Merge branch 'MDL-78427-master' of https://github.com/davewoloszyn/moodle

admin/settings/appearance.php

@@ -293,14 +293,27 @@ if ($hassiteconfig or has_any_capability($capabilities, $systemcontext)) { // sp
         new lang_string('configthemedesignermode', 'admin'), 0);
     $setting->set_updatedcallback('theme_reset_all_caches');
     $temp->add($setting);
-    $temp->add(new admin_setting_configcheckbox('allowuserthemes', new lang_string('allowuserthemes', 'admin'),
-        new lang_string('configallowuserthemes', 'admin'), 0));
-    $temp->add(new admin_setting_configcheckbox('allowcoursethemes', new lang_string('allowcoursethemes', 'admin'),
-        new lang_string('configallowcoursethemes', 'admin'), 0));
-    $temp->add(new admin_setting_configcheckbox('allowcategorythemes',  new lang_string('allowcategorythemes', 'admin'),
-        new lang_string('configallowcategorythemes', 'admin'), 0));
-    $temp->add(new admin_setting_configcheckbox('allowcohortthemes',  new lang_string('allowcohortthemes', 'admin'),
-        new lang_string('configallowcohortthemes', 'admin'), 0));
+
+    $setting = new admin_setting_configcheckbox('allowuserthemes', new lang_string('allowuserthemes', 'admin'),
+        new lang_string('configallowuserthemes', 'admin'), 0);
+    $setting->set_updatedcallback('theme_purge_used_in_context_caches');
+    $temp->add($setting);
+
+    $setting = new admin_setting_configcheckbox('allowcoursethemes', new lang_string('allowcoursethemes', 'admin'),
+        new lang_string('configallowcoursethemes', 'admin'), 0);
+    $setting->set_updatedcallback('theme_purge_used_in_context_caches');
+    $temp->add($setting);
+
+    $setting = new admin_setting_configcheckbox('allowcategorythemes',  new lang_string('allowcategorythemes', 'admin'),
+        new lang_string('configallowcategorythemes', 'admin'), 0);
+    $setting->set_updatedcallback('theme_purge_used_in_context_caches');
+    $temp->add($setting);
+
+    $setting = new admin_setting_configcheckbox('allowcohortthemes',  new lang_string('allowcohortthemes', 'admin'),
+        new lang_string('configallowcohortthemes', 'admin'), 0);
+    $setting->set_updatedcallback('theme_purge_used_in_context_caches');
+    $temp->add($setting);
+
     $temp->add(new admin_setting_configcheckbox('allowthemechangeonurl',  new lang_string('allowthemechangeonurl', 'admin'),
         new lang_string('configallowthemechangeonurl', 'admin'), 0));
     $temp->add(new admin_setting_configcheckbox('allowuserblockhiding', new lang_string('allowuserblockhiding', 'admin'),

admin/templates/themeselector/theme_card.mustache

@@ -27,7 +27,8 @@
         "current": true,
         "actionurl": "http://moodlesite/admin/themeselector.php",
         "sesskey": "123XYZ",
-        "settingsurl": "http://moodlesite/admin/settings.php?section=themesettingboost"
+        "settingsurl": "http://moodlesite/admin/settings.php?section=themesettingboost",
+        "reporturl": "http://moodlesite/report/themeusage/index.php?themechoice=boost"
     }
 }}
 <div class="card dashboard-card" role="listitem" id="theme-card-{{choose}}" aria-labelledby="theme-name-{{choose}} {{#current}}current-theme-{{choose}}{{/current}}">
@@ -53,6 +54,16 @@
                     <i class="icon fa fa-info-circle m-0" aria-hidden="true"></i>
                     <span class="sr-only">{{#str}}previewthemename, moodle, {{name}}{{/str}}</span>
                 </button>
+                {{#reporturl}}
+                    <a
+                        href="{{reporturl}}"
+                        id="theme-usage-report-{{choose}}"
+                        class="btn btn-link p-0 ml-2"
+                        title="{{#str}}themeusagereportname, admin, {{name}}{{/str}}">
+                        <i class="icon fa fa-area-chart m-0" aria-hidden="true"></i>
+                        <span class="sr-only">{{#str}}themeusagereportname, admin, {{name}}{{/str}}</span>
+                    </a>
+                {{/reporturl}}
                 {{#settingsurl}}
                     <a
                         href="{{settingsurl}}"

admin/themeselector.php

@@ -127,6 +127,13 @@ foreach ($themes as $themename => $themedir) {
         $themedata['settingsurl'] = $settingsurl;
     }
 
+    // Link to the theme usage report if override enabled and it is being used in at least one context.
+    if (\core\output\theme_usage::is_theme_used_in_any_context($themename) === \core\output\theme_usage::THEME_IS_USED) {
+        $reporturl = new moodle_url($CFG->wwwroot . '/report/themeusage/index.php');
+        $reporturl->params(['themechoice' => $themename]);
+        $themedata['reporturl'] = $reporturl->out(false);
+    }
+
     $data[$index] = $themedata;
     $index++;
 }

cohort/lib.php

@@ -101,6 +101,15 @@ function cohort_update_cohort($cohort) {
     if (empty($CFG->allowcohortthemes) && isset($cohort->theme)) {
         unset($cohort->theme);
     }
+
+    // Delete theme usage cache if the theme has been changed.
+    if (isset($cohort->theme)) {
+        $oldcohort = $DB->get_record('cohort', ['id' => $cohort->id]);
+        if ($cohort->theme != $oldcohort->theme) {
+            theme_delete_used_in_context_cache($cohort->theme, $oldcohort->theme);
+        }
+    }
+
     $cohort->timemodified = time();
 
