MDL-44902: Several additions to External Tool (LTI)

* LTI service related changes:
** Fixing exceptions in OAuth library.
** Added new launch option, Existing window: replaces entire page with the LTI object.
** The LTI tool ID used to perform the launch is now sent with the LTI launch parameters.  This is sent back to Moodle on subsequent requests.
** Added $CFG->mod_lti_forcessl to force SSL on all LTI launches.
** Added new LTI launch parameter: tool_consumer_instance_name.  Default value is site full name, but can be customized with $CFG->mod_lti_institution_name.
** The LTI grade service endpoints now set the affected user to the session.  This was required for event listeners.
** Fix the grade deletion service.  Was deleting the grade item instead of just the grade.
** Send error response when LTI instance does not accept grades and grades are being sent.
** Added a method for writing incoming LTI requests to disk for debugging.  Disabled by default.
* Changes for ltisource plugins:
** Can now to plug into backup/restore.
** Can now have settings.php files.
** Can now hook into the LTI launch and edit parameters.
* Several grade changes:
** Added standard_grading_coursemodule_elements to LTI instance edit form.  This means LTI instances can be configured with a grade.
** No longer assumes that grade is out of 100.
** Replaced modl/lti:grade capability with mod/lti:view.
* JS on mod/lti/view.php for resizing the content object has been converted to YUI3.
* Fixed misspellings in language file.
* Added hooks for log post and view actions.
* Bug fix for lti_get_url_thumbprint() when the URL is missing a schema.

mod/lti/classes/factory.php

@@ -0,0 +1,118 @@
+<?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/>.
+
+/**
+ * Class Builder
+ *
+ * @package    mod
+ * @subpackage lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+
+namespace mod_lti;
+
+use coding_exception;
+use mod_lti\observer\dispatcher;
+
+/**
+ * Builds various classes
+ *
+ * @package    mod_lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+class factory {
+    /**
+     * Given a component and class name suffix, create a full
+     * class name and ensure that it exists.
+     *
+     * Classes are namespace based.
+     *
+     * @param string $component The component to find the class file in
+     * @param string $suffix This is appended to the component name, together make the class name we want
+     * @return string
+     * @throws \coding_exception
+     */
+    protected function build_class_name($component, $suffix) {
+        $classname = "\\$component\\$suffix";
+        if (!class_exists($classname)) {
+            throw new coding_exception("Expected to find $classname in the classes directory of $component");
+        }
+        return $classname;
+    }
+
+    /**
+     * Instantiate a class and optionally verify parent class
+     *
+     * @param string $class Create a new instance of this class
+     * @param null|string $parent Ensure that this is the parent class
+     * @return mixed
+     * @throws coding_exception
+     */
+    protected function build_generic_instance($class, $parent = null) {
+        if (!is_null($parent)) {
+            $reflection = new \ReflectionClass($class);
+            if (!$reflection->isSubclassOf($parent)) {
+                throw new coding_exception("The $class must be a subclass of $parent");
+            }
+        }
+        return new $class();
+    }
+
+    /**
+     * Builds a single ltisource plugin listener
+     *
+     * @param string $component The component to find the class file in
+     * @return \mod_lti\observer\listener_interface
+     */
+    public function build_listener($component) {
+        return $this->build_generic_instance(
+            $this->build_class_name($component, 'listener'),
+            '\mod_lti\observer\listener_interface'
+        );
+    }
+
+    /**
+     * Builds ltisource plugin listeners
+     *
+     * @return \mod_lti\observer\listener_interface[]
+     */
+    public function build_listeners() {
+        $plugins   = \core_component::get_plugin_list('ltisource');
+        $listeners = array();
+        foreach (array_keys($plugins) as $pluginname) {
+            try {
+                $listeners[] = $this->build_listener('ltisource_'.$pluginname);
+            } catch (\Exception $e) {
+                // Class is optional, so ignore if not found.
+            }
+        }
+        return $listeners;
+    }
+
+    /**
+     * Builds an event dispatcher with listeners.
+     *
+     * @return dispatcher
+     */
+    public function build_dispatcher() {
+        $dispatcher = new dispatcher();
+        $dispatcher->set_listeners($this->build_listeners());
+
+        return $dispatcher;
+    }
+}

