        hash_t hash;
        struct group_state *groups; /* [board_size2()], indexed by group_t */
        unsigned char *groups_known; /* Bitmap of known groups. */
};

/* Using board cache: this turns out to be actually a 10% slowdown,
 * since we reuse data in the cache only very little within single
 * move. */
// #define CACHE_STATE
/* Reusing board cache across moves if they are successive on the
 * board; only cache entries within cfg distance 2 of the last move
 * are cleared. */
// #define PERSISTENT_STATE

#ifdef CACHE_STATE
static __thread struct board_state *ss;

static bool
board_state_reuse(struct board_state *s, struct board *b)
{
        /* Decide how much of the board state we can reuse. */
        /* We do not cache ladder decisions, so we don't have
         * to worry about this. */
        coord_t c = b->last_move.coord;

        if (unlikely(is_pass(c))) {
                /* Passes don't change anything. */
                return true;
        }

        if (unlikely(board_at(b, c) == S_NONE)) {
                /* Suicide is hopeless. */
                return false;
        }

        /* XXX: we can make some moves self-atari. */

        if (neighbor_count_at(b, c, S_BLACK) + neighbor_count_at(b, c, S_WHITE) == 0) {
                /* We are not taking off liberties of any other stones. */
                return true;
        }

        return false;
}

static inline struct board_state *
board_state_init(struct board *b)
{
        if (ss) {
                if (ss->bsize2 != board_size2(b)) {
                        free(ss->groups);
                        free(ss->groups_known);
                        free(ss); ss = NULL;
                }
#ifdef PERSISTENT_STATE
                /* Only one stone added to the board, nothing removed. */
                else if (ss->hash == (b->hash ^ hash_at(b, b->last_move.coord, b->last_move.color))) {
                        ss->hash = b->hash;
                        if (likely(board_state_reuse(ss, b)))
                                return ss;
                }
#endif
        }
        if (!ss) {
                ss = malloc2(sizeof(*ss));
                ss->bsize2 = board_size2(b);
                ss->groups = malloc2(board_size2(b) * sizeof(*ss->groups));
                ss->groups_known = malloc2(board_size2(b) / 8 + 1);
        }
        ss->hash = b->hash;
        memset(ss->groups_known, 0, board_size2(b) / 8 + 1);
        return ss;
}

#define group_is_known(s, g) (s->groups_known[g >> 3] & (1 << (g & 7)))
#define group_set_known(s, g) (s->groups_known[g >> 3] |= (1 << (g & 7)))
#define group_trait_ready(s, g, color, gstat, trait) do { \
        if (!group_is_known(s, g)) { \
                memset(&s->groups[g], 0, sizeof(s->groups[g])); \
                group_set_known(s, g); \
        } \
        s->groups[g].status = gstat; \
        s->groups[g].trait ## _ready |= color; \
} while (0)
#define group_trait_is_ready(s, g, color, trait) (s->groups[g].trait ## _ready & color)
#define group_trait_set(s, g, color, trait, val) s->groups[g].trait = (s->groups[g].trait & ~color) | (!!val * color)
#define group_trait_get(s, g, color, trait) (s->groups[g].trait & color)

#else

#define board_state_init(b) NULL
#define group_is_known(s, g) false
#define group_set_known(s, g)
#define group_trait_ready(s, g, color, gstat, trait)
#define group_trait_is_ready(s, g, color, trait) false
#define group_trait_set(s, g, color, trait, val)
#define group_trait_get(s, g, color, trait) false
#endif


static char moggy_patterns_src[][11] = {
        /* hane pattern - enclosing hane */
        "XOX"
        "..."
        "???",
        /* hane pattern - non-cutting hane */
        "XO."
        "..."
        "?.?",
        /* hane pattern - magari */
        "XO?"
        "X.."
        "x.?",
        /* hane pattern - thin hane */
        "XOO"
        "..."
        "?.?" "X",
        /* generic pattern - katatsuke or diagonal attachment; similar to magari */
        ".O."
        "X.."
        "...",
        /* cut1 pattern (kiri) - unprotected cut */
        "XO?"
        "O.o"
        "?o?",
        /* cut1 pattern (kiri) - peeped cut */
        "XO?"
        "O.X"
        "???",
        /* cut2 pattern (de) */
        "?X?"
        "O.O"
        "ooo",
        /* cut keima (not in Mogo) */
        "OX?"
        "o.O"
        "???", /* o?? has some pathological tsumego cases */
        /* side pattern - chase */
        "X.?"
        "O.?"
        "##?",
        /* side pattern - block side cut */
        "OX?"
        "X.O"
        "###",
        /* side pattern - block side connection */
        "?X?"
        "x.O"
        "###",
        /* side pattern - sagari (SUSPICIOUS) */
        "?XO"
        "x.x" /* Mogo has "x.?" */
        "###" /* Mogo has "X" */,
        /* side pattern - throw-in (SUSPICIOUS) */
#if 0
        "?OX"
        "o.O"
        "?##" "X",
#endif
        /* side pattern - cut (SUSPICIOUS) */
        "?OX"
        "X.O"
        "###" /* Mogo has "X" */,
};
#define moggy_patterns_src_n sizeof(moggy_patterns_src) / sizeof(moggy_patterns_src[0])

