From fffadb829a8074c39c0ecfe77649b214fdd6cb3c Mon Sep 17 00:00:00 2001
From: Starbeamrainbowlabs <sbrl@starbeamrainbowlabs.com>
Date: Mon, 2 Jul 2018 23:44:10 +0100
Subject: [PATCH] Add history-revert action, but it isn't tested yet.

---
 Changelog.md                 |   1 +
 build/index.php              | 192 +++++++++++++++++++++++++++--------
 core.php                     |  14 +--
 module_index.json            |   8 +-
 modules/api-status.php       |   8 +-
 modules/feature-history.php  | 120 ++++++++++++++++++++--
 modules/feature-redirect.php |  46 +++++----
 7 files changed, 307 insertions(+), 82 deletions(-)

diff --git a/Changelog.md b/Changelog.md
index 9e8c175..77ac4cd 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -8,6 +8,7 @@ This file holds the changelog for Pepperminty Wiki. This is the master list of t
  - [Rest API] Add `user-add` and `set-password` moderator actions
  - Added `random_page_exclude_redirects` setting that prevents the `random` action from returning redirect pages.
  - Added link to user table on the credits page
+ - Added history reversion via the `history-revert` action
 
 ### Fixed
  - Updated the search system to transliterate characters to better support searching pages that are written in other languages.
diff --git a/build/index.php b/build/index.php
index 228115b..733635a 100644
--- a/build/index.php
+++ b/build/index.php
@@ -402,7 +402,7 @@ if($settings->sessionprefix == "auto")
 /////////////////////////////////////////////////////////////////////////////
 /** The version of Pepperminty Wiki currently running. */
 $version = "v0.17-dev";
-$commit = "10b374871faaaebe84139ac36c7708c2598313ca";
+$commit = "2853cf4da595832f9d7e3519c3fb96cfb714d745";
 /// Environment ///
 /** Holds information about the current request environment. */
 $env = new stdClass();
@@ -503,15 +503,15 @@ if($env->is_logged_in)
 /**
  * @apiDefine Admin	Only the wiki administrator may use this call.
  */
- /**
-  * @apiDefine Moderator	Only users loggged with a moderator account may use this call.
-  */
 /**
-* @apiDefine User		Only users loggged in may use this call.
-*/
+ * @apiDefine Moderator	Only users loggged with a moderator account may use this call.
+ */
 /**
-* @apiDefine Anonymous	Anybody may use this call.
-*/
+ * @apiDefine User		Only users loggged in may use this call.
+ */
+/**
+ * @apiDefine Anonymous	Anybody may use this call.
+ */
 /**
  * @apiDefine	UserNotLoggedInError
  * @apiError	UserNotLoggedInError	You didn't log in before sending this request.
@@ -2347,7 +2347,7 @@ register_module([
 	"name" => "API status",
 	"version" => "0.1",
 	"author" => "Starbeamrainbowlabs",
-	"description" => "Provides a basic JSON status action that provices a few useful bits of information for API consumption.",
+	"description" => "Provides a basic JSON status action that provides a few useful bits of information for API consumption.",
 	"id" => "api-status",
 	"code" => function() {
 		global $settings;
@@ -2360,7 +2360,13 @@ register_module([
 		 * @apiParam	{boolean}	Whether or not the result should be minified JSON. Default: false
 		 */
 		
-		
+	 	/*
+	 	 * ███████ ████████  █████  ████████ ██    ██ ███████
+	 	 * ██         ██    ██   ██    ██    ██    ██ ██
+	 	 * ███████    ██    ███████    ██    ██    ██ ███████
+	 	 *      ██    ██    ██   ██    ██    ██    ██      ██
+	 	 * ███████    ██    ██   ██    ██     ██████  ███████
+	 	 */
 		add_action("status", function() {
 			global $version, $env, $settings, $actions;
 			
@@ -3210,7 +3216,7 @@ register_module([
 		 * @apiGroup Page
 		 * @apiPermission Anonymous
 		 * 
-		 * @apiParam {string}	page	The page name to return a revision list for.
+		 * @apiUse PageParameter
 		 * @apiParam {string}	format	The format to return the list of pages in. available values: html, json, text. Default: html
 		 */
 		
