MDL-61380 Questions: Editing configuration of existing random questions

Editing "random" questions follows a different procedure than adding them.
This commit takes care of editing a "random" question's configuration.
This commit also introduces mod_quiz\form\randomquestion_form, so mod_quiz
can edit random questions without having to use the form that is inside qtype_random.

mod/quiz/classes/form/randomquestion_form.php

@@ -0,0 +1,84 @@
+<?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 the editing form for random questions.
+ *
+ * @package    mod_quiz
+ * @copyright  2018 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace mod_quiz\form;
+
+defined('MOODLE_INTERNAL') || die();
+
+require_once($CFG->dirroot.'/lib/formslib.php');
+
+/**
+ * Class randomquestion_form
+ *
+ * @package    mod_quiz
+ * @copyright  2018 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class randomquestion_form extends \moodleform {
+
+    /**
+     * Form definiton.
+     */
+    public function definition() {
+        $mform = $this->_form;
+
+        $contexts = $this->_customdata['contexts'];
+        $usablecontexts = $contexts->having_cap('moodle/question:useall');
+
+        // Standard fields at the start of the form.
+        $mform->addElement('header', 'generalheader', get_string("general", 'form'));
+
+        $mform->addElement('questioncategory', 'category', get_string('category', 'question'),
+                array('contexts' => $usablecontexts, 'top' => true));
+
+        $mform->addElement('advcheckbox', 'includesubcategories', get_string('recurse', 'quiz'), null, null, array(0, 1));
+
+        $tops = question_get_top_categories_for_contexts(array_column($contexts->all(), 'id'));
+        $mform->hideIf('includesubcategories', 'category', 'in', $tops);
+
+        $tags = \core_tag_tag::get_tags_by_area_in_contexts('core_question', 'question', $usablecontexts);
+        $tagstrings = array();
+        foreach ($tags as $tag) {
+            $tagstrings["{$tag->id},{$tag->name}"] = $tag->name;
+        }
+        $options = array(
+                'multiple' => true,
+                'noselectionstring' => get_string('anytags', 'quiz'),
+        );
+        $mform->addElement('autocomplete', 'fromtags', get_string('randomquestiontags', 'mod_quiz'), $tagstrings, $options);
+        $mform->addHelpButton('fromtags', 'randomquestiontags', 'mod_quiz');
+
+        $mform->addElement('hidden', 'slotid');
+        $mform->setType('slotid', PARAM_INT);
+
+        $mform->addElement('hidden', 'returnurl');
+        $mform->setType('returnurl', PARAM_LOCALURL);
+
+        $buttonarray = array();
+        $buttonarray[] = $mform->createElement('submit', 'submitbutton', get_string('savechanges'));
+        $buttonarray[] = $mform->createElement('cancel');
+        $mform->addGroup($buttonarray, 'buttonar', '', array(' '), false);
+        $mform->closeHeaderBefore('buttonar');
+    }
+}

mod/quiz/classes/output/edit_renderer.php

@@ -958,16 +958,16 @@ class edit_renderer extends \plugin_renderer_base {
      * and also to see that category in the question bank.
      *
      * @param structure $structure object containing the structure of the quiz.
-     * @param int $slot which slot we are outputting.
+     * @param int $slotnumber which slot we are outputting.
      * @param \moodle_url $pageurl the canonical URL of this page.
      * @return string HTML to output.
      */
-    public function random_question(structure $structure, $slot, $pageurl) {
+    public function random_question(structure $structure, $slotnumber, $pageurl) {
 
-        $question = $structure->get_question_in_slot($slot);
-        $editurl = new \moodle_url('/question/question.php', array(
-                'returnurl' => $pageurl->out_as_local_url(),
-                'cmid' => $structure->get_cmid(), 'id' => $question->id));
+        $question = $structure->get_question_in_slot($slotnumber);
+        $slot = $structure->get_slot_by_number($slotnumber);
+        $editurl = new \moodle_url('/mod/quiz/editrandom.php',
+                array('returnurl' => $pageurl->out_as_local_url(), 'slotid' => $slot->id));
 
         $temp = clone($question);
         $temp->questiontext = '';

mod/quiz/classes/structure.php

@@ -409,6 +409,23 @@ class structure {
         return $this->slots[$slotid];
     }
 
+    /**
+     * Get a slot by it's slot number. Throws an exception if it is missing.
+     *
+     * @param int $slotnumber The slot number
+     * @return \stdClass
+     * @throws \coding_exception
+     */
+    public function get_slot_by_number($slotnumber) {
+        foreach ($this->slots as $slot) {
+            if ($slot->slot == $slotnumber) {
+                return $slot;
+            }
+        }
+
+        throw new \coding_exception('The \'slotnumber\' could not be found.');
+    }
+
     /**
      * Check whether adding a section heading is possible
      * @param int $pagenumber the number of the page.