     // Update custom fields if there are any of them in the form.

course/classes/category.php

@@ -628,6 +628,14 @@ class core_course_category implements renderable, cacheable_object, IteratorAggr
             fix_course_sortorder();
         }
 
+        // Delete theme usage cache if the theme has been changed.
+        if (isset($data->theme)) {
+            $oldcategory = $DB->get_record('course_categories', ['id' => $data->id]);
+            if ($data->theme != $oldcategory->theme) {
+                theme_delete_used_in_context_cache($data->theme, (string)$oldcategory->theme);
+            }
+        }
+
         $newcategory->timemodified = time();
 
         $categorycontext = $this->get_context();

course/edit_form.php

@@ -488,7 +488,6 @@ class course_edit_form extends moodleform {
         // Tweak the form with values provided by custom fields in use.
         $handler  = core_course\customfield\course_handler::create();
         $handler->instance_form_definition_after_data($mform, empty($courseid) ? 0 : $courseid);
-
     }
 
     /**

course/lib.php

@@ -2485,6 +2485,11 @@ function update_course($data, $editoroptions = NULL) {
         $DB->delete_records('course_format_options',
                 array('courseid' => $course->id, 'format' => $oldcourse->format));
     }
+
+    // Delete theme usage cache if the theme has been changed.
+    if (isset($data->theme) && ($data->theme != $oldcourse->theme)) {
+        theme_delete_used_in_context_cache($data->theme, $oldcourse->theme);
+    }
 }
 
 /**

lang/en/admin.php

@@ -1463,6 +1463,8 @@ $string['themeselect'] = 'Change theme';
 $string['themeselector'] = 'Themes';
 $string['themesettingsadvanced'] = 'Advanced theme settings';
 $string['themeeditsettingsname'] = 'Edit theme settings \'{$a}\'';
+$string['themesettingsname'] = 'Theme settings \'{$a}\'';
+$string['themeusagereportname'] = 'Theme usage report \'{$a}\'';
 $string['therewereerrors'] = 'There were errors in your data';
 $string['thirdpartylibrary'] = 'Library';
 $string['thirdpartylibrarylocation'] = 'Location';

lang/en/cache.php

@@ -96,6 +96,7 @@ $string['cachedef_grade_letters'] = 'Grade letter queries';
 $string['cachedef_string'] = 'Language string cache';
 $string['cachedef_tags'] = 'Tags collections and areas';
 $string['cachedef_temp_tables'] = 'Temporary tables cache';
+$string['cachedef_theme_usedincontext'] = 'A theme has been used in context to override the default theme';
 $string['cachedef_userselections'] = 'Data used to persist user selections throughout Moodle';
 $string['cachedef_user_favourite_course_content_items'] = 'User\'s starred items';
 $string['cachedef_user_group_groupings'] = 'User\'s groupings and groups per course';

