lib/listlib.php

   1 <?php
   2
   3 // This file is part of Moodle - http://moodle.org/
   4 //
   5 // Moodle is free software: you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation, either version 3 of the License, or
   8 // (at your option) any later version.
   9 //
  10 // Moodle is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14 //
  15 // You should have received a copy of the GNU General Public License
  16 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  17
  18 /**
  19  * Classes for displaying and editing a nested list of items.
  20  *
  21  * Handles functionality for :
  22  *
  23  *    Construction of nested list from db records with some key pointing to a parent id.
  24  *    Display of list with or without editing icons with optional pagination.
  25  *    Reordering of items works across pages.
  26  *    Processing of editing actions on list.
  27  *
  28  * @package    core
  29  * @subpackage lib
  30  * @copyright  Jamie Pratt
  31  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  32  */
  33
  34 defined('MOODLE_INTERNAL') || die();
  35
  36 /**
  37  * Clues to reading this code:
  38  *
  39  * The functions that move things around the tree structure just update the
  40  * database - they don't update the in-memory structure, instead they trigger a
  41  * page reload so everything is rebuilt from scratch.
  42  *
  43  * @package moodlecore
  44  * @copyright Jamie Pratt
  45  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  46  */
  47 abstract class moodle_list {
  48     public $attributes;
  49     public $listitemclassname = 'list_item';
  50
  51     /** @var array of $listitemclassname objects. */
  52     public $items = array();
  53
  54     /** @var string 'ol' or 'ul'. */
  55     public $type;
  56
  57     /** @var list_item or derived class. */
  58     public $parentitem = null;
  59     public $table;
  60     public $fieldnamesparent = 'parent';
  61
  62     /** @var array Records from db, only used in top level list. */
  63     public $records = array();
  64
  65     public $editable;
  66
  67     /** @var array keys are child ids, values are parents. */
  68     public $childparent;
  69
  70 //------------------------------------------------------
  71 //vars used for pagination.
  72     public $page = 0; // 0 means no pagination
  73     public $firstitem = 1;
  74     public $lastitem = 999999;
  75     public $pagecount;
  76     public $paged = false;
  77     public $offset = 0;
  78 //------------------------------------------------------
  79     public $pageurl;
  80     public $pageparamname;
  81
  82     /**
  83      * Constructor.
  84      *
  85      * @param string $type
  86      * @param string $attributes
  87      * @param boolean $editable
  88      * @param moodle_url $pageurl url for this page
  89      * @param integer $page if 0 no pagination. (These three params only used in top level list.)
  90      * @param string $pageparamname name of url param that is used for passing page no
  91      * @param integer $itemsperpage no of top level items.
  92      */
  93     public function __construct($type='ul', $attributes='', $editable = false, $pageurl=null, $page = 0, $pageparamname = 'page', $itemsperpage = 20) {
  94         global $PAGE;
  95
  96         $this->editable = $editable;
  97         $this->attributes = $attributes;
  98         $this->type = $type;
  99         $this->page = $page;
 100         $this->pageparamname = $pageparamname;
 101         $this->itemsperpage = $itemsperpage;
 102         if ($pageurl === null) {
 103             $this->pageurl = new moodle_url($PAGE->url);
 104             $this->pageurl->params(array($this->pageparamname => $this->page));
 105         } else {
 106             $this->pageurl = $pageurl;
 107         }
 108     }
 109
 110     /**
 111      * Returns html string.
 112      *
 113      * @param integer $indent depth of indentation.
 114      */
 115     public function to_html($indent=0, $extraargs=array()) {
 116         if (count($this->items)) {
 117             $tabs = str_repeat("\t", $indent);
 118             $first = true;
 119             $itemiter = 1;
 120             $lastitem = '';
 121             $html = '';
 122
 123             foreach ($this->items as $item) {
 124                 $last = (count($this->items) == $itemiter);
 125                 if ($this->editable) {
 126                     $item->set_icon_html($first, $last, $lastitem);
 127                 }
 128                 if ($itemhtml = $item->to_html($indent+1, $extraargs)) {
 129                     $html .= "$tabs\t<li".((!empty($item->attributes))?(' '.$item->attributes):'').">";
 130                     $html .= $itemhtml;
 131                     $html .= "</li>\n";
 132                 }
 133                 $first = false;
 134                 $lastitem = $item;
 135                 $itemiter++;
 136             }
 137         } else {
 138             $html = '';
 139         }
 140         if ($html) { //if there are list items to display then wrap them in ul / ol tag.
