Index: textpattern/include/txp_article.php
===================================================================
--- textpattern/include/txp_article.php	(revision 2651)
+++ textpattern/include/txp_article.php	(working copy)
@@ -12,6 +12,7 @@
 */
 
 include_once(txpath.'/lib/classMarkup.php');
+include_once(txpath.'/lib/txplib_revisions.php');
 
 if (!defined('txpinterface')) die('txpinterface is undefined.');
 
@@ -150,6 +151,8 @@
 				uid             = '".md5(uniqid(rand(),true))."',
 				feed_time       = now()"
 			);
+
+			add_article_revision($ID);
 			
 			if ($Status>=4) {
 				
@@ -273,6 +276,8 @@
 			"ID = $ID"
 		);
 
+		add_article_revision($ID);
+
 		if($Status >= 4) {
 			if ($oldArticle['Status'] < 4) {
 				do_pings();
@@ -301,6 +306,8 @@
 		} else {
 			$ID = gps('ID');
 		}
+		
+		$rev = gps('revision');
 
 		// switch to 'text' view upon page load and after article post
 		if(!$view || gps('save') || gps('publish')) {
@@ -317,14 +324,26 @@
 			&& $from_view != 'html') {
 
 			$ID = assert_int($ID);
-			$article = safe_row(
-				"*, unix_timestamp(Posted) as sPosted,
-				unix_timestamp(Expires) as sExpires,
-				unix_timestamp(LastMod) as sLastMod",
-				"textpattern",
-				"ID=$ID"
-			);
+			
+			if (!empty($rev)) {
+				$article_rev = get_revision($ID,$rev);
 
+				if ($article_rev) {
+					$article = $article_rev['data'];
+					$article['sPosted'] = strtotime($article['Posted']);
+					$article['sExpires'] = ($article['Expires'] == '0000-00-00 00:00:00') ? 0 : strtotime($article['Expires']);
+					$article['sLastMod'] = strtotime($article['LastMod']);
+				}
+			} else {
+				$article = safe_row(
+					"*, unix_timestamp(Posted) as sPosted,
+					unix_timestamp(Expires) as sExpires,
+					unix_timestamp(LastMod) as sLastMod",
+					"textpattern",
+					"ID=$ID"
+				);
+			}
+
 			extract($article);
 
 			$article['reset_time'] = $article['publish_now'] = ($Status < 4);
@@ -389,11 +408,14 @@
 		{
 			echo hInput('store', base64_encode(serialize($article)));
 		}
+		
+		$revision = gps('revision');
 
 		echo hInput('ID', $ID).
 			eInput('article').
 			sInput($step).
 			'<input type="hidden" name="view" />'.
+			(!empty($revision) ? hInput('revision', $revision) : '').
 
 			startTable('edit').
 
@@ -454,8 +476,29 @@
 
 				echo '</ul>';
 			}
+			echo '</div>';
 
-			echo '</div>';
+			$revisions = get_revisions($ID);
+			
+			if (!empty($revisions)) {
+				echo '<h3 class="plain"><a href="#revisions" onclick="toggleDisplay(\'revisions\'); return false;">'.gTxt('revision_history').'</a>'.'</h3>'.
+				'<div id="revisions" style="display:none;">';
+
+				$rev_count = 1;
+				foreach ($revisions as $rev)
+				{
+					if ($rev_count++ == 1)
+					{
+						echo n.t.'<div class="revision"><a href="?event=article'.a.'step=edit'.a.'ID='.$ID.'">'.gTxt('revision', array($rev['version'], $rev['user'])).
+							'</a><div>'. $rev['modified'] . '</div></div>';
+					} else {
+						echo n.t.'<div class="revision"><a href="?event=article'.a.'step=edit'.a.'ID='.$ID.a.'revision='.$rev['version'].'">'.gTxt('revision', array($rev['version'], $rev['user'])).
+							'</a><div>'. $rev['modified'] . '</div></div>';
+					}
+				}
+				
+				echo '</div>';
+			}
 		}
 
 		else
@@ -481,12 +524,17 @@
 		{
 			echo '<p><label for="title">'.gTxt('title').'</label>';
 
-			if ( ($Status == 4 or $Status == 5) and $step != 'create') {
+			$revision = gps('revision');
+
+			if ( ($Status == 4 or $Status == 5) and $step != 'create' and empty($revision)) {
 				include_once txpath.'/publish/taghandlers.php';
 
 				echo sp.sp.'[<a href="'.permlinkurl_id($ID).'">'.gTxt('view').'</a>]';
 			}
 
+			if (!empty($revision))
+				echo sp.sp.'['.gTxt('Revision',array($revision)).']';
+
 			echo '<br />'.
 				n.'<input type="text" id="title" name="Title" value="'.cleanfInput($Title).'" class="edit" size="65" tabindex="1" /></p>';
 		}
@@ -1010,4 +1058,29 @@
 		}
 	}
 
