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Developer Documentation

  • Bug fixes for general core bugs in 3.11.x will end 9 May 2022 (12 months).
  • Bug fixes for security issues in 3.11.x will end 14 November 2022 (18 months).
  • PHP version: minimum PHP 7.3.0 Note: minimum PHP version has increased since Moodle 3.10. PHP 7.4.x is supported too.
  • Differences Between: [Versions 35 and 311] [Versions 36 and 311]

       1  <?php
       2  // This file is part of Moodle - http://moodle.org/
       3  //
       4  // Moodle is free software: you can redistribute it and/or modify
       5  // it under the terms of the GNU General Public License as published by
       6  // the Free Software Foundation, either version 3 of the License, or
       7  // (at your option) any later version.
       8  //
       9  // Moodle is distributed in the hope that it will be useful,
      10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
      11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      12  // GNU General Public License for more details.
      13  //
      14  // You should have received a copy of the GNU General Public License
      15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
      16  
      17  /**
      18   * Book module local lib functions
      19   *
      20   * @package    mod_book
      21   * @copyright  2010-2011 Petr Skoda {@link http://skodak.org}
      22   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
      23   */
      24  
      25  defined('MOODLE_INTERNAL') || die;
      26  
      27  require_once (__DIR__.'/lib.php');
      28  require_once($CFG->libdir.'/filelib.php');
      29  
      30  /**
      31   * The following defines are used to define how the chapters and subchapters of a book should be displayed in that table of contents.
      32   * BOOK_NUM_NONE        No special styling will applied and the editor will be able to do what ever thay want in the title
      33   * BOOK_NUM_NUMBERS     Chapters and subchapters are numbered (1, 1.1, 1.2, 2, ...)
      34   * BOOK_NUM_BULLETS     Subchapters are indented and displayed with bullets
      35   * BOOK_NUM_INDENTED    Subchapters are indented
      36   */
      37  define('BOOK_NUM_NONE',     '0');
      38  define('BOOK_NUM_NUMBERS',  '1');
      39  define('BOOK_NUM_BULLETS',  '2');
      40  define('BOOK_NUM_INDENTED', '3');
      41  
      42  /**
      43   * The following defines are used to define the navigation style used within a book.
      44   * BOOK_LINK_TOCONLY    Only the table of contents is shown, in a side region.
      45   * BOOK_LINK_IMAGE      Arrows link to previous/next/exit pages, in addition to the TOC.
      46   * BOOK_LINK_TEXT       Page names and arrows link to previous/next/exit pages, in addition to the TOC.
      47   */
      48  define ('BOOK_LINK_TOCONLY', '0');
      49  define ('BOOK_LINK_IMAGE', '1');
      50  define ('BOOK_LINK_TEXT', '2');
      51  
      52  /**
      53   * Preload book chapters and fix toc structure if necessary.
      54   *
      55   * Returns array of chapters with standard 'pagenum', 'id, pagenum, subchapter, title, content, contentformat, hidden'
      56   * and extra 'parent, number, subchapters, prev, next'.
      57   * Please note the content/text of chapters is not included.