@@ -3235,8 +3241,8 @@ register_module([
 						$content .= "\t\t<ul class='page-list'>\n";
 						foreach(array_reverse($pageindex->{$env->page}->history) as $revisionData)
 						{
-							// Only display edits for now
-							if($revisionData->type != "edit")
+							// Only display edits & reverts for now
+							if($revisionData->type != "edit" || $revisionData->type != "revert")
 							continue;
 							
 							// The number (and the sign) of the size difference to display
@@ -3246,7 +3252,11 @@ register_module([
 							$size_display_class .= " significant";
 							$size_title_display = human_filesize($revisionData->newsize - $revisionData->sizediff) . " -> " .  human_filesize($revisionData->newsize);
 							
-							$content .= "<li><a href='?page=" . rawurlencode($env->page) . "&revision=$revisionData->rid'>#$revisionData->rid</a> " . render_editor(page_renderer::render_username($revisionData->editor)) . " " . render_timestamp($revisionData->timestamp) . " <span class='cursor-query $size_display_class' title='$size_title_display'>($size_display)</span>";
+							$content .= "<li>";
+							$content .= "<a href='?page=" . rawurlencode($env->page) . "&revision=$revisionData->rid'>#$revisionData->rid</a> " . render_editor(page_renderer::render_username($revisionData->editor)) . " " . render_timestamp($revisionData->timestamp) . " <span class='cursor-query $size_display_class' title='$size_title_display'>($size_display)</span>";
+							if($env->is_logged_in || ($settings->history_revert_require_moderator && $env->is_admin && $env->is_logged_in))
+								$content .= " <small>(<a class='revert-button' href='?action=history-revert&page=" . rawurlencode($env->page) . "&revision=$revisionData->rid'>restore this revision</a>)</small>";
+							$content .= "</li>";
 						}
 					}
 					else
@@ -3281,12 +3291,105 @@ register_module([
 			
 		});
 		
+		/**
+		 * @api {get} ?action=history-revert&page={pageName}&revision={rid}	Revert a page to a previous version
+		 * @apiName HistoryRevert
+		 * @apiGroup Editing
+		 * @apiPermission User
+		 * @apiUse	PageParameter
+		 * @apiUse	UserNotLoggedInError
+		 * @apiUse	UserNotModeratorError
+		 * 
+		 * @apiParam {string}	revision	The page revision number to revert to.
+		 */
+		/*
+		 * ██   ██ ██ ███████ ████████  ██████  ██████  ██    ██
+		 * ██   ██ ██ ██         ██    ██    ██ ██   ██  ██  ██
+		 * ███████ ██ ███████    ██    ██    ██ ██████    ████  █████
+		 * ██   ██ ██      ██    ██    ██    ██ ██   ██    ██
+		 * ██   ██ ██ ███████    ██     ██████  ██   ██    ██
+		 * 
+		 * ██████  ███████ ██    ██ ███████ ██████  ████████
+		 * ██   ██ ██      ██    ██ ██      ██   ██    ██
+		 * ██████  █████   ██    ██ █████   ██████     ██
+		 * ██   ██ ██       ██  ██  ██      ██   ██    ██
+		 * ██   ██ ███████   ████   ███████ ██   ██    ██
+		 */
+		add_action("history-revert", function() {
+			global $env, $settings, $pageindex;
+			
+			if((!$env->is_admin && $settings->history_revert_require_moderator) ||
+				$env->is_logged_in) {
+				http_response_code(401);
+				exit(page_renderer::render_main("Unauthorised - $settings->sitename", "<p>You can't revert pages to a previous revision because " . ($settings->history_revert_require_moderator && $env->is_logged_in ? "you aren't logged in as a moderator. You can try <a href='?action=logout'>logging out</a> and then" : "you aren't logged in. You can try") . " <a href='?action=login&returnto=" . rawurlencode("?action=history-revert&revision={$env->history->revision_number}&page=" . rawurlencode($env->page)) . "logging in</a>."));
+			}
+			
+			$current_revision_filepath = "$env->storage_prefix/{$pageindex->{$env->page}->filename}";
+			
+			// Figure out what we're saving
+			$newsource = file_get_contents($env->page_filename); // The old revision content - the Pepperminty Wiki core sorts this out for us
+			$oldsource = file_get_contents($current_revision_filepath); // The current revision's content
+			
+			// Save the old content over the current content
+			file_put_contents($current_revision_filepath, $newsource);
+			
+			// NOTE: We don't run the save preprocessors here because they are run when a page is edited - reversion is special and requires different treatment.
+			// FUTURE: We may want ot refactor the save preprocessor system ot take a single object instead - then we can add as many params as we like and we could execute the save preprocessors as normal :P
+			
+			// Add the old content as a new revision
+			$result = history_add_revision(
+				$pageindex->{$env->page},
+				$newsource,
+				$oldsource,
+				true, // Yep, go ahead and save the page index
+				"revert" // It's a revert, not an edit
+			);
+			
+			// Update the redirect metadata, if the redirect module is installed
+			if(module_exists("feature-redirect"))
+				update_redirect_metadata($pageindex->{$env->page}, $newsource);
+			
+			// Add an entry to the recent changes log, if the module exists
+			if($result !== false && module_exists("feature-recent-changes"))
+				add_recent_change([
+					"type" => "revert",
+					"timestamp" => time(),
+					"page" => $env->page,
+					"user" => $env->user,
+					"newsize" => strlen($newsource),
+					"sizediff" => strlen($newsource) - strlen($oldsource)
+				]);
+			
+			if($result === false) {
+				http_response_code(503);
+				exit(page_renderer::render_main("Server Error - Revert - $settings->sitename", "<p>A server error occurred when $settings->sitename tried to save the reversion of <code>" . htmlentities($env->page) . "</code>. Please contact $settings->sitename's administrator $settings->admindetails_name, whose email address can be found at the bottom of every page (including this one).</p>"));
+			}
+			
+			http_response_code(201);
+			exit(page_renderer::render_main("Reverting " . htmlentities($env->page) . " - $settings->sitename", "<p>" . htmlentities($env->page) . " has been reverted back to revision {$env->history->revision_number} successfully.</p>
+			<p><a href='?page=" . rawurlencode($env->page) . "'>Go back</a> to the page, or continue <a href='?action=history&page = " . rawurlencode($env->page) . "'>reviewing its history</a>.</p>"));
+			
+			// $env->page_filename
+			// 
+		});
 		
