From a28f677a5d93ec54073eb7e90d858ca8f53845c4 Mon Sep 17 00:00:00 2001
From: Steffen Pegenau <steffen.pegenau@hrz.tu-darmstadt.de>
Date: Tue, 5 Apr 2016 11:55:04 +0200
Subject: [PATCH] Adds a simple table of contents to each wiki page

---
 lang/en/ouwiki.php  |   2 +
 renderer.php        |   9 +++
 tableofcontents.php | 161 ++++++++++++++++++++++++++++++++++++++++++++
 version.php         |   2 +-
 4 files changed, 173 insertions(+), 1 deletion(-)
 create mode 100644 tableofcontents.php

diff --git a/lang/en/ouwiki.php b/lang/en/ouwiki.php
index 6a0f4cb..13bc0c2 100644
--- a/lang/en/ouwiki.php
+++ b/lang/en/ouwiki.php
@@ -588,3 +588,5 @@
 $string['event:ouwikipageupdated'] = 'ouwiki page updated';
 $string['event:savefailed'] = 'Session fail on page save';
 $string['ouwikicrontask'] = 'OU wiki maintenance jobs';
+
+$string['tableofcontents'] = 'Table of contents';
diff --git a/renderer.php b/renderer.php
index f1b95a6..f91b53a 100644
--- a/renderer.php
+++ b/renderer.php
@@ -206,8 +206,17 @@ public function get_topheading_section($title, $gewgaws, $pageversion, $annotati
         $cm = $this->params->cm;
         $output = html_writer::start_tag('div', array('class' => 'ouw_topheading'));
         $output .= html_writer::start_tag('div', array('class' => 'ouw_heading'));
+
         $output .= html_writer::tag('h2', format_string($title),
                 array('class' => 'ouw_topheading'));
+
+        // Add table of contents
+        global $CFG;
+        require_once($CFG->dirroot.'/mod/ouwiki/tableofcontents.php');
+        $toc = new TableOfContents($pageversion->xhtml);
+        $output .= $toc->toHtml();
+
+        
         if ($gewgaws) {
             $output .= $this->render_heading_bit(1, $pageversion->title, $subwiki,
                     $cm, null, $annotations, $pageversion->locked, $files,
diff --git a/tableofcontents.php b/tableofcontents.php
new file mode 100644
index 0000000..3bb306e
--- /dev/null
+++ b/tableofcontents.php
@@ -0,0 +1,161 @@
+<?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/>.
+
+/**
+ * Version.
+ *
+ * @package mod_ouwiki
+ * @copyright 2016 The Open University
+ * @author Steffen Pegenau
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+class TableOfContents {
+  // The table of contents is saved in a 6xn-Array
+  // 6: <h1> - <h6>
+  // n: the number of headings
+  private $ToC = array(array(array(array(array(array())))));
+  private $html = "";
+
+  private $lastH1 = 0;
+  private $lastH2 = 0;
+  private $lastH3 = 0;
+  private $lastH4 = 0;
+  private $lastH5 = 0;
+  private $lastH6 = 0;
+  private $lastLvl = 0;
+
+  public function __construct($html) {
+    $this->html = $html;
+    $this->parseHtml($html);
+  }
+
+  /*
+  * returns the table of contents as printable html
+  */
+  public function toHtml() {
+    $toc = $this->ToC;
+    $output = "<h3>" . get_string('tableofcontents', 'ouwiki') . "</h3>";
+    $output .= "<ul>";
+    foreach($toc as $h1 => $h2tree) {
+      foreach($h2tree as $h2 => $h3tree) {
+        foreach($h3tree as $h3 => $h4tree) {
+          foreach($h4tree as $h4 => $h5tree) {
+            foreach($h5tree as $h5 => $h6tree) {
+              foreach($h6tree as $h6 => $obj) {
+                if($obj) {
+                  $output .= '<li><a href="#'.$obj->id.'">'.$obj->name .'</a></li>';
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+    $output .= "</ul>";
+
+    return $output;
+  }
+
+  /*
+  * Parses the html-Code and generates the table of contents
+  *
+  * @param String $html The html-snippet to parse
+  */
+  private function parseHtml($html) {
+    $reader = new XMLReader();
+    $reader->xml($html);
+
+    $headings = [];
+    $output = "";
+
+    $lastlevel = 0;
+
+    // traverse the tree
+    while($reader->read() !== false) {
+      $tag = $reader->name;
+      $content = $reader->readString();
+      $matches = null;
+
+      // is it a h1-h6 heading?
+      preg_match('/[hH][1-6]/', $tag, $matches);
+      if(!empty($content) && count($matches) > 0) {
+        // example: h1 -> 1
+        $lvl = substr($tag, 1);
+        // <h1 id="ouw_s0_0"> => ouw_s0_0
+        $id = $reader->getAttribute("id");
+        $this->addToTree($lvl, $content, $id);
+      }
+    }
+  }
+
+  /**
+  * Adds an entry with name and level to the table of contents
+  *
+  * param int $lvl The level of the heading
+  * param string $name The title of the heading
+  * param string $id html attribute id of heading
+  */
+  private function addToTree($lvl, $name, $id) {
+    if($lvl < $this->lastLvl) {
+      $lvlToDelete = $lvl + 1;
+      switch($lvlToDelete) {
+        case 1:
+        $this->lastH1 = 0;
+        case 2:
+        $this->lastH2 = 0;
+        case 3:
+        $this->lastH3 = 0;
+        case 4:
+        $this->lastH4 = 0;
+        case 5:
+        $this->lastH5 = 0;
+        case 6:
+        $this->lastH6 = 0;
+        break;
+      }
+    }
+
+    switch ($lvl) {
+      case 1:
+      ++$this->lastH1;
+      break;
+      case 2:
+      ++$this->lastH2;
+      break;
+      case 3:
+      ++$this->lastH3;
+      break;
+      case 4:
+      ++$this->lastH4;
+      break;
+      case 5:
+      ++$this->lastH5;
+      break;
+      case 6:
+      ++$this->lastH6;
+      break;
+    }
+    $element = new stdClass();
+    $element->name = $name;
+    $element->id = $id;
+
+    // Save element in array
+    $this->ToC[$this->lastH1][$this->lastH2][$this->lastH3][$this->lastH4][$this->lastH5][$this->lastH6] = $element;
+
+    $this->lastLvl = $lvl;
+  }
+}
diff --git a/version.php b/version.php
index fe0bd84..6cc9db6 100644
--- a/version.php
+++ b/version.php
@@ -22,7 +22,7 @@
  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
-$plugin->version  = 2015101501;
+$plugin->version  = 2016040500;
 $plugin->requires = 2014051200;
 $plugin->component = 'mod_ouwiki';
 $plugin->maturity = MATURITY_STABLE;