MDL-36135 Display the workshop grading evaluation method chooser

Teachers can now choose the actual grading evaluation method to use
during the grading evaluation phase. The workshopeval_best is still used
as the default one (this may be made configurable later, although there
is no big benefit of it).

mod/workshop/lang/en/workshop.php

@@ -100,7 +100,7 @@
 $string['evaluategradeswait'] = 'Please wait until the assessments are evaluated and the grades are calculated';
 $string['evaluation'] = 'Grading evaluation';
 $string['evaluationmethod'] = 'Grading evaluation method';
-$string['evaluationmethod_help'] = 'The grading evaluation method determines how the grade for assessment is calculated. There is currently just one option - comparison with the best assessment.';
+$string['evaluationmethod_help'] = 'The grading evaluation method determines how the grade for assessment is calculated. You can let it re-calculate grades repeatedly with different settings unless you are happy with the result.';
 $string['example'] = 'Example submission';
 $string['exampleadd'] = 'Add example submission';
 $string['exampleassess'] = 'Assess example submission';

mod/workshop/lib.php

@@ -136,7 +136,6 @@ function workshop_update_instance(stdclass $workshop) {
     $workshop->useselfassessment     = (int)!empty($workshop->useselfassessment);
     $workshop->latesubmissions       = (int)!empty($workshop->latesubmissions);
     $workshop->phaseswitchassessment = (int)!empty($workshop->phaseswitchassessment);
-    $workshop->evaluation            = 'best';
 
     // todo - if the grading strategy is being changed, we must replace all aggregated peer grades with nulls
     // todo - if maximum grades are being changed, we should probably recalculate or invalidate them

mod/workshop/locallib.php

@@ -185,7 +185,6 @@ public function __construct(stdclass $dbrecord, stdclass $cm, stdclass $course,
         } else {
             $this->context = $context;
         }
-        $this->evaluation   = 'best';   // todo make this configurable although we have no alternatives yet
     }
 
     ////////////////////////////////////////////////////////////////////////////////
@@ -283,6 +282,19 @@ public static function available_strategies_list() {
         return $forms;
     }
 
+    /**
+     * Returns the list of available grading evaluation methods
+     *
+     * @return array of (string)name => (string)localized title
+     */
+    public static function available_evaluators_list() {
+        $evals = array();
+        foreach (get_plugin_list_with_file('workshopeval', 'lib.php', false) as $eval => $evalpath) {
+            $evals[$eval] = get_string('pluginname', 'workshopeval_' . $eval);
+        }
+        return $evals;
+    }
+
     /**
      * Return an array of possible values of assessment dimension weight
      *
@@ -1229,6 +1241,28 @@ public function grading_strategy_instance() {
         return $this->strategyinstance;
     }
 
+    /**
+     * Sets the current evaluation method to the given plugin.
+     *
+     * @param string $method the name of the workshopeval subplugin
+     * @return bool true if successfully set
+     * @throws coding_exception if attempting to set a non-installed evaluation method
+     */
+    public function set_grading_evaluation_method($method) {
+        global $DB;
+
+        $evaluationlib = dirname(__FILE__) . '/eval/' . $method . '/lib.php';
+
+        if (is_readable($evaluationlib)) {
+            $this->evaluationinstance = null;
+            $this->evaluation = $method;
+            $DB->set_field('workshop', 'evaluation', $method, array('id' => $this->id));
+            return true;
+        }
+
+        throw new coding_exception('Attempt to set a non-existing evaluation method.');
+    }
+
     /**
      * Returns instance of grading evaluation class
      *

mod/workshop/styles.css

@@ -520,3 +520,8 @@
 .path-mod-workshop div.buttonwithhelp div {
     display: inline;
 }
+
+.path-mod-workshop #evaluationmethodchooser {
+    margin: 2em auto;
+    text-align: center;
+}

mod/workshop/view.php

@@ -38,6 +38,7 @@
 $perpage    = optional_param('perpage', null, PARAM_INT);
 $sortby     = optional_param('sortby', 'lastname', PARAM_ALPHA);
 $sorthow    = optional_param('sorthow', 'ASC', PARAM_ALPHA);
+$eval       = optional_param('eval', null, PARAM_PLUGIN);
 
 if ($id) {
     $cm         = get_coursemodule_from_id('workshop', $id, 0, false, MUST_EXIST);
@@ -73,6 +74,13 @@
     redirect($PAGE->url);
 }
 
+if ($eval) {
+    require_sesskey();
+    require_capability('mod/workshop:overridegrades', $workshop->context);
+    $workshop->set_grading_evaluation_method($eval);
+    redirect($PAGE->url);
+}
+
 $output = $PAGE->get_renderer('mod_workshop');
 $userplan = new workshop_user_plan($workshop, $USER->id);
 
@@ -395,6 +403,13 @@
             $showreviewernames  = has_capability('mod/workshop:viewreviewernames', $workshop->context);
 
             if (has_capability('mod/workshop:overridegrades', $PAGE->context)) {
+                // Print a drop-down selector to change the current evaluation method.
+                $selector = new single_select($PAGE->url, 'eval', workshop::available_evaluators_list(),
+                    $workshop->evaluation, false, 'evaluationmethodchooser');
+                $selector->set_label(get_string('evaluationmethod', 'mod_workshop'));
+                $selector->set_help_icon('evaluationmethod', 'mod_workshop');
+                $selector->method = 'post';
+                echo $output->render($selector);
                 // load the grading evaluator
                 $evaluator = $workshop->grading_evaluation_instance();
                 $form = $evaluator->get_settings_form(new moodle_url($workshop->aggregate_url(),