3 files changed, 307 insertions, 0 deletions
diff --git a/phpBB/includes/constants.php b/phpBB/includes/constants.php
index 68af41ab20..68c96a2759 100644
--- a/phpBB/includes/constants.php
+++ b/phpBB/includes/constants.php
@@ -237,6 +237,7 @@ define('ICONS_TABLE',				$table_prefix . 'icons');
 define('LANG_TABLE',				$table_prefix . 'lang');
 define('LOG_TABLE',					$table_prefix . 'log');
 define('LOGIN_ATTEMPT_TABLE',		$table_prefix . 'login_attempts');
+define('MIGRATIONS_TABLE',			$table_prefix . 'migrations');
 define('MODERATOR_CACHE_TABLE',		$table_prefix . 'moderator_cache');
 define('MODULES_TABLE',				$table_prefix . 'modules');
 define('POLL_OPTIONS_TABLE',		$table_prefix . 'poll_options');
diff --git a/phpBB/includes/db/migration.php b/phpBB/includes/db/migration.php
new file mode 100644
index 0000000000..f96fcb9568
--- /dev/null
+++ b/phpBB/includes/db/migration.php
@@ -0,0 +1,79 @@
+<?php
+/**
+*
+* @package db
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Abstract base class for database migrations
+*
+* Each migration consists of a set of schema and data changes to be implemented
+* in a subclass. This class provides various utility methods to simplify editing
+* a phpBB.
+*
+* @package db
+*/
+class phpbb_db_migration
+{
+	var $db;
+	var $db_tools;
+
+	/**
+	* Migration constructor
+	*
+	* @param dbal			$db			Connected database abstraction instance
+	* @param phpbb_db_tools	$db_tools	Instance of db schema manipulation tools
+	*/
+	function phpbb_db_migration(&$db, &$db_tools)
+	{
+		$this->db = &$db;
+		$this->db_tools = &$db_tools;
+	}
+
+	/**
+	* Defines other migrationsto be applied first (abstract method)
+	*
+	* @return array An array of migration class names
+	*/
+	function depends_on()
+	{
+		return array();
+	}
+
+	/**
+	* Updates the database schema
+	*
+	* @return null
+	*/
+	function update_schema()
+	{
+	}
+
+	/**
+	* Updates data
+	*
+	* @return null
+	*/
+	function update_data()
+	{
+	}
+
+	/**
+	* Adds a column to a database table
+	*/
+	function db_column_add($table_name, $column_name, $column_data)
+	{
+		$this->db_tools->sql_column_add($table_name, $column_name, $column_data);
+	}
+}
diff --git a/phpBB/includes/db/migrator.php b/phpBB/includes/db/migrator.php
new file mode 100644
index 0000000000..d5d938ca28
--- /dev/null
+++ b/phpBB/includes/db/migrator.php
@@ -0,0 +1,227 @@
+<?php
+/**
+*
+* @package db
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* The migrator is responsible for applying new migrations in the correct order.
+*
+* @package db
+*/
+class phpbb_db_migrator
+{
+	var $db;
+	var $db_tools;
+
+	var $migrations_table;
+	var $migration_state;
+
+	var $migrations;
+
+	/**
+	* Constructor of the database migrator
+	*
+	* @param dbal			$db			Connected database abstraction instance
+	* @param phpbb_db_tools	$db_tools	Instance of db schema manipulation tools
+	* @param string			$migrations_table The name of the db table storing
+	*									information on applied migrations
+	*/
+	function phpbb_db_migrator(&$db, &$db_tools, $migrations_table)
+	{
+		$this->db = &$db;
+		$this->db_tools = &$db_tools;
+		$this->migrations_table = $migrations_table;
+		$this->migrations = array();
+
+		$this->load_migration_state();
+	}
+
+	/**
+	* Loads all migrations and their application state from the database.
