/lib/classes/plugin_manager.php

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<?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/>.

/**
 * Defines classes used for plugins management
 *
 * This library provides a unified interface to various plugin types in
 * Moodle. It is mainly used by the plugins management admin page and the
 * plugins check page during the upgrade.
 *
 * @package    core
 * @copyright  2011 David Mudrak <david@moodle.com>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

/**
 * Singleton class providing general plugins management functionality.
 */
class core_plugin_manager {

    /** the plugin is shipped with standard Moodle distribution */
    const PLUGIN_SOURCE_STANDARD    = 'std';
    /** the plugin is added extension */
    const PLUGIN_SOURCE_EXTENSION   = 'ext';

    /** the plugin uses neither database nor capabilities, no versions */
    const PLUGIN_STATUS_NODB        = 'nodb';
    /** the plugin is up-to-date */
    const PLUGIN_STATUS_UPTODATE    = 'uptodate';
    /** the plugin is about to be installed */
    const PLUGIN_STATUS_NEW         = 'new';
    /** the plugin is about to be upgraded */
    const PLUGIN_STATUS_UPGRADE     = 'upgrade';
    /** the standard plugin is about to be deleted */
    const PLUGIN_STATUS_DELETE     = 'delete';
    /** the version at the disk is lower than the one already installed */
    const PLUGIN_STATUS_DOWNGRADE   = 'downgrade';
    /** the plugin is installed but missing from disk */
    const PLUGIN_STATUS_MISSING     = 'missing';

    /** the given requirement/dependency is fulfilled */
    const REQUIREMENT_STATUS_OK = 'ok';
    /** the plugin requires higher core/other plugin version than is currently installed */
    const REQUIREMENT_STATUS_OUTDATED = 'outdated';
    /** the required dependency is not installed */
    const REQUIREMENT_STATUS_MISSING = 'missing';
    /** the current Moodle version is too high for plugin. */
    const REQUIREMENT_STATUS_NEWER = 'newer';

    /** the required dependency is available in the plugins directory */
    const REQUIREMENT_AVAILABLE = 'available';
    /** the required dependency is available in the plugins directory */
    const REQUIREMENT_UNAVAILABLE = 'unavailable';

    /** the moodle version is explicitly supported */
    const VERSION_SUPPORTED = 'supported';
    /** the moodle version is not explicitly supported */
    const VERSION_NOT_SUPPORTED = 'notsupported';
    /** the plugin does not specify supports */
    const VERSION_NO_SUPPORTS = 'nosupports';

    /** @var core_plugin_manager holds the singleton instance */
    protected static $singletoninstance;
    /** @var array of raw plugins information */
    protected $pluginsinfo = null;
    /** @var array of raw subplugins information */
    protected $subpluginsinfo = null;
    /** @var array cache information about availability in the plugins directory if requesting "at least" version */
    protected $remotepluginsinfoatleast = null;
    /** @var array cache information about availability in the plugins directory if requesting exact version */
    protected $remotepluginsinfoexact = null;
    /** @var array list of installed plugins $name=>$version */
    protected $installedplugins = null;
    /** @var array list of all enabled plugins $name=>$name */
    protected $enabledplugins = null;
    /** @var array list of all enabled plugins $name=>$diskversion */
    protected $presentplugins = null;
    /** @var array reordered list of plugin types */
    protected $plugintypes = null;
    /** @var \core\update\code_manager code manager to use for plugins code operations */
    protected $codemanager = null;
    /** @var \core\update\api client instance to use for accessing download.moodle.org/api/ */
    protected $updateapiclient = null;

    /**
     * Direct initiation not allowed, use the factory method {@link self::instance()}
     */
    protected function __construct() {
    }

    /**
     * Sorry, this is singleton
     */
    protected function __clone() {
    }

    /**
     * Factory method for this class
     *
     * @return core_plugin_manager the singleton instance
     */
    public static function instance() {
        if (is_null(static::$singletoninstance)) {
            static::$singletoninstance = new static();
        }
        return static::$singletoninstance;
    }

    /**
     * Reset all caches.
     * @param bool $phpunitreset
     */
    public static function reset_caches($phpunitreset = false) {
        if ($phpunitreset) {
            static::$singletoninstance = null;
        } else {
            if (static::$singletoninstance) {
                static::$singletoninstance->pluginsinfo = null;
                static::$singletoninstance->subpluginsinfo = null;
                static::$singletoninstance->remotepluginsinfoatleast = null;
                static::$singletoninstance->remotepluginsinfoexact = null;
                static::$singletoninstance->installedplugins = null;
                static::$singletoninstance->enabledplugins = null;
                static::$singletoninstance->presentplugins = null;
                static::$singletoninstance->plugintypes = null;
                static::$singletoninstance->codemanager = null;
                static::$singletoninstance->updateapiclient = null;
            }
        }
        $cache = cache::make('core', 'plugin_manager');
        $cache->purge();
    }

    /**
     * Returns the result of {@link core_component::get_plugin_types()} ordered for humans
     *
     * @see self::reorder_plugin_types()
     * @return array (string)name => (string)location
     */
    public function get_plugin_types() {
        if (func_num_args() > 0) {
            if (!func_get_arg(0)) {
                throw new coding_exception('core_plugin_manager->get_plugin_types() does not support relative paths.');
            }
        }
        if ($this->plugintypes) {
            return $this->plugintypes;
        }

