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