      58   *
      59   * @param  stdClass $book
      60   * @return array of id=>chapter
      61   */
      62  function book_preload_chapters($book) {
      63      global $DB;
      64      $chapters = $DB->get_records('book_chapters', array('bookid' => $book->id), 'pagenum', 'id, pagenum,
      65              subchapter, title, content, contentformat, hidden');
      66      if (!$chapters) {
      67          return array();
      68      }
      69  
      70      $prev = null;
      71      $prevsub = null;
      72  
      73      $first = true;
      74      $hidesub = true;
      75      $parent = null;
      76      $pagenum = 0; // chapter sort
      77      $i = 0;       // main chapter num
      78      $j = 0;       // subchapter num
      79      foreach ($chapters as $id => $ch) {
      80          $oldch = clone($ch);
      81          $pagenum++;
      82          $ch->pagenum = $pagenum;
      83          if ($first) {
      84              // book can not start with a subchapter
      85              $ch->subchapter = 0;
      86              $first = false;
      87          }
      88          if (!$ch->subchapter) {
      89              if ($ch->hidden) {
      90                  if ($book->numbering == BOOK_NUM_NUMBERS) {
      91                      $ch->number = 'x';
      92                  } else {
      93                      $ch->number = null;
      94                  }
      95              } else {
      96                  $i++;
      97                  $ch->number = $i;
      98              }
      99              $j = 0;
     100              $prevsub = null;
     101              $hidesub = $ch->hidden;
     102              $parent = $ch->id;
     103              $ch->parent = null;
     104              $ch->subchapters = array();
     105          } else {
     106              $ch->parent = $parent;
     107              $ch->subchapters = null;
     108              $chapters[$parent]->subchapters[$ch->id] = $ch->id;
     109              if ($hidesub) {
     110                  // all subchapters in hidden chapter must be hidden too
     111                  $ch->hidden = 1;
     112              }
     113              if ($ch->hidden) {
     114                  if ($book->numbering == BOOK_NUM_NUMBERS) {
     115                      $ch->number = 'x';
     116                  } else {
     117                      $ch->number = null;
     118                  }
     119              } else {
     120                  $j++;
     121                  $ch->number = $j;
     122              }
     123          }
     124  
     125          if ($oldch->subchapter != $ch->subchapter or $oldch->pagenum != $ch->pagenum or $oldch->hidden != $ch->hidden) {
     126              // update only if something changed
     127              $DB->update_record('book_chapters', $ch);
     128          }
     129          $chapters[$id] = $ch;
     130      }
     131  
     132      return $chapters;
     133  }
     134  
     135  /**
     136   * Returns the title for a given chapter
     137   *
     138   * @param int $chid
     139   * @param array $chapters
     140   * @param stdClass $book
     141   * @param context_module $context
     142   * @return string
     143   */
     144  function book_get_chapter_title($chid, $chapters, $book, $context) {
     145      $ch = $chapters[$chid];
     146      $title = trim(format_string($ch->title, true, array('context'=>$context)));
     147      $numbers = array();
     148      if ($book->numbering == BOOK_NUM_NUMBERS) {
     149          if ($ch->parent and $chapters[$ch->parent]->number) {
     150              $numbers[] = $chapters[$ch->parent]->number;
     151          }
     152          if ($ch->number) {
     153              $numbers[] = $ch->number;
     154          }
     155      }
     156  
     157      if ($numbers) {
     158          $title = implode('.', $numbers) . '. ' . $title;
     159      }
     160  
     161      return $title;
     162  }
     163  
     164  /**
     165   * Add the book TOC sticky block to the default region.
     166   *
     167   * @param   array       $chapters   The Chapters in the book
     168   * @param   stdClass    $chapter    The current chapter
     169   * @param   stdClass    $book       The book
     170   * @param   stdClass    $cm         The course module
     171   * @param   bool|null   $edit       Whether the user is editing
     172   */
     173  function book_add_fake_block($chapters, $chapter, $book, $cm, $edit = null) {
     174      global $PAGE, $USER;
     175  
     176      if ($edit === null) {
     177          if (has_capability('mod/book:edit', context_module::instance($cm->id))) {
     178              if (isset($USER->editing)) {
     179                  $edit = $USER->editing;
     180              } else {
     181                  $edit = 0;
     182              }
     183          } else {
     184              $edit = 0;
     185          }
     186      }
     187  
     188      $toc = book_get_toc($chapters, $chapter, $book, $cm, $edit);
     189  
     190      $bc = new block_contents();
     191      $bc->title = get_string('toc', 'mod_book');
     192      $bc->attributes['class'] = 'block block_book_toc';
     193      $bc->content = $toc;
     194  
     195      $defaultregion = $PAGE->blocks->get_default_region();
     196      $PAGE->blocks->add_fake_block($bc, $defaultregion);
     197  }
     198  
     199  /**
     200   * Generate toc structure
     201   *
     202   * @param array $chapters
     203   * @param stdClass $chapter
     204   * @param stdClass $book
     205   * @param stdClass $cm
     206   * @param bool $edit
     207   * @return string
     208   */
     209  function book_get_toc($chapters, $chapter, $book, $cm, $edit) {
     210      global $USER, $OUTPUT;
     211  
     212      $toc = '';
     213      $nch = 0;   // Chapter number
     214      $ns = 0;    // Subchapter number
     215      $first = 1;
     216  
     217      $context = context_module::instance($cm->id);
     218      $viewhidden = has_capability('mod/book:viewhiddenchapters', $context);
     219  
     220      switch ($book->numbering) {
     221          case BOOK_NUM_NONE:
     222              $toc .= html_writer::start_tag('div', array('class' => 'book_toc book_toc_none clearfix'));
     223              break;
     224          case BOOK_NUM_NUMBERS:
     225              $toc .= html_writer::start_tag('div', array('class' => 'book_toc book_toc_numbered clearfix'));
     226              break;
     227          case BOOK_NUM_BULLETS:
     228              $toc .= html_writer::start_tag('div', array('class' => 'book_toc book_toc_bullets clearfix'));
     229              break;
     230          case BOOK_NUM_INDENTED:
     231              $toc .= html_writer::start_tag('div', array('class' => 'book_toc book_toc_indented clearfix'));
     232              break;
     233      }
     234  
     235      if ($edit) { // Editing on (Teacher's TOC).
