Proyectos de Subversion Moodle

<?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/>.

/**

 * Functions for interacting with the message system

 *

 * @package   core_message

 * @copyright 2008 Luis Rodrigues and Martin Dougiamas

 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

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

require_once(__DIR__ . '/../message/lib.php');

/**

 * Called when a message provider wants to send a message.

 * This functions checks the message recipient's message processor configuration then

 * sends the message to the configured processors

 *

 * Required parameters of the $eventdata object:

 *  component string component name. must exist in message_providers

 *  name string message type name. must exist in message_providers

 *  userfrom object|int the user sending the message

 *  userto object|int the message recipient

 *  subject string the message subject

 *  fullmessage string the full message in a given format

 *  fullmessageformat int the format if the full message (FORMAT_MOODLE, FORMAT_HTML, ..)

 *  fullmessagehtml string the full version (the message processor will choose with one to use)

 *  smallmessage string the small version of the message

 *

 * Optional parameters of the $eventdata object:

 *  notification bool should the message be considered as a notification rather than a personal message

 *  contexturl string if this is a notification then you can specify a url to view the event. For example the forum post the user is being notified of.

 *  contexturlname string the display text for contexturl

 *

 * Note: processor failure will not reported as false return value in all scenarios,

 *       for example when it is called while a database transaction is open,

 *       earlier versions did not do it consistently either.

 *

 * @category message

 * @param \core\message\message $eventdata information about the message (component, userfrom, userto, ...)

 * @return mixed the integer ID of the new message or false if there was a problem (with submitted data or sending the message to the message processor)

 */

function message_send(\core\message\message $eventdata) {

    global $CFG, $DB, $SITE;

    //new message ID to return

    $messageid = false;

    // Fetch default (site) preferences

    $defaultpreferences = get_message_output_default_preferences();

    $preferencebase = $eventdata->component.'_'.$eventdata->name;

    // If the message provider is disabled via preferences, then don't send the message.

    if (!empty($defaultpreferences->{$preferencebase.'_disable'})) {

        return $messageid;

    }

    // By default a message is a notification. Only personal/private messages aren't notifications.

    if (!isset($eventdata->notification)) {

        $eventdata->notification = 1;

    }

    if (!is_object($eventdata->userfrom)) {

        $eventdata->userfrom = core_user::get_user($eventdata->userfrom);

    }

    if (!$eventdata->userfrom) {

        debugging('Attempt to send msg from unknown user', DEBUG_NORMAL);

        return false;

    }

    // Legacy messages (FROM a single user TO a single user) must be converted into conversation messages.

    // Then, these will be passed through the conversation messages code below.

    if (!$eventdata->notification && !$eventdata->convid) {

        // If messaging is disabled at the site level, then the 'instantmessage' provider is always disabled.

        // Given this is the only 'message' type message provider, we can exit now if this is the case.

        // Don't waste processing time trying to work out the other conversation member, if it's an individual

        // conversation, just throw a generic debugging notice and return.

        if (empty($CFG->messaging) || $eventdata->component !== 'moodle' || $eventdata->name !== 'instantmessage') {

            debugging('Attempt to send msg from a provider '.$eventdata->component.'/'.$eventdata->name.

                ' that is inactive or not allowed for the user id='.$eventdata->userto->id, DEBUG_NORMAL);

            return false;

        }

        if (!is_object($eventdata->userto)) {

            $eventdata->userto = core_user::get_user($eventdata->userto);

        }

        if (!$eventdata->userto) {

            debugging('Attempt to send msg to unknown user', DEBUG_NORMAL);

            return false;

        }

        // Verify all necessary data fields are present.

        if (!isset($eventdata->userto->auth) or !isset($eventdata->userto->suspended)

            or !isset($eventdata->userto->deleted) or !isset($eventdata->userto->emailstop)) {

            debugging('Necessary properties missing in userto object, fetching full record', DEBUG_DEVELOPER);

            $eventdata->userto = core_user::get_user($eventdata->userto->id);

        }

        $usertoisrealuser = (core_user::is_real_user($eventdata->userto->id) != false);

        // If recipient is internal user (noreply user), and emailstop is set then don't send any msg.

        if (!$usertoisrealuser && !empty($eventdata->userto->emailstop)) {

            debugging('Attempt to send msg to internal (noreply) user', DEBUG_NORMAL);

            return false;

        }

        if ($eventdata->userfrom->id == $eventdata->userto->id) {

            // It's a self conversation.