 		register_save_preprocessor("history_add_revision");
 	}
 ]);
 
-function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pageindex = true) {
+/**
+ * Adds a history revision against a page.
+ * Note: Does not updaate the current page content! This function _only_ 
+ * records a new revision against a page name. Thus it is possible to have a 
+ * disparaty between the history revisions and the actual content displayed in 
+ * the current revision if you're not careful!
+ * @param object  $pageinfo       The pageindex object of the page to operate on.
+ * @param string  $newsource      The page content to save as the new revision.
+ * @param string  $oldsource      The old page content that is the current revision (before the update).
+ * @param boolean $save_pageindex Whether the page index should be saved to disk.
+ * @param string  $change_type    The type of change to record this as in the history revision log
+ */
+function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pageindex = true, $change_type = "edit") {
 	global $pageindex, $paths, $env;
 	
 	if(!isset($pageinfo->history))
@@ -3294,8 +3397,7 @@ function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pagein
 	
 	// Save the *new source* as a revision
 	// This results in 2 copies of the current source, but this is ok
-	// since any time someone changes something, it create a new
-	// revision
+	// since any time someone changes something, it creates a new revision
 	// Note that we can't save the old source here because we'd have no
 	// clue who edited it since $pageinfo has already been updated by
 	// this point
@@ -3305,7 +3407,7 @@ function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pagein
 	$ridFilename = "$pageinfo->filename.r$nextRid";
 	// Insert a new entry into the history
 	$pageinfo->history[] = [
-		"type" => "edit", // We might want to store other types later (e.g. page moves)
+		"type" => $change_type, // We might want to store other types later (e.g. page moves)
 		"rid" => $nextRid,
 		"timestamp" => time(),
 		"filename" => $ridFilename,
@@ -3315,11 +3417,13 @@ function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pagein
 	];
 	
 	// Save the new source as a revision
-	file_put_contents("$env->storage_prefix$ridFilename", $newsource);
+	$result = file_put_contents("$env->storage_prefix$ridFilename", $newsource);
 	
 	// Save the edited pageindex
-	if($save_pageindex)
-		file_put_contents($paths->pageindex, json_encode($pageindex, JSON_PRETTY_PRINT));
+	if($result !== false && $save_pageindex)
+		$result = file_put_contents($paths->pageindex, json_encode($pageindex, JSON_PRETTY_PRINT));
+	
+	return $result;
 }
 