lib/classes/output/theme_usage.php

@@ -0,0 +1,127 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace core\output;
+
+/**
+ * This class houses methods for checking theme usage in a given context.
+ *
+ * @package    core
+ * @category   output
+ * @copyright  2024 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class theme_usage {
+
+    /** @var string The theme usage type for users. */
+    public const THEME_USAGE_TYPE_USER = 'user';
+
+    /** @var string The theme usage type for courses. */
+    public const THEME_USAGE_TYPE_COURSE = 'course';
+
+    /** @var string The theme usage type for cohorts. */
+    public const THEME_USAGE_TYPE_COHORT = 'cohort';
+
+    /** @var string The theme usage type for categories. */
+    public const THEME_USAGE_TYPE_CATEGORY = 'category';
+
+    /** @var string The theme usage type for all. */
+    public const THEME_USAGE_TYPE_ALL = 'all';
+
+    /** @var int The theme is used in context. */
+    public const THEME_IS_USED = 1;
+
+    /** @var int The theme is not used in context. */
+    public const THEME_IS_NOT_USED = 0;
+
+    /**
+     * Check if the theme is used in any context (e.g. user, course, cohort, category).
+     *
+     * This query is cached.
+     *
+     * @param string $themename The theme to check.
+     * @return int Return 1 if at least one record was found, 0 if none.
+     */
+    public static function is_theme_used_in_any_context(string $themename): int {
+        global $DB;
+        $cache = \cache::make('core', 'theme_usedincontext');
+        $isused = $cache->get($themename);
+
+        if ($isused === false) {
+
+            $sqlunions = [];
+
+            // For each context, check if the config is enabled and there is at least one use.
+            if (get_config('core', 'allowuserthemes')) {
+                $sqlunions[self::THEME_USAGE_TYPE_USER] = "
+                        SELECT u.id
+                            FROM {user} u
+                            WHERE u.theme = :usertheme
+                            ";
+            }
+
+            if (get_config('core', 'allowcoursethemes')) {
+                $sqlunions[self::THEME_USAGE_TYPE_COURSE] = "
+                        SELECT c.id
+                            FROM {course} c
+                            WHERE c.theme = :coursetheme
+                            ";
+            }
+
+            if (get_config('core', 'allowcohortthemes')) {
+                $sqlunions[self::THEME_USAGE_TYPE_COHORT] = "
+                        SELECT co.id
+                            FROM {cohort} co
+                            WHERE co.theme = :cohorttheme
+                            ";
+            }
+
+            if (get_config('core', 'allowcategorythemes')) {
+                $sqlunions[self::THEME_USAGE_TYPE_CATEGORY] = "
+                        SELECT cat.id
+                            FROM {course_categories} cat
+                            WHERE cat.theme = :categorytheme
+                            ";
+            }
+
+            // Union the sql statements from the different tables.
+            if (!empty($sqlunions)) {
+                $sql = implode(' UNION ', $sqlunions);
+
+                // Prepare params.
+                $params = [];
+                foreach ($sqlunions as $type => $val) {
+                    $params[$type . 'theme'] = $themename;
+                }
+
+                $result = $DB->record_exists_sql($sql, $params);
+            }
+
+            if (!empty($result)) {
+                $isused = self::THEME_IS_USED;
+            } else {
+                $isused = self::THEME_IS_NOT_USED;
+            }
+
+            // Cache the result so we don't have to keep checking for this theme.
+            $cache->set($themename, $isused);
+            return $isused;
+
+        } else {
+            return $isused;
+        }
+    }
+}

lib/db/caches.php

@@ -609,4 +609,13 @@ $definitions = array(
             'changesincourse',
         ],
     ],
+
+    // A theme has been used in context to override the default theme.
+    // Applies to user, cohort, category and course.
+    'theme_usedincontext' => [
+        'mode' => cache_store::MODE_APPLICATION,
+        'simplekeys' => true,
+        'simpledata' => true,
+        'staticacceleration' => true,
+    ],
 );

lib/outputlib.php

@@ -300,6 +300,33 @@ function theme_set_designer_mod($state) {
     theme_reset_all_caches();
 }
 
+/**
+ * Purge theme used in context caches.
+ */
+function theme_purge_used_in_context_caches() {
+    \cache::make('core', 'theme_usedincontext')->purge();
+}
+
+/**
+ * Delete theme used in context cache for a particular theme.
+ *
+ * When switching themes, both old and new theme caches are deleted.
+ * This gives the query the opportunity to recache accurate results for both themes.
+ *
+ * @param string $newtheme The incoming new theme.
+ * @param string $oldtheme The theme that was already set.
+ */
+function theme_delete_used_in_context_cache(string $newtheme, string $oldtheme): void {
+    if ((strlen($newtheme) > 0) && (strlen($oldtheme) > 0)) {
+        // Theme -> theme.
+        \cache::make('core', 'theme_usedincontext')->delete($oldtheme);
+        \cache::make('core', 'theme_usedincontext')->delete($newtheme);
+    } else {
+        // No theme -> theme, or theme -> no theme.
+        \cache::make('core', 'theme_usedincontext')->delete($newtheme . $oldtheme);
+    }
+}
+
 /**
  * This class represents the configuration variables of a Moodle theme.
  *

report/themeusage/classes/form/theme_usage_form.php

@@ -0,0 +1,98 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace report_themeusage\form;
+
+use moodleform;
+use core\output\theme_usage;
+
+/**
+ * Defines the form for generating theme usage report data.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL Juv3 or later
+ */
+class theme_usage_form extends moodleform {
+
+    /**
+     * Build the form definition.
+     */
+    protected function definition() {
+        $mform = $this->_form;
+
+        // Theme choices (e.g. boost, classic).
+        $themechoice = $this->_customdata['themechoice'];
+        $themechoices = array_merge(['' => get_string('select') . '...'], self::get_theme_choices());
+        $mform->addElement('select', 'themechoice', get_string('themename', 'report_themeusage'), $themechoices);
+        $mform->setType('themechoice', PARAM_TEXT);
+        $mform->addRule('themechoice', get_string('required'), 'required', null, 'client');
+        if (!empty($themechoice)) {
+            $mform->setDefault('themechoice', $themechoice);
+        }
+
+        // Theme usage types (e.g. user, course, cohort, category).
+        $typechoices = self::get_type_choices();
+        $mform->addElement('select', 'typechoice', get_string('usagetype', 'report_themeusage'), $typechoices);
+        $mform->setType('typechoice', PARAM_TEXT);
+        $mform->addRule('typechoice', get_string('required'), 'required', null, 'client');
+        $mform->setDefault(theme_usage::THEME_USAGE_TYPE_ALL, $themechoice);
+
+        // Submit button.
+        $mform->addElement('submit', 'submit', get_string('getreport', 'report_themeusage'));
+    }
+
+    /**
+     * Get a list of available theme usage types.
+     *
+     * @return array
+     */
+    public static function get_type_choices(): array {
+        return [
+            theme_usage::THEME_USAGE_TYPE_ALL => get_string('all'),
+            theme_usage::THEME_USAGE_TYPE_USER => get_string('user'),
+            theme_usage::THEME_USAGE_TYPE_COURSE => get_string('course'),
+            theme_usage::THEME_USAGE_TYPE_COHORT => get_string('cohort', 'cohort'),
+            theme_usage::THEME_USAGE_TYPE_CATEGORY => get_string('category'),
+        ];
+    }
+
+    /**
+     * Get a list of available themes.
+     *
+     * @return array
+     */
+    public static function get_theme_choices(): array {
+        $themes = \core_component::get_plugin_list('theme');
+        foreach ($themes as $themename => $themedir) {
+            $themechoices[$themename] = get_string('pluginname', 'theme_'.$themename);
+        }
+        return $themechoices;
+    }
+
+    /**
+     * Check the requested theme is in a list of available themes.
+     *
+     * @param string $themechoice The theme name.
+     * @return bool
+     */
+    public static function validate_theme_choice_param(string $themechoice): bool {
+        if (!empty($themechoice) && !array_key_exists($themechoice, self::get_theme_choices())) {
+            return false;
+        }
+        return true;
+    }
+}