-?>
+
+//--------------------------------------------------------------
+	function add_article_revision($ID)
+	{
+		global $prefs;
+
+		if ($ID) {
+			// get the new article
+			$rs = safe_row('*', 'textpattern', "ID = $ID");
+	
+			if ($rs) {
+				// get the article's last version
+				$rev = get_revision($ID);
+				
+				if (isset($prefs['custom_article_compare_func']) and is_callable($prefs['custom_article_compare_func']))
+					$changed = call_user_func($prefs['custom_article_compare_func'], array($rs, $rev));
+				else
+					$changed = true;
+				
+				if ($changed)
+					add_revision($ID, $rs);
+			}
+		}
+	}
+
+?>
\ No newline at end of file
Index: textpattern/lib/txplib_revisions.php
===================================================================
--- textpattern/lib/txplib_revisions.php	(revision 0)
+++ textpattern/lib/txplib_revisions.php	(revision 0)
@@ -0,0 +1,149 @@
+<?php
+/*
+Copyright 2007 Michael Manfre http://manfre.net
+
+$HeadURL$
+$LastChangedRevision$
+*/
+
+//-------------------------------------------------------------
+	function encode_revision_data($data)
+	{
+		if (function_exists('gzcompress'))
+			return base64_encode(gzcompress(serialize($data)));
+		
+		return base64_encode(serialize($data));
+	}
+
+//-------------------------------------------------------------
+	function decode_revision_data($data)
+	{
+		if (function_exists('gzuncompress'))
+			return unserialize(gzuncompress(base64_decode($data)));
+		
+		return unserialize(base64_decode($data));
+	}
+
+//-------------------------------------------------------------
+	function get_revisions($id, $fetch_data=false, $type='article',$sort='version desc')
+	{
+		if (empty($id))
+			return false;
+
+		$id = assert_int($id);
+		$type = doSlash($type);
+		$sort = doSlash($sort);
+
+		$revs = array();
+		
+		if ($id !== false) {
+			$fields = $fetch_data ? '*' : 'id,type,user,modified,version';
+			
+			$rs = safe_rows_start($fields, 'txp_revisions', "`id` = $id AND `type` = '$type'" . 
+				(!empty($sort) ? "ORDER BY $sort" : ''));
+			
+			if ($rs) {
+				while($a = nextRow($rs)) {
+					$a['data'] = $fetch_data ? decode_revision_data($a['data']) : '';
+					$revs[] = $a;						
+				}
+			}
+		}
+		
+		return $revs;
+	}
+
+//-------------------------------------------------------------
+	function get_revision($id, $ver=false, $type='article')
+	{
+		global $DB;
+		
+		if (empty($id))
+			return false;
+
+		$id = assert_int($id);
+		$type = doSlash($type);
+		if ($ver !== false)
+			$ver = assert_int($ver);
+
+		$rev = false;
+
+		if (!empty($type) && $id !== false && $ver !== false) {
+			$rev = safe_row('*', 'txp_revisions', "type = '$type' AND id = $id" 
+						. ($ver === false ? ' ORDER BY version DESC ' . $DB->limit(1) : " AND version = $ver") );
+
+			if ($rev)
+				$rev['data'] = decode_revision_data($rev['data']);
+		}
+
+		return $rev;
+	}
+
+//-------------------------------------------------------------
+	function get_revision_count($id, $type='article')
+	{
+		if (empty($id))
+			return false;
+
+		$id = assert_int($id);
+		$type = doSlash($type);
+		
+		if ($id !== false && !empty($type))
+			return safe_count('txp_revisions', "type = '$type' AND id = $id");
+		
+		return false;
+	}
+
+//-------------------------------------------------------------
+	function get_next_revision_number($id, $type='article')
+	{
+		global $DB;
+
+		if (empty($id))
+			return false;
+
+		$id = assert_int($id);
+		$type = doSlash($type);
+
+		$rev = 0;
+
+		if ($id !== false && !empty($type)) {
+			$rev = safe_field('version', 'txp_revisions', "type = '$type' AND id = $id ORDER BY version DESC " . $DB->limit(1));
+			
+			if (!$rev)
+				$rev = 0;
+				
+		}
+		
+		return $rev + 1;
+	}
+
+//-------------------------------------------------------------
+	function add_revision($id, $data, $type='article', $user='')
+	{
+		global $txp_user;
+		
+		if (empty($id))
+			return false;
+
+		if (empty($user)) $user = $txp_user;
+
+		$id = assert_int($id);
+		
+		$data = encode_revision_data($data);
+
+		if ($id !== false && !empty($type) && !empty($user)) {
+			
+			$version = get_next_revision_number($id, $type);
+
+			$id = doSlash($id);
+			$version = doSlash($version);
+			$type = doSlash($type);
+			$user = doSlash($user);
+			
+			return safe_insert('txp_revisions', "id = $id, version = $version, type = '$type', user = '$user', modified = now(), data = '$data'");
+		}
+		
+		return false;
+	}
+?>
\ No newline at end of file
Index: textpattern/model/txp_tables.php
===================================================================
--- textpattern/model/txp_tables.php	(revision 2651)
+++ textpattern/model/txp_tables.php	(working copy)
@@ -449,4 +449,27 @@
 
