MDL-51569 mod_choice: Check choice availability prior to do any action

mod/choice/lib.php

@@ -921,3 +921,29 @@ function choice_print_overview($courses, &$htmlarray) {
     }
     return;
 }
+
+/**
+ * Check if a choice is available for the current user.
+ *
+ * @param  stdClass  $choice            choice record
+ * @return array                       status (available or not and possible warnings)
+ */
+function choice_get_availability_status($choice) {
+    $available = true;
+    $warnings = array();
+
+    if ($choice->timeclose != 0) {
+        $timenow = time();
+
+        if ($choice->timeopen > $timenow) {
+            $available = false;
+            $warnings['notopenyet'] = userdate($choice->timeopen);
+        } else if ($timenow > $choice->timeclose) {
+            $available = false;
+            $warnings['expired'] = userdate($choice->timeclose);
+        }
+    }
+
+    // Choice is available.
+    return array($available, $warnings);
+}

mod/choice/view.php

@@ -34,7 +34,10 @@ $strchoices = get_string('modulenameplural', 'choice');
 
 $context = context_module::instance($cm->id);
 
-if ($action == 'delchoice' and confirm_sesskey() and is_enrolled($context, NULL, 'mod/choice:choose') and $choice->allowupdate) {
+list($choiceavailable, $warnings) = choice_get_availability_status($choice);
+
+if ($action == 'delchoice' and confirm_sesskey() and is_enrolled($context, NULL, 'mod/choice:choose') and $choice->allowupdate
+        and $choiceavailable) {
     $answercount = $DB->count_records('choice_answers', array('choiceid' => $choice->id, 'userid' => $USER->id));
     if ($answercount > 0) {
         $DB->delete_records('choice_answers', array('choiceid' => $choice->id, 'userid' => $USER->id));
@@ -71,6 +74,11 @@ if (data_submitted() && is_enrolled($context, NULL, 'mod/choice:choose') && conf
         $answer = optional_param('answer', '', PARAM_INT);
     }
 
+    if (!$choiceavailable) {
+        $reason = current(array_keys($warnings));
+        throw new moodle_exception($reason, 'choice', '', $warnings[$reason]);
+    }
+
     if ($answer) {
         choice_user_submit_response($answer, $choice, $USER->id, $course, $cm);
         redirect(new moodle_url('/mod/choice/view.php',