     236          $toc .= html_writer::start_tag('ul');
     237          $i = 0;
     238          foreach ($chapters as $ch) {
     239              $i++;
     240              $title = trim(format_string($ch->title, true, array('context' => $context)));
     241              $titleunescaped = trim(format_string($ch->title, true, array('context' => $context, 'escape' => false)));
     242              $titleout = $title;
     243  
     244              if (!$ch->subchapter) {
     245  
     246                  if ($first) {
     247                      $toc .= html_writer::start_tag('li');
     248                  } else {
     249                      $toc .= html_writer::end_tag('ul');
     250                      $toc .= html_writer::end_tag('li');
     251                      $toc .= html_writer::start_tag('li');
     252                  }
     253  
     254                  if (!$ch->hidden) {
     255                      $nch++;
     256                      $ns = 0;
     257                      if ($book->numbering == BOOK_NUM_NUMBERS) {
     258                          $title = "$nch. $title";
     259                          $titleout = $title;
     260                      }
     261                  } else {
     262                      if ($book->numbering == BOOK_NUM_NUMBERS) {
     263                          $title = "x. $title";
     264                      }
     265                      $titleout = html_writer::tag('span', $title, array('class' => 'dimmed_text'));
     266                  }
     267              } else {
     268  
     269                  if ($first) {
     270                      $toc .= html_writer::start_tag('li');
     271                      $toc .= html_writer::start_tag('ul');
     272                      $toc .= html_writer::start_tag('li');
     273                  } else {
     274                      $toc .= html_writer::start_tag('li');
     275                  }
     276  
     277                  if (!$ch->hidden) {
     278                      $ns++;
     279                      if ($book->numbering == BOOK_NUM_NUMBERS) {
     280                          $title = "$nch.$ns. $title";
     281                          $titleout = $title;
     282                      }
     283                  } else {
     284                      if ($book->numbering == BOOK_NUM_NUMBERS) {
     285                          if (empty($chapters[$ch->parent]->hidden)) {
     286                              $title = "$nch.x. $title";
     287                          } else {
     288                              $title = "x.x. $title";
     289                          }
     290                      }
     291                      $titleout = html_writer::tag('span', $title, array('class' => 'dimmed_text'));
     292                  }
     293              }
     294              $toc .= html_writer::start_tag('div', array('class' => 'd-flex'));
     295              if ($ch->id == $chapter->id) {
     296                  $toc .= html_writer::tag('strong', $titleout, array('class' => 'text-truncate'));
     297              } else {
     298                  $toc .= html_writer::link(new moodle_url('view.php', array('id' => $cm->id, 'chapterid' => $ch->id)), $titleout,
     299                      array('title' => $titleunescaped, 'class' => 'text-truncate'));
     300              }
     301  
     302              $toc .= html_writer::start_tag('div', array('class' => 'action-list d-flex ml-auto'));
     303              if ($i != 1) {
     304                  $toc .= html_writer::link(new moodle_url('move.php', array('id' => $cm->id, 'chapterid' => $ch->id, 'up' => '1', 'sesskey' => $USER->sesskey)),
     305                          $OUTPUT->pix_icon('t/up', get_string('movechapterup', 'mod_book', $title)),
     306                          array('title' => get_string('movechapterup', 'mod_book', $titleunescaped)));
     307              }
     308              if ($i != count($chapters)) {
     309                  $toc .= html_writer::link(new moodle_url('move.php', array('id' => $cm->id, 'chapterid' => $ch->id, 'up' => '0', 'sesskey' => $USER->sesskey)),
     310                          $OUTPUT->pix_icon('t/down', get_string('movechapterdown', 'mod_book', $title)),
     311                          array('title' => get_string('movechapterdown', 'mod_book', $titleunescaped)));
     312              }
     313              $toc .= html_writer::link(new moodle_url('edit.php', array('cmid' => $cm->id, 'id' => $ch->id)),
     314                      $OUTPUT->pix_icon('t/edit', get_string('editchapter', 'mod_book', $title)),
     315                      array('title' => get_string('editchapter', 'mod_book', $titleunescaped)));
     316  
     317              $deleteaction = new confirm_action(get_string('deletechapter', 'mod_book', $titleunescaped));
     318              $toc .= $OUTPUT->action_icon(
     319                      new moodle_url('delete.php', [
     320                              'id'        => $cm->id,
     321                              'chapterid' => $ch->id,
     322                              'sesskey'   => sesskey(),
     323                              'confirm'   => 1,
     324                          ]),
