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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   * Data registry business logic methods. Mostly internal stuff.
  19   *
  20   * All methods should be considered part of the internal tool_dataprivacy API
  21   * unless something different is specified.
  22   *
  23   * @package    tool_dataprivacy
  24   * @copyright  2018 David Monllao
  25   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  26   */
  27  
  28  namespace tool_dataprivacy;
  29  
  30  use coding_exception;
  31  use core\persistent;
  32  
  33  defined('MOODLE_INTERNAL') || die();
  34  
  35  /**
  36   * Data registry business logic methods. Mostly internal stuff.
  37   *
  38   * @copyright  2018 David Monllao
  39   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  40   */
  41  class data_registry {
  42      /**
  43       * Returns purpose and category var names from a context class name
  44       *
  45       * @param string $classname The context level's class.
  46       * @param string $pluginname The name of the plugin associated with the context level.
  47       * @return string[]
  48       */
  49      public static function var_names_from_context($classname, $pluginname = '') {
  50          // Unfortunately authors of privacy API did not expect that we would be
  51          // on day fixing auto-loading of context classes.
  52          // The best way would have been probably level numbers at the end of vars,
  53          // but it is probably too late to fix it.
  54          $classname = preg_replace('/^[a-z0-9_]+\\\\context\\\\/', 'context_', $classname);
  55  
  56          $pluginname = trim($pluginname ?? '');
  57          if (!empty($pluginname)) {
  58              $categoryvar = $classname . '_' . $pluginname . '_category';
  59              $purposevar = $classname . '_' . $pluginname . '_purpose';
  60          } else {
  61              $categoryvar = $classname . '_category';
  62              $purposevar = $classname . '_purpose';
  63          }
  64          return [
  65              $purposevar,
  66              $categoryvar
  67          ];
  68      }
  69  
  70      /**
  71       * Returns the default purpose id and category id for the provided context level.
  72       *
  73       * The caller code is responsible of checking that $contextlevel is an integer.
  74       *
  75       * @param int $contextlevel The context level.
  76       * @param string $pluginname The name of the plugin associated with the context level.
  77       * @return int[]|false[]
  78       */
  79      public static function get_defaults($contextlevel, $pluginname = '') {
  80          $classname = \context_helper::get_class_for_level($contextlevel);
  81          list($purposevar, $categoryvar) = self::var_names_from_context($classname, $pluginname);
  82  
  83          $purposeid = get_config('tool_dataprivacy', $purposevar);
  84          $categoryid = get_config('tool_dataprivacy', $categoryvar);
  85  
  86          if (!empty($pluginname)) {
  87              list($purposevar, $categoryvar) = self::var_names_from_context($classname);
  88              // If the plugin-level doesn't have a default purpose set, try the context level.
  89              if ($purposeid == false) {
  90                  $purposeid = get_config('tool_dataprivacy', $purposevar);
  91              }
  92  
  93              // If the plugin-level doesn't have a default category set, try the context level.
  94              if ($categoryid == false) {
  95                  $categoryid = get_config('tool_dataprivacy', $categoryvar);
  96              }
  97          }
  98  
  99          if (empty($purposeid)) {
 100              $purposeid = context_instance::NOTSET;
 101          }
 102          if (empty($categoryid)) {
 103              $categoryid = context_instance::NOTSET;
 104          }
 105  
 106          return [$purposeid, $categoryid];
 107      }
 108  
 109      /**
 110       * Are data registry defaults set?
 111       *
 112       * At least the system defaults need to be set.
 113       *
 114       * @return bool
 115       */
 116      public static function defaults_set() {
 117          list($purposeid, $categoryid) = self::get_defaults(CONTEXT_SYSTEM);
 118          if (empty($purposeid) || empty($categoryid)) {
 119              return false;
 120          }
 121          return true;
 122      }
 123  
 124      /**
 125       * Returns all site categories that are visible to the current user.
 126       *
 127       * @return \core_course_category[]
 128       */
 129      public static function get_site_categories() {
 130          global $DB;
 131  
 132          if (method_exists('\core_course_category', 'get_all')) {
 133              $categories = \core_course_category::get_all(['returnhidden' => true]);
 134          } else {
 135              // Fallback (to be removed once this gets integrated into master).
 136              $ids = $DB->get_fieldset_select('course_categories', 'id', '');
 137              $categories = \core_course_category::get_many($ids);
 138          }
 139  
 140          foreach ($categories as $key => $category) {
 141              if (!$category->is_uservisible()) {
 142                  unset($categories[$key]);
 143              }
 144          }
 145          return $categories;
 146      }
 147  
 148      /**
 149       * Returns the roles assigned to the provided level.