mod/lti/classes/observer/before_launch_event.php

@@ -0,0 +1,69 @@
+<?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/>.
+
+/**
+ * Event for ltisource plugins.
+ *
+ * @package    mod
+ * @subpackage lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+
+namespace mod_lti\observer;
+
+/**
+ * This event occurs prior to an LTI launch.
+ *
+ * @package    mod_lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+class before_launch_event {
+    /**
+     * LTI activity instance
+     *
+     * @var \stdClass
+     */
+    public $instance;
+
+    /**
+     * Launch URL
+     *
+     * @var string
+     */
+    public $endpoint;
+
+    /**
+     * Launch request parameters
+     *
+     * @var array
+     */
+    public $params;
+
+    /**
+     * Constructor
+     *
+     * @param \stdClass $instance
+     * @param string $endpoint
+     * @param array $params
+     */
+    public function __construct($instance, $endpoint, array $params) {
+        $this->instance = $instance;
+        $this->endpoint = $endpoint;
+        $this->params   = $params;
+    }
+}

mod/lti/classes/observer/dispatcher.php

@@ -0,0 +1,87 @@
+<?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/>.
+
+/**
+ * Dispatches events to ltisource plugin listeners
+ *
+ * @package    mod
+ * @subpackage lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+
+namespace mod_lti\observer;
+
+/**
+ * Event dispatcher
+ *
+ * @package    mod_lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+class dispatcher {
+    /**
+     * @var listener_interface[]
+     */
+    protected $listeners = array();
+
+    /**
+     * Add a listener
+     *
+     * @param listener_interface $listener
+     */
+    public function add_listener(listener_interface $listener) {
+        $this->listeners[] = $listener;
+    }
+
+    /**
+     * Set a list of listeners
+     *
+     * @param listener_interface[] $listeners
+     */
+    public function set_listeners($listeners) {
+        $this->listeners = array();
+        foreach ($listeners as $listener) {
+            $this->add_listener($listener);
+        }
+    }
+
+    /**
+     * Dispatches an event.
+     *
+     * Very trivial right now.
+     *
+     * @param string $name Event name
+     * @param mixed $event The event object
+     * @throws \coding_exception
+     */
+    public function dispatch($name, $event) {
+        foreach ($this->listeners as $listener) {
+            $subscribed = $listener->get_subscribed_events();
+
+            if (!array_key_exists($name, $subscribed)) {
+                continue;
+            }
+            $callable = array($listener, $subscribed[$name]);
+            if (!is_callable($callable)) {
+                throw new \coding_exception(
+                    sprintf('The method %s is not callable on %s class', $subscribed[$name], get_class($listener))
+                );
+            }
+            call_user_func($callable, $event);
+        }
+    }
+}

mod/lti/classes/observer/events.php

@@ -0,0 +1,44 @@
+<?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 internal events that ltisource
+ * plugins can subscribe to.
+ *
+ * @package    mod
+ * @subpackage lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+
+namespace mod_lti\observer;
+
+/**
+ * These are all of the event names
+ *
+ * @package    mod_lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+final class events {
+    /**
+     * This is thrown before an LTI launch
+     *
+     * The event listener will recevie an instance
+     * of \mod_lti\observer\before_launch_event
+     */
+    const BEFORE_LAUNCH = 'before.launch';
+}

mod/lti/classes/observer/listener_interface.php

@@ -0,0 +1,47 @@
+<?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/>.
+
+/**
+ * Listener interface for ltisource plugins
+ *
+ * @package    mod
+ * @subpackage lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+
+namespace mod_lti\observer;
+
+/**
+ * This interface allows a class to define the ltisource
+ * plugin events that the class would like to subscribe
+ * to
+ *
+ * @package    mod_lti
+ * @copyright  Copyright (c) 2009 Moodlerooms Inc. (http://www.moodlerooms.com)
+ * @license    http://opensource.org/licenses/gpl-3.0.html GNU Public License
+ */
+interface listener_interface {
+    /**
+     * Register for events
+     *
+     * Example return:
+     *      array('eventname' => 'methodToCall');
+     *
+     * @return array
+     */
+    public function get_subscribed_events();
+}