Activity form: mission selector updates name+descr

mod_form.php

@@ -46,19 +46,33 @@ class mod_labnbook_mod_form extends moodleform_mod {
         $mform = $this->_form;
 
         $missions = session::load()->getMissions();
+        $mform->addElement('html', '<script>var missions = ' . json_encode($missions) . ';</script>');
+
         $missionsList = array_map(
             function($x) { return "[{$x->code}] {$x->name}"; },
             $missions
         );
-        $mform->addElement('header', 'general', "LabNbook");
-        $mform->addElement('select', 'missionid', get_string('mission', 'mod_labnbook'), array_merge(['' => "-"], $missionsList));
+        $mform->addElement('header', 'external', "LabNbook");
+        $mform->addElement(
+            'select',
+            'missionid',
+            get_string('mission', 'mod_labnbook'),
+            array_merge(['' => "-"], $missionsList),
+            [
+                'onchange' => 'javascript: '
+                    . 'document.querySelector("#id_name").value = missions[this.value].name;'
+                    // try to update the Atto text, but Atto is undocumented stuff (wiki pages are all dead)
+                    . 'document.querySelector("#id_introeditor").innerHTML = missions[this.value].description;'
+                    . 'document.querySelector("#id_introeditoreditable").innerHTML = missions[this.value].description;'
+                ]
+        );
         $mform->addRule('missionid', null, 'required', null, 'client');
 
         // Adding the "general" fieldset, where all the common settings are showed.
         $mform->addElement('header', 'general', get_string('general', 'form'));
 
         // Adding the standard "name" field.
-        $mform->addElement('text', 'name', get_string('instancename', 'mod_labnbook'), array('size' => '64'));
+        $mform->addElement('text', 'name', get_string('instancename', 'mod_labnbook'), ['size' => '64']);
 
         if (!empty($CFG->formatstringstriptags)) {
             $mform->setType('name', PARAM_TEXT);