static inline bool
test_pattern3_here(struct playout_policy *p, struct board *b, struct move *m)
{
        struct moggy_policy *pp = p->data;
        /* Check if 3x3 pattern is matched by given move... */
        if (!pattern3_move_here(&pp->patterns, b, m))
                return false;
        /* ...and the move is not obviously stupid. */
        if (is_bad_selfatari(b, m->color, m->coord))
                return false;
        /* Ladder moves are stupid. */
        group_t atari_neighbor = board_get_atari_neighbor(b, m->coord, m->color);
        if (atari_neighbor && is_ladder(b, m->coord, atari_neighbor, pp->borderladders, pp->ladders))
                return false;
        return true;
}

static void
apply_pattern_here(struct playout_policy *p, struct board *b, coord_t c, enum stone color, struct move_queue *q)
{
        struct move m2 = { .coord = c, .color = color };
        if (board_is_valid_move(b, &m2) && test_pattern3_here(p, b, &m2))
                mq_add(q, c);
}

/* Check if we match any pattern around given move (with the other color to play). */
static void
apply_pattern(struct playout_policy *p, struct board *b, struct move *m, struct move *mm, struct move_queue *q)
{
        /* Suicides do not make any patterns and confuse us. */
        if (board_at(b, m->coord) == S_NONE || board_at(b, m->coord) == S_OFFBOARD)
                return;

        foreach_8neighbor(b, m->coord) {
                apply_pattern_here(p, b, c, stone_other(m->color), q);
        } foreach_8neighbor_end;

        if (mm) { /* Second move for pattern searching */
                foreach_8neighbor(b, mm->coord) {
                        if (coord_is_8adjecent(m->coord, c, b))
                                continue;
                        apply_pattern_here(p, b, c, stone_other(m->color), q);
                } foreach_8neighbor_end;
        }

        if (PLDEBUGL(5))
                mq_print(q, b, "Pattern");
}


static bool
can_play_on_lib(struct playout_policy *p, struct board_state *s,
                struct board *b, group_t g, enum stone to_play)
{
        if (group_is_known(s, g) && group_trait_is_ready(s, g, to_play, capturable)) {
                /* We have already seen this group. */
                assert(s->groups[g].status == G_ATARI);
                if (group_trait_get(s, g, to_play, capturable))
                        return true;
                else
                        return false;
        }

        /* Cache miss. Set up cache entry, default at capturable = false. */
        group_trait_ready(s, g, to_play, G_ATARI, capturable);

        coord_t capture = board_group_info(b, g).lib[0];
        if (PLDEBUGL(6))
                fprintf(stderr, "can capture group %d (%s)?\n",
                        g, coord2sstr(capture, b));
        /* Does playing on the liberty usefully capture the group? */
        if (board_is_valid_play(b, to_play, capture)
            && !is_bad_selfatari(b, to_play, capture)) {
                group_trait_set(s, g, to_play, capturable, true);
                return true;
        }

        return false;
}

/* For given position @c, decide if this is a group that is in danger from
 * @capturer and @to_play can do anything about it (play at the last
 * liberty to either capture or escape). */
/* Note that @to_play is important; e.g. consider snapback, it's good
 * to play at the last liberty by attacker, but not defender. */
static __attribute__((always_inline)) bool
capturable_group(struct playout_policy *p, struct board_state *s,
                 struct board *b, enum stone capturer, coord_t c,
                 enum stone to_play)
{
        group_t g = group_at(b, c);
        if (likely(board_at(b, c) != stone_other(capturer)
                   || board_group_info(b, g).libs > 1))
                return false;