 
@@ -3619,31 +3723,39 @@ register_module([
 	"code" => function() {
 		global $settings;
 		
-		register_save_preprocessor(function(&$index_entry, &$pagedata) {
-			$matches = [];
-			if(preg_match("/^# ?REDIRECT ?\[\[([^\]]+)\]\]/i", $pagedata, $matches) === 1)
-			{
-				//error_log("matches: " . var_export($matches, true));
-				// We have found a redirect page!
-				// Update the metadata to reflect this.
-				$index_entry->redirect = true;
-				$index_entry->redirect_target = $matches[1];
-			}
-			else
-			{
-				// This page isn't a redirect. Unset the metadata just in case.
-				if(isset($index_entry->redirect))
-					unset($index_entry->redirect);
-				if(isset($index_entry->redirect_target))
-					unset($index_entry->redirect_target);
-			}
-		});
+		register_save_preprocessor("update_redirect_metadata");
 		
 		// Register a help section
 		add_help_section("25-redirect", "Redirect Pages", "<p>$settings->sitename supports redirect pages. To create a redirect page, enter something like <code># REDIRECT [[pagename]]</code> on the first line of the redirect page's content. This <em>must</em> appear as the first line of the page, with no whitespace before it. You can include content beneath the redirect if you want, too (such as a reason for redirecting the page).</p>");
 	}
 ]);
 
+/**
+ * Updates the metadata associated with redirects in the pageindex entry
+ * specified utilising the provided page content.
+ * @param  object $index_entry The page index entry object to update.
+ * @param  string $pagedata    The page content to operate on.
+ */
+function update_redirect_metadata(&$index_entry, &$pagedata) {
+	$matches = [];
+	if(preg_match("/^# ?REDIRECT ?\[\[([^\]]+)\]\]/i", $pagedata, $matches) === 1)
+	{
+		//error_log("matches: " . var_export($matches, true));
+		// We have found a redirect page!
+		// Update the metadata to reflect this.
+		$index_entry->redirect = true;
+		$index_entry->redirect_target = $matches[1];
+	}
+	else
+	{
+		// This page isn't a redirect. Unset the metadata just in case.
+		if(isset($index_entry->redirect))
+			unset($index_entry->redirect);
+		if(isset($index_entry->redirect_target))
+			unset($index_entry->redirect_target);
+	}
+}
+
 
 
 
diff --git a/core.php b/core.php
index ca13bbd..de5ca7a 100644
--- a/core.php
+++ b/core.php
@@ -111,15 +111,15 @@ if($env->is_logged_in)
 /**
  * @apiDefine Admin	Only the wiki administrator may use this call.
  */
- /**
-  * @apiDefine Moderator	Only users loggged with a moderator account may use this call.
-  */
 /**
-* @apiDefine User		Only users loggged in may use this call.
-*/
+ * @apiDefine Moderator	Only users loggged with a moderator account may use this call.
+ */
 /**
-* @apiDefine Anonymous	Anybody may use this call.
-*/
+ * @apiDefine User		Only users loggged in may use this call.
+ */
+/**
+ * @apiDefine Anonymous	Anybody may use this call.
+ */
 /**
  * @apiDefine	UserNotLoggedInError
  * @apiError	UserNotLoggedInError	You didn't log in before sending this request.
diff --git a/module_index.json b/module_index.json
index f88f3c1..972a7c0 100755
--- a/module_index.json
+++ b/module_index.json
@@ -39,9 +39,9 @@
         "name": "API status",
         "version": "0.1",
         "author": "Starbeamrainbowlabs",
-        "description": "Provides a basic JSON status action that provices a few useful bits of information for API consumption.",
+        "description": "Provides a basic JSON status action that provides a few useful bits of information for API consumption.",
         "id": "api-status",
-        "lastupdate": 1523055259,
+        "lastupdate": 1530565418,
         "optional": false
     },
     {
@@ -77,7 +77,7 @@
         "author": "Starbeamrainbowlabs",
         "description": "Adds the ability to keep unlimited page history, limited only by your disk space. Note that this doesn't store file history (yet). Currently depends on feature-recent-changes for rendering of the history page.",
         "id": "feature-history",
-        "lastupdate": 1518645062,
+        "lastupdate": 1530571420,
         "optional": false
     },
     {
@@ -95,7 +95,7 @@
         "author": "Starbeamrainbowlabs",
         "description": "Adds support for redirect pages. Uses the same syntax that Mediawiki does.",
         "id": "feature-redirect",
-        "lastupdate": 1498646092,
+        "lastupdate": 1530570852,
         "optional": false
     },
     {
diff --git a/modules/api-status.php b/modules/api-status.php
index c2f73af..21da6a0 100644
--- a/modules/api-status.php
+++ b/modules/api-status.php
@@ -16,7 +16,13 @@ register_module([
 		 * @apiParam	{boolean}	Whether or not the result should be minified JSON. Default: false
 		 */
 		