report/themeusage/classes/privacy/provider.php

@@ -0,0 +1,45 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Privacy Subsystem implementation for report_themeusage.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace report_themeusage\privacy;
+
+/**
+ * Privacy Subsystem for report_themeusage implementing null_provider.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class provider implements \core_privacy\local\metadata\null_provider {
+
+    /**
+     * Get the language string identifier with the component's language
+     * file to explain why this plugin stores no data.
+     *
+     * @return  string
+     */
+    public static function get_reason(): string {
+        return 'privacy:metadata';
+    }
+}

report/themeusage/classes/reportbuilder/local/entities/theme.php

@@ -0,0 +1,134 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace report_themeusage\reportbuilder\local\entities;
+
+use core_reportbuilder\local\entities\base;
+use core_reportbuilder\local\report\column;
+use lang_string;
+
+/**
+ * Theme entity.
+ *
+ * Defines all the columns and filters that can be added to reports that use this entity.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class theme extends base {
+
+    /**
+     * Database tables that this entity uses.
+     *
+     * @return array
+     */
+    protected function get_default_tables(): array {
+        return [
+            'config_plugins',
+        ];
+    }
+
+    /**
+     * The default title for this entity.
+     *
+     * @return lang_string
+     */
+    protected function get_default_entity_title(): lang_string {
+        return new lang_string('theme');
+    }
+
+    /**
+     * Initialize the entity.
+     *
+     * @return base
+     */
+    public function initialise(): base {
+        $columns = $this->get_all_columns();
+        foreach ($columns as $column) {
+            $this->add_column($column);
+        }
+
+        return $this;
+    }
+
+    /**
+     * Returns list of all available columns.
+     *
+     * @return column[]
+     */
+    protected function get_all_columns(): array {
+        global $DB;
+        $themealias = $this->get_table_alias('config_plugins');
+        $sqlsubstring = $DB->sql_substr("{$themealias}.plugin", 7);
+
+        $courselabel = get_string('course');
+        $cohortlabel = get_string('cohort', 'cohort');
+        $userlabel = get_string('user');
+        $categorylabel = get_string('category');
+
+        // Force theme column.
+        $columns[] = (new column(
+            'forcetheme',
+            new lang_string('forcetheme'),
+            $this->get_entity_name()
+        ))
+            ->add_joins($this->get_joins())
+            ->set_type(column::TYPE_TEXT)
+            ->add_fields("{$themealias}.plugin")
+            ->add_callback(static function(?string $theme): string {
+                $theme = get_string('pluginname', $theme);
+                return format_text($theme, FORMAT_PLAIN);
+            });
+
+        // Usage type column.
+        $columns[] = (new column(
+            'usagetype',
+            new lang_string('usagetype', 'report_themeusage'),
+            $this->get_entity_name()
+        ))
+            ->add_joins($this->get_joins())
+            ->add_join("LEFT JOIN (
+                           SELECT '{$courselabel}' AS usagetype, theme, COUNT(theme) AS themecount
+                             FROM {course}
+                            WHERE " . $DB->sql_isnotempty('course', 'theme', false, false) . "
+                         GROUP BY theme
+                            UNION
+                           SELECT '{$userlabel}' AS usagetype, theme, COUNT(theme) AS themecount
+                             FROM {user}
+                            WHERE " . $DB->sql_isnotempty('user', 'theme', false, false) . "
+                         GROUP BY theme
+                            UNION
+                           SELECT '{$cohortlabel}' AS usagetype, theme, COUNT(theme) AS themecount
+                             FROM {cohort}
+                            WHERE " . $DB->sql_isnotempty('cohort', 'theme', false, false) . "
+                         GROUP BY theme
+                            UNION
+                           SELECT '{$categorylabel}' AS usagetype, theme, COUNT(theme) AS themecount
+                             FROM {course_categories}
+                            WHERE " . $DB->sql_isnotempty('course_categories', 'theme', false, false) . "
+                         GROUP BY theme
+                        ) tuse ON tuse.theme={$sqlsubstring}")
+            ->set_type(column::TYPE_TEXT)
+            ->add_fields("tuse.usagetype, tuse.themecount")
+            ->add_callback(static function(?string $usagetype, \stdClass $row): string {
+                $count = $row->themecount ?? 0;
+                return format_text($usagetype . ' ('. $count . ')', FORMAT_PLAIN);
+            });
+
+        return $columns;
+    }
+}

report/themeusage/classes/reportbuilder/local/systemreports/theme_usage_report.php