     325                      new pix_icon('t/delete', get_string('deletechapter', 'mod_book', $title)),
     326                      $deleteaction,
     327                      ['title' => get_string('deletechapter', 'mod_book', $titleunescaped)]
     328                  );
     329  
     330              if ($ch->hidden) {
     331                  $toc .= html_writer::link(new moodle_url('show.php', array('id' => $cm->id, 'chapterid' => $ch->id, 'sesskey' => $USER->sesskey)),
     332                          $OUTPUT->pix_icon('t/show', get_string('showchapter', 'mod_book', $title)),
     333                          array('title' => get_string('showchapter', 'mod_book', $titleunescaped)));
     334              } else {
     335                  $toc .= html_writer::link(new moodle_url('show.php', array('id' => $cm->id, 'chapterid' => $ch->id, 'sesskey' => $USER->sesskey)),
     336                          $OUTPUT->pix_icon('t/hide', get_string('hidechapter', 'mod_book', $title)),
     337                          array('title' => get_string('hidechapter', 'mod_book', $titleunescaped)));
     338              }
     339  
     340              $buttontitle = get_string('addafterchapter', 'mod_book', ['title' => $ch->title]);
     341              $toc .= html_writer::link(new moodle_url('edit.php', array('cmid' => $cm->id, 'pagenum' => $ch->pagenum, 'subchapter' => $ch->subchapter)),
     342                                              $OUTPUT->pix_icon('add', $buttontitle, 'mod_book'), array('title' => $buttontitle));
     343              $toc .= html_writer::end_tag('div');
     344              $toc .= html_writer::end_tag('div');
     345  
     346              if (!$ch->subchapter) {
     347                  $toc .= html_writer::start_tag('ul');
     348              } else {
     349                  $toc .= html_writer::end_tag('li');
     350              }
     351              $first = 0;
     352          }
     353  
     354          $toc .= html_writer::end_tag('ul');
     355          $toc .= html_writer::end_tag('li');
     356          $toc .= html_writer::end_tag('ul');
     357  
     358      } else { // Editing off. Normal students, teachers view.
     359          $toc .= html_writer::start_tag('ul');
     360          foreach ($chapters as $ch) {
     361              $title = trim(format_string($ch->title, true, array('context'=>$context)));
     362              $titleunescaped = trim(format_string($ch->title, true, array('context' => $context, 'escape' => false)));
     363              if (!$ch->hidden || ($ch->hidden && $viewhidden)) {
     364                  if (!$ch->subchapter) {
     365                      $nch++;
     366                      $ns = 0;
     367  
     368                      if ($first) {
     369                          $toc .= html_writer::start_tag('li');
     370                      } else {
     371                          $toc .= html_writer::end_tag('ul');
     372                          $toc .= html_writer::end_tag('li');
     373                          $toc .= html_writer::start_tag('li');
     374                      }
     375  
     376                      if ($book->numbering == BOOK_NUM_NUMBERS) {
     377                            $title = "$nch. $title";
     378                      }
     379                  } else {
     380                      $ns++;
     381  
     382                      if ($first) {
     383                          $toc .= html_writer::start_tag('li');
     384                          $toc .= html_writer::start_tag('ul');
     385                          $toc .= html_writer::start_tag('li');
     386                      } else {
     387                          $toc .= html_writer::start_tag('li');
     388                      }
     389  
     390                      if ($book->numbering == BOOK_NUM_NUMBERS) {
     391                            $title = "$nch.$ns. $title";
     392                      }
     393                  }
     394  
     395                  $cssclass = ($ch->hidden && $viewhidden) ? 'dimmed_text' : '';
     396  
     397                  if ($ch->id == $chapter->id) {
     398                      $toc .= html_writer::tag('strong', $title, array('class' => $cssclass));
     399                  } else {
     400                      $toc .= html_writer::link(new moodle_url('view.php',
     401                                                array('id' => $cm->id, 'chapterid' => $ch->id)),
     402                                                $title, array('title' => s($titleunescaped), 'class' => $cssclass));
     403                  }
     404  
     405                  if (!$ch->subchapter) {
     406                      $toc .= html_writer::start_tag('ul');
     407                  } else {
     408                      $toc .= html_writer::end_tag('li');
     409                  }
     410  
     411                  $first = 0;
     412              }
     413          }
     414  
     415          $toc .= html_writer::end_tag('ul');
     416          $toc .= html_writer::end_tag('li');
     417          $toc .= html_writer::end_tag('ul');
     418  
     419      }
     420  
     421      $toc .= html_writer::end_tag('div');
     422  
     423      $toc = str_replace('<ul></ul>', '', $toc); // Cleanup of invalid structures.