            $conversation = \core_message\api::get_self_conversation($eventdata->userfrom->id);

            if (empty($conversation)) {

                $conversation = \core_message\api::create_conversation(

                    \core_message\api::MESSAGE_CONVERSATION_TYPE_SELF,

                    [$eventdata->userfrom->id]

                );

            }

        } else {

            if (!$conversationid = \core_message\api::get_conversation_between_users([$eventdata->userfrom->id,

                                                                                      $eventdata->userto->id])) {

                // It's a private conversation between users.

                $conversation = \core_message\api::create_conversation(

                    \core_message\api::MESSAGE_CONVERSATION_TYPE_INDIVIDUAL,

                    [

                        $eventdata->userfrom->id,

                        $eventdata->userto->id

                    ]

                );

            }

        }

        // We either have found a conversation, or created one.

        $conversationid = !empty($conversationid) ? $conversationid : $conversation->id;

        $eventdata->convid = $conversationid;

    }

    // This is a message directed to a conversation, not a specific user as was the way in legacy messaging.

    // The above code has adapted the legacy messages into conversation messages.

    // We must call send_message_to_conversation(), which handles per-member processor iteration and triggers

    // a per-conversation event.

    // All eventdata for messages should now have a convid, as we fixed this above.

    if (!$eventdata->notification) {

        // Only one message will be saved to the DB.

        $conversationid = $eventdata->convid;

        $table = 'messages';

        $tabledata = new stdClass();

        $tabledata->courseid = $eventdata->courseid;

        $tabledata->useridfrom = $eventdata->userfrom->id;

        $tabledata->conversationid = $conversationid;

        $tabledata->subject = $eventdata->subject;

        $tabledata->fullmessage = $eventdata->fullmessage;

        $tabledata->fullmessageformat = $eventdata->fullmessageformat;

        $tabledata->fullmessagehtml = $eventdata->fullmessagehtml;

        $tabledata->smallmessage = $eventdata->smallmessage;

        $tabledata->timecreated = time();

        $tabledata->customdata = $eventdata->customdata;

        // The Trusted Content system.

        // Texts created or uploaded by such users will be marked as trusted and will not be cleaned before display.

        if (trusttext_active()) {

            // Individual conversations are always in system context.

            $messagecontext = \context_system::instance();

            // We need to know the type of conversation and the contextid if it is a group conversation.

            if ($conv = $DB->get_record('message_conversations', ['id' => $conversationid], 'id, type, contextid')) {

                if ($conv->type == \core_message\api::MESSAGE_CONVERSATION_TYPE_GROUP && $conv->contextid) {

                    $messagecontext = \context::instance_by_id($conv->contextid);

                }

            }

            $tabledata->fullmessagetrust = trusttext_trusted($messagecontext);

        } else {

            $tabledata->fullmessagetrust = false;

        }

        if ($messageid = message_handle_phpunit_redirection($eventdata, $table, $tabledata)) {

            return $messageid;

        }

        // Cache messages.

        if (!empty($eventdata->convid)) {

            // Cache the timecreated value of the last message in this conversation.

            $cache = cache::make('core', 'message_time_last_message_between_users');

            $key = \core_message\helper::get_last_message_time_created_cache_key($eventdata->convid);

            $cache->set($key, $tabledata->timecreated);

        }

        // Store unread message just in case we get a fatal error any time later.

        $tabledata->id = $DB->insert_record($table, $tabledata);

        $eventdata->savedmessageid = $tabledata->id;

        return \core\message\manager::send_message_to_conversation($eventdata, $tabledata);

    }

    // Else the message is a notification.

    if (!is_object($eventdata->userto)) {

        $eventdata->userto = core_user::get_user($eventdata->userto);

    }

    if (!$eventdata->userto) {

        debugging('Attempt to send msg to unknown user', DEBUG_NORMAL);

        return false;

    }

    // If the provider's component is disabled or the user can't receive messages from it, don't send the message.