 }
 
+class txp_revisions_table extends zem_table 
+{
+	
+	var $_table_name = 'txp_revisions';
+	
+	var $_cols = array(
+		'id' => ZEM_FOREIGN_KEY .' NOT NULL',
+		'version' => "smallint NOT NULL default '1'",
+		'type' => "varchar(64) NOT NULL default ''",
+		'user' => "varchar(64) NOT NULL default ''",
+		'modified' => ZEM_DATETIME . " NOT NULL default '0000-00-00 00:00:00'",
+		'data' => ZEM_MEDIUMTEXT,
+	);
+	
+	var $_primary_key = '';
+	
+	function create_table(){
+		parent::create_table();
+		safe_upgrade_index($this->_table_name,'revision_version','UNIQUE','type,id,version');
+	}
+}
+
+
 ?>
\ No newline at end of file
Index: textpattern/setup/txpsql.php
===================================================================
--- textpattern/setup/txpsql.php	(revision 2651)
+++ textpattern/setup/txpsql.php	(working copy)
@@ -28,6 +28,7 @@
 	$datetime = 'timestamp without time zone';
 	$autoinc = 'SERIAL NOT NULL';
 	$mediumtext = 'text';
+	$longtext = 'text';
 	$tinytext = 'text';
 	$tabletype = '';
 	$incval = 'DEFAULT';
@@ -53,6 +54,7 @@
 	$datetime = 'datetime';
 	$autoinc = 'INT NOT NULL AUTO_INCREMENT';
 	$incval = 'NULL';
+	$longtext = 'longtext';
 	$mediumtext = 'mediumtext';
 	$tinytext = 'tinytext';
 }
@@ -64,6 +66,7 @@
 	$zerodatetime = $zerodate.' 00:00:00';
 	$datetime = 'datetime';
 	$autoinc = 'INTEGER';
+	$longtext = 'text';
 	$mediumtext = 'text';
 	$tinytext = 'text';
 	$tabletype = '';
@@ -416,6 +419,16 @@
 $create_sql[] = "INSERT INTO ".PFX."txp_prefs VALUES (1, 'dbupdatetime', '1122194504', 2, 'publish', 'text_input', 0)";
 $create_sql[] = "INSERT INTO ".PFX."txp_prefs VALUES (1, 'version', '1.0rc4', 2, 'publish', 'text_input', 0)";
 
+$create_sql[] = "CREATE TABLE ".PFX."txp_revisions (
+	id bigint NOT NULL,
+	version smallint NOT NULL default '1',
+	type varchar(64) NOT NULL default '',
+	user varchar(64) NOT NULL default '',
+	modified $datetime NOT NULL default '$zerodatetime',
+	data $mediumtext NOT NULL default '',
+	KEY (id, version, type)
+) $tabletype";
+
 $create_sql[] = "CREATE TABLE ".PFX."txp_section (
   name varchar(128) NOT NULL default '',
   page varchar(128) NOT NULL default '',
Index: textpattern/textpattern.css
===================================================================
--- textpattern/textpattern.css	(revision 2651)
+++ textpattern/textpattern.css	(working copy)
@@ -522,6 +522,17 @@
 height: 85px;
 }
 
+#revisions {
+border-top: 1px dashed #ccc;
+}
+
+.revision {
+padding-top: .5em;
+padding-bottom: .5em;
+border-bottom: 1px dashed #ccc;
+}
+
+
 /* comments
 ----------------------------------------------- */