        $this->plugintypes = $this->reorder_plugin_types(core_component::get_plugin_types());
        return $this->plugintypes;
    }

    /**
     * Load list of installed plugins,
     * always call before using $this->installedplugins.
     *
     * This method is caching results for all plugins.
     */
    protected function load_installed_plugins() {
        global $DB, $CFG;

        if ($this->installedplugins) {
            return;
        }

        if (empty($CFG->version)) {
            // Nothing installed yet.
            $this->installedplugins = array();
            return;
        }

        $cache = cache::make('core', 'plugin_manager');
        $installed = $cache->get('installed');

        if (is_array($installed)) {
            $this->installedplugins = $installed;
            return;
        }

        $this->installedplugins = array();

        $versions = $DB->get_records('config_plugins', array('name'=>'version'));
        foreach ($versions as $version) {
            $parts = explode('_', $version->plugin, 2);
            if (!isset($parts[1])) {
                // Invalid component, there must be at least one "_".
                continue;
            }
            // Do not verify here if plugin type and name are valid.
            $this->installedplugins[$parts[0]][$parts[1]] = $version->value;
        }

        foreach ($this->installedplugins as $key => $value) {
            ksort($this->installedplugins[$key]);
        }

        $cache->set('installed', $this->installedplugins);
    }

    /**
     * Return list of installed plugins of given type.
     * @param string $type
     * @return array $name=>$version
     */
    public function get_installed_plugins($type) {
        $this->load_installed_plugins();
        if (isset($this->installedplugins[$type])) {
            return $this->installedplugins[$type];
        }
        return array();
    }

    /**
     * Load list of all enabled plugins,
     * call before using $this->enabledplugins.
     *
     * This method is caching results from individual plugin info classes.
     */
    protected function load_enabled_plugins() {
        global $CFG;

        if ($this->enabledplugins) {
            return;
        }

        if (empty($CFG->version)) {
            $this->enabledplugins = array();
            return;
        }

        $cache = cache::make('core', 'plugin_manager');
        $enabled = $cache->get('enabled');

        if (is_array($enabled)) {
            $this->enabledplugins = $enabled;
            return;
        }

        $this->enabledplugins = array();

        require_once($CFG->libdir.'/adminlib.php');

        $plugintypes = core_component::get_plugin_types();
        foreach ($plugintypes as $plugintype => $fulldir) {
            $plugininfoclass = static::resolve_plugininfo_class($plugintype);
            if (class_exists($plugininfoclass)) {
                $enabled = $plugininfoclass::get_enabled_plugins();
                if (!is_array($enabled)) {
                    continue;
                }
                $this->enabledplugins[$plugintype] = $enabled;
            }
        }

        $cache->set('enabled', $this->enabledplugins);
    }

    /**
     * Get list of enabled plugins of given type,
     * the result may contain missing plugins.
     *
     * @param string $type
     * @return array|null  list of enabled plugins of this type, null if unknown
     */
    public function get_enabled_plugins($type) {
        $this->load_enabled_plugins();
        if (isset($this->enabledplugins[$type])) {
            return $this->enabledplugins[$type];
        }
        return null;
    }

    /**
     * Load list of all present plugins - call before using $this->presentplugins.
     */
    protected function load_present_plugins() {
        if ($this->presentplugins) {
            return;
        }

        $cache = cache::make('core', 'plugin_manager');
        $present = $cache->get('present');

        if (is_array($present)) {
            $this->presentplugins = $present;
            return;
        }

        $this->presentplugins = array();

        $plugintypes = core_component::get_plugin_types();
        foreach ($plugintypes as $type => $typedir) {
            $plugs = core_component::get_plugin_list($type);
            foreach ($plugs as $plug => $fullplug) {
                $module = new stdClass();
                $plugin = new stdClass();
                $plugin->version = null;
                include($fullplug.'/version.php');

                // Check if the legacy $module syntax is still used.
                if (!is_object($module) or (count((array)$module) > 0)) {
                    debugging('Unsupported $module syntax detected in version.php of the '.$type.'_'.$plug.' plugin.');
                    $skipcache = true;
                }

                // Check if the component is properly declared.
                if (empty($plugin->component) or ($plugin->component !== $type.'_'.$plug)) {
                    debugging('Plugin '.$type.'_'.$plug.' does not declare valid $plugin->component in its version.php.');
                    $skipcache = true;
                }

                $this->presentplugins[$type][$plug] = $plugin;
            }
        }

        if (empty($skipcache)) {
            $cache->set('present', $this->presentplugins);
        }
    }

    /**
     * Get list of present plugins of given type.
     *
     * @param string $type
     * @return array|null  list of presnet plugins $name=>$diskversion, null if unknown
     */
    public function get_present_plugins($type) {
        $this->load_present_plugins();
        if (isset($this->presentplugins[$type])) {
            return $this->presentplugins[$type];
        }
        return null;
    }

    /**
     * Returns a tree of known plugins and information about them
     *
     * @return array 2D array. The first keys are plugin type names (e.g. qtype);
     *      the second keys are the plugin local name (e.g. multichoice); and
     *      the values are the corresponding objects extending {@link \core\plugininfo\base}
     */
    public function get_plugins() {
        $this->init_pluginsinfo_property();