    $isproviderallowed = false;

    foreach (message_get_providers_for_user($eventdata->userto->id) as $provider) {

        if ($provider->component === $eventdata->component && $provider->name === $eventdata->name) {

            $isproviderallowed = true;

            break;

        }

    }

    if (!$isproviderallowed) {

        debugging('Attempt to send msg from a provider '.$eventdata->component.'/'.$eventdata->name.

            ' that is inactive or not allowed for the user id='.$eventdata->userto->id, DEBUG_NORMAL);

        return false;

    }

    // Verify all necessary data fields are present.

    if (!isset($eventdata->userto->auth) or !isset($eventdata->userto->suspended)

            or !isset($eventdata->userto->deleted) or !isset($eventdata->userto->emailstop)) {

        debugging('Necessary properties missing in userto object, fetching full record', DEBUG_DEVELOPER);

        $eventdata->userto = core_user::get_user($eventdata->userto->id);

    }

    $usertoisrealuser = (core_user::is_real_user($eventdata->userto->id) != false);

    // If recipient is internal user (noreply user), and emailstop is set then don't send any msg.

    if (!$usertoisrealuser && !empty($eventdata->userto->emailstop)) {

        debugging('Attempt to send msg to internal (noreply) user', DEBUG_NORMAL);

        return false;

    }

    // Check if we are creating a notification or message.

    $table = 'notifications';

    $tabledata = new stdClass();

    $tabledata->useridfrom = $eventdata->userfrom->id;

    $tabledata->useridto = $eventdata->userto->id;

    $tabledata->subject = $eventdata->subject;

    $tabledata->fullmessage = $eventdata->fullmessage;

    $tabledata->fullmessageformat = $eventdata->fullmessageformat;

    $tabledata->fullmessagehtml = $eventdata->fullmessagehtml;

    $tabledata->smallmessage = $eventdata->smallmessage;

    $tabledata->eventtype = $eventdata->name;

    $tabledata->component = $eventdata->component;

    $tabledata->timecreated = time();

    $tabledata->customdata = $eventdata->customdata;

    if (!empty($eventdata->contexturl)) {

        $tabledata->contexturl = (string)$eventdata->contexturl;

    } else {

        $tabledata->contexturl = null;

    }

    if (!empty($eventdata->contexturlname)) {

        $tabledata->contexturlname = (string)$eventdata->contexturlname;

    } else {

        $tabledata->contexturlname = null;

    }

    if ($messageid = message_handle_phpunit_redirection($eventdata, $table, $tabledata)) {

        return $messageid;

    }

    // Fetch enabled processors.

    $processors = get_message_processors(true);

    // Preset variables

    $processorlist = array();

    // Fill in the array of processors to be used based on default and user preferences

    foreach ($processors as $processor) {

        // Skip adding processors for internal user, if processor doesn't support sending message to internal user.

        if (!$usertoisrealuser && !$processor->object->can_send_to_any_users()) {

            continue;

        }

        // First find out permissions

        $defaultlockedpreference = $processor->name . '_provider_' . $preferencebase . '_locked';

        $locked = false;

        if (isset($defaultpreferences->{$defaultlockedpreference})) {

            $locked = $defaultpreferences->{$defaultlockedpreference};

        } else {

            // MDL-25114 They supplied an $eventdata->component $eventdata->name combination which doesn't

            // exist in the message_provider table (thus there is no default settings for them).