        return can_play_on_lib(p, s, b, g, to_play);
}

/* For given atari group @group owned by @owner, decide if @to_play
 * can save it / keep it in danger by dealing with one of the
 * neighboring groups. */
static bool
can_countercapture(struct playout_policy *p, struct board_state *s,
                   struct board *b, enum stone owner, group_t g,
                   enum stone to_play, struct move_queue *q)
{
        if (b->clen < 2)
                return false;
        if (group_is_known(s, g) && group_trait_is_ready(s, g, to_play, can_countercapture)) {
                /* We have already seen this group. */
                assert(s->groups[g].status == G_ATARI);
                if (group_trait_get(s, g, to_play, can_countercapture)) {
                        if (q) { /* Scan for countercapture liberties. */
                                goto scan;
                        }
                        return true;
                } else {
                        return false;
                }
        }

        /* Cache miss. Set up cache entry, default at can_countercapture = true. */
        group_trait_ready(s, g, to_play, G_ATARI, can_countercapture);
        group_trait_set(s, g, to_play, can_countercapture, true);

scan:;
        unsigned int qmoves_prev = q ? q->moves : 0;

        foreach_in_group(b, g) {
                foreach_neighbor(b, c, {
                        if (!capturable_group(p, s, b, owner, c, to_play))
                                continue;

                        if (!q) {
                                return true;
                        }
                        mq_add(q, board_group_info(b, group_at(b, c)).lib[0]);
                        mq_nodup(q);
                });
        } foreach_in_group_end;

        bool can = q ? q->moves > qmoves_prev : false;
        group_trait_set(s, g, to_play, can_countercapture, can);
        return can;
}

#ifdef NO_DOOMED_GROUPS
static bool
can_be_rescued(struct playout_policy *p, struct board_state *s,
               struct board *b, group_t group, enum stone color)
{
        /* Does playing on the liberty rescue the group? */
        if (can_play_on_lib(p, s, b, group, color))
                return true;

        /* Then, maybe we can capture one of our neighbors? */
        return can_countercapture(p, s, b, color, group, color, NULL);
}
#endif

/* ladder != NULL implies to always enqueue all relevant moves. */
static void
group_atari_check(struct playout_policy *p, struct board *b, group_t group, enum stone to_play,
                  struct move_queue *q, coord_t *ladder, struct board_state *s)
{
        struct moggy_policy *pp = p->data;
        int qmoves_prev = q->moves;

        /* We don't use @to_play almost anywhere since any moves here are good
         * for both defender and attacker. */

        enum stone color = board_at(b, group_base(group));
        coord_t lib = board_group_info(b, group).lib[0];

        assert(color != S_OFFBOARD && color != S_NONE);
        if (PLDEBUGL(5))
                fprintf(stderr, "[%s] atariiiiiiiii %s of color %d\n",
                        coord2sstr(group, b), coord2sstr(lib, b), color);
        assert(board_at(b, lib) == S_NONE);

        /* Can we capture some neighbor? */
        bool ccap = can_countercapture(p, s, b, color, group, to_play, q);
        if (ccap && !ladder && pp->alwaysccaprate > fast_random(100))
                return;

        /* Otherwise, do not save kos. */
        if (group_is_onestone(b, group)
            && neighbor_count_at(b, lib, color) + neighbor_count_at(b, lib, S_OFFBOARD) == 4)
                return;

        /* Do not suicide... */
        if (!can_play_on_lib(p, s, b, group, to_play))
                return;
#ifdef NO_DOOMED_GROUPS
        /* Do not remove group that cannot be saved by the opponent. */
        if (to_play != color && !can_be_rescued(p, s, b, group, color))
                return;
#endif
        if (PLDEBUGL(6))
                fprintf(stderr, "...escape route valid\n");
        