 150       *
 151       * Important to note that it returns course-level assigned roles
 152       * if the provided context level is below course.
 153       *
 154       * @param \context $context
 155       * @return array
 156       */
 157      public static function get_subject_scope(\context $context) {
 158  
 159          if ($contextcourse = $context->get_course_context(false)) {
 160              // Below course level we look at module or block level roles + course-assigned roles.
 161              $courseroles = get_roles_used_in_context($contextcourse, false);
 162              $roles = $courseroles + get_roles_used_in_context($context, false);
 163          } else {
 164              // We list category + system for others (we don't work with user instances so no need to work about them).
 165              $roles = get_roles_used_in_context($context);
 166          }
 167  
 168          return array_map(function($role) {
 169              if ($role->name) {
 170                  return $role->name;
 171              } else {
 172                  return $role->shortname;
 173              }
 174          }, $roles);
 175      }
 176  
 177      /**
 178       * Returns the effective value given a context instance
 179       *
 180       * @param \context $context
 181       * @param string $element 'category' or 'purpose'
 182       * @param int|false $forcedvalue Use this value as if this was this context instance value.
 183       * @return persistent|false It return a 'purpose' instance or a 'category' instance, depending on $element
 184       */
 185      public static function get_effective_context_value(\context $context, $element, $forcedvalue = false) {
 186          global $DB;
 187  
 188          if ($element !== 'purpose' && $element !== 'category') {
 189              throw new coding_exception('Only \'purpose\' and \'category\' are supported.');
 190          }
 191          $fieldname = $element . 'id';
 192  
 193          if (!empty($forcedvalue) && ($forcedvalue == context_instance::INHERIT)) {
 194              // Do not include the current context when calculating the value.
 195              // This has the effect that an inheritted value is calculated.
 196              $parentcontextids = $context->get_parent_context_ids(false);
 197          } else if (!empty($forcedvalue) && ($forcedvalue != context_instance::NOTSET)) {
 198              return self::get_element_instance($element, $forcedvalue);
 199          } else {
 200              // Fetch all parent contexts, including self.
 201              $parentcontextids = $context->get_parent_context_ids(true);
 202          }
 203          list($insql, $inparams) = $DB->get_in_or_equal($parentcontextids, SQL_PARAMS_NAMED);
 204          $inparams['contextmodule'] = CONTEXT_MODULE;
 205  
 206          if ('purpose' === $element) {
 207               $elementjoin = 'LEFT JOIN {tool_dataprivacy_purpose} ele ON ctxins.purposeid = ele.id';
 208               $elementfields = purpose::get_sql_fields('ele', 'ele');
 209          } else {
 210               $elementjoin = 'LEFT JOIN {tool_dataprivacy_category} ele ON ctxins.categoryid = ele.id';
 211               $elementfields = category::get_sql_fields('ele', 'ele');
 212          }
 213          $contextfields = \context_helper::get_preload_record_columns_sql('ctx');
 214          $fields = implode(', ', ['ctx.id', 'm.name AS modname', $contextfields, $elementfields]);
 215  
 216          $sql = "SELECT $fields
 217                    FROM {context} ctx
 218               LEFT JOIN {tool_dataprivacy_ctxinstance} ctxins ON ctx.id = ctxins.contextid
 219               LEFT JOIN {course_modules} cm ON ctx.contextlevel = :contextmodule AND ctx.instanceid = cm.id
 220               LEFT JOIN {modules} m ON m.id = cm.module
 221               {$elementjoin}
 222                   WHERE ctx.id {$insql}
 223                ORDER BY ctx.path DESC";
 224          $contextinstances = $DB->get_records_sql($sql, $inparams);
 225  
 226          // Check whether this context is a user context, or a child of a user context.
 227          // All children of a User context share the same context and cannot be set individually.
 228          foreach ($contextinstances as $record) {
 229              \context_helper::preload_from_record($record);
 230              $parent = \context::instance_by_id($record->id, false);
 231  
 232              if ($parent->contextlevel == CONTEXT_USER) {
 233                  // Use the context level value for the user.
 234                  return self::get_effective_contextlevel_value(CONTEXT_USER, $element);
 235              }
 236          }
 237  
 238          foreach ($contextinstances as $record) {
 239              $parent = \context::instance_by_id($record->id, false);
 240  
 241              $checkcontextlevel = false;
 242              if (empty($record->eleid)) {
 243                  $checkcontextlevel = true;
 244              }
 245  
 246              if (!empty($forcedvalue) && context_instance::NOTSET == $forcedvalue) {
 247                  $checkcontextlevel = true;
 248              }
 249  
 250              if ($checkcontextlevel) {
 251                  // Check for a value at the contextlevel
 252                  $forplugin = empty($record->modname) ? '' : $record->modname;
 253                  list($purposeid, $categoryid) = self::get_effective_default_contextlevel_purpose_and_category(
 254                          $parent->contextlevel, false, false, $forplugin);
 255  
 256                  $instancevalue = $$fieldname;
 257  
 258                  if (context_instance::NOTSET != $instancevalue && context_instance::INHERIT != $instancevalue) {
 259                      // There is an actual value. Return it.