            $preferrormsg = "Could not load preference $defaultlockedpreference. Make sure the component and name you supplied

                    to message_send() are valid.";

            throw new coding_exception($preferrormsg);

        }

        $preferencename = 'message_provider_'.$preferencebase.'_enabled';

        $forced = false;

        if ($locked && isset($defaultpreferences->{$preferencename})) {

            $userpreference = $defaultpreferences->{$preferencename};

            $forced = in_array($processor->name, explode(',', $userpreference));

        }

        // Find out if user has configured this output

        // Some processors cannot function without settings from the user

        $userisconfigured = $processor->object->is_user_configured($eventdata->userto);

        // DEBUG: notify if we are forcing unconfigured output

        if ($forced && !$userisconfigured) {

            debugging('Attempt to force message delivery to user who has "'.$processor->name.'" output unconfigured', DEBUG_NORMAL);

        }

        // Populate the list of processors we will be using

        if ($forced && $userisconfigured) {

            // An admin is forcing users to use this message processor. Use this processor unconditionally.

            $processorlist[] = $processor->name;

        } else if (!$forced && !$locked && $userisconfigured && !$eventdata->userto->emailstop) {

            // User has not disabled notifications

            // See if user set any notification preferences, otherwise use site default ones

            if ($userpreference = get_user_preferences($preferencename, null, $eventdata->userto)) {

                if (in_array($processor->name, explode(',', $userpreference))) {

                    $processorlist[] = $processor->name;

                }

            } else if (isset($defaultpreferences->{$preferencename})) {

                if (in_array($processor->name, explode(',', $defaultpreferences->{$preferencename}))) {

                    $processorlist[] = $processor->name;

                }

            }

        }

    }

    // Store unread message just in case we get a fatal error any time later.

    $tabledata->id = $DB->insert_record($table, $tabledata);

    $eventdata->savedmessageid = $tabledata->id;

    // Let the manager do the sending or buffering when db transaction in progress.

    try {

        return \core\message\manager::send_message($eventdata, $tabledata, $processorlist);

    } catch (\moodle_exception $exception) {

        return false;

    }

}

/**

 * Helper method containing the PHPUnit specific code, used to redirect and capture messages/notifications.

 *

 * @param \core\message\message $eventdata the message object

 * @param string $table the table to store the tabledata in, either messages or notifications.

 * @param stdClass $tabledata the data to be stored when creating the message/notification.

 * @return int the id of the stored message.

 */

function message_handle_phpunit_redirection(\core\message\message $eventdata, string $table, \stdClass $tabledata) {

    global $DB;

    if (PHPUNIT_TEST and class_exists('phpunit_util')) {

        // Add some more tests to make sure the normal code can actually work.

        $componentdir = core_component::get_component_directory($eventdata->component);

        if (!$componentdir or !is_dir($componentdir)) {

            throw new coding_exception('Invalid component specified in message-send(): '.$eventdata->component);

        }

        if (!file_exists("$componentdir/db/messages.php")) {

            throw new coding_exception("$eventdata->component does not contain db/messages.php necessary for message_send()");

        }

        $messageproviders = null;

        include("$componentdir/db/messages.php");

        if (!isset($messageproviders[$eventdata->name])) {

            throw new coding_exception("Missing messaging defaults for event '$eventdata->name' in '$eventdata->component' " .

                "messages.php file");

        }

        unset($componentdir);

        unset($messageproviders);

        // Now ask phpunit if it wants to catch this message.

        if (phpunit_util::is_redirecting_messages()) {

            $messageid = $DB->insert_record($table, $tabledata);

            $message = $DB->get_record($table, array('id' => $messageid));

            if ($eventdata->notification) {

                // Add the useridto attribute for BC.

                $message->useridto = $eventdata->userto->id;

                // Mark the notification as read.

                \core_message\api::mark_notification_as_read($message);

            } else {

                // Add the useridto attribute for BC.

                if (isset($eventdata->userto)) {

                    $message->useridto = $eventdata->userto->id;

                }

                // Mark the message as read for each of the other users.

                $sql = "SELECT u.*

                  FROM {message_conversation_members} mcm

                  JOIN {user} u

                    ON (mcm.conversationid = :convid AND u.id = mcm.userid AND u.id != :userid)";

                $otherusers = $DB->get_records_sql($sql, ['convid' => $eventdata->convid, 'userid' => $eventdata->userfrom->id]);

                foreach ($otherusers as $othermember) {

                    \core_message\api::mark_message_as_read($othermember->id, $message);

                }

            }

            // Unit tests need this detail.