        /* ...or play out ladders. */
        if (is_ladder(b, lib, group, pp->borderladders, pp->ladders)) {
                /* Sometimes we want to keep the ladder move in the
                 * queue in order to discourage it. */
                if (!ladder)
                        return;
                else
                        *ladder = lib;
        }
        if (PLDEBUGL(6))
                fprintf(stderr, "...no ladder\n");

        if (to_play != color) {
                /* We are the attacker! In that case, throw away the moves
                 * that defend our groups, since we can capture the culprit. */
                q->moves = qmoves_prev;
        }

        mq_add(q, lib);
        mq_nodup(q);
}

static void
joseki_check(struct playout_policy *p, struct board *b, enum stone to_play, struct board_state *s, struct move_queue *q)
{
        struct moggy_policy *pp = p->data;
        if (!pp->jdict)
                return;

        for (int i = 0; i < 4; i++) {
                hash_t h = b->qhash[i] & joseki_hash_mask;
                coord_t *cc = pp->jdict->patterns[h].moves[to_play];
                if (!cc) continue;
                for (; !is_pass(*cc); cc++) {
                        if (coord_quadrant(*cc, b) != i)
                                continue;
                        mq_add(q, *cc);
                }
        }

        if (q->moves > 0 && PLDEBUGL(5))
                mq_print(q, b, "Joseki");
}

static void
global_atari_check(struct playout_policy *p, struct board *b, enum stone to_play, struct board_state *s, struct move_queue *q)
{
        if (b->clen == 0)
                return;

        int g_base = fast_random(b->clen);
        for (int g = g_base; g < b->clen; g++) {
                group_atari_check(p, b, group_at(b, group_base(b->c[g])), to_play, q, NULL, s);
                if (q->moves > 0) {
                        /* XXX: Try carrying on. */
                        if (PLDEBUGL(5))
                                mq_print(q, b, "Global atari");
                        return;
                }
        }
        for (int g = 0; g < g_base; g++) {
                group_atari_check(p, b, group_at(b, group_base(b->c[g])), to_play, q, NULL, s);
                if (q->moves > 0) {
                        /* XXX: Try carrying on. */
                        if (PLDEBUGL(5))
                                mq_print(q, b, "Global atari");
                        return;
                }
        }
        return;
}

static void
local_atari_check(struct playout_policy *p, struct board *b, struct move *m, struct board_state *s, struct move_queue *q)
{
        /* Did the opponent play a self-atari? */
        if (board_group_info(b, group_at(b, m->coord)).libs == 1) {
                group_atari_check(p, b, group_at(b, m->coord), stone_other(m->color), q, NULL, s);
        }

        foreach_neighbor(b, m->coord, {
                group_t g = group_at(b, c);
                if (!g || board_group_info(b, g).libs != 1)
                        continue;
                group_atari_check(p, b, g, stone_other(m->color), q, NULL, s);
        });

        if (PLDEBUGL(5))
                mq_print(q, b, "Local atari");
}

static bool
miai_2lib(struct board *b, group_t group, enum stone color)
{
        bool can_connect = false, can_pull_out = false;
        /* We have miai if we can either connect on both libs,
         * or connect on one lib and escape on another. (Just
         * having two escape routes can be risky.) We must make
         * sure that we don't consider following as miai:
         * X X X O
         * X . . O
         * O O X O - left dot would be pull-out, right dot connect */
        foreach_neighbor(b, board_group_info(b, group).lib[0], {
                enum stone cc = board_at(b, c);
                if (cc == S_NONE && cc != board_at(b, board_group_info(b, group).lib[1])) {
                        can_pull_out = true;
                } else if (cc != color) {
                        continue;
                }

                group_t cg = group_at(b, c);
                if (cg && cg != group && board_group_info(b, cg).libs > 1)
                        can_connect = true;
        });
        foreach_neighbor(b, board_group_info(b, group).lib[1], {
                enum stone cc = board_at(b, c);
                if (c == board_group_info(b, group).lib[0])
                        continue;
                if (cc == S_NONE && can_connect) {
                        return true;
                } else if (cc != color) {
                        continue;
                }

                group_t cg = group_at(b, c);
                if (cg && cg != group && board_group_info(b, cg).libs > 1)
                        return (can_connect || can_pull_out);
        });
        return false;
}

static void
check_group_atari(struct board *b, group_t group, enum stone owner,
                  enum stone to_play, struct move_queue *q)
{
        for (int i = 0; i < 2; i++) {
                coord_t lib = board_group_info(b, group).lib[i];
                assert(board_at(b, lib) == S_NONE);
                if (!board_is_valid_play(b, to_play, lib))
                        continue;

                /* Don't play at the spot if it is extremely short
                 * of liberties... */
                /* XXX: This looks harmful, could significantly
                 * prefer atari to throwin:
                 *
                 * XXXOOOOOXX
                 * .OO.....OX
                 * XXXOOOOOOX */
#if 0
                if (neighbor_count_at(b, lib, stone_other(owner)) + immediate_liberty_count(b, lib) < 2)
                        continue;
#endif