 141             $tabs = str_repeat("\t", $indent);
 142             $html = $tabs.'<'.$this->type.((!empty($this->attributes))?(' '.$this->attributes):'').">\n".$html;
 143             $html .= $tabs."</".$this->type.">\n";
 144         } else {
 145             $html ='';
 146         }
 147         return $html;
 148     }
 149
 150     /**
 151      * Recurse down the tree and find an item by it's id.
 152      *
 153      * @param integer $id
 154      * @param boolean $suppresserror error if not item found?
 155      * @return list_item *copy* or null if item is not found
 156      */
 157     public function find_item($id, $suppresserror = false) {
 158         if (isset($this->items)) {
 159             foreach ($this->items as $key => $child) {
 160                 if ($child->id == $id) {
 161                     return $this->items[$key];
 162                 }
 163             }
 164             foreach (array_keys($this->items) as $key) {
 165                 $thischild = $this->items[$key];
 166                 $ref = $thischild->children->find_item($id, true);//error always reported at top level
 167                 if ($ref !== null) {
 168                     return $ref;
 169                 }
 170             }
 171         }
 172
 173         if (!$suppresserror) {
 174             throw new \moodle_exception('listnoitem');
 175         }
 176         return null;
 177     }
 178
 179     public function add_item($item) {
 180         $this->items[] = $item;
 181     }
 182
 183     public function set_parent($parent) {
 184         $this->parentitem = $parent;
 185     }
 186
 187     /**
 188      * Produces a hierarchical tree of list items from a flat array of records.
 189      * 'parent' field is expected to point to a parent record.
 190      * records are already sorted.
 191      * If the parent field doesn't point to another record in the array then this is
 192      * a top level list
 193      *
 194      * @param integer $offset how many list toplevel items are there in lists before this one
 195      * @return array(boolean, integer) whether there is more than one page, $offset + how many toplevel items where there in this list.
 196      *
 197      */
 198     public function list_from_records($paged = false, $offset = 0) {
 199         $this->paged = $paged;
 200         $this->offset = $offset;
 201         $this->get_records();
 202         $records = $this->records;
 203         $page = $this->page;
 204         if (!empty($page)) {
 205             $this->firstitem = ($page - 1) * $this->itemsperpage;
 206             $this->lastitem = $this->firstitem + $this->itemsperpage - 1;
 207         }
 208         $itemiter = $offset;
 209         //make a simple array which is easier to search
 210         $this->childparent = array();
 211         foreach ($records as $record) {
 212             $this->childparent[$record->id] = $record->parent;
 213         }
 214
 215         //create top level list items and they're responsible for creating their children
 216         foreach ($records as $record) {
 217             if (array_key_exists($record->parent, $this->childparent)) {
 218                 // This record is a child of another record, so it will be dealt
 219                 // with by a call to list_item::create_children, not here.
 220                 continue;
 221             }
 222
 223             $inpage = $itemiter >= $this->firstitem && $itemiter <= $this->lastitem;
 224
 225             // Make list item for top level for all items
 226             // we need the info about the top level items for reordering peers.
 227             if ($this->parentitem !== null) {
 228                 $newattributes = $this->parentitem->attributes;
 229             } else {
 230                 $newattributes = '';
 231             }
 232
 233             $this->items[$itemiter] = new $this->listitemclassname($record, $this, $newattributes, $inpage);
 234
 235             if ($inpage) {
 236                 $this->items[$itemiter]->create_children($records, $this->childparent, $record->id);
 237             } else {
 238                 // Don't recurse down the tree for items that are not on this page
 239                 $this->paged = true;
 240             }
 241
 242             $itemiter++;
 243         }
 244         return array($this->paged, $itemiter);
 245     }
 246
 247     /**
 248      * Should be overriden to return an array of records of list items.
 249      */
 250     public abstract function get_records();
 251
 252     /**
 253      * display list of page numbers for navigation
 254      */
 255     public function display_page_numbers() {
 256         $html = '';
 257         $topcount = count($this->items);
 258         $this->pagecount = (integer) ceil(($topcount + $this->offset)/ QUESTION_PAGE_LENGTH );
 259         if (!empty($this->page) && ($this->paged)) {
 260             $html = "<div class=\"paging\">".get_string('page').":\n";
 261             foreach (range(1,$this->pagecount) as $currentpage) {
 262                 if ($this->page == $currentpage) {
 263                     $html .= " $currentpage \n";
 264                 }
 265                 else {
 266                     $html .= "<a href=\"".$this->pageurl->out(true, array($this->pageparamname => $currentpage))."\">";
 267                     $html .= " $currentpage </a>\n";
 268                 }
 269             }
 270             $html .= "</div>";
 271         }
 272         return $html;
 273     }
 274
 275     /**
 276      * Returns an array of ids of peers of an item.