@@ -0,0 +1,256 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace report_themeusage\reportbuilder\local\systemreports;
+
+use context_system;
+use core_reportbuilder\local\entities\{course, user};
+use core_cohort\reportbuilder\local\entities\cohort;
+use core_course\reportbuilder\local\entities\course_category;
+use core_reportbuilder\local\helpers\database;
+use core_reportbuilder\system_report;
+use core\output\theme_usage;
+use report_themeusage\reportbuilder\local\entities\theme;
+
+/**
+ * Config changes system report class implementation
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class theme_usage_report extends system_report {
+
+    /**
+     * Initialise report, we need to set the main table, load our entities and set columns/filters.
+     */
+    protected function initialise(): void {
+        // Show results depending on the theme and type chosen.
+        $themechoice = $this->get_parameter('themechoice', '', PARAM_TEXT);
+        $typechoice = $this->get_parameter('typechoice', '', PARAM_TEXT);
+
+        $themename = get_string('pluginname', 'theme_'.$themechoice);
+
+        $themeentity = new theme();
+        $themealias = $themeentity->get_table_alias('config_plugins');
+        $this->set_main_table('config_plugins', $themealias);
+        $this->add_entity($themeentity);
+
+        $param1 = database::generate_param_name();
+        $param2 = database::generate_param_name();
+        $params = [$param1 => 'theme_' . $themechoice, $param2 => 'version'];
+
+        $this->add_base_condition_sql("{$themealias}.plugin = :{$param1} AND {$themealias}.name = :{$param2}", $params);
+
+        switch ($typechoice) {
+
+            case theme_usage::THEME_USAGE_TYPE_ALL:
+
+                $this->add_columns_theme();
+                $this->set_downloadable(true, get_string('themeusagereportall', 'report_themeusage', $themename));
+
+                break;
+
+            case theme_usage::THEME_USAGE_TYPE_USER:
+
+                $userentity = new user();
+                $useralias = $userentity->get_table_alias('user');
+
+                $this->add_entity($userentity->add_join(
+                    "JOIN {user} {$useralias}
+                       ON $useralias.theme = '{$themechoice}'
+                      AND {$themealias}.plugin = 'theme_{$themechoice}'"));
+
+                $this->add_columns_user();
+                $this->add_filters_user();
+                $this->set_downloadable(true, get_string('themeusagereportuser', 'report_themeusage', $themename));
+                break;
+
+            case theme_usage::THEME_USAGE_TYPE_COURSE:
+
+                $courseentity = new course();
+                $coursealias = $courseentity->get_table_alias('course');
+
+                $this->add_entity($courseentity->add_join(
+                    "JOIN {course} {$coursealias}
+                       ON $coursealias.theme = '{$themechoice}'
+                      AND {$themealias}.plugin = 'theme_{$themechoice}'"));
+
+                $this->add_columns_course();
+                $this->add_filters_course();
+                $this->set_downloadable(true, get_string('themeusagereportcourse', 'report_themeusage', $themename));
+                break;
+
+            case theme_usage::THEME_USAGE_TYPE_COHORT:
+
+                $cohortentity = new cohort();
+                $cohortalias = $cohortentity->get_table_alias('cohort');
+
+                $this->add_entity($cohortentity->add_join(
+                    "JOIN {cohort} {$cohortalias}
+                       ON $cohortalias.theme = '{$themechoice}'
+                      AND {$themealias}.plugin = 'theme_{$themechoice}'"));
+
+                $this->add_columns_cohort();
+                $this->add_filters_cohort();
+                $this->set_downloadable(true, get_string('themeusagereportcohort', 'report_themeusage', $themename));
+                break;
+
+            case theme_usage::THEME_USAGE_TYPE_CATEGORY:
+
+                $categoryentity = new course_category();
+                $categoryalias = $categoryentity->get_table_alias('course_categories');
+
+                $this->add_entity($categoryentity->add_join(
+                    "JOIN {course_categories} {$categoryalias}
+                       ON $categoryalias.theme = '{$themechoice}'
+                      AND {$themealias}.plugin = 'theme_{$themechoice}'"));
+
+                $this->add_columns_category();
+                $this->add_filters_category();
+                $this->set_downloadable(true, get_string('themeusagereportcategory', 'report_themeusage', $themename));
+                break;
+
+            default:
+                break;
+        }
+    }
+
+    /**
+     * Validates access to view this report.
+     *
+     * @return bool
+     */
+    protected function can_view(): bool {
+        return has_capability('moodle/site:config', context_system::instance());
+    }
+
+    /**
+     * Adds the columns we want to display in the report for 'theme'.
+     */
+    protected function add_columns_theme(): void {
+        $columns = [
+            'theme:usagetype',
+            'theme:forcetheme',
+        ];
+
+        $this->add_columns_from_entities($columns);
+        $this->set_initial_sort_column('theme:forcetheme', SORT_ASC);
+    }
+
+    /**
+     * Adds the columns we want to display in the report for 'user'.
+     */
+    protected function add_columns_user(): void {
+        $columns = [
+            'user:firstname',
+            'user:lastname',
+            'theme:forcetheme',
+        ];
+
+        $this->add_columns_from_entities($columns);
+        $this->set_initial_sort_column('user:firstname', SORT_ASC);
+    }
+
+    /**
+     * Adds the filters we want to display in the report for 'user'.
+     */
+    protected function add_filters_user(): void {
+        $filters = [
+            'user:firstname',
+            'user:lastname',
+        ];
+
+        $this->add_filters_from_entities($filters);
+    }
+
+    /**
+     * Adds the columns we want to display in the report for 'course'.
+     */
+    protected function add_columns_course(): void {
+        $columns = [
+            'course:fullname',
+            'course:shortname',
+            'theme:forcetheme',
+        ];
+
+        $this->add_columns_from_entities($columns);
+        $this->set_initial_sort_column('course:fullname', SORT_ASC);
+    }
+
+    /**
+     * Adds the filters we want to display in the report for 'course'.
+     */
+    protected function add_filters_course(): void {
+        $filters = [
+            'course:fullname',
+            'course:shortname',
+        ];
+
+        $this->add_filters_from_entities($filters);
+    }
+
+    /**
+     * Adds the columns we want to display in the report for 'cohort'.
+     */
+    protected function add_columns_cohort(): void {
+        $columns = [
+            'cohort:name',
+            'cohort:context',
+            'theme:forcetheme',
+        ];
+
+        $this->add_columns_from_entities($columns);
+        $this->set_initial_sort_column('cohort:name', SORT_ASC);
+    }
+
+    /**
+     * Adds the filters we want to display in the report for 'cohort'.
+     */
+    protected function add_filters_cohort(): void {
+        $filters = [
+            'cohort:name',
+            'cohort:context',
+        ];
+
+        $this->add_filters_from_entities($filters);
+    }
+
+    /**
+     * Adds the columns we want to display in the report for 'category'.
+     */
+    protected function add_columns_category(): void {
+        $columns = [
+            'course_category:name',
+            'course_category:coursecount',
+            'theme:forcetheme',
+        ];
+
+        $this->add_columns_from_entities($columns);
+        $this->set_initial_sort_column('course_category:name', SORT_ASC);
+    }
+
+    /**
+     * Adds the filters we want to display in the report for 'category'.
+     */
+    protected function add_filters_category(): void {
+        $filters = [
+            'course_category:name',
+        ];
+
+        $this->add_filters_from_entities($filters);
+    }
+}