        // Make sure all types are initialised.
        foreach ($this->pluginsinfo as $plugintype => $list) {
            if ($list === null) {
                $this->get_plugins_of_type($plugintype);
            }
        }

        return $this->pluginsinfo;
    }

    /**
     * Returns list of known plugins of the given type.
     *
     * This method returns the subset of the tree returned by {@link self::get_plugins()}.
     * If the given type is not known, empty array is returned.
     *
     * @param string $type plugin type, e.g. 'mod' or 'workshopallocation'
     * @return \core\plugininfo\base[] (string)plugin name (e.g. 'workshop') => corresponding subclass of {@link \core\plugininfo\base}
     */
    public function get_plugins_of_type($type) {
        global $CFG;

        $this->init_pluginsinfo_property();

        if (!array_key_exists($type, $this->pluginsinfo)) {
            return array();
        }

        if (is_array($this->pluginsinfo[$type])) {
            return $this->pluginsinfo[$type];
        }

        $types = core_component::get_plugin_types();

        if (!isset($types[$type])) {
            // Orphaned subplugins!
            $plugintypeclass = static::resolve_plugininfo_class($type);
            $this->pluginsinfo[$type] = $plugintypeclass::get_plugins($type, null, $plugintypeclass, $this);
            return $this->pluginsinfo[$type];
        }

        /** @var \core\plugininfo\base $plugintypeclass */
        $plugintypeclass = static::resolve_plugininfo_class($type);
        $plugins = $plugintypeclass::get_plugins($type, $types[$type], $plugintypeclass, $this);
        $this->pluginsinfo[$type] = $plugins;

        return $this->pluginsinfo[$type];
    }

    /**
     * Init placeholder array for plugin infos.
     */
    protected function init_pluginsinfo_property() {
        if (is_array($this->pluginsinfo)) {
            return;
        }
        $this->pluginsinfo = array();

        $plugintypes = $this->get_plugin_types();

        foreach ($plugintypes as $plugintype => $plugintyperootdir) {
            $this->pluginsinfo[$plugintype] = null;
        }

        // Add orphaned subplugin types.
        $this->load_installed_plugins();
        foreach ($this->installedplugins as $plugintype => $unused) {
            if (!isset($plugintypes[$plugintype])) {
                $this->pluginsinfo[$plugintype] = null;
            }
        }
    }

    /**
     * Find the plugin info class for given type.
     *
     * @param string $type
     * @return string name of pluginfo class for give plugin type
     */
    public static function resolve_plugininfo_class($type) {
        $plugintypes = core_component::get_plugin_types();
        if (!isset($plugintypes[$type])) {
            return '\core\plugininfo\orphaned';
        }

        $parent = core_component::get_subtype_parent($type);

        if ($parent) {
            $class = '\\'.$parent.'\plugininfo\\' . $type;
            if (class_exists($class)) {
                $plugintypeclass = $class;
            } else {
                if ($dir = core_component::get_component_directory($parent)) {
                    // BC only - use namespace instead!
                    if (file_exists("$dir/adminlib.php")) {
                        global $CFG;
                        include_once("$dir/adminlib.php");
                    }
                    if (class_exists('plugininfo_' . $type)) {
                        $plugintypeclass = 'plugininfo_' . $type;
                        debugging('Class "'.$plugintypeclass.'" is deprecated, migrate to "'.$class.'"', DEBUG_DEVELOPER);
                    } else {
                        debugging('Subplugin type "'.$type.'" should define class "'.$class.'"', DEBUG_DEVELOPER);
                        $plugintypeclass = '\core\plugininfo\general';
                    }
                } else {
                    $plugintypeclass = '\core\plugininfo\general';
                }
            }
        } else {
            $class = '\core\plugininfo\\' . $type;
            if (class_exists($class)) {
                $plugintypeclass = $class;
            } else {
                debugging('All standard types including "'.$type.'" should have plugininfo class!', DEBUG_DEVELOPER);
                $plugintypeclass = '\core\plugininfo\general';
            }
        }

        if (!in_array('core\plugininfo\base', class_parents($plugintypeclass))) {
            throw new coding_exception('Class ' . $plugintypeclass . ' must extend \core\plugininfo\base');
        }

        return $plugintypeclass;
    }

    /**
     * Returns list of all known subplugins of the given plugin.
     *
     * For plugins that do not provide subplugins (i.e. there is no support for it),
     * empty array is returned.
     *
     * @param string $component full component name, e.g. 'mod_workshop'
     * @return array (string) component name (e.g. 'workshopallocation_random') => subclass of {@link \core\plugininfo\base}
     */
    public function get_subplugins_of_plugin($component) {

        $pluginfo = $this->get_plugin_info($component);

        if (is_null($pluginfo)) {
            return array();
        }

        $subplugins = $this->get_subplugins();

        if (!isset($subplugins[$pluginfo->component])) {
            return array();
        }

        $list = array();

        foreach ($subplugins[$pluginfo->component] as $subdata) {
            foreach ($this->get_plugins_of_type($subdata->type) as $subpluginfo) {
                $list[$subpluginfo->component] = $subpluginfo;
            }
        }

        return $list;
    }

    /**
     * Returns list of plugins that define their subplugins and the information
     * about them from the db/subplugins.json file.
     *
     * @return array with keys like 'mod_quiz', and values the data from the
     *      corresponding db/subplugins.json file.
     */
    public function get_subplugins() {

        if (is_array($this->subpluginsinfo)) {
            return $this->subpluginsinfo;
        }