     424  
     425      return $toc;
     426  }
     427  
     428  /**
     429   * Returns book chapters tagged with a specified tag.
     430   *
     431   * This is a callback used by the tag area mod_book/book_chapters to search for book chapters
     432   * tagged with a specific tag.
     433   *
     434   * @param core_tag_tag $tag
     435   * @param bool $exclusivemode if set to true it means that no other entities tagged with this tag
     436   *             are displayed on the page and the per-page limit may be bigger
     437   * @param int $fromctx context id where the link was displayed, may be used by callbacks
     438   *            to display items in the same context first
     439   * @param int $ctx context id where to search for records
     440   * @param bool $rec search in subcontexts as well
     441   * @param int $page 0-based number of page being displayed
     442   * @return \core_tag\output\tagindex
     443   */
     444  function mod_book_get_tagged_chapters($tag, $exclusivemode = false, $fromctx = 0, $ctx = 0, $rec = true, $page = 0) {
     445      global $OUTPUT;
     446      $perpage = $exclusivemode ? 20 : 5;
     447  
     448      // Build the SQL query.
     449      $ctxselect = context_helper::get_preload_record_columns_sql('ctx');
     450      $query = "SELECT bc.id, bc.title, bc.bookid, bc.hidden,
     451                      cm.id AS cmid, c.id AS courseid, c.shortname, c.fullname, $ctxselect
     452                  FROM {book_chapters} bc
     453                  JOIN {book} b ON b.id = bc.bookid
     454                  JOIN {modules} m ON m.name='book'
     455                  JOIN {course_modules} cm ON cm.module = m.id AND cm.instance = b.id
     456                  JOIN {tag_instance} tt ON bc.id = tt.itemid
     457                  JOIN {course} c ON cm.course = c.id
     458                  JOIN {context} ctx ON ctx.instanceid = cm.id AND ctx.contextlevel = :coursemodulecontextlevel
     459                 WHERE tt.itemtype = :itemtype AND tt.tagid = :tagid AND tt.component = :component
     460                   AND cm.deletioninprogress = 0
     461                   AND bc.id %ITEMFILTER% AND c.id %COURSEFILTER%";
     462  
     463      $params = array('itemtype' => 'book_chapters', 'tagid' => $tag->id, 'component' => 'mod_book',
     464                      'coursemodulecontextlevel' => CONTEXT_MODULE);
     465  
     466      if ($ctx) {
     467          $context = $ctx ? context::instance_by_id($ctx) : context_system::instance();
     468          $query .= $rec ? ' AND (ctx.id = :contextid OR ctx.path LIKE :path)' : ' AND ctx.id = :contextid';
     469          $params['contextid'] = $context->id;
     470          $params['path'] = $context->path.'/%';
     471      }
     472  
     473      $query .= " ORDER BY ";
     474      if ($fromctx) {
     475          // In order-clause specify that modules from inside "fromctx" context should be returned first.
     476          $fromcontext = context::instance_by_id($fromctx);
     477          $query .= ' (CASE WHEN ctx.id = :fromcontextid OR ctx.path LIKE :frompath THEN 0 ELSE 1 END),';
     478          $params['fromcontextid'] = $fromcontext->id;
     479          $params['frompath'] = $fromcontext->path.'/%';
     480      }
     481      $query .= ' c.sortorder, cm.id, bc.id';
     482  
     483      $totalpages = $page + 1;
     484  
     485      // Use core_tag_index_builder to build and filter the list of items.