                /* If the move is too "lumpy", do not play it:
                 *
                 * #######
                 * ..O.X.X <- always play the left one!
                 * OXXXXXX */
                if (neighbor_count_at(b, lib, stone_other(owner)) + neighbor_count_at(b, lib, S_OFFBOARD) == 3)
                        continue;

#ifdef NO_DOOMED_GROUPS
                /* If the owner can't play at the spot, we don't want
                 * to bother either. */
                if (is_bad_selfatari(b, owner, lib))
                        continue;
#endif

                /* Of course we don't want to play bad selfatari
                 * ourselves, if we are the attacker... */
                if (
#ifdef NO_DOOMED_GROUPS
                    to_play != owner &&
#endif
                    is_bad_selfatari(b, to_play, lib))
                        continue;

                /* Tasty! Crispy! Good! */
                mq_add(q, lib);
                mq_nodup(q);
        }
}

static void
group_2lib_check(struct playout_policy *p, struct board *b, group_t group, enum stone to_play,
                 struct move_queue *q, struct board_state *s)
{
        enum stone color = board_at(b, group_base(group));
        assert(color != S_OFFBOARD && color != S_NONE);

        if (PLDEBUGL(5))
                fprintf(stderr, "[%s] 2lib check of color %d\n",
                        coord2sstr(group, b), color);

        /* Do not try to atari groups that cannot be harmed. */
        if (miai_2lib(b, group, color))
                return;

        check_group_atari(b, group, color, to_play, q);

        /* Can we counter-atari another group, if we are the defender? */
        if (to_play != color)
                return;
        foreach_in_group(b, group) {
                foreach_neighbor(b, c, {
                        if (board_at(b, c) != stone_other(color))
                                continue;
                        group_t g2 = group_at(b, c);
                        if (board_group_info(b, g2).libs == 1) {
                                /* We can capture a neighbor. */
                                mq_add(q, board_group_info(b, g2).lib[0]);
                                continue;
                        }
                        if (board_group_info(b, g2).libs != 2)
                                continue;
                        check_group_atari(b, g2, color, to_play, q);
                });
        } foreach_in_group_end;
}

static void
local_2lib_check(struct playout_policy *p, struct board *b, struct move *m, struct board_state *s, struct move_queue *q)
{
        /* Does the opponent have just two liberties? */
        if (board_group_info(b, group_at(b, m->coord)).libs == 2) {
                group_2lib_check(p, b, group_at(b, m->coord), stone_other(m->color), q, s);
#if 0
                /* We always prefer to take off an enemy chain liberty
                 * before pulling out ourselves. */
                /* XXX: We aren't guaranteed to return to that group
                 * later. */
                if (q->moves)
                        return q->move[fast_random(q->moves)];
#endif
        }

        /* Then he took a third liberty from neighboring chain? */
        foreach_neighbor(b, m->coord, {
                group_t g = group_at(b, c);
                if (!g || board_group_info(b, g).libs != 2)
                        continue;
                group_2lib_check(p, b, g, stone_other(m->color), q, s);
        });

        if (PLDEBUGL(5))
                mq_print(q, b, "Local 2lib");
}

coord_t
fillboard_check(struct playout_policy *p, struct board *b)
{
        struct moggy_policy *pp = p->data;
        unsigned int fbtries = b->flen / 8;
        if (pp->fillboardtries < fbtries)
                fbtries = pp->fillboardtries;

        for (unsigned int i = 0; i < fbtries; i++) {
                coord_t coord = b->f[fast_random(b->flen)];
                if (immediate_liberty_count(b, coord) != 4)
                        continue;
                foreach_diag_neighbor(b, coord) {
                        if (board_at(b, c) != S_NONE)
                                goto next_try;
                } foreach_diag_neighbor_end;
                return coord;
next_try:;
        }
        return pass;
}

coord_t
playout_moggy_choose(struct playout_policy *p, struct board *b, enum stone to_play)
{
        struct moggy_policy *pp = p->data;
        struct board_state *s = board_state_init(b);

        if (PLDEBUGL(5))
                board_print(b, stderr);

        /* Ko fight check */
        if (!is_pass(b->last_ko.coord) && is_pass(b->ko.coord)
            && b->moves - b->last_ko_age < pp->koage
            && pp->korate > fast_random(100)) {
                if (board_is_valid_play(b, to_play, b->last_ko.coord)
                    && !is_bad_selfatari(b, to_play, b->last_ko.coord))
                        return b->last_ko.coord;
        }