        $plugintypes = core_component::get_plugin_types();

        $this->subpluginsinfo = array();
        foreach (core_component::get_plugin_types_with_subplugins() as $type => $ignored) {
            foreach (core_component::get_plugin_list($type) as $plugin => $componentdir) {
                $component = $type.'_'.$plugin;
                $subplugins = core_component::get_subplugins($component);
                if (!$subplugins) {
                    continue;
                }
                $this->subpluginsinfo[$component] = array();
                foreach ($subplugins as $subplugintype => $ignored) {
                    $subplugin = new stdClass();
                    $subplugin->type = $subplugintype;
                    $subplugin->typerootdir = $plugintypes[$subplugintype];
                    $this->subpluginsinfo[$component][$subplugintype] = $subplugin;
                }
            }
        }
        return $this->subpluginsinfo;
    }

    /**
     * Returns the name of the plugin that defines the given subplugin type
     *
     * If the given subplugin type is not actually a subplugin, returns false.
     *
     * @param string $subplugintype the name of subplugin type, eg. workshopform or quiz
     * @return false|string the name of the parent plugin, eg. mod_workshop
     */
    public function get_parent_of_subplugin($subplugintype) {
        $parent = core_component::get_subtype_parent($subplugintype);
        if (!$parent) {
            return false;
        }
        return $parent;
    }

    /**
     * Returns a localized name of a given plugin
     *
     * @param string $component name of the plugin, eg mod_workshop or auth_ldap
     * @return string
     */
    public function plugin_name($component) {

        $pluginfo = $this->get_plugin_info($component);

        if (is_null($pluginfo)) {
            throw new moodle_exception('err_unknown_plugin', 'core_plugin', '', array('plugin' => $component));
        }

        return $pluginfo->displayname;
    }

    /**
     * Returns a localized name of a plugin typed in singular form
     *
     * Most plugin types define their names in core_plugin lang file. In case of subplugins,
     * we try to ask the parent plugin for the name. In the worst case, we will return
     * the value of the passed $type parameter.
     *
     * @param string $type the type of the plugin, e.g. mod or workshopform
     * @return string
     */
    public function plugintype_name($type) {

        if (get_string_manager()->string_exists('type_' . $type, 'core_plugin')) {
            // For most plugin types, their names are defined in core_plugin lang file.
            return get_string('type_' . $type, 'core_plugin');

        } else if ($parent = $this->get_parent_of_subplugin($type)) {
            // If this is a subplugin, try to ask the parent plugin for the name.
            if (get_string_manager()->string_exists('subplugintype_' . $type, $parent)) {
                return $this->plugin_name($parent) . ' / ' . get_string('subplugintype_' . $type, $parent);
            } else {
                return $this->plugin_name($parent) . ' / ' . $type;
            }

        } else {
            return $type;
        }
    }

    /**
     * Returns a localized name of a plugin type in plural form
     *
     * Most plugin types define their names in core_plugin lang file. In case of subplugins,
     * we try to ask the parent plugin for the name. In the worst case, we will return
     * the value of the passed $type parameter.
     *
     * @param string $type the type of the plugin, e.g. mod or workshopform
     * @return string
     */
    public function plugintype_name_plural($type) {

        if (get_string_manager()->string_exists('type_' . $type . '_plural', 'core_plugin')) {
            // For most plugin types, their names are defined in core_plugin lang file.
            return get_string('type_' . $type . '_plural', 'core_plugin');

        } else if ($parent = $this->get_parent_of_subplugin($type)) {
            // If this is a subplugin, try to ask the parent plugin for the name.
            if (get_string_manager()->string_exists('subplugintype_' . $type . '_plural', $parent)) {
                return $this->plugin_name($parent) . ' / ' . get_string('subplugintype_' . $type . '_plural', $parent);
            } else {
                return $this->plugin_name($parent) . ' / ' . $type;
            }

        } else {
            return $type;
        }
    }

    /**
     * Returns information about the known plugin, or null
     *
     * @param string $component frankenstyle component name.
     * @return \core\plugininfo\base|null the corresponding plugin information.
     */
    public function get_plugin_info($component) {
        list($type, $name) = core_component::normalize_component($component);
        $plugins = $this->get_plugins_of_type($type);
        if (isset($plugins[$name])) {
            return $plugins[$name];
        } else {
            return null;
        }
    }

    /**
     * Check to see if the current version of the plugin seems to be a checkout of an external repository.
     *
     * @param string $component frankenstyle component name
     * @return false|string
     */
    public function plugin_external_source($component) {

        $plugininfo = $this->get_plugin_info($component);

        if (is_null($plugininfo)) {
            return false;
        }

        $pluginroot = $plugininfo->rootdir;

        if (is_dir($pluginroot.'/.git')) {
            return 'git';
        }

        if (is_file($pluginroot.'/.git')) {
            return 'git-submodule';
        }

        if (is_dir($pluginroot.'/CVS')) {
            return 'cvs';
        }

        if (is_dir($pluginroot.'/.svn')) {
            return 'svn';
        }

        if (is_dir($pluginroot.'/.hg')) {
            return 'mercurial';
        }

        return false;
    }

    /**
     * Get a list of any other plugins that require this one.
     * @param string $component frankenstyle component name.
     * @return array of frankensyle component names that require this one.
     */
    public function other_plugins_that_require($component) {
        $others = array();
        foreach ($this->get_plugins() as $type => $plugins) {
            foreach ($plugins as $plugin) {
                $required = $plugin->get_other_required_plugins();
                if (isset($required[$component])) {
                    $others[] = $plugin->component;
                }
            }
        }
        return $others;
    }