 277      *
 278      * @param    int itemid - if given, restrict records to those with this parent id.
 279      * @return   array peer ids
 280      */
 281     public function get_items_peers($itemid) {
 282         $itemref = $this->find_item($itemid);
 283         $peerids = $itemref->parentlist->get_child_ids();
 284         return $peerids;
 285     }
 286
 287     /**
 288      * Returns an array of ids of child items.
 289      *
 290      * @return   array peer ids
 291      */
 292     public function get_child_ids() {
 293         $childids = array();
 294         foreach ($this->items as $child) {
 295            $childids[] = $child->id;
 296         }
 297         return $childids;
 298     }
 299
 300     /**
 301      * Returns the value to be used as the parent for the $item when it goes to the top level.
 302      * Override if needed.
 303      *
 304      * @param list_item $item The item which its top level parent is going to be returned.
 305      * @return int
 306      */
 307     public function get_top_level_parent_id($item) {
 308         return 0; // Top level items have no parent.
 309     }
 310
 311     /**
 312      * Move a record up or down
 313      *
 314      * @param string $direction up / down
 315      * @param integer $id
 316      */
 317     public function move_item_up_down($direction, $id) {
 318         $peers = $this->get_items_peers($id);
 319         $itemkey = array_search($id, $peers);
 320         switch ($direction) {
 321             case 'down' :
 322                 if (isset($peers[$itemkey+1])) {
 323                     $olditem = $peers[$itemkey+1];
 324                     $peers[$itemkey+1] = $id;
 325                     $peers[$itemkey] = $olditem;
 326                 } else {
 327                     throw new \moodle_exception('listcantmoveup');
 328                 }
 329                 break;
 330
 331             case 'up' :
 332                 if (isset($peers[$itemkey-1])) {
 333                     $olditem = $peers[$itemkey-1];
 334                     $peers[$itemkey-1] = $id;
 335                     $peers[$itemkey] = $olditem;
 336                 } else {
 337                     throw new \moodle_exception('listcantmovedown');
 338                 }
 339                 break;
 340         }
 341         $this->reorder_peers($peers);
 342     }
 343
 344     public function reorder_peers($peers) {
 345         global $DB;
 346         foreach ($peers as $key => $peer) {
 347             $DB->set_field($this->table, "sortorder", $key, array("id"=>$peer));
 348         }
 349     }
 350
 351     /**
 352      * Moves the item one step up in the tree.
 353      *
 354      * @param int $id an item index.
 355      * @return list_item the item that used to be the parent of the item moved.
 356      */
 357     public function move_item_left($id) {
 358         global $DB;
 359
 360         $item = $this->find_item($id);
 361         if (!isset($item->parentlist->parentitem->parentlist)) {
 362             throw new \moodle_exception('listcantmoveleft');
 363         } else {
 364             $newpeers = $this->get_items_peers($item->parentlist->parentitem->id);
 365             if (isset($item->parentlist->parentitem->parentlist->parentitem)) {
 366                 $newparent = $item->parentlist->parentitem->parentlist->parentitem->id;
 367             } else {
 368                 $newparent = $this->get_top_level_parent_id($item);
 369             }
 370             $DB->set_field($this->table, "parent", $newparent, array("id"=>$item->id));
 371             $oldparentkey = array_search($item->parentlist->parentitem->id, $newpeers);
 372             $neworder = array_merge(array_slice($newpeers, 0, $oldparentkey+1), array($item->id), array_slice($newpeers, $oldparentkey+1));
 373             $this->reorder_peers($neworder);
 374         }
 375         return $item->parentlist->parentitem;
 376     }
 377
 378     /**
 379      * Make item with id $id the child of the peer that is just above it in the sort order.
 380      *
 381      * @param integer $id
 382      */
 383     public function move_item_right($id) {
 384         global $DB;
 385
 386         $peers = $this->get_items_peers($id);
 387         $itemkey = array_search($id, $peers);
 388         if (!isset($peers[$itemkey-1])) {
 389             throw new \moodle_exception('listcantmoveright');
 390         } else {
 391             $DB->set_field($this->table, "parent", $peers[$itemkey-1], array("id"=>$peers[$itemkey]));
 392             $newparent = $this->find_item($peers[$itemkey-1]);
 393             if (isset($newparent->children)) {
 394                 $newpeers = $newparent->children->get_child_ids();
 395             }
 396             if ($newpeers) {
 397                 $newpeers[] = $peers[$itemkey];
 398                 $this->reorder_peers($newpeers);
 399             }
 400         }
 401     }
 402
 403     /**
 404      * process any actions.