        /* Local checks */
        if (!is_pass(b->last_move.coord)) {
                /* Local group in atari? */
                if (pp->lcapturerate > fast_random(100)) {
                        struct move_queue q = { .moves = 0 };
                        local_atari_check(p, b, &b->last_move, s, &q);
                        if (!q.moves > 0)
                                return mq_pick(&q);
                }

                /* Local group can be PUT in atari? */
                if (pp->atarirate > fast_random(100)) {
                        struct move_queue q = { .moves = 0 };
                        local_2lib_check(p, b, &b->last_move, s, &q);
                        if (!q.moves > 0)
                                return mq_pick(&q);
                }

                /* Check for patterns we know */
                if (pp->patternrate > fast_random(100)) {
                        struct move_queue q = { .moves = 0 };
                        apply_pattern(p, b, &b->last_move,
                                          pp->pattern2 && b->last_move2.coord >= 0 ? &b->last_move2 : NULL,
                                          &q);
                        if (!q.moves > 0)
                                return mq_pick(&q);
                }
        }

        /* Global checks */

        /* Any groups in atari? */
        if (pp->capturerate > fast_random(100)) {
                struct move_queue q = { .moves = 0 };
                global_atari_check(p, b, to_play, s, &q);
                if (!q.moves > 0)
                        return mq_pick(&q);
        }

        /* Joseki moves? */
        if (pp->josekirate > fast_random(100)) {
                struct move_queue q = { .moves = 0 };
                joseki_check(p, b, to_play, s, &q);
                if (!q.moves > 0)
                        return mq_pick(&q);
        }

        /* Fill board */
        if (pp->fillboardtries > 0) {
                coord_t c = fillboard_check(p, b);
                if (!is_pass(c))
                        return c;
        }

        return pass;
}


static coord_t
selfatari_cousin(struct board *b, enum stone color, coord_t coord)
{
        group_t groups[4]; int groups_n = 0;
        foreach_neighbor(b, coord, {
                enum stone s = board_at(b, c);
                if (s != color) continue;
                group_t g = group_at(b, c);
                if (board_group_info(b, g).libs == 2)
                        groups[groups_n++] = g;
        });

        if (!groups_n)
                return pass;
        group_t group = groups[fast_random(groups_n)];

        coord_t lib2 = board_group_other_lib(b, group, coord);
        if (is_bad_selfatari(b, color, lib2))
                return pass;
        return lib2;
}

static int
assess_local_bonus(struct playout_policy *p, struct board *board, coord_t a, coord_t b, int games)
{
        struct moggy_policy *pp = p->data;
        if (!pp->assess_local)
                return games;

        int dx = abs(coord_x(a, board) - coord_x(b, board));
        int dy = abs(coord_y(a, board) - coord_y(b, board));
        /* adjecent move, directly or diagonally? */
        if (dx + dy <= 1 + (dx && dy))
                return games;
        else
                return games / 2;
}

void
playout_moggy_assess_group(struct playout_policy *p, struct prior_map *map, group_t g, int games,
                           struct board_state *s)
{
        struct moggy_policy *pp = p->data;
        struct board *b = map->b;
        struct move_queue q; q.moves = 0;

        if (board_group_info(b, g).libs > 2)
                return;

        if (PLDEBUGL(5)) {
                fprintf(stderr, "ASSESS of group %s:\n", coord2sstr(g, b));
                board_print(b, stderr);
        }

        if (board_group_info(b, g).libs == 2) {
                if (!pp->atarirate)
                        return;
                group_2lib_check(p, b, g, map->to_play, &q, s);
                while (q.moves--) {
                        coord_t coord = q.move[q.moves];
                        if (PLDEBUGL(5))
                                fprintf(stderr, "1.0: 2lib %s\n", coord2sstr(coord, b));
                        int assess = assess_local_bonus(p, b, b->last_move.coord, coord, games) / 2;
                        add_prior_value(map, coord, 1, assess);
                }
                return;
        }

        /* This group, sir, is in atari! */

        if (!pp->capturerate && !pp->lcapturerate && !pp->ladderassess)
                return;

        coord_t ladder = pass;
        group_atari_check(p, b, g, map->to_play, &q, &ladder, s);
        while (q.moves--) {
                coord_t coord = q.move[q.moves];