    /**
     * Check a dependencies list against the list of installed plugins.
     * @param array $dependencies compenent name to required version or ANY_VERSION.
     * @return bool true if all the dependencies are satisfied.
     */
    public function are_dependencies_satisfied($dependencies) {
        foreach ($dependencies as $component => $requiredversion) {
            $otherplugin = $this->get_plugin_info($component);
            if (is_null($otherplugin)) {
                return false;
            }

            if ($requiredversion != ANY_VERSION and $otherplugin->versiondisk < $requiredversion) {
                return false;
            }
        }

        return true;
    }

    /**
     * Checks all dependencies for all installed plugins
     *
     * This is used by install and upgrade. The array passed by reference as the second
     * argument is populated with the list of plugins that have failed dependencies (note that
     * a single plugin can appear multiple times in the $failedplugins).
     *
     * @param int $moodleversion the version from version.php.
     * @param array $failedplugins to return the list of plugins with non-satisfied dependencies
     * @param int $branch the current moodle branch, null if not provided
     * @return bool true if all the dependencies are satisfied for all plugins.
     */
    public function all_plugins_ok($moodleversion, &$failedplugins = array(), $branch = null) {
        global $CFG;
        if (empty($branch)) {
            $branch = $CFG->branch;
            if (empty($branch)) {
                // During initial install there is no branch set.
                require($CFG->dirroot . '/version.php');
                $branch = (int)$branch;
                // Force CFG->branch to int value during install.
                $CFG->branch = $branch;
            }
        }
        $return = true;
        foreach ($this->get_plugins() as $type => $plugins) {
            foreach ($plugins as $plugin) {

                if (!$plugin->is_core_dependency_satisfied($moodleversion)) {
                    $return = false;
                    $failedplugins[] = $plugin->component;
                }

                if (!$this->are_dependencies_satisfied($plugin->get_other_required_plugins())) {
                    $return = false;
                    $failedplugins[] = $plugin->component;
                }

                if (!$plugin->is_core_compatible_satisfied($branch)) {
                    $return = false;
                    $failedplugins[] = $plugin->component;
                }
            }
        }

        return $return;
    }

    /**
     * Resolve requirements and dependencies of a plugin.
     *
     * Returns an array of objects describing the requirement/dependency,
     * indexed by the frankenstyle name of the component. The returned array
     * can be empty. The objects in the array have following properties:
     *
     *  ->(numeric)hasver
     *  ->(numeric)reqver
     *  ->(string)status
     *  ->(string)availability
     *
     * @param \core\plugininfo\base $plugin the plugin we are checking
     * @param null|string|int|double $moodleversion explicit moodle core version to check against, defaults to $CFG->version
     * @param null|string|int $moodlebranch explicit moodle core branch to check against, defaults to $CFG->branch
     * @return array of objects
     */
    public function resolve_requirements(\core\plugininfo\base $plugin, $moodleversion=null, $moodlebranch=null) {
        global $CFG;

        if ($plugin->versiondisk === null) {
            // Missing from disk, we have no version.php to read from.
            return array();
        }

        if ($moodleversion === null) {
            $moodleversion = $CFG->version;
        }

        if ($moodlebranch === null) {
            $moodlebranch = $CFG->branch;
        }

        $reqs = array();
        $reqcore = $this->resolve_core_requirements($plugin, $moodleversion, $moodlebranch);

        if (!empty($reqcore)) {
            $reqs['core'] = $reqcore;
        }

        foreach ($plugin->get_other_required_plugins() as $reqplug => $reqver) {
            $reqs[$reqplug] = $this->resolve_dependency_requirements($plugin, $reqplug, $reqver, $moodlebranch);
        }

        return $reqs;
    }

    /**
     * Helper method to resolve plugin's requirements on the moodle core.
     *
     * @param \core\plugininfo\base $plugin the plugin we are checking
     * @param string|int|double $moodleversion moodle core branch to check against
     * @return stdObject
     */
    protected function resolve_core_requirements(\core\plugininfo\base $plugin, $moodleversion, $moodlebranch) {

        $reqs = (object)array(
            'hasver' => null,
            'reqver' => null,
            'status' => null,
            'availability' => null,
        );
        $reqs->hasver = $moodleversion;

        if (empty($plugin->versionrequires)) {
            $reqs->reqver = ANY_VERSION;
        } else {
            $reqs->reqver = $plugin->versionrequires;
        }

        if ($plugin->is_core_dependency_satisfied($moodleversion)) {
            $reqs->status = self::REQUIREMENT_STATUS_OK;
        } else {
            $reqs->status = self::REQUIREMENT_STATUS_OUTDATED;
        }

        // Now check if there is an explicit incompatible, supersedes requires.
        if (isset($plugin->pluginincompatible) && $plugin->pluginincompatible != null) {
            if (!$plugin->is_core_compatible_satisfied($moodlebranch)) {