-		
+	 	/*
+	 	 * ███████ ████████  █████  ████████ ██    ██ ███████
+	 	 * ██         ██    ██   ██    ██    ██    ██ ██
+	 	 * ███████    ██    ███████    ██    ██    ██ ███████
+	 	 *      ██    ██    ██   ██    ██    ██    ██      ██
+	 	 * ███████    ██    ██   ██    ██     ██████  ███████
+	 	 */
 		add_action("status", function() {
 			global $version, $env, $settings, $actions;
 			
diff --git a/modules/feature-history.php b/modules/feature-history.php
index 517a7be..e090b38 100644
--- a/modules/feature-history.php
+++ b/modules/feature-history.php
@@ -12,7 +12,7 @@ register_module([
 		 * @apiGroup Page
 		 * @apiPermission Anonymous
 		 * 
-		 * @apiParam {string}	page	The page name to return a revision list for.
+		 * @apiUse PageParameter
 		 * @apiParam {string}	format	The format to return the list of pages in. available values: html, json, text. Default: html
 		 */
 		
@@ -37,8 +37,8 @@ register_module([
 						$content .= "\t\t<ul class='page-list'>\n";
 						foreach(array_reverse($pageindex->{$env->page}->history) as $revisionData)
 						{
-							// Only display edits for now
-							if($revisionData->type != "edit")
+							// Only display edits & reverts for now
+							if($revisionData->type != "edit" || $revisionData->type != "revert")
 							continue;
 							
 							// The number (and the sign) of the size difference to display
@@ -48,7 +48,11 @@ register_module([
 							$size_display_class .= " significant";
 							$size_title_display = human_filesize($revisionData->newsize - $revisionData->sizediff) . " -> " .  human_filesize($revisionData->newsize);
 							
-							$content .= "<li><a href='?page=" . rawurlencode($env->page) . "&revision=$revisionData->rid'>#$revisionData->rid</a> " . render_editor(page_renderer::render_username($revisionData->editor)) . " " . render_timestamp($revisionData->timestamp) . " <span class='cursor-query $size_display_class' title='$size_title_display'>($size_display)</span>";
+							$content .= "<li>";
+							$content .= "<a href='?page=" . rawurlencode($env->page) . "&revision=$revisionData->rid'>#$revisionData->rid</a> " . render_editor(page_renderer::render_username($revisionData->editor)) . " " . render_timestamp($revisionData->timestamp) . " <span class='cursor-query $size_display_class' title='$size_title_display'>($size_display)</span>";
+							if($env->is_logged_in || ($settings->history_revert_require_moderator && $env->is_admin && $env->is_logged_in))
+								$content .= " <small>(<a class='revert-button' href='?action=history-revert&page=" . rawurlencode($env->page) . "&revision=$revisionData->rid'>restore this revision</a>)</small>";
+							$content .= "</li>";
 						}
 					}
 					else
@@ -83,12 +87,105 @@ register_module([
 			
 		});
 		