                /* _Never_ play here if this move plays out
                 * a caught ladder. */
                if (coord == ladder && !board_playing_ko_threat(b)) {
                        /* Note that the opposite is not guarded against;
                         * we do not advise against capturing a laddered
                         * group (but we don't encourage it either). Such
                         * a move can simplify tactical situations if we
                         * can afford it. */
                        if (!pp->ladderassess || map->to_play != board_at(b, g))
                                continue;
                        /* FIXME: We give the malus even if this move
                         * captures another group. */
                        if (PLDEBUGL(5))
                                fprintf(stderr, "0.0: ladder %s\n", coord2sstr(coord, b));
                        add_prior_value(map, coord, 0, games);
                        continue;
                }

                if (!pp->capturerate && !pp->lcapturerate)
                        continue;

                if (PLDEBUGL(5))
                        fprintf(stderr, "1.0: atari %s\n", coord2sstr(coord, b));
                int assess = assess_local_bonus(p, b, b->last_move.coord, coord, games) * 2;
                add_prior_value(map, coord, 1, assess);
        }
}

void
playout_moggy_assess_one(struct playout_policy *p, struct prior_map *map, coord_t coord, int games)
{
        struct moggy_policy *pp = p->data;
        struct board *b = map->b;

        if (PLDEBUGL(5)) {
                fprintf(stderr, "ASSESS of move %s:\n", coord2sstr(coord, b));
                board_print(b, stderr);
        }

        /* Is this move a self-atari? */
        if (pp->selfatarirate) {
                if (!board_playing_ko_threat(b) && is_bad_selfatari(b, map->to_play, coord)) {
                        if (PLDEBUGL(5))
                                fprintf(stderr, "0.0: self-atari\n");
                        add_prior_value(map, coord, 0, games);
                        if (!pp->selfatari_other)
                                return;
                        /* If we can play on the other liberty of the
                         * endangered group, do! */
                        coord = selfatari_cousin(b, map->to_play, coord);
                        if (is_pass(coord))
                                return;
                        if (PLDEBUGL(5))
                                fprintf(stderr, "1.0: self-atari redirect %s\n", coord2sstr(coord, b));
                        add_prior_value(map, coord, 1.0, games);
                        return;
                }
        }

        /* Pattern check */
        if (pp->patternrate) {
                struct move m = { .color = map->to_play, .coord = coord };
                if (test_pattern3_here(p, b, &m)) {
                        if (PLDEBUGL(5))
                                fprintf(stderr, "1.0: pattern\n");
                        int assess = assess_local_bonus(p, b, b->last_move.coord, coord, games);
                        add_prior_value(map, coord, 1, assess);
                }
        }

        return;
}

void
playout_moggy_assess(struct playout_policy *p, struct prior_map *map, int games)
{
        struct moggy_policy *pp = p->data;

        struct board_state *s = board_state_init(map->b);

        /* First, go through all endangered groups. */
        if (pp->lcapturerate || pp->capturerate || pp->atarirate || pp->ladderassess)
                for (group_t g = 1; g < board_size2(map->b); g++)
                        if (group_at(map->b, g) == g)
                                playout_moggy_assess_group(p, map, g, games, s);

        /* Then, assess individual moves. */
        if (!pp->patternrate && !pp->selfatarirate)
                return;
        foreach_free_point(map->b) {
                if (map->consider[c])
                        playout_moggy_assess_one(p, map, c, games);
        } foreach_free_point_end;
}

bool
playout_moggy_permit(struct playout_policy *p, struct board *b, struct move *m)
{
        struct moggy_policy *pp = p->data;

        /* The idea is simple for now - never allow self-atari moves.
         * They suck in general, but this also permits us to actually
         * handle seki in the playout stage. */

        if (fast_random(100) >= pp->selfatarirate) {
                if (PLDEBUGL(5))
                        fprintf(stderr, "skipping sar test\n");
                return true;
        }
        bool selfatari = is_bad_selfatari(b, m->color, m->coord);
        if (selfatari) {
                if (PLDEBUGL(5))
                        fprintf(stderr, "__ Prohibiting self-atari %s %s\n",
                                stone2str(m->color), coord2sstr(m->coord, b));
                if (pp->selfatari_other) {
                        /* Ok, try the other liberty of the atari'd group. */
                        coord_t c = selfatari_cousin(b, m->color, m->coord);
                        if (is_pass(c)) return false;
                        if (PLDEBUGL(5))
                                fprintf(stderr, "___ Redirecting to other lib %s\n",
                                        coord2sstr(c, b));
                        m->coord = c;
                        return true;
                }
                return false;
        }
        return true;
}