                $reqs->status = self::REQUIREMENT_STATUS_NEWER;
            }
        }

        return $reqs;
    }

    /**
     * Helper method to resolve plugin's dependecies on other plugins.
     *
     * @param \core\plugininfo\base $plugin the plugin we are checking
     * @param string $otherpluginname
     * @param string|int $requiredversion
     * @param string|int $moodlebranch explicit moodle core branch to check against, defaults to $CFG->branch
     * @return stdClass
     */
    protected function resolve_dependency_requirements(\core\plugininfo\base $plugin, $otherpluginname,
            $requiredversion, $moodlebranch) {

        $reqs = (object)array(
            'hasver' => null,
            'reqver' => null,
            'status' => null,
            'availability' => null,
        );

        $otherplugin = $this->get_plugin_info($otherpluginname);

        if ($otherplugin !== null) {
            // The required plugin is installed.
            $reqs->hasver = $otherplugin->versiondisk;
            $reqs->reqver = $requiredversion;
            // Check it has sufficient version.
            if ($requiredversion == ANY_VERSION or $otherplugin->versiondisk >= $requiredversion) {
                $reqs->status = self::REQUIREMENT_STATUS_OK;
            } else {
                $reqs->status = self::REQUIREMENT_STATUS_OUTDATED;
            }

        } else {
            // The required plugin is not installed.
            $reqs->hasver = null;
            $reqs->reqver = $requiredversion;
            $reqs->status = self::REQUIREMENT_STATUS_MISSING;
        }

        if ($reqs->status !== self::REQUIREMENT_STATUS_OK) {
            if ($this->is_remote_plugin_available($otherpluginname, $requiredversion, false)) {
                $reqs->availability = self::REQUIREMENT_AVAILABLE;
            } else {
                $reqs->availability = self::REQUIREMENT_UNAVAILABLE;
            }
        }

        return $reqs;
    }

    /**
     * Helper method to determine whether a moodle version is explicitly supported.
     *
     * @param \core\plugininfo\base $plugin the plugin we are checking
     * @param int $branch the moodle branch to check support for
     * @return string
     */
    public function check_explicitly_supported($plugin, $branch) : string {
        // Check for correctly formed supported.
        if (isset($plugin->pluginsupported)) {
            // Broken apart for readability.
            $error = false;
            if (!is_array($plugin->pluginsupported)) {
                $error = true;
            }
            if (!is_int($plugin->pluginsupported[0]) || !is_int($plugin->pluginsupported[1])) {
                $error = true;
            }
            if (count($plugin->pluginsupported) != 2) {
                $error = true;
            }
            if ($error) {
                throw new coding_exception(get_string('err_supported_syntax', 'core_plugin'));
            }
        }

        if (isset($plugin->pluginsupported) && $plugin->pluginsupported != null) {
            if ($plugin->pluginsupported[0] <= $branch && $branch <= $plugin->pluginsupported[1]) {
                return self::VERSION_SUPPORTED;
            } else {
                return self::VERSION_NOT_SUPPORTED;
            }
        } else {
            // If supports aren't specified, but incompatible is, return not supported if not incompatible.
            if (!isset($plugin->pluginsupported) && isset($plugin->pluginincompatible) && !empty($plugin->pluginincompatible)) {
                if (!$plugin->is_core_compatible_satisfied($branch)) {
                    return self::VERSION_NOT_SUPPORTED;
                }
            }
            return self::VERSION_NO_SUPPORTS;
        }
    }

    /**
     * Is the given plugin version available in the plugins directory?
     *
     * See {@link self::get_remote_plugin_info()} for the full explanation of how the $version
     * parameter is interpretted.
     *
     * @param string $component plugin frankenstyle name
     * @param string|int $version ANY_VERSION or the version number
     * @param bool $exactmatch false if "given version or higher" is requested
     * @return boolean
     */
    public function is_remote_plugin_available($component, $version, $exactmatch) {

        $info = $this->get_remote_plugin_info($component, $version, $exactmatch);

        if (empty($info)) {
            // There is no available plugin of that name.
            return false;
        }

        if (empty($info->version)) {
            // Plugin is known, but no suitable version was found.
            return false;
        }

        return true;
    }

    /**
     * Can the given plugin version be installed via the admin UI?
     *
     * This check should be used whenever attempting to install a plugin from
     * the plugins directory (new install, available update, missing dependency).
     *
     * @param string $component
     * @param int $version version number
     * @param string $reason returned code of the reason why it is not
     * @return boolean
     */
    public function is_remote_plugin_installable($component, $version, &$reason=null) {
        global $CFG;

        // Make sure the feature is not disabled.
        if (!empty($CFG->disableupdateautodeploy)) {
            $reason = 'disabled';
            return false;
        }

        // Make sure the version is available.
        if (!$this->is_remote_plugin_available($component, $version, true)) {
            $reason = 'remoteunavailable';
            return false;
        }

        // Make sure the plugin type root directory is writable.
        list($plugintype, $pluginname) = core_component::normalize_component($component);
        if (!$this->is_plugintype_writable($plugintype)) {
            $reason = 'notwritableplugintype';
            return false;
        }

        $remoteinfo = $this->get_remote_plugin_info($component, $version, true);
        $localinfo = $this->get_plugin_info($component);

        if ($localinfo) {
            // If the plugin is already present, prevent downgrade.
            if ($localinfo->versiondb > $remoteinfo->version->version) {
                $reason = 'cannotdowngrade';
                return false;
            }