report/themeusage/index.php

@@ -0,0 +1,83 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Display usage information about themes.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+use core_reportbuilder\system_report_factory;
+use report_themeusage\form\theme_usage_form;
+use report_themeusage\reportbuilder\local\systemreports\theme_usage_report;
+
+require(__DIR__.'/../../config.php');
+require_once($CFG->libdir.'/adminlib.php');
+
+require_login();
+admin_externalpage_setup('reportthemeusage');
+
+// Get URL parameters.
+$themechoice = optional_param('themechoice', '', PARAM_TEXT);
+
+// Check the requested theme is a valid one.
+if (!theme_usage_form::validate_theme_choice_param($themechoice)) {
+    throw new \moodle_exception(get_string('invalidparametertheme', 'report_themeusage'));
+}
+
+// Set up the page.
+$pageurl = new moodle_url($CFG->wwwroot . '/report/themeusage/index.php');
+$PAGE->set_url($pageurl);
+$PAGE->set_context(context_system::instance());
+$PAGE->set_pagelayout('report');
+$PAGE->set_primary_active_tab('siteadminnode');
+echo $OUTPUT->header();
+
+// Show heading.
+$heading = get_string('themeusage', 'report_themeusage');
+echo $OUTPUT->heading($heading);
+
+// Build form with prepared data.
+$cutomdata['themechoice'] = $themechoice;
+$form = new theme_usage_form($pageurl, $cutomdata);
+$form->display();
+
+if ($data = $form->get_data()) {
+    // Build report using submitted form data.
+    $themechoice = $data->themechoice;
+    $typechoice = $data->typechoice;
+
+} else if (!empty($themechoice)) {
+    // Build report with incoming theme choice and set the type to 'all'.
+    $typechoice  = 'all';
+}
+
+if (!empty($themechoice) && !empty($typechoice)) {
+    // Show a heading that explains what the report is showing.
+    $themename = get_string('pluginname', 'theme_' . $themechoice);
+    $reportheading = get_string('themeusagereport' . $typechoice, 'report_themeusage', $themename);
+    echo $OUTPUT->heading($reportheading, 3, 'mt-4');
+
+    // Build the report.
+    $reportparams = ['themechoice' => $themechoice, 'typechoice' => $typechoice];
+    $report = system_report_factory::create(theme_usage_report::class, context_system::instance(), '', '', 0, $reportparams);
+    echo $report->output();
+}
+
+// Show footer.
+echo $OUTPUT->footer();