 405      *
 406      * @param integer $left id of item to move left
 407      * @param integer $right id of item to move right
 408      * @param integer $moveup id of item to move up
 409      * @param integer $movedown id of item to move down
 410      * @return unknown
 411      */
 412     public function process_actions($left, $right, $moveup, $movedown) {
 413         //should this action be processed by this list object?
 414         if (!(array_key_exists($left, $this->records) || array_key_exists($right, $this->records) || array_key_exists($moveup, $this->records) || array_key_exists($movedown, $this->records))) {
 415             return false;
 416         }
 417         if (!empty($left)) {
 418             $oldparentitem = $this->move_item_left($left);
 419             if ($this->item_is_last_on_page($oldparentitem->id)) {
 420                 // Item has jumped onto the next page, change page when we redirect.
 421                 $this->page ++;
 422                 $this->pageurl->params(array($this->pageparamname => $this->page));
 423             }
 424         } else if (!empty($right)) {
 425             $this->move_item_right($right);
 426             if ($this->item_is_first_on_page($right)) {
 427                 // Item has jumped onto the previous page, change page when we redirect.
 428                 $this->page --;
 429                 $this->pageurl->params(array($this->pageparamname => $this->page));
 430             }
 431         } else if (!empty($moveup)) {
 432             $this->move_item_up_down('up', $moveup);
 433             if ($this->item_is_first_on_page($moveup)) {
 434                 // Item has jumped onto the previous page, change page when we redirect.
 435                 $this->page --;
 436                 $this->pageurl->params(array($this->pageparamname => $this->page));
 437             }
 438         } else if (!empty($movedown)) {
 439             $this->move_item_up_down('down', $movedown);
 440             if ($this->item_is_last_on_page($movedown)) {
 441                 // Item has jumped onto the next page, change page when we redirect.
 442                 $this->page ++;
 443                 $this->pageurl->params(array($this->pageparamname => $this->page));
 444             }
 445         } else {
 446             return false;
 447         }
 448
 449         redirect($this->pageurl);
 450     }
 451
 452     /**
 453      * @param integer $itemid an item id.
 454      * @return boolean Is the item with the given id the first top-level item on
 455      * the current page?
 456      */
 457     public function item_is_first_on_page($itemid) {
 458         return $this->page && isset($this->items[$this->firstitem]) &&
 459                 $itemid == $this->items[$this->firstitem]->id;
 460     }
 461
 462     /**
 463      * @param integer $itemid an item id.
 464      * @return boolean Is the item with the given id the last top-level item on
 465      * the current page?
 466      */
 467     public function item_is_last_on_page($itemid) {
 468         return $this->page && isset($this->items[$this->lastitem]) &&
 469                 $itemid == $this->items[$this->lastitem]->id;
 470     }
 471 }
 472
 473 /**
 474  * @package moodlecore
 475  * @copyright Jamie Pratt
 476  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 477  */
 478 abstract class list_item {
 479     /** @var integer id of record, used if list is editable. */
 480     public $id;
 481
 482     /** @var string name of this item, used if list is editable. */
 483     public $name;
 484
 485     /** @var mixed The object or string representing this item. */
 486     public $item;
 487     public $fieldnamesname = 'name';
 488     public $attributes;
 489     public $display;
 490     public $icons = array();
 491
 492     /** @var moodle_list */
 493     public $parentlist;
 494
 495     /** @var moodle_list Set if there are any children of this listitem. */
 496     public $children;
 497
 498     /**
 499      * Constructor
 500      * @param mixed $item fragment of html for list item or record
 501      * @param object $parent reference to parent of this item
 502      * @param string $attributes attributes for li tag
 503      * @param boolean $display whether this item is displayed. Some items may be loaded so we have a complete
 504      *                              structure in memory to work with for actions but are not displayed.
 505      * @return list_item
 506      */
 507     public function __construct($item, $parent, $attributes = '', $display = true) {
 508         $this->item = $item;
 509         if (is_object($this->item)) {
 510             $this->id = $this->item->id;
 511             $this->name = $this->item->{$this->fieldnamesname};
 512         }
 513         $this->set_parent($parent);
 514         $this->attributes = $attributes;
 515         $parentlistclass = get_class($parent);
 516         $this->children = new $parentlistclass($parent->type, $parent->attributes, $parent->editable, $parent->pageurl, 0);
 517         $this->children->set_parent($this);
 518         $this->display = $display;
 519     }
 520
 521     /**
 522      * Output the html just for this item. Called by to_html which adds html for children.