+		/**
+		 * @api {get} ?action=history-revert&page={pageName}&revision={rid}	Revert a page to a previous version
+		 * @apiName HistoryRevert
+		 * @apiGroup Editing
+		 * @apiPermission User
+		 * @apiUse	PageParameter
+		 * @apiUse	UserNotLoggedInError
+		 * @apiUse	UserNotModeratorError
+		 * 
+		 * @apiParam {string}	revision	The page revision number to revert to.
+		 */
+		/*
+		 * ██   ██ ██ ███████ ████████  ██████  ██████  ██    ██
+		 * ██   ██ ██ ██         ██    ██    ██ ██   ██  ██  ██
+		 * ███████ ██ ███████    ██    ██    ██ ██████    ████  █████
+		 * ██   ██ ██      ██    ██    ██    ██ ██   ██    ██
+		 * ██   ██ ██ ███████    ██     ██████  ██   ██    ██
+		 * 
+		 * ██████  ███████ ██    ██ ███████ ██████  ████████
+		 * ██   ██ ██      ██    ██ ██      ██   ██    ██
+		 * ██████  █████   ██    ██ █████   ██████     ██
+		 * ██   ██ ██       ██  ██  ██      ██   ██    ██
+		 * ██   ██ ███████   ████   ███████ ██   ██    ██
+		 */
+		add_action("history-revert", function() {
+			global $env, $settings, $pageindex;
+			
+			if((!$env->is_admin && $settings->history_revert_require_moderator) ||
+				$env->is_logged_in) {
+				http_response_code(401);
+				exit(page_renderer::render_main("Unauthorised - $settings->sitename", "<p>You can't revert pages to a previous revision because " . ($settings->history_revert_require_moderator && $env->is_logged_in ? "you aren't logged in as a moderator. You can try <a href='?action=logout'>logging out</a> and then" : "you aren't logged in. You can try") . " <a href='?action=login&returnto=" . rawurlencode("?action=history-revert&revision={$env->history->revision_number}&page=" . rawurlencode($env->page)) . "logging in</a>."));
+			}
+			
+			$current_revision_filepath = "$env->storage_prefix/{$pageindex->{$env->page}->filename}";
+			
+			// Figure out what we're saving
+			$newsource = file_get_contents($env->page_filename); // The old revision content - the Pepperminty Wiki core sorts this out for us
+			$oldsource = file_get_contents($current_revision_filepath); // The current revision's content
+			
+			// Save the old content over the current content
+			file_put_contents($current_revision_filepath, $newsource);
+			
+			// NOTE: We don't run the save preprocessors here because they are run when a page is edited - reversion is special and requires different treatment.
+			// FUTURE: We may want ot refactor the save preprocessor system ot take a single object instead - then we can add as many params as we like and we could execute the save preprocessors as normal :P
+			
+			// Add the old content as a new revision
+			$result = history_add_revision(
+				$pageindex->{$env->page},
+				$newsource,
+				$oldsource,
+				true, // Yep, go ahead and save the page index
+				"revert" // It's a revert, not an edit
+			);
+			
+			// Update the redirect metadata, if the redirect module is installed
+			if(module_exists("feature-redirect"))
+				update_redirect_metadata($pageindex->{$env->page}, $newsource);
+			
+			// Add an entry to the recent changes log, if the module exists
+			if($result !== false && module_exists("feature-recent-changes"))
+				add_recent_change([
+					"type" => "revert",
+					"timestamp" => time(),
+					"page" => $env->page,
+					"user" => $env->user,
+					"newsize" => strlen($newsource),
+					"sizediff" => strlen($newsource) - strlen($oldsource)
+				]);
+			
+			if($result === false) {
+				http_response_code(503);
+				exit(page_renderer::render_main("Server Error - Revert - $settings->sitename", "<p>A server error occurred when $settings->sitename tried to save the reversion of <code>" . htmlentities($env->page) . "</code>. Please contact $settings->sitename's administrator $settings->admindetails_name, whose email address can be found at the bottom of every page (including this one).</p>"));
+			}
+			
+			http_response_code(201);
+			exit(page_renderer::render_main("Reverting " . htmlentities($env->page) . " - $settings->sitename", "<p>" . htmlentities($env->page) . " has been reverted back to revision {$env->history->revision_number} successfully.</p>
+			<p><a href='?page=" . rawurlencode($env->page) . "'>Go back</a> to the page, or continue <a href='?action=history&page = " . rawurlencode($env->page) . "'>reviewing its history</a>.</p>"));
+			
+			// $env->page_filename
+			// 
+		});
 		
 		register_save_preprocessor("history_add_revision");
 	}
 ]);
 
-function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pageindex = true) {
+/**
+ * Adds a history revision against a page.
+ * Note: Does not updaate the current page content! This function _only_ 
+ * records a new revision against a page name. Thus it is possible to have a 
+ * disparaty between the history revisions and the actual content displayed in 
+ * the current revision if you're not careful!
+ * @param object  $pageinfo       The pageindex object of the page to operate on.
+ * @param string  $newsource      The page content to save as the new revision.
+ * @param string  $oldsource      The old page content that is the current revision (before the update).
+ * @param boolean $save_pageindex Whether the page index should be saved to disk.
+ * @param string  $change_type    The type of change to record this as in the history revision log
+ */
+function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pageindex = true, $change_type = "edit") {
 	global $pageindex, $paths, $env;
 	
 	if(!isset($pageinfo->history))
@@ -96,8 +193,7 @@ function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pagein
 	