     486      $builder = new core_tag_index_builder('mod_book', 'book_chapters', $query, $params, $page * $perpage, $perpage + 1);
     487      while ($item = $builder->has_item_that_needs_access_check()) {
     488          context_helper::preload_from_record($item);
     489          $courseid = $item->courseid;
     490          if (!$builder->can_access_course($courseid)) {
     491              $builder->set_accessible($item, false);
     492              continue;
     493          }
     494          $modinfo = get_fast_modinfo($builder->get_course($courseid));
     495          // Set accessibility of this item and all other items in the same course.
     496          $builder->walk(function ($taggeditem) use ($courseid, $modinfo, $builder) {
     497              if ($taggeditem->courseid == $courseid) {
     498                  $accessible = false;
     499                  if (($cm = $modinfo->get_cm($taggeditem->cmid)) && $cm->uservisible) {
     500                      if (empty($taggeditem->hidden)) {
     501                          $accessible = true;
     502                      } else {
     503                          $accessible = has_capability('mod/book:viewhiddenchapters', context_module::instance($cm->id));
     504                      }
     505                  }
     506                  $builder->set_accessible($taggeditem, $accessible);
     507              }
     508          });
     509      }
     510  
     511      $items = $builder->get_items();
     512      if (count($items) > $perpage) {
     513          $totalpages = $page + 2; // We don't need exact page count, just indicate that the next page exists.
     514          array_pop($items);
     515      }
     516  
     517      // Build the display contents.
     518      if ($items) {
     519          $tagfeed = new core_tag\output\tagfeed();
     520          foreach ($items as $item) {
     521              context_helper::preload_from_record($item);
     522              $modinfo = get_fast_modinfo($item->courseid);
     523              $cm = $modinfo->get_cm($item->cmid);
     524              $pageurl = new moodle_url('/mod/book/view.php', array('chapterid' => $item->id, 'b' => $item->bookid));
     525              $pagename = format_string($item->title, true, array('context' => context_module::instance($item->cmid)));
     526              $pagename = html_writer::link($pageurl, $pagename);
     527              $courseurl = course_get_url($item->courseid, $cm->sectionnum);
     528              $cmname = html_writer::link($cm->url, $cm->get_formatted_name());
     529              $coursename = format_string($item->fullname, true, array('context' => context_course::instance($item->courseid)));
     530              $coursename = html_writer::link($courseurl, $coursename);
     531              $icon = html_writer::link($pageurl, html_writer::empty_tag('img', array('src' => $cm->get_icon_url())));
     532              $tagfeed->add($icon, $pagename, $cmname.'<br>'.$coursename);
     533          }
     534  
     535          $content = $OUTPUT->render_from_template('core_tag/tagfeed',
     536              $tagfeed->export_for_template($OUTPUT));
     537  
     538          return new core_tag\output\tagindex($tag, 'mod_book', 'book_chapters', $content,
     539              $exclusivemode, $fromctx, $ctx, $rec, $page, $totalpages);
     540      }
     541  }
     542  
     543  /**
     544   * File browsing support class
     545   *
     546   * @copyright  2010-2011 Petr Skoda {@link http://skodak.org}
     547   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
     548   */
     549  class book_file_info extends file_info {
     550      /** @var stdClass Course object */
     551      protected $course;
     552      /** @var stdClass Course module object */
     553      protected $cm;
     554      /** @var array Available file areas */
     555      protected $areas;
     556      /** @var string File area to browse */
     557      protected $filearea;
     558  
     559      /**
     560       * Constructor
     561       *
     562       * @param file_browser $browser file_browser instance
     563       * @param stdClass $course course object
     564       * @param stdClass $cm course module object
     565       * @param stdClass $context module context
     566       * @param array $areas available file areas
     567       * @param string $filearea file area to browse
     568       */
     569      public function __construct($browser, $course, $cm, $context, $areas, $filearea) {
     570          parent::__construct($browser, $context);
     571          $this->course   = $course;
     572          $this->cm       = $cm;
     573          $this->areas    = $areas;
     574          $this->filearea = $filearea;
     575      }
     576  
     577      /**
     578       * Returns list of standard virtual file/directory identification.