+	*
+	* @return null
+	*/
+	function load_migration_state()
+	{
+		$sql = "SELECT *
+			FROM " . $this->migrations_table;
+		$result = $this->db->sql_query($sql);
+
+		$this->migration_state = array();
+		while ($migration = $this->db->sql_fetchrow($result))
+		{
+			$this->migration_state[$migration['migration_name']] = $migration;
+		}
+
+		$this->db->sql_freeresult($result);
+	}
+
+	/**
+	* Sets the list of available migration class names to the given array.
+	*
+	* @param array $class_names An array of migration class names
+	* @return null
+	*/
+	function set_migrations($class_names)
+	{
+		$this->migrations = $class_names;
+	}
+
+	/**
+	* Runs a single update step from the next migration to be applied.
+	*
+	* The update step can either be a schema or a (partial) data update. To
+	* check if update() needs to be called again use the finished() method.
+	*
+	* @return null
+	*/
+	function update()
+	{
+		foreach ($this->migrations as $name)
+		{
+			if (!isset($this->migration_state[$name]) ||
+				!$this->migration_state[$name]['migration_schema_done'] ||
+				!$this->migration_state[$name]['migration_data_done'])
+			{
+				if (!$this->try_apply($name))
+				{
+					continue;
+				}
+				else
+				{
+					return;
+				}
+			}
+		}
+	}
+
+	/**
+	* Attempts to apply a step of the given migration or one of its dependencies
+	*
+	* @param	string	The class name of the migration
+	* @return	bool	Whether any update step was successfully run
+	*/
+	function try_apply($name)
+	{
+		if (!class_exists($name))
+		{
+			return false;
+		}
+
+		$migration =& new $name($this->db, $this->db_tools);
+		$state = (isset($this->migration_state[$name])) ?
+			$this->migration_state[$name] :
+			array(
+				'migration_schema_done' => false,
+				'migration_data_done' => false,
+				'migration_data_state' => '',
+			);
+
+		$depends = $migration->depends_on();
+
+		foreach ($depends as $depend)
+		{
+			if (!isset($this->migration_state[$depend]) ||
+				!$this->migration_state[$depend]['migration_schema_done'] ||
+				!$this->migration_state[$depend]['migration_data_done'])
+			{
+				return $this->try_apply($depend);
+			}
+		}
+
+		if (!$state['migration_schema_done'])
+		{
+			$migration->update_schema();
+			$state['migration_schema_done'] = true;
+		}
+		else
+		{
+			$migration->update_data();
+			$state['migration_data_done'] = true;
+		}
+
+		$sql = 'UPDATE ' . $this->migrations_table . '
+			SET ' . $this->db->sql_build_array('UPDATE', $state) . "
+			WHERE migration_name = '" . $this->db->sql_escape($name) . "'";
+		$this->db->sql_query($sql);
+
+		$this->migration_state[$name] = $state;
+
+		return true;
+	}
+
+	/**
+	* Checks if a migration's dependencies can even theoretically be satisfied.
+	*
+	* @param	string	$name	The class name of the migration
+	* @return	bool			Whether the migration cannot be fulfilled
+	*/
+	function unfulfillable($name)
+	{
+		if (isset($this->migration_state[$name]))
+		{
+			return false;
+		}
+
+		if (!class_exists($name))
+		{
+			return true;
+		}
+
+		$migration =& new $name($this->db, $this->db_tools);
+		$depends = $migration->depends_on();
+
+		foreach ($depends as $depend)
+		{
+			if ($this->unfulfillable($depend))
+			{
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	* Checks whether all available, fulfillable migrations have been applied.
+	*
+	* @return bool Whether the migrations have been applied
+	*/
+	function finished()
+	{
+		foreach ($this->migrations as $name)
+		{
+			if (!isset($this->migration_state[$name]))
+			{
+				// skip unfulfillable migrations, but fulfillables mean we
+				// are not finished yet
+				if ($this->unfulfillable($name))
+				{
+					continue;
+				}
+				return false;
+			}
+
+			$migration = $this->migration_state[$name];
+
+			if (!$migration['migration_schema_done'] || !$migration['migration_data_done'])
+			{
+				return false;
+			}
+		}
+
+		return true;
+	}
+}