From b197da877061ab04f03b953d9c54dce72c7f78e4 Mon Sep 17 00:00:00 2001
From: Marina Glancy <marina@moodle.com>
Date: Fri, 6 Apr 2018 17:27:56 +0800
Subject: [PATCH] MDL-61876 question: apply format_text to input only

---
 question/type/gapselect/renderer.php     |  3 +-
 question/type/gapselect/rendererbase.php | 42 ++++++++++++++++++++++--
 question/type/upgrade.txt                |  3 ++
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/question/type/gapselect/renderer.php b/question/type/gapselect/renderer.php
index 177e0e5881264..386a687606f16 100644
--- a/question/type/gapselect/renderer.php
+++ b/question/type/gapselect/renderer.php
@@ -57,7 +57,8 @@ protected function embedded_element(question_attempt $qa, $place,
         $orderedchoices = $question->get_ordered_choices($group);
         $selectoptions = array();
         foreach ($orderedchoices as $orderedchoicevalue => $orderedchoice) {
-            $selectoptions[$orderedchoicevalue] = $orderedchoice->text;
+            $selectoptions[$orderedchoicevalue] = $question->format_text($orderedchoice->text,
+                $question->questiontextformat, $qa, 'question', 'questiontext', $question->id);
         }
 
         $feedbackimage = '';
diff --git a/question/type/gapselect/rendererbase.php b/question/type/gapselect/rendererbase.php
index dc619fa65895b..0577a21925188 100644
--- a/question/type/gapselect/rendererbase.php
+++ b/question/type/gapselect/rendererbase.php
@@ -40,16 +40,26 @@ public function formulation_and_controls(question_attempt $qa,
         $question = $qa->get_question();
 
         $questiontext = '';
+        // Glue question fragments together using unique placeholders, apply format_text to the result
+        // and then substitute each placeholder with the embedded element.
+        // This will ensure that format_text() is applied to the whole question but not to the embedded elements.
+        $placeholders = $this->get_fragments_glue_placeholders($question->textfragments);
         foreach ($question->textfragments as $i => $fragment) {
             if ($i > 0) {
-                $questiontext .= $this->embedded_element($qa, $i, $options);
+                $questiontext .= $placeholders[$i];
+                $embeddedelements[$placeholders[$i]] = $this->embedded_element($qa, $i, $options);
             }
             $questiontext .= $fragment;
         }
+        $questiontext = $question->format_text($questiontext,
+            $question->questiontextformat, $qa, 'question', 'questiontext', $question->id);
+        foreach ($placeholders as $i => $placeholder) {
+            $questiontext = preg_replace('/'. preg_quote($placeholder, '/') . '/',
+                $embeddedelements[$placeholder], $questiontext);
+        }
 
         $result = '';
-        $result .= html_writer::tag('div', $question->format_text($questiontext,
-                $question->questiontextformat, $qa, 'question', 'questiontext', $question->id),
+        $result .= html_writer::tag('div', $questiontext,
                 array('class' => $this->qtext_classname(), 'id' => $this->qtext_id($qa)));
 
         $result .= $this->post_qtext_elements($qa, $options);
@@ -63,6 +73,32 @@ public function formulation_and_controls(question_attempt $qa,
         return $result;
     }
 
+    /**
+     * Find strings that we can use to glue the fragments with
+     *
+     * These strings have to be all different and neither of them can be present in the text
+     *
+     * @param array $fragments
+     * @return array array with indexes from 1 to count($fragments)-1
+     */
+    protected function get_fragments_glue_placeholders($fragments) {
+        $fragmentscount = count($fragments);
+        if ($fragmentscount <= 1) {
+            return [];
+        }
+        $prefix = '[[$';
+        $postfix = ']]';
+        $text = join('', $fragments);
+        while (preg_match('/' . preg_quote($prefix, '/') . '\\d+' . preg_quote($postfix, '/') . '/', $text)) {
+            $prefix .= '$';
+        }
+        $glues = [];
+        for ($i = 1; $i < $fragmentscount; $i++) {
+            $glues[$i] = $prefix . $i . $postfix;
+        }
+        return $glues;
+    }
+
     protected function qtext_classname() {
         return 'qtext';
     }
diff --git a/question/type/upgrade.txt b/question/type/upgrade.txt
index c9a70f3f73e3f..f7fd3cb93e08d 100644
--- a/question/type/upgrade.txt
+++ b/question/type/upgrade.txt
@@ -8,6 +8,9 @@ This files describes API changes for question type plugins.
    question_manually_gradable.
   + The default implementation of is_gradable_response has been moved from question_graded_automatically to
    question_with_responses.
+  + Note that format_text() is no longer applied to the results of
+   qtype_elements_embedded_in_question_text_renderer::embedded_element(). If question type overrides
+   this method make sure you apply format_text() to any text that came from a user.
 
 === 3.1.5, 3.2.2, 3.3 ===