            $message->notification = $eventdata->notification;

            phpunit_util::message_sent($message);

            return $messageid;

        }

    }

}

/**

 * Updates the message_providers table with the current set of message providers

 *

 * @param string $component For example 'moodle', 'mod_forum' or 'block_activity_results'

 * @return boolean True on success

 */

function message_update_providers($component='moodle') {

    global $DB;

    // load message providers from files

    $fileproviders = message_get_providers_from_file($component);

    // load message providers from the database

    $dbproviders = message_get_providers_from_db($component);

    foreach ($fileproviders as $messagename => $fileprovider) {

        if (!empty($dbproviders[$messagename])) {   // Already exists in the database

            // check if capability has changed

            if ($dbproviders[$messagename]->capability == $fileprovider['capability']) {  // Same, so ignore

                // exact same message provider already present in db, ignore this entry

                unset($dbproviders[$messagename]);

                continue;

            } else {                                // Update existing one

                $provider = new stdClass();

                $provider->id         = $dbproviders[$messagename]->id;

                $provider->capability = $fileprovider['capability'];

                $DB->update_record('message_providers', $provider);

                unset($dbproviders[$messagename]);

                continue;

            }

        } else {             // New message provider, add it

            $provider = new stdClass();

            $provider->name       = $messagename;

            $provider->component  = $component;

            $provider->capability = $fileprovider['capability'];

            $transaction = $DB->start_delegated_transaction();

            $DB->insert_record('message_providers', $provider);

            message_set_default_message_preference($component, $messagename, $fileprovider);

            $transaction->allow_commit();

        }

    }

    foreach ($dbproviders as $dbprovider) {  // Delete old ones

        $DB->delete_records('message_providers', array('id' => $dbprovider->id));

        $DB->delete_records_select('config_plugins', "plugin = 'message' AND ".$DB->sql_like('name', '?', false), array("%_provider_{$component}_{$dbprovider->name}_%"));

        $DB->delete_records_select('user_preferences', $DB->sql_like('name', '?', false), array("message_provider_{$component}_{$dbprovider->name}_%"));

        cache_helper::invalidate_by_definition('core', 'config', array(), 'message');

    }

    return true;

}

/**

 * This function populates default message preferences for all existing providers

 * when the new message processor is added.

 *

 * @param string $processorname The name of message processor plugin (e.g. 'email', 'jabber')

 * @throws invalid_parameter_exception if $processorname does not exist in the database

 */

function message_update_processors($processorname) {

    global $DB;

    // validate if our processor exists

    $processor = $DB->get_records('message_processors', array('name' => $processorname));

    if (empty($processor)) {

        throw new invalid_parameter_exception();

    }

    $providers = $DB->get_records_sql('SELECT DISTINCT component FROM {message_providers}');

    $transaction = $DB->start_delegated_transaction();

    foreach ($providers as $provider) {

        // load message providers from files

        $fileproviders = message_get_providers_from_file($provider->component);

        foreach ($fileproviders as $messagename => $fileprovider) {

            message_set_default_message_preference($provider->component, $messagename, $fileprovider, $processorname);

        }

    }

    $transaction->allow_commit();

}

/**

 * Setting default messaging preferences for particular message provider

 *

 * @param  string $component   The name of component (e.g. moodle, mod_forum, etc.)

 * @param  string $messagename The name of message provider

 * @param  array  $fileprovider The value of $messagename key in the array defined in plugin messages.php

 * @param  string $processorname The optional name of message processor

 */

function message_set_default_message_preference($component, $messagename, $fileprovider, $processorname='') {

    global $DB;

    // Fetch message processors

    $condition = null;

    // If we need to process a particular processor, set the select condition

    if (!empty($processorname)) {

       $condition = array('name' => $processorname);

    }

    $processors = $DB->get_records('message_processors', $condition);

    // load default messaging preferences

    $defaultpreferences = get_message_output_default_preferences();

    // Setting default preference

    $componentproviderbase = $component.'_'.$messagename;

    $enabledpref = [];

    // Set 'locked' preference first for each messaging processor.

    foreach ($processors as $processor) {

        $preferencename = $processor->name.'_provider_'.$componentproviderbase.'_locked';

        // If we do not have this setting yet, set it.

        if (!isset($defaultpreferences->{$preferencename})) {

            // Determine plugin default settings.

