From 2ab797c90bc34d8b0f1eec59f7312203b8e5dc42 Mon Sep 17 00:00:00 2001
From: Brendan Heywood <brendan@catalyst-au.net>
Date: Fri, 5 Feb 2016 19:45:00 +1100
Subject: [PATCH] MDL-28030 weblib: Added $CFG->urlrewriteclass in config.php

    This enables a plugin to implement rewriting rules enabling
    'clean' or 'semantic' urls such as /course/COMP100/ instead
    of /course/view.php?id=1234
---
 config-dist.php                     |  5 +++
 lib/classes/output/url_rewriter.php | 58 +++++++++++++++++++++++++++++
 lib/outputrenderers.php             |  7 ++++
 lib/upgrade.txt                     |  2 +
 lib/weblib.php                      | 32 ++++++++++++++++
 5 files changed, 104 insertions(+)
 create mode 100644 lib/classes/output/url_rewriter.php

diff --git a/config-dist.php b/config-dist.php
index 04b51d7bda1..469884d211f 100644
--- a/config-dist.php
+++ b/config-dist.php
@@ -298,6 +298,11 @@ $CFG->admin = 'admin';
 // This setting will make some graphs (eg user logs) use lines instead of bars
 //      $CFG->preferlinegraphs = true;
 //
+// This setting allows you to specify a class to rewrite outgoing urls
+// enabling 'clean urls' in conjunction with an apache / nginx handler.
+// The handler must implement \core\output\url_rewriter.
+//      $CFG->urlrewriteclass = '\local_cleanurls\url_rewriter';
+//
 // Enabling this will allow custom scripts to replace existing moodle scripts.
 // For example: if $CFG->customscripts/course/view.php exists then
 // it will be used instead of $CFG->wwwroot/course/view.php
diff --git a/lib/classes/output/url_rewriter.php b/lib/classes/output/url_rewriter.php
new file mode 100644
index 00000000000..435bd55afb9
--- /dev/null
+++ b/lib/classes/output/url_rewriter.php
@@ -0,0 +1,58 @@
+<?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/>.
+
+/**
+ * URL rewriter base.
+ *
+ * @package    core
+ * @author     Brendan Heywood <brendan@catalyst-au.net>
+ * @copyright  Catalyst IT
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core\output;
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * URL rewriter interface
+ *
+ * @package    core
+ * @author     Brendan Heywood <brendan@catalyst-au.net>
+ * @copyright  Catalyst IT
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+interface url_rewriter {
+
+    /**
+     * Rewrite moodle_urls into another form.
+     *
+     * @param moodle_url $url a url to potentially rewrite
+     * @return moodle_url Returns a new, or the original, moodle_url;
+     */
+    public static function url_rewrite(\moodle_url $url);
+
+    /**
+     * Gives a url rewriting plugin a chance to rewrite the current page url
+     * avoiding redirects and improving performance.
+     *
+     * @return void
+     */
+    public static function html_head_setup();
+
+
+}
+
diff --git a/lib/outputrenderers.php b/lib/outputrenderers.php
index 858061ea009..5df8eaf3443 100644
--- a/lib/outputrenderers.php
+++ b/lib/outputrenderers.php
@@ -475,6 +475,13 @@ class core_renderer extends renderer_base {
         }
 
         $output = '';
+
+        // Allow a url_rewrite plugin to setup any dynamic head content.
+        if (isset($CFG->urlrewriteclass) && !isset($CFG->upgraderunning)) {
+            $class = $CFG->urlrewriteclass;
+            $output .= $class::html_head_setup();
+        }
+
         $output .= '<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />' . "\n";
         $output .= '<meta name="keywords" content="moodle, ' . $this->page->title . '" />' . "\n";
         // This is only set by the {@link redirect()} method
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index 255b7647e41..081b0a13cfa 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -39,6 +39,8 @@ information provided here is intended especially for developers.
   Note than you will need to bump the plugin version so moodle is aware that you removed the plugin's event handlers.
 * mforms validation functions are not available in the global JS namespace anymore, event listeners
   are assigned to fields and buttons through a self-contained JS function.
+* Added $CFG->urlrewriteclass option to config.php allowing clean / semantic urls to
+  be implemented in a plugin, eg local_cleanurls.
 
 === 3.0 ===
 
diff --git a/lib/weblib.php b/lib/weblib.php
index 2f2adf77bfd..8f3c3330f4c 100644
--- a/lib/weblib.php
+++ b/lib/weblib.php
@@ -553,6 +553,38 @@ class moodle_url {
      * @return string Resulting URL
      */
     public function out($escaped = true, array $overrideparams = null) {
+
+        global $CFG;
+
+        if (!is_bool($escaped)) {
+            debugging('Escape parameter must be of type boolean, '.gettype($escaped).' given instead.');
+        }
+
+        $url = $this;
+
+        // Allow url's to be rewritten by a plugin.
+        if (isset($CFG->urlrewriteclass) && !isset($CFG->upgraderunning)) {
+            $class = $CFG->urlrewriteclass;
+            $pluginurl = $class::url_rewrite($url);
+            if ($pluginurl instanceof moodle_url) {
+                $url = $pluginurl;
+            }
+        }
+
+        return $url->raw_out($escaped, $overrideparams);
+
+    }
+
+    /**
+     * Output url without any rewrites
+     *
+     * This is identical in signature and use to out() but doesn't call the rewrite handler.
+     *
+     * @param bool $escaped Use &amp; as params separator instead of plain &
+     * @param array $overrideparams params to add to the output url, these override existing ones with the same name.
+     * @return string Resulting URL
+     */
+    public function raw_out($escaped = true, array $overrideparams = null) {
         if (!is_bool($escaped)) {
             debugging('Escape parameter must be of type boolean, '.gettype($escaped).' given instead.');
         }