            // Make sure we have write access to all the existing code.
            if (is_dir($localinfo->rootdir)) {
                if (!$this->is_plugin_folder_removable($component)) {
                    $reason = 'notwritableplugin';
                    return false;
                }
            }
        }

        // Looks like it could work.
        return true;
    }

    /**
     * Given the list of remote plugin infos, return just those installable.
     *
     * This is typically used on lists returned by
     * {@link self::available_updates()} or {@link self::missing_dependencies()}
     * to perform bulk installation of remote plugins.
     *
     * @param array $remoteinfos list of {@link \core\update\remote_info}
     * @return array
     */
    public function filter_installable($remoteinfos) {
        global $CFG;

        if (!empty($CFG->disableupdateautodeploy)) {
            return array();
        }
        if (empty($remoteinfos)) {
            return array();
        }
        $installable = array();
        foreach ($remoteinfos as $index => $remoteinfo) {
            if ($this->is_remote_plugin_installable($remoteinfo->component, $remoteinfo->version->version)) {
                $installable[$index] = $remoteinfo;
            }
        }
        return $installable;
    }

    /**
     * Returns information about a plugin in the plugins directory.
     *
     * This is typically used when checking for available dependencies (in
     * which case the $version represents minimal version we need), or
     * when installing an available update or a new plugin from the plugins
     * directory (in which case the $version is exact version we are
     * interested in). The interpretation of the $version is controlled
     * by the $exactmatch argument.
     *
     * If a plugin with the given component name is found, data about the
     * plugin are returned as an object. The ->version property of the object
     * contains the information about the particular plugin version that
     * matches best the given critera. The ->version property is false if no
     * suitable version of the plugin was found (yet the plugin itself is
     * known).
     *
     * See {@link \core\update\api::validate_pluginfo_format()} for the
     * returned data structure.
     *
     * @param string $component plugin frankenstyle name
     * @param string|int $version ANY_VERSION or the version number
     * @param bool $exactmatch false if "given version or higher" is requested
     * @return \core\update\remote_info|bool
     */
    public function get_remote_plugin_info($component, $version, $exactmatch) {

        if ($exactmatch and $version == ANY_VERSION) {
            throw new coding_exception('Invalid request for exactly any version, it does not make sense.');
        }

        $client = $this->get_update_api_client();

        if ($exactmatch) {
            // Use client's get_plugin_info() method.
            if (!isset($this->remotepluginsinfoexact[$component][$version])) {
                $this->remotepluginsinfoexact[$component][$version] = $client->get_plugin_info($component, $version);
            }
            return $this->remotepluginsinfoexact[$component][$version];

        } else {
            // Use client's find_plugin() method.
            if (!isset($this->remotepluginsinfoatleast[$component][$version])) {
                $this->remotepluginsinfoatleast[$component][$version] = $client->find_plugin($component, $version);
            }
            return $this->remotepluginsinfoatleast[$component][$version];
        }
    }

    /**
     * Obtain the plugin ZIP file from the given URL
     *
     * The caller is supposed to know both downloads URL and the MD5 hash of
     * the ZIP contents in advance, typically by using the API requests against
     * the plugins directory.
     *
     * @param string $url
     * @param string $md5
     * @return string|bool full path to the file, false on error
     */
    public function get_remote_plugin_zip($url, $md5) {
        global $CFG;

        if (!empty($CFG->disableupdateautodeploy)) {
            return false;
        }
        return $this->get_code_manager()->get_remote_plugin_zip($url, $md5);
    }

    /**
     * Extracts the saved plugin ZIP file.
     *
     * Returns the list of files found in the ZIP. The format of that list is
     * array of (string)filerelpath => (bool|string) where the array value is
     * either true or a string describing the problematic file.
     *
     * @see zip_packer::extract_to_pathname()
     * @param string $zipfilepath full path to the saved ZIP file
     * @param string $targetdir full path to the directory to extract the ZIP file to
     * @param string $rootdir explicitly rename the root directory of the ZIP into this non-empty value
     * @return array list of extracted files as returned by {@link zip_packer::extract_to_pathname()}
     */
    public function unzip_plugin_file($zipfilepath, $targetdir, $rootdir = '') {
        return $this->get_code_manager()->unzip_plugin_file($zipfilepath, $targetdir, $rootdir);
    }

    /**
     * Detects the plugin's name from its ZIP file.
     *
     * Plugin ZIP packages are expected to contain a single directory and the
     * directory name would become the plugin name once extracted to the Moodle
     * dirroot.
     *
     * @param string $zipfilepath full path to the ZIP files
     * @return string|bool false on error
     */
    public function get_plugin_zip_root_dir($zipfilepath) {
        return $this->get_code_manager()->get_plugin_zip_root_dir($zipfilepath);
    }

    /**
     * Return a list of missing dependencies.
     *
     * This should provide the full list of plugins that should be installed to
     * fulfill the requirements of all plugins, if possible.
     *
     * @param bool $availableonly return only available missing dependencies
     * @return array of \core\update\remote_info|bool indexed by the component name
     */
    public function missing_dependencies($availableonly=false) {