            $plugindefault = 0;

            if (isset($fileprovider['defaults'][$processor->name])) {

                $plugindefault = $fileprovider['defaults'][$processor->name];

            }

            // Get string values of the settings.

            list($locked, $enabled) = translate_message_default_setting($plugindefault, $processor->name);

            // Store default preferences for current processor.

            set_config($preferencename, $locked, 'message');

            // Save enabled settings.

            if ($enabled) {

                $enabledpref[] = $processor->name;

            }

        }

    }

    // Now set enabled preferences.

    if (!empty($enabledpref)) {

        $preferencename = 'message_provider_'.$componentproviderbase.'_enabled';

        if (isset($defaultpreferences->{$preferencename})) {

            // We have the default preferences for this message provider, which

            // likely means that we have been adding a new processor. Add defaults

            // to exisitng preferences.

            $enabledpref = array_merge($enabledpref, explode(',', $defaultpreferences->{$preferencename}));

        }

        set_config($preferencename, join(',', $enabledpref), 'message');

    }

}

/**

 * Returns the active providers for the user specified, based on capability

 *

 * @param int $userid id of user

 * @return array An array of message providers

 */

function message_get_providers_for_user($userid) {

    global $DB, $CFG;

    $providers = get_message_providers();

    // Ensure user is not allowed to configure instantmessage if it is globally disabled.

    if (!$CFG->messaging) {

        foreach ($providers as $providerid => $provider) {

            if ($provider->name == 'instantmessage') {

                unset($providers[$providerid]);

                break;

            }

        }

    }

    // If the component is an enrolment plugin, check it is enabled

    foreach ($providers as $providerid => $provider) {

        list($type, $name) = core_component::normalize_component($provider->component);

        if ($type == 'enrol' && !enrol_is_enabled($name)) {

            unset($providers[$providerid]);

        }

    }

    // Now we need to check capabilities. We need to eliminate the providers

    // where the user does not have the corresponding capability anywhere.

    // Here we deal with the common simple case of the user having the

    // capability in the system context. That handles $CFG->defaultuserroleid.

    // For the remaining providers/capabilities, we need to do a more complex

    // query involving all overrides everywhere.

    $unsureproviders = array();

    $unsurecapabilities = array();

    $systemcontext = context_system::instance();

    foreach ($providers as $providerid => $provider) {

        if (empty($provider->capability) || has_capability($provider->capability, $systemcontext, $userid)) {

            // The provider is relevant to this user.

            continue;

        }

        $unsureproviders[$providerid] = $provider;

        $unsurecapabilities[$provider->capability] = 1;

        unset($providers[$providerid]);

    }

    if (empty($unsureproviders)) {

        // More complex checks are not required.

        return $providers;

    }

    // Now check the unsure capabilities.

    list($capcondition, $params) = $DB->get_in_or_equal(

            array_keys($unsurecapabilities), SQL_PARAMS_NAMED);

    $params['userid'] = $userid;

    $sql = "SELECT DISTINCT rc.capability, 1

              FROM {role_assignments} ra

              JOIN {context} actx ON actx.id = ra.contextid

              JOIN {role_capabilities} rc ON rc.roleid = ra.roleid

              JOIN {context} cctx ON cctx.id = rc.contextid

             WHERE ra.userid = :userid

               AND rc.capability $capcondition

               AND rc.permission > 0

               AND (".$DB->sql_concat('actx.path', "'/'")." LIKE ".$DB->sql_concat('cctx.path', "'/%'").

