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   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   * Base class for a single availability condition.
  19   *
  20   * All condition types must extend this class.
  21   *
  22   * @package core_availability
  23   * @copyright 2014 The Open University
  24   * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25   */
  26  
  27  namespace core_availability;
  28  
  29  defined('MOODLE_INTERNAL') || die();
  30  
  31  /**
  32   * Base class for a single availability condition.
  33   *
  34   * All condition types must extend this class.
  35   *
  36   * The structure of a condition in JSON input data is:
  37   *
  38   * { type:'date', ... }
  39   *
  40   * where 'date' is the name of the plugin (availability_date in this case) and
  41   * ... is arbitrary extra data to be used by the plugin.
  42   *
  43   * Conditions require a constructor with one parameter: $structure. This will
  44   * contain all the JSON data for the condition. If the structure of the data
  45   * is incorrect (e.g. missing fields) then the constructor may throw a
  46   * coding_exception. However, the constructor should cope with all data that
  47   * was previously valid (e.g. if the format changes, old data may still be
  48   * present in a restore, so there should be a default value for any new fields
  49   * and old ones should be handled correctly).
  50   *
  51   * @package core_availability
  52   * @copyright 2014 The Open University
  53   * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  54   */
  55  abstract class condition extends tree_node {
  56  
  57      /**
  58       * Determines whether a particular item is currently available
  59       * according to this availability condition.
  60       *
  61       * If implementations require a course or modinfo, they should use
  62       * the get methods in $info.
  63       *
  64       * The $not option is potentially confusing. This option always indicates
  65       * the 'real' value of NOT. For example, a condition inside a 'NOT AND'
  66       * group will get this called with $not = true, but if you put another
  67       * 'NOT OR' group inside the first group, then a condition inside that will
  68       * be called with $not = false. We need to use the real values, rather than
  69       * the more natural use of the current value at this point inside the tree,
  70       * so that the information displayed to users makes sense.
  71       *
  72       * @param bool $not Set true if we are inverting the condition
  73       * @param info $info Item we're checking
  74       * @param bool $grabthelot Performance hint: if true, caches information
  75       *   required for all course-modules, to make the front page and similar
  76       *   pages work more quickly (works only for current user)
  77       * @param int $userid User ID to check availability for
  78       * @return bool True if available
  79       */
  80      public abstract function is_available($not, info $info, $grabthelot, $userid);
  81  
  82      public function check_available($not, info $info, $grabthelot, $userid) {
  83          // Use is_available, and we always display (at this stage).
  84          $allow = $this->is_available($not, $info, $grabthelot, $userid);
  85          return new result($allow, $this);
  86      }
  87  
  88      public function is_available_for_all($not = false) {
  89          // Default is that all conditions may make something unavailable.
  90          return false;
  91      }
  92  
  93      /**
  94       * Display a representation of this condition (used for debugging).
  95       *
  96       * @return string Text representation of condition
  97       */
  98      public function __toString() {
  99          return '{' . $this->get_type() . ':' . $this->get_debug_string() . '}';
 100      }
 101  
 102      /**
 103       * Gets the type name (e.g. 'date' for availability_date) of plugin.
 104       *
 105       * @return string The type name for this plugin
 106       */
 107      protected function get_type() {
 108          return preg_replace('~^availability_(.*?)\\\\condition$~', '$1', get_class($this));
 109      }
 110  
 111      /**
 112       * Returns a marker indicating that an activity name should be placed in a description.
 113       *
 114       * Gets placeholder text which will be decoded by info::format_info later when we can safely
 115       * display names.
 116       *
 117       * @param int $cmid Course-module id
 118       * @return string Placeholder text
 119       * @since Moodle 3.11.3
 120       */
 121      public static function description_cm_name(int $cmid): string {
 122          return '<AVAILABILITY_CMNAME_' . $cmid . '/>';
 123      }
 124  
 125      /**
 126       * Returns a marker indicating that formatted text should be placed in a description.
 127       *
 128       * Gets placeholder text which will be decoded by info::format_info later when we can safely
 129       * call format_string.
 130       *
 131       * @param string $str Text to be processed with format_string
 132       * @return string Placeholder text
 133       * @since Moodle 3.11.3
 134       */
 135      public static function description_format_string(string $str): string {
 136          return '<AVAILABILITY_FORMAT_STRING>' . htmlspecialchars($str, ENT_NOQUOTES) .