        $dependencies = array();

        foreach ($this->get_plugins() as $plugintype => $pluginfos) {
            foreach ($pluginfos as $pluginname => $pluginfo) {
                foreach ($this->resolve_requirements($pluginfo) as $reqname => $reqinfo) {
                    if ($reqname === 'core') {
                        continue;
                    }
                    if ($reqinfo->status != self::REQUIREMENT_STATUS_OK) {
                        if ($reqinfo->availability == self::REQUIREMENT_AVAILABLE) {
                            $remoteinfo = $this->get_remote_plugin_info($reqname, $reqinfo->reqver, false);

                            if (empty($dependencies[$reqname])) {
                                $dependencies[$reqname] = $remoteinfo;
                            } else {
                                // If resolving requirements has led to two different versions of the same
                                // remote plugin, pick the higher version. This can happen in cases like one
                                // plugin requiring ANY_VERSION and another plugin requiring specific higher
                                // version with lower maturity of a remote plugin.
                                if ($remoteinfo->version->version > $dependencies[$reqname]->version->version) {
                                    $dependencies[$reqname] = $remoteinfo;
                                }
                            }

                        } else {
                            if (!isset($dependencies[$reqname])) {
                                // Unable to find a plugin fulfilling the requirements.
                                $dependencies[$reqname] = false;
                            }
                        }
                    }
                }
            }
        }

        if ($availableonly) {
            foreach ($dependencies as $component => $info) {
                if (empty($info) or empty($info->version)) {
                    unset($dependencies[$component]);
                }
            }
        }

        return $dependencies;
    }

    /**
     * Is it possible to uninstall the given plugin?
     *
     * False is returned if the plugininfo subclass declares the uninstall should
     * not be allowed via {@link \core\plugininfo\base::is_uninstall_allowed()} or if the
     * core vetoes it (e.g. becase the plugin or some of its subplugins is required
     * by some other installed plugin).
     *
     * @param string $component full frankenstyle name, e.g. mod_foobar
     * @return bool
     */
    public function can_uninstall_plugin($component) {

        $pluginfo = $this->get_plugin_info($component);

        if (is_null($pluginfo)) {
            return false;
        }

        if (!$this->common_uninstall_check($pluginfo)) {
            return false;
        }

        // Verify only if something else requires the subplugins, do not verify their common_uninstall_check()!
        $subplugins = $this->get_subplugins_of_plugin($pluginfo->component);
        foreach ($subplugins as $subpluginfo) {
            // Check if there are some other plugins requiring this subplugin
            // (but the parent and siblings).
            foreach ($this->other_plugins_that_require($subpluginfo->component) as $requiresme) {
                $ismyparent = ($pluginfo->component === $requiresme);
                $ismysibling = in_array($requiresme, array_keys($subplugins));
                if (!$ismyparent and !$ismysibling) {
                    return false;
                }
            }
        }

        // Check if there are some other plugins requiring this plugin
        // (but its subplugins).
        foreach ($this->other_plugins_that_require($pluginfo->component) as $requiresme) {
            $ismysubplugin = in_array($requiresme, array_keys($subplugins));
            if (!$ismysubplugin) {
                return false;
            }
        }

        return true;
    }

    /**
     * Perform the installation of plugins.
     *
     * If used for installation of remote plugins from the Moodle Plugins
     * directory, the $plugins must be list of {@link \core\update\remote_info}
     * object that represent installable remote plugins. The caller can use
     * {@link self::filter_installable()} to prepare the list.
     *
     * If used for installation of plugins from locally available ZIP files,
     * the $plugins should be list of objects with properties ->component and
     * ->zipfilepath.
     *
     * The method uses {@link mtrace()} to produce direct output and can be
     * used in both web and cli interfaces.
     *
     * @param array $plugins list of plugins
     * @param bool $confirmed should the files be really deployed into the dirroot?
     * @param bool $silent perform without output
     * @return bool true on success
     */
    public function install_plugins(array $plugins, $confirmed, $silent) {
        global $CFG, $OUTPUT;

        if (!empty($CFG->disableupdateautodeploy)) {
            return false;
        }

        if (empty($plugins)) {
            return false;
        }

        $ok = get_string('ok', 'core');

        // Let admins know they can expect more verbose output.
        $silent or $this->mtrace(get_string('packagesdebug', 'core_plugin'), PHP_EOL, DEBUG_NORMAL);

        // Download all ZIP packages if we do not have them yet.
        $zips = array();
        foreach ($plugins as $plugin) {
            if ($plugin instanceof \core\update\remote_info) {
                $zips[$plugin->component] = $this->get_remote_plugin_zip($plugin->version->downloadurl,
                    $plugin->version->downloadmd5);
                $silent or $this->mtrace(get_string('packagesdownloading', 'core_plugin', $plugin->component), ' ... ');
                $silent or $this->mtrace(PHP_EOL.' <- '.$plugin->version->downloadurl, '', DEBUG_DEVELOPER);
                $silent or $this->mtrace(PHP_EOL.' -> '.$zips[$plugin->component], ' ... ', DEBUG_DEVELOPER);
                if (!$zips[$plugin->component]) {
                    $silent or $this->mtrace(get_string('error'));
                    return false;
                }
                $silent or $this->mtrace($ok);
            } else {
                if (empty($plugin->zipfilepath)) {
                    throw new coding_exception('Unexpected data structure provided');
                }
                $zips[$plugin->component] = $plugin->zipfilepath;
                $silent or $this->m…

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