               " OR ".$DB->sql_concat('cctx.path', "'/'")." LIKE ".$DB->sql_concat('actx.path', "'/%'").")";

    if (!empty($CFG->defaultfrontpageroleid)) {

        $frontpagecontext = context_course::instance(SITEID);

        list($capcondition2, $params2) = $DB->get_in_or_equal(

                array_keys($unsurecapabilities), SQL_PARAMS_NAMED);

        $params = array_merge($params, $params2);

        $params['frontpageroleid'] = $CFG->defaultfrontpageroleid;

        $params['frontpagepathpattern'] = $frontpagecontext->path . '/';

        $sql .= "

             UNION

            SELECT DISTINCT rc.capability, 1

              FROM {role_capabilities} rc

              JOIN {context} cctx ON cctx.id = rc.contextid

             WHERE rc.roleid = :frontpageroleid

               AND rc.capability $capcondition2

               AND rc.permission > 0

               AND ".$DB->sql_concat('cctx.path', "'/'")." LIKE :frontpagepathpattern";

    }

    $relevantcapabilities = $DB->get_records_sql_menu($sql, $params);

    // Add back any providers based on the detailed capability check.

    foreach ($unsureproviders as $providerid => $provider) {

        if (array_key_exists($provider->capability, $relevantcapabilities)) {

            $providers[$providerid] = $provider;

        }

    }

    return $providers;

}

/**

 * Gets the message providers that are in the database for this component.

 *

 * This is an internal function used within messagelib.php

 *

 * @see message_update_providers()

 * @param string $component A moodle component like 'moodle', 'mod_forum', 'block_activity_results'

 * @return array An array of message providers

 */

function message_get_providers_from_db($component) {

    global $DB;

    return $DB->get_records('message_providers', array('component'=>$component), '', 'name, id, component, capability');  // Name is unique per component

}

/**

 * Loads the messages definitions for a component from file

 *

 * If no messages are defined for the component, return an empty array.

 * This is an internal function used within messagelib.php

 *

 * @see message_update_providers()

 * @see message_update_processors()

 * @param string $component A moodle component like 'moodle', 'mod_forum', 'block_activity_results'

 * @return array An array of message providers or empty array if not exists

 */

function message_get_providers_from_file($component) {

    $defpath = core_component::get_component_directory($component).'/db/messages.php';

    $messageproviders = array();

    if (file_exists($defpath)) {

        require($defpath);

    }

    foreach ($messageproviders as $name => $messageprovider) {   // Fix up missing values if required

        if (empty($messageprovider['capability'])) {

            $messageproviders[$name]['capability'] = NULL;

        }

        if (empty($messageprovider['defaults'])) {

            $messageproviders[$name]['defaults'] = array();

        }

    }

    return $messageproviders;

}

/**

 * Remove all message providers for particular component and corresponding settings

 *

 * @param string $component A moodle component like 'moodle', 'mod_forum', 'block_activity_results'

 * @return void

 */

function message_provider_uninstall($component) {

    global $DB;

    $transaction = $DB->start_delegated_transaction();

    $DB->delete_records('message_providers', array('component' => $component));

    $DB->delete_records_select('config_plugins', "plugin = 'message' AND ".$DB->sql_like('name', '?', false), array("%_provider_{$component}_%"));

    $DB->delete_records_select('user_preferences', $DB->sql_like('name', '?', false), array("message_provider_{$component}_%"));

    $transaction->allow_commit();

    // Purge all messaging settings from the caches. They are stored by plugin so we have to clear all message settings.

    cache_helper::invalidate_by_definition('core', 'config', array(), 'message');

}

/**

 * Uninstall a message processor

 *

 * @param string $name A message processor name like 'email', 'jabber'

 */

function message_processor_uninstall($name) {

    global $DB;

    $transaction = $DB->start_delegated_transaction();

    $DB->delete_records('message_processors', array('name' => $name));

    $DB->delete_records_select('config_plugins', "plugin = ?", array("message_{$name}"));

    // Delete permission preferences only, we do not care about enabled defaults,

    // they will be removed on the next attempt to update the preferences.

    $DB->delete_records_select('config_plugins', "plugin = 'message' AND ".$DB->sql_like('name', '?', false), array("{$name}_provider_%"));

    $transaction->allow_commit();

    // Purge all messaging settings from the caches. They are stored by plugin so we have to clear all message settings.

    cache_helper::invalidate_by_definition('core', 'config', array(), array('message', "message_{$name}"));

}