 	// Save the *new source* as a revision
 	// This results in 2 copies of the current source, but this is ok
-	// since any time someone changes something, it create a new
-	// revision
+	// since any time someone changes something, it creates a new revision
 	// Note that we can't save the old source here because we'd have no
 	// clue who edited it since $pageinfo has already been updated by
 	// this point
@@ -107,7 +203,7 @@ function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pagein
 	$ridFilename = "$pageinfo->filename.r$nextRid";
 	// Insert a new entry into the history
 	$pageinfo->history[] = [
-		"type" => "edit", // We might want to store other types later (e.g. page moves)
+		"type" => $change_type, // We might want to store other types later (e.g. page moves)
 		"rid" => $nextRid,
 		"timestamp" => time(),
 		"filename" => $ridFilename,
@@ -117,11 +213,13 @@ function history_add_revision(&$pageinfo, &$newsource, &$oldsource, $save_pagein
 	];
 	
 	// Save the new source as a revision
-	file_put_contents("$env->storage_prefix$ridFilename", $newsource);
+	$result = file_put_contents("$env->storage_prefix$ridFilename", $newsource);
 	
 	// Save the edited pageindex
-	if($save_pageindex)
-		file_put_contents($paths->pageindex, json_encode($pageindex, JSON_PRETTY_PRINT));
+	if($result !== false && $save_pageindex)
+		$result = file_put_contents($paths->pageindex, json_encode($pageindex, JSON_PRETTY_PRINT));
+	
+	return $result;
 }
 
 ?>
diff --git a/modules/feature-redirect.php b/modules/feature-redirect.php
index 66fd0d8..3b8ec98 100644
--- a/modules/feature-redirect.php
+++ b/modules/feature-redirect.php
@@ -8,29 +8,37 @@ register_module([
 	"code" => function() {
 		global $settings;
 		
-		register_save_preprocessor(function(&$index_entry, &$pagedata) {
-			$matches = [];
-			if(preg_match("/^# ?REDIRECT ?\[\[([^\]]+)\]\]/i", $pagedata, $matches) === 1)
-			{
-				//error_log("matches: " . var_export($matches, true));
-				// We have found a redirect page!
-				// Update the metadata to reflect this.
-				$index_entry->redirect = true;
-				$index_entry->redirect_target = $matches[1];
-			}
-			else
-			{
-				// This page isn't a redirect. Unset the metadata just in case.
-				if(isset($index_entry->redirect))
-					unset($index_entry->redirect);
-				if(isset($index_entry->redirect_target))
-					unset($index_entry->redirect_target);
-			}
-		});
+		register_save_preprocessor("update_redirect_metadata");
 		
 		// Register a help section
 		add_help_section("25-redirect", "Redirect Pages", "<p>$settings->sitename supports redirect pages. To create a redirect page, enter something like <code># REDIRECT [[pagename]]</code> on the first line of the redirect page's content. This <em>must</em> appear as the first line of the page, with no whitespace before it. You can include content beneath the redirect if you want, too (such as a reason for redirecting the page).</p>");
 	}
 ]);
 
+/**
+ * Updates the metadata associated with redirects in the pageindex entry
+ * specified utilising the provided page content.
+ * @param  object $index_entry The page index entry object to update.
+ * @param  string $pagedata    The page content to operate on.
+ */
+function update_redirect_metadata(&$index_entry, &$pagedata) {
+	$matches = [];
+	if(preg_match("/^# ?REDIRECT ?\[\[([^\]]+)\]\]/i", $pagedata, $matches) === 1)
+	{
+		//error_log("matches: " . var_export($matches, true));
+		// We have found a redirect page!
+		// Update the metadata to reflect this.
+		$index_entry->redirect = true;
+		$index_entry->redirect_target = $matches[1];
+	}
+	else
+	{
+		// This page isn't a redirect. Unset the metadata just in case.
+		if(isset($index_entry->redirect))
+			unset($index_entry->redirect);
+		if(isset($index_entry->redirect_target))
+			unset($index_entry->redirect_target);
+	}
+}
+
 ?>