mod/quiz/editrandom.php

@@ -0,0 +1,152 @@
+<?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/>.
+
+/**
+ * Page for editing random questions.
+ *
+ * @package    mod_quiz
+ * @copyright  2018 Shamim Rezaie <shamim@moodle.com>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+require_once(__DIR__ . '/../../config.php');
+require_once($CFG->dirroot . '/mod/quiz/locallib.php');
+
+$slotid = required_param('slotid', PARAM_INT);
+$returnurl = optional_param('returnurl', '', PARAM_LOCALURL);
+
+// Get the quiz slot.
+$slot = $DB->get_record('quiz_slots', array('id' => $slotid));
+if (!$slot || empty($slot->questioncategoryid)) {
+    print_error('invalidrandomslot', 'mod_quiz');
+}
+
+if (!$quiz = $DB->get_record('quiz', array('id' => $slot->quizid))) {
+    print_error('invalidquizid', 'quiz');
+}
+
+$cm = get_coursemodule_from_instance('quiz', $slot->quizid, $quiz->course);
+
+require_login($cm->course, false, $cm);
+
+if ($returnurl) {
+    $returnurl = new moodle_url($returnurl);
+} else {
+    $returnurl = new moodle_url('/mod/quiz/edit.php', array('cmid' => $cm->id));
+}
+
+$url = new moodle_url('/mod/quiz/editrandom.php', array('slotid' => $slotid));
+$PAGE->set_url($url);
+$PAGE->set_pagelayout('admin');
+
+if (!$question = $DB->get_record('question', array('id' => $slot->questionid))) {
+    print_error('questiondoesnotexist', 'question', $returnurl);
+}
+
+$qtypeobj = question_bank::get_qtype('random');
+
+// Validate the question category.
+if (!$category = $DB->get_record('question_categories', array('id' => $question->category))) {
+    print_error('categorydoesnotexist', 'question', $returnurl);
+}
+
+// Check permissions.
+question_require_capability_on($question, 'edit');
+
+$thiscontext = context_module::instance($cm->id);
+$contexts = new question_edit_contexts($thiscontext);
+
+// Create the question editing form.
+$mform = new mod_quiz\form\randomquestion_form(new moodle_url('/mod/quiz/editrandom.php'),
+        array('contexts' => $contexts));
+
+// Send the question object and a few more parameters to the form.
+$toform = fullclone($question);
+$toform->category = "{$category->id},{$category->contextid}";
+$toform->includesubcategories = $slot->includingsubcategories;
+$toform->fromtags = array();
+if ($slot->tags) {
+    $tags = quiz_extract_random_question_tags($slot->tags);
+    foreach ($tags as $tag) {
+        $toform->fromtags[] = "{$tag->id},{$tag->name}";
+    }
+}
+$toform->returnurl = $returnurl;
+
+if ($cm !== null) {
+    $toform->cmid = $cm->id;
+    $toform->courseid = $cm->course;
+} else {
+    $toform->courseid = $COURSE->id;
+}
+
+$toform->slotid = $slotid;
+
+$mform->set_data($toform);
+
+if ($mform->is_cancelled()) {
+    redirect($returnurl);
+} else if ($fromform = $mform->get_data()) {
+
+    // If we are moving a question, check we have permission to move it from
+    // whence it came. Where we are moving to is validated by the form.
+    list($newcatid, $newcontextid) = explode(',', $fromform->category);
+    if (!empty($question->id) && $newcatid != $question->category) {
+        $contextid = $newcontextid;
+        question_require_capability_on($question, 'move');
+    } else {
+        $contextid = $category->contextid;
+    }
+
+    $question = $qtypeobj->save_question($question, $fromform);
+
+    // We need to save some data into the quiz_slots table.
+    $slot->questioncategoryid = $fromform->category;
+    $slot->includingsubcategories = $fromform->includesubcategories;
+
+    $tags = [];
+    foreach ($fromform->fromtags as $tagstring) {
+        list($tagid, $tagname) = explode(',', $tagstring);
+        $tags[] = (object) [
+            'id' => $tagid,
+            'name' => $tagname
+        ];
+    }
+    $slot->tags = quiz_build_random_question_tag_json($tags);
+
+    $DB->update_record('quiz_slots', $slot);
+
+    // Purge this question from the cache.
+    question_bank::notify_question_edited($question->id);
+
+    $returnurl->param('lastchanged', $question->id);
+    redirect($returnurl);
+}
+
+$streditingquestion = $qtypeobj->get_heading();
+$PAGE->set_title($streditingquestion);
+$PAGE->set_heading($COURSE->fullname);
+$PAGE->navbar->add($streditingquestion);
+
+// Display a heading, question editing form and possibly some extra content needed for
+// for this question type.
+echo $OUTPUT->header();
+$heading = get_string('randomediting', 'mod_quiz');
+echo $OUTPUT->heading_with_help($heading, 'randomquestion', 'mod_quiz');
+
+$mform->display();
+
+echo $OUTPUT->footer();