 260                      return self::get_element_instance($element, $instancevalue);
 261                  }
 262              } else {
 263                  $elementclass = "\\tool_dataprivacy\\{$element}";
 264                  $instance = new $elementclass(null, $elementclass::extract_record($record, 'ele'));
 265                  $instance->validate();
 266  
 267                  return $instance;
 268              }
 269          }
 270  
 271          throw new coding_exception('Something went wrong, system defaults should be set and we should already have a value.');
 272      }
 273  
 274      /**
 275       * Returns the effective value for a context level.
 276       *
 277       * Note that this is different from the effective default context level
 278       * (see get_effective_default_contextlevel_purpose_and_category) as this is returning
 279       * the value set in the data registry, not in the defaults page.
 280       *
 281       * @param int $contextlevel
 282       * @param string $element 'category' or 'purpose'
 283       * @return \tool_dataprivacy\purpose|false
 284       */
 285      public static function get_effective_contextlevel_value($contextlevel, $element) {
 286          if ($element !== 'purpose' && $element !== 'category') {
 287              throw new coding_exception('Only \'purpose\' and \'category\' are supported.');
 288          }
 289          $fieldname = $element . 'id';
 290  
 291          if ($contextlevel != CONTEXT_SYSTEM && $contextlevel != CONTEXT_USER) {
 292              throw new \coding_exception('Only context_system and context_user values can be retrieved, no other context levels ' .
 293                  'have a purpose or a category.');
 294          }
 295  
 296          list($purposeid, $categoryid) = self::get_effective_default_contextlevel_purpose_and_category($contextlevel);
 297  
 298          // Note: The $$fieldname points to either $purposeid, or $categoryid.
 299          if (context_instance::NOTSET != $$fieldname && context_instance::INHERIT != $$fieldname) {
 300              // There is a specific value set.
 301              return self::get_element_instance($element, $$fieldname);
 302          }
 303  
 304          throw new coding_exception('Something went wrong, system defaults should be set and we should already have a value.');
 305      }
 306  
 307      /**
 308       * Returns the effective default purpose and category for a context level.
 309       *
 310       * @param int $contextlevel
 311       * @param int|bool $forcedpurposevalue Use this value as if this was this context level purpose.
 312       * @param int|bool $forcedcategoryvalue Use this value as if this was this context level category.
 313       * @param string $component The name of the component to check.
 314       * @return int[]
 315       */
 316      public static function get_effective_default_contextlevel_purpose_and_category($contextlevel, $forcedpurposevalue = false,
 317                                                                                     $forcedcategoryvalue = false, $component = '') {
 318          // Get the defaults for this context level.
 319          list($purposeid, $categoryid) = self::get_defaults($contextlevel, $component);
 320  
 321          // Honour forced values.
 322          if ($forcedpurposevalue) {
 323              $purposeid = $forcedpurposevalue;
 324          }
 325          if ($forcedcategoryvalue) {
 326              $categoryid = $forcedcategoryvalue;
 327          }
 328  
 329          if ($contextlevel == CONTEXT_USER) {
 330              // Only user context levels inherit from a parent context level.
 331              list($parentpurposeid, $parentcategoryid) = self::get_defaults(CONTEXT_SYSTEM);
 332  
 333              if (context_instance::INHERIT == $purposeid || context_instance::NOTSET == $purposeid) {
 334                  $purposeid = (int)$parentpurposeid;
 335              }
 336  
 337              if (context_instance::INHERIT == $categoryid || context_instance::NOTSET == $categoryid) {
 338                  $categoryid = $parentcategoryid;
 339              }
 340          }
 341  
 342          return [$purposeid, $categoryid];
 343      }
 344  
 345      /**
 346       * Returns an instance of the provided element.
 347       *
 348       * @throws \coding_exception
 349       * @param string $element The element name 'purpose' or 'category'
 350       * @param int $id The element id
 351       * @return \core\persistent
 352       */
 353      private static function get_element_instance($element, $id) {
 354          if ($element !== 'purpose' && $element !== 'category') {
 355              throw new coding_exception('No other elements than purpose and category are allowed');
 356          }
 357  
 358          $classname = '\tool_dataprivacy\\' . $element;
 359          return new $classname($id);
 360      }
 361  }