 523      *
 524      */
 525     public function item_html($extraargs = array()) {
 526         if (is_string($this->item)) {
 527             $html = $this->item;
 528         } elseif (is_object($this->item)) {
 529             //for debug purposes only. You should create a sub class to
 530             //properly handle the record
 531             $html = join(', ', (array)$this->item);
 532         }
 533         return $html;
 534     }
 535
 536     /**
 537      * Returns html
 538      *
 539      * @param integer $indent
 540      * @param array $extraargs any extra data that is needed to print the list item
 541      *                            may be used by sub class.
 542      * @return string html
 543      */
 544     public function to_html($indent = 0, $extraargs = array()) {
 545         if (!$this->display) {
 546             return '';
 547         }
 548         $tabs = str_repeat("\t", $indent);
 549
 550         if (isset($this->children)) {
 551             $childrenhtml = $this->children->to_html($indent+1, $extraargs);
 552         } else {
 553             $childrenhtml = '';
 554         }
 555         return $this->item_html($extraargs).'&nbsp;'.(join('', $this->icons)).(($childrenhtml !='')?("\n".$childrenhtml):'');
 556     }
 557
 558     public function set_icon_html($first, $last, $lastitem) {
 559         global $CFG;
 560         $strmoveup = get_string('moveup');
 561         $strmovedown = get_string('movedown');
 562         $strmoveleft = get_string('maketoplevelitem', 'question');
 563
 564         if (right_to_left()) {   // Exchange arrows on RTL
 565             $rightarrow = 'left';
 566             $leftarrow  = 'right';
 567         } else {
 568             $rightarrow = 'right';
 569             $leftarrow  = 'left';
 570         }
 571
 572         if (isset($this->parentlist->parentitem)) {
 573             $parentitem = $this->parentlist->parentitem;
 574             if (isset($parentitem->parentlist->parentitem)) {
 575                 $action = get_string('makechildof', 'question', $parentitem->parentlist->parentitem->name);
 576             } else {
 577                 $action = $strmoveleft;
 578             }
 579             $url = new moodle_url($this->parentlist->pageurl, (array('sesskey'=>sesskey(), 'left'=>$this->id)));
 580             $this->icons['left'] = $this->image_icon($action, $url, $leftarrow);
 581         } else {
 582             $this->icons['left'] =  $this->image_spacer();
 583         }
 584
 585         if (!$first) {
 586             $url = new moodle_url($this->parentlist->pageurl, (array('sesskey'=>sesskey(), 'moveup'=>$this->id)));
 587             $this->icons['up'] = $this->image_icon($strmoveup, $url, 'up');
 588         } else {
 589             $this->icons['up'] =  $this->image_spacer();
 590         }
 591
 592         if (!$last) {
 593             $url = new moodle_url($this->parentlist->pageurl, (array('sesskey'=>sesskey(), 'movedown'=>$this->id)));
 594             $this->icons['down'] = $this->image_icon($strmovedown, $url, 'down');
 595         } else {
 596             $this->icons['down'] =  $this->image_spacer();
 597         }
 598
 599         if (!empty($lastitem)) {
 600             $makechildof = get_string('makechildof', 'question', $lastitem->name);
 601             $url = new moodle_url($this->parentlist->pageurl, (array('sesskey'=>sesskey(), 'right'=>$this->id)));
 602             $this->icons['right'] = $this->image_icon($makechildof, $url, $rightarrow);
 603         } else {
 604             $this->icons['right'] =  $this->image_spacer();
 605         }
 606     }
 607
 608     public function image_icon($action, $url, $icon) {
 609         global $OUTPUT;
 610         return '<a title="' . s($action) .'" href="'.$url.'">' .
 611                 $OUTPUT->pix_icon('t/' . $icon, $action) . '</a> ';
 612     }
 613
 614     public function image_spacer() {
 615         global $OUTPUT;
 616         return $OUTPUT->spacer();
 617     }
 618
 619     /**
 620      * Recurse down tree creating list_items, called from moodle_list::list_from_records
 621      *
 622      * @param array $records
 623      * @param array $children
 624      * @param integer $thisrecordid
 625      */
 626     public function create_children(&$records, &$children, $thisrecordid) {
 627         //keys where value is $thisrecordid
 628         $thischildren = array_keys($children, $thisrecordid);
 629         foreach ($thischildren as $child) {
 630             $thisclass = get_class($this);
 631             $newlistitem = new $thisclass($records[$child], $this->children, $this->attributes);
 632             $this->children->add_item($newlistitem);
 633             $newlistitem->create_children($records, $children, $records[$child]->id);
 634         }
 635     }
 636
 637     public function set_parent($parent) {
 638         $this->parentlist = $parent;
 639     }
 640 }