report/themeusage/lang/en/report_themeusage.php

@@ -0,0 +1,37 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Lang strings for theme usage report.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+$string['getreport'] = 'Get report';
+$string['invalidparametertheme'] = 'Invalid paramater set for theme';
+$string['pluginname'] = 'Theme usage';
+$string['privacy:metadata'] = 'The theme report plugin does not store any personal data.';
+$string['themename'] = 'Theme name';
+$string['themeusage'] = 'Theme usage';
+$string['themeusagereport'] = 'Theme usage report';
+$string['themeusagereportall'] = 'All uses of {$a}';
+$string['themeusagereportcategory'] = 'Categories using {$a}';
+$string['themeusagereportcohort'] = 'Cohorts using {$a}';
+$string['themeusagereportcourse'] = 'Courses using {$a}';
+$string['themeusagereportuser'] = 'Users using {$a}';
+$string['usagetype'] = 'Usage type';

report/themeusage/settings.php

@@ -0,0 +1,37 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Settings and links.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die;
+
+$ADMIN->add('reports',
+    new admin_externalpage(
+        'reportthemeusage',
+        get_string('pluginname', 'report_themeusage'),
+        "$CFG->wwwroot/report/themeusage/index.php",
+        'moodle/site:config',
+    ),
+);
+
+// No report settings.
+$settings = null;

report/themeusage/tests/behat/theme_usage.feature

@@ -0,0 +1,92 @@
+@report @report_themeusage
+Feature: Navigate to a theme usage report
+  In order to see a theme usage report
+  As an admin
+  I need to set a theme for user/course/category/cohort and view the report
+
+  Background:
+    Given the following config values are set as admin:
+      | allowuserthemes     | 1 |
+      | allowcoursethemes   | 1 |
+      | allowcategorythemes | 1 |
+      | allowcohortthemes   | 1 |
+    And I log in as "admin"
+
+  Scenario: I am able to see theme usage report for all contexts overriding the default theme
+    Given the following "courses" exist:
+      | fullname | shortname | theme |
+      | Course 1 | course1   | boost |
+      | Course 2 | course2   | boost |
+    And the following "user" exists:
+      | username  | student1 |
+      | firstname | Student  |
+      | lastname  | One      |
+      | theme     | boost    |
+    And I navigate to "Reports > Theme usage" in site administration
+    And I set the field "Theme name" to "boost"
+    And I set the field "Usage type" to "all"
+    When I press "Get report"
+    Then the following should exist in the "reportbuilder-table" table:
+      | Usage type | Force theme |
+      | Course (2) | Boost       |
+      | User (1)   | Boost       |
+
+  Scenario: I am able to see theme usage report for courses overriding the default theme
+    Given the following "course" exists:
+      | fullname  | Course 1 |
+      | shortname | course1  |
+      | theme     | boost    |
+    And I navigate to "Reports > Theme usage" in site administration
+    And I set the field "Theme name" to "boost"
+    And I set the field "Usage type" to "course"
+    When I press "Get report"
+    Then the following should exist in the "reportbuilder-table" table:
+      | Course full name | Course short name | Force theme |
+      | Course 1         | course1           | Boost       |
+
+  Scenario: I am able to see theme usage report for users overriding the default theme
+    Given the following "user" exists:
+      | username  | student1 |
+      | firstname | Student  |
+      | lastname  | One      |
+      | theme     | boost    |
+    And I navigate to "Reports > Theme usage" in site administration
+    And I set the field "Theme name" to "boost"
+    And I set the field "Usage type" to "user"
+    When I press "Get report"
+    Then the following should exist in the "reportbuilder-table" table:
+      | First name | Last name | Force theme |
+      | Student    | One       | Boost       |
+
+  Scenario: I am able to see theme usage report for cohorts overriding the default theme
+    Given the following "cohort" exists:
+      | name     | Cohort 1 |
+      | idnumber | cohort1  |
+      | context  | system   |
+    And I navigate to "Users > Accounts > Cohorts" in site administration
+    And I press "Edit" action in the "cohort1" report row
+    And I set the field "theme" to "boost"
+    And I press "Save changes"
+    And I navigate to "Reports > Theme usage" in site administration
+    And I set the field "Theme name" to "boost"
+    And I set the field "Usage type" to "cohort"
+    When I press "Get report"
+    Then the following should exist in the "reportbuilder-table" table:
+      | Name     | Category | Force theme |
+      | Cohort 1 | System   | Boost       |
+
+  Scenario: I am able to see theme usage report for categories overriding the default theme
+    Given the following "categories" exist:
+      | name       | category | idnumber  |
+      | Category 1 | 0        | category1 |
+    And I navigate to "Courses > Manage courses and categories" in site administration
+    And I click on "edit" action for "Category 1" in management category listing
+    And I set the field "theme" to "boost"
+    And I press "Save changes"
+    And I navigate to "Reports > Theme usage" in site administration
+    And I set the field "Theme name" to "boost"
+    And I set the field "Usage type" to "category"
+    When I press "Get report"
+    Then the following should exist in the "reportbuilder-table" table:
+      | Category name  | Course count | Force theme |
+      | Category 1     | 0            | Boost       |