mod/quiz/lang/en/quiz.php

@@ -439,6 +439,7 @@ $string['invalidcategory'] = 'Category ID is invalid';
 $string['invalidoverrideid'] = 'Invalid override id';
 $string['invalidquestionid'] = 'Invalid question id';
 $string['invalidquizid'] = 'Invalid quiz ID';
+$string['invalidrandomslot'] = 'Invalid random question slot id.';
 $string['invalidsource'] = 'The source is not accepted as valid.';
 $string['invalidsourcetype'] = 'Invalid source type.';
 $string['invalidstateid'] = 'Invalid state id';
@@ -696,10 +697,13 @@ $string['quiztimer'] = 'Quiz Timer';
 $string['quizwillopen'] = 'This quiz will open {$a}';
 $string['random'] = 'Random question';
 $string['randomcreate'] = 'Create random questions';
+$string['randomediting'] = 'Editing a random question';
 $string['randomfromcategory'] = 'Random question from category:';
 $string['randomfromexistingcategory'] = 'Random question from an existing category';
 $string['randomnumber'] = 'Number of random questions';
 $string['randomnosubcat'] = 'Questions from this category only, not its subcategories.';
+$string['randomquestion'] = 'Random question';
+$string['randomquestion_help'] = 'A random question is a way of inserting a randomly-chosen question from a specified category or by a specified tag into an activity.';
 $string['randomquestiontags'] = 'Tags';
 $string['randomquestiontags_help'] = 'You can restrict the selection criteria further by specifying some question tags here.
 

mod/quiz/locallib.php

@@ -2436,3 +2436,60 @@ function quiz_is_overriden_calendar_event(\calendar_event $event) {
 
     return $DB->record_exists('quiz_overrides', $overrideparams);
 }
+
+/**
+ * Providing a list of tag records, this function validates each pair and builds a json string
+ * that can be stored in the quiz_slots.tags field.
+ *
+ * @param stdClass[] $tagrecords List of tag objects with id and name properties.
+ * @return string
+ */
+function quiz_build_random_question_tag_json($tagrecords) {
+    $tags = [];
+    foreach ($tagrecords as $tagrecord) {
+        if ($tag = core_tag_tag::get($tagrecord->id, 'id, name')) {
+            $tags[] = [
+                'id' => (int)$tagrecord->id,
+                'name' => $tag->name
+            ];
+        } else if ($tag = core_tag_tag::get_by_name(0, $tagrecord->name, 'id, name')) {
+            $tags[] = [
+                'id' => $tag->id,
+                'name' => $tagrecord->name
+            ];
+        } else {
+            $tags[] = [
+                'id' => null,
+                'name' => $tagrecord->name
+            ];
+        }
+    }
+    return json_encode($tags);
+}
+
+/**
+ * Providing tags data in the JSON format, this function returns tag records containing the id and name properties.
+ *
+ * @param string $tagsjson The JSON string representing an array of tags in the [{"id":tagid,"name":"tagname"}] format.
+ *      E.g. [{"id":1,"name":"tag1"},{"id":2,"name":"tag2"}]
+ *      Usually equal to the value of the tags field retrieved from the quiz_slots table.
+ * @return array An array of tags containing the id and name properties, indexed by tag ids.
+ */
+function quiz_extract_random_question_tags($tagsjson) {
+    $tagrecords = [];
+    if (!empty($tagsjson)) {
+        $tags = json_decode($tagsjson);
+        // Only work with tags that exist.
+        foreach ($tags as $tagdata) {
+            if (!array_key_exists($tagdata->id, $tagrecords)) {
+                if ($tag = core_tag_tag::get($tagdata->id, 'id, name')) {
+                    $tagrecords[$tag->id] = $tag->to_object();
+                } else if ($tag = core_tag_tag::get_by_name(0, $tagdata->name, 'id, name')) {
+                    $tagrecords[$tag->id] = $tag->to_object();
+                }
+            }
+        }
+    }
+
+    return $tagrecords;
+}