 137                  '</AVAILABILITY_FORMAT_STRING>';
 138      }
 139  
 140      /**
 141       * Returns a marker indicating that some of the description text should be computed at display
 142       * time.
 143       *
 144       * This will result in a call to the get_description_callback_value static function within
 145       * the condition class.
 146       *
 147       * Gets placeholder text which will be decoded by info::format_info later when we can safely
 148       * call most Moodle functions.
 149       *
 150       * @param string[] $params Array of arbitrary parameters
 151       * @return string Placeholder text
 152       * @since Moodle 3.11.3
 153       */
 154      public function description_callback(array $params): string {
 155          $out = '<AVAILABILITY_CALLBACK type="' . $this->get_type() . '">';
 156          $first = true;
 157          foreach ($params as $param) {
 158              if ($first) {
 159                  $first = false;
 160              } else {
 161                  $out .= '<P/>';
 162              }
 163              $out .= htmlspecialchars($param, ENT_NOQUOTES);
 164          }
 165          $out .= '</AVAILABILITY_CALLBACK>';
 166          return $out;
 167      }
 168  
 169      /**
 170       * Obtains a string describing this restriction (whether or not
 171       * it actually applies). Used to obtain information that is displayed to
 172       * students if the activity is not available to them, and for staff to see
 173       * what conditions are.
 174       *
 175       * The $full parameter can be used to distinguish between 'staff' cases
 176       * (when displaying all information about the activity) and 'student' cases
 177       * (when displaying only conditions they don't meet).
 178       *
 179       * If implementations require a course or modinfo, they should use
 180       * the get methods in $info. They should not use any other functions that
 181       * might rely on modinfo, such as format_string.
 182       *
 183       * To work around this limitation, use the functions:
 184       *
 185       * description_cm_name()
 186       * description_format_string()
 187       * description_callback()
 188       *
 189       * These return special markers which will be added to the string and processed
 190       * later after modinfo is complete.
 191       *
 192       * @param bool $full Set true if this is the 'full information' view
 193       * @param bool $not Set true if we are inverting the condition
 194       * @param info $info Item we're checking
 195       * @return string Information string (for admin) about all restrictions on
 196       *   this item
 197       */
 198      public abstract function get_description($full, $not, info $info);
 199  
 200      /**
 201       * Obtains a string describing this restriction, used when there is only
 202       * a single restriction to display. (I.e. this provides a 'short form'
 203       * rather than showing in a list.)
 204       *
 205       * Default behaviour sticks the prefix text, normally displayed above
 206       * the list, in front of the standard get_description call.
 207       *
 208       * If implementations require a course or modinfo, they should use
 209       * the get methods in $info. They should not use any other functions that
 210       * might rely on modinfo, such as format_string.
 211       *
 212       * To work around this limitation, use the functions:
 213       *
 214       * description_cm_name()
 215       * description_format_string()
 216       * description_callback()
 217       *
 218       * These return special markers which will be added to the string and processed
 219       * later after modinfo is complete.
 220       *
 221       * @param bool $full Set true if this is the 'full information' view
 222       * @param bool $not Set true if we are inverting the condition
 223       * @param info $info Item we're checking
 224       * @return string Information string (for admin) about all restrictions on
 225       *   this item
 226       */
 227      public function get_standalone_description($full, $not, info $info) {
 228          return get_string('list_root_and', 'availability') . ' ' .
 229                  $this->get_description($full, $not, $info);
 230      }
 231  
 232      /**
 233       * Obtains a representation of the options of this condition as a string,
 234       * for debugging.
 235       *
 236       * @return string Text representation of parameters
 237       */
 238      protected abstract function get_debug_string();
 239  
 240      public function update_dependency_id($table, $oldid, $newid) {
 241          // By default, assumes there are no dependent ids.
 242          return false;
 243      }
 244  
 245      /**
 246       * If the plugin has been configured to rely on a particular activity's
 247       * completion value, it should return true here. (This is necessary so that
 248       * we know the course page needs to update when that activity becomes
 249       * complete.)
 250       *
 251       * Default implementation returns false.
 252       *
 253       * @param \stdClass $course Moodle course object
 254       * @param int $cmid ID of activity whose completion value is considered
 255       * @return boolean True if the availability of something else may rely on it
 256       */
 257      public static function completion_value_used($course, $cmid) {
 258          return false;
 259      }
 260  }