report/themeusage/tests/theme_usage_test.php

@@ -0,0 +1,101 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace report_themeusage;
+
+use testing_data_generator;
+use core\output\theme_usage;
+
+/**
+ * Unit tests for theme usage.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class theme_usage_test extends \advanced_testcase {
+
+    /** @var testing_data_generator Data generator. */
+    private testing_data_generator $generator;
+
+    /**
+     * Set up function for tests.
+     */
+    protected function setUp(): void {
+        parent::setUp();
+
+        $this->resetAfterTest();
+        $this->generator = $this->getDataGenerator();
+    }
+
+    /**
+     * Test is_theme_used_in_any_context method.
+     *
+     * @covers ::is_theme_used_in_any_context
+     * @covers ::theme_purge_used_in_context_caches
+     */
+    public function test_is_theme_used_in_any_context(): void {
+        // Enable theme overrides.
+        set_config('allowuserthemes', 1);
+        set_config('allowcoursethemes', 1);
+        set_config('allowcohortthemes', 1);
+        set_config('allowcategorythemes', 1);
+
+        $theme = 'boost';
+
+        // Check there are no contexts using 'boost' as their preferred theme yet.
+        $usedinanycontext = theme_usage::is_theme_used_in_any_context($theme);
+        $this->assertEquals(theme_usage::THEME_IS_NOT_USED, $usedinanycontext);
+
+        // Create a user and set its theme preference to 'boost'.
+        // The outcome of this test should be the same if we use a cohort/course/category.
+        $this->generator->create_user(['theme' => $theme]);
+
+        // Because we have already checked and cached a response, purge this cache.
+        theme_purge_used_in_context_caches();
+
+        $usedinanycontext = theme_usage::is_theme_used_in_any_context($theme);
+        $this->assertEquals(theme_usage::THEME_IS_USED, $usedinanycontext);
+
+        // Double-check the the cache is set for the theme.
+        $cache = \cache::make('core', 'theme_usedincontext')->get($theme);
+        $this->assertEquals(theme_usage::THEME_IS_USED, $cache);
+    }
+
+    /**
+     * Test the deleting of cache using theme_delete_used_in_context_cache.
+     *
+     * @covers ::theme_delete_used_in_context_cache
+     */
+    public function test_theme_delete_used_in_context_cache(): void {
+        // Enable theme override.
+        set_config('allowuserthemes', 1);
+
+        // Create a user and set its theme preference to 'boost'.
+        $theme = 'boost';
+        $user = $this->generator->create_user(['theme' => $theme]);
+
+        // Check for theme usage. This will create a cached result.
+        theme_usage::is_theme_used_in_any_context($theme);
+        $cache = \cache::make('core', 'theme_usedincontext')->get($theme);
+        $this->assertEquals(theme_usage::THEME_IS_USED, $cache);
+
+        // Delete the cache by switching themes.
+        theme_delete_used_in_context_cache('classic', $user->theme);
+        $cache = \cache::make('core', 'theme_usedincontext')->get($theme);
+        $this->assertFalse($cache);
+    }
+}

report/themeusage/version.php

@@ -0,0 +1,29 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Version info.
+ *
+ * @package    report_themeusage
+ * @copyright  2023 David Woloszyn <david.woloszyn@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die;
+
+$plugin->version   = 2023110900;     // The current plugin version (Date: YYYYMMDDXX).
+$plugin->requires  = 2023100900;     // Requires this Moodle version.
+$plugin->component = 'report_themeusage'; // Full name of the plugin (used for diagnostics).

user/editadvanced_form.php

@@ -241,6 +241,14 @@ class user_editadvanced_form extends moodleform {
             }
         }
 
+        // User changing their preferred theme will delete the cache for this theme.
+        if ($mform->elementExists('theme') && $mform->isSubmitted()) {
+            $theme = $mform->getSubmitValue('theme');
+            if (!empty($user) && ($theme != $user->theme)) {
+                theme_delete_used_in_context_cache($theme, $user->theme);
+            }
+        }
+
         // Next the customisable profile fields.
         profile_definition_after_data($mform, $userid);
     }

user/lib.php

@@ -209,6 +209,15 @@ function user_update_user($user, $updatepassword = true, $triggerevent = true) {
         unset($user->calendartype);
     }
 
+    // Delete theme usage cache if the theme has been changed.
+    if (isset($user->theme)) {
+        if ($user->theme != $currentrecord->theme) {
+            theme_delete_used_in_context_cache($user->theme, $currentrecord->theme);
+        }
+    }
+
+    $user->timemodified = time();
+
     // Validate user data object.
     $uservalidation = core_user::validate($user);
     if ($uservalidation !== true) {