struct playout_policy *
playout_moggy_init(char *arg, struct board *b, struct joseki_dict *jdict)
{
        struct playout_policy *p = calloc2(1, sizeof(*p));
        struct moggy_policy *pp = calloc2(1, sizeof(*pp));
        p->data = pp;
        p->choose = playout_moggy_choose;
        p->assess = playout_moggy_assess;
        p->permit = playout_moggy_permit;

        pp->jdict = jdict;

        int rate = 90;

        pp->lcapturerate = pp->atarirate = pp->capturerate = pp->patternrate
                        = pp->selfatarirate = pp->josekirate = -1U;
        pp->korate = 0; pp->koage = 4;
        pp->alwaysccaprate = 0;
        pp->ladders = pp->borderladders = true;
        pp->ladderassess = true;
        pp->selfatari_other = true;

        if (arg) {
                char *optspec, *next = arg;
                while (*next) {
                        optspec = next;
                        next += strcspn(next, ":");
                        if (*next) { *next++ = 0; } else { *next = 0; }

                        char *optname = optspec;
                        char *optval = strchr(optspec, '=');
                        if (optval) *optval++ = 0;

                        if (!strcasecmp(optname, "debug") && optval) {
                                p->debug_level = atoi(optval);
                        } else if (!strcasecmp(optname, "lcapturerate") && optval) {
                                pp->lcapturerate = atoi(optval);
                        } else if (!strcasecmp(optname, "atarirate") && optval) {
                                pp->atarirate = atoi(optval);
                        } else if (!strcasecmp(optname, "capturerate") && optval) {
                                pp->capturerate = atoi(optval);
                        } else if (!strcasecmp(optname, "patternrate") && optval) {
                                pp->patternrate = atoi(optval);
                        } else if (!strcasecmp(optname, "selfatarirate") && optval) {
                                pp->selfatarirate = atoi(optval);
                        } else if (!strcasecmp(optname, "korate") && optval) {
                                pp->korate = atoi(optval);
                        } else if (!strcasecmp(optname, "josekirate") && optval) {
                                pp->josekirate = atoi(optval);
                        } else if (!strcasecmp(optname, "alwaysccaprate") && optval) {
                                pp->alwaysccaprate = atoi(optval);
                        } else if (!strcasecmp(optname, "rate") && optval) {
                                rate = atoi(optval);
                        } else if (!strcasecmp(optname, "fillboardtries")) {
                                pp->fillboardtries = atoi(optval);
                        } else if (!strcasecmp(optname, "koage") && optval) {
                                pp->koage = atoi(optval);
                        } else if (!strcasecmp(optname, "ladders")) {
                                pp->ladders = optval && *optval == '0' ? false : true;
                        } else if (!strcasecmp(optname, "borderladders")) {
                                pp->borderladders = optval && *optval == '0' ? false : true;
                        } else if (!strcasecmp(optname, "ladderassess")) {
                                pp->ladderassess = optval && *optval == '0' ? false : true;
                        } else if (!strcasecmp(optname, "assess_local")) {
                                pp->assess_local = optval && *optval == '0' ? false : true;
                        } else if (!strcasecmp(optname, "pattern2")) {
                                pp->pattern2 = optval && *optval == '0' ? false : true;
                        } else if (!strcasecmp(optname, "selfatari_other")) {
                                pp->selfatari_other = optval && *optval == '0' ? false : true;
                        } else {
                                fprintf(stderr, "playout-moggy: Invalid policy argument %s or missing value\n", optname);
                                exit(1);
                        }
                }
        }
        if (pp->lcapturerate == -1U) pp->lcapturerate = rate;
        if (pp->atarirate == -1U) pp->atarirate = rate;
        if (pp->capturerate == -1U) pp->capturerate = rate;
        if (pp->patternrate == -1U) pp->patternrate = rate;
        if (pp->selfatarirate == -1U) pp->selfatarirate = rate;
        if (pp->korate == -1U) pp->korate = rate;
        if (pp->josekirate == -1U) pp->josekirate = rate;
        if (pp->alwaysccaprate == -1U) pp->alwaysccaprate = rate;

        pattern3s_init(&pp->patterns, moggy_patterns_src, moggy_patterns_src_n);

        return p;
}