     579       * The difference from stored_file parameters is that null values
     580       * are allowed in all fields
     581       * @return array with keys contextid, filearea, itemid, filepath and filename
     582       */
     583      public function get_params() {
     584          return array('contextid'=>$this->context->id,
     585                       'component'=>'mod_book',
     586                       'filearea' =>$this->filearea,
     587                       'itemid'   =>null,
     588                       'filepath' =>null,
     589                       'filename' =>null);
     590      }
     591  
     592      /**
     593       * Returns localised visible name.
     594       * @return string
     595       */
     596      public function get_visible_name() {
     597          return $this->areas[$this->filearea];
     598      }
     599  
     600      /**
     601       * Can I add new files or directories?
     602       * @return bool
     603       */
     604      public function is_writable() {
     605          return false;
     606      }
     607  
     608      /**
     609       * Is directory?
     610       * @return bool
     611       */
     612      public function is_directory() {
     613          return true;
     614      }
     615  
     616      /**
     617       * Returns list of children.
     618       * @return array of file_info instances
     619       */
     620      public function get_children() {
     621          return $this->get_filtered_children('*', false, true);
     622      }
     623  
     624      /**
     625       * Help function to return files matching extensions or their count
     626       *
     627       * @param string|array $extensions, either '*' or array of lowercase extensions, i.e. array('.gif','.jpg')
     628       * @param bool|int $countonly if false returns the children, if an int returns just the
     629       *    count of children but stops counting when $countonly number of children is reached
     630       * @param bool $returnemptyfolders if true returns items that don't have matching files inside
     631       * @return array|int array of file_info instances or the count
     632       */
     633      private function get_filtered_children($extensions = '*', $countonly = false, $returnemptyfolders = false) {
     634          global $DB;
     635          $params = array('contextid' => $this->context->id,
     636              'component' => 'mod_book',
     637              'filearea' => $this->filearea,
     638              'bookid' => $this->cm->instance);
     639          $sql = 'SELECT DISTINCT bc.id, bc.pagenum
     640                      FROM {files} f, {book_chapters} bc
     641                      WHERE f.contextid = :contextid
     642                      AND f.component = :component
     643                      AND f.filearea = :filearea
     644                      AND bc.bookid = :bookid
     645                      AND bc.id = f.itemid';
     646          if (!$returnemptyfolders) {
     647              $sql .= ' AND filename <> :emptyfilename';
     648              $params['emptyfilename'] = '.';
     649          }
     650          list($sql2, $params2) = $this->build_search_files_sql($extensions, 'f');
     651          $sql .= ' '.$sql2;
     652          $params = array_merge($params, $params2);
     653          if ($countonly === false) {
     654              $sql .= ' ORDER BY bc.pagenum';
     655          }
     656  
     657          $rs = $DB->get_recordset_sql($sql, $params);
     658          $children = array();
     659          foreach ($rs as $record) {
     660              if ($child = $this->browser->get_file_info($this->context, 'mod_book', $this->filearea, $record->id)) {
     661                  if ($returnemptyfolders || $child->count_non_empty_children($extensions)) {
     662                      $children[] = $child;
     663                  }
     664              }
     665              if ($countonly !== false && count($children) >= $countonly) {
     666                  break;
     667              }
     668          }
     669          $rs->close();
     670          if ($countonly !== false) {
     671              return count($children);
     672          }
     673          return $children;
     674      }
     675  
     676      /**
     677       * Returns list of children which are either files matching the specified extensions
     678       * or folders that contain at least one such file.
     679       *
     680       * @param string|array $extensions, either '*' or array of lowercase extensions, i.e. array('.gif','.jpg')
     681       * @return array of file_info instances
     682       */
     683      public function get_non_empty_children($extensions = '*') {
     684          return $this->get_filtered_children($extensions, false);
     685      }
     686  
     687      /**
     688       * Returns the number of children which are either files matching the specified extensions
     689       * or folders containing at least one such file.
     690       *
     691       * @param string|array $extensions, for example '*' or array('.gif','.jpg')
     692       * @param int $limit stop counting after at least $limit non-empty children are found
     693       * @return int
     694       */
     695      public function count_non_empty_children($extensions = '*', $limit = 1) {
     696          return $this->get_filtered_children($extensions, $limit);
     697      }
     698  
     699      /**
     700       * Returns parent file_info instance
     701       * @return file_info or null for root
     702       */
     703      public function get_parent() {
     704          return $this->browser->get_file_info($this->context);
     705      }
     706  }