<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.2.4 or newer
 *
 * NOTICE OF LICENSE
 *
 * Licensed under the Open Software License version 3.0
 *
 * This source file is subject to the Open Software License (OSL 3.0) that is
 * bundled with this package in the files license.txt / license.rst.  It is
 * also available through the world wide web at this URL:
 * http://opensource.org/licenses/OSL-3.0
 * If you did not receive a copy of the license and are unable to obtain it
 * through the world wide web, please send an email to
 * licensing@ellislab.com so we can send you a copy immediately.
 *
 * @package		CodeIgniter
 * @author		EllisLab Dev Team
 * @copyright	Copyright (c) 2006 - 2012, EllisLab, Inc. (http://ellislab.com/)
 * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
 * @link		http://codeigniter.com
 * @since		Version 3.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * Migration Class
 *
 * All migrations should implement this, forces up() and down() and gives
 * access to the CI super-global.
 *
 * @package		CodeIgniter
 * @subpackage	Libraries
 * @category	Libraries
 * @author		Reactor Engineers
 * @link
 */
class CI_Migration {

	/**
	 * Whether the library is enabled
	 *
	 * @var bool
	 */
	protected $_migration_enabled = FALSE;
	
	/**
	 * Migration numbering type
	 *
	 * @var bool
	 */
	protected $_migration_type = 'sequential';

	/**
	 * Path to migration classes
	 *
	 * @var string
	 */
	protected $_migration_path = NULL;

	/**
	 * Current migration version
	 *
	 * @var mixed
	 */
	protected $_migration_version = 0;

	/**
	 * Database table with migration info
	 *
	 * @var string
	 */
	protected $_migration_table = 'migrations';

	/**
	 * Whether to automatically run migrations
	 *
	 * @var bool
	 */
	protected $_migration_auto_latest = FALSE;
	
	/**
	 * Migration basename regex
	 *
	 * @var bool
	 */
	protected $_migration_regex = NULL;

	/**
	 * Error message
	 *
	 * @var string
	 */
	protected $_error_string = '';

	/**
	 * Initialize Migration Class
	 *
	 * @param	array
	 * @return	void
	 */
	public function __construct($config = array())
	{
		# Only run this constructor on main library load
		if (get_parent_class($this) !== FALSE)
		{
			return;
		}

		foreach ($config as $key => $val)
		{
			$this->{'_'.$key} = $val;
		}

		log_message('debug', 'Migrations class initialized');

		// Are they trying to use migrations while it is disabled?
		if ($this->_migration_enabled !== TRUE)
		{
			show_error('Migrations has been loaded but is disabled or set up incorrectly.');
		}

		// If not set, set it
		$this->_migration_path !== '' OR $this->_migration_path = APPPATH.'migrations/';

		// Add trailing slash if not set
		$this->_migration_path = rtrim($this->_migration_path, '/').'/';

		// Load migration language
		$this->lang->load('migration');

		// They'll probably be using dbforge
		$this->load->dbforge();

		// Make sure the migration table name was set.
		if (empty($this->_migration_table))
		{
			show_error('Migrations configuration file (migration.php) must have "migration_table" set.');
		}
		
		// Migration basename regex
		$this->_migration_regex = ($this->_migration_type === 'timestamp')
		                        ? '/^\d{14}_(\w+)$/'
		                        : '/^\d{3}_(\w+)$/';
		
		// Make sure a valid migration numbering type was set.
		if ( ! in_array($this->_migration_type, array('sequential', 'timestamp')))
		{
			show_error('An invalid migration numbering type was specified: '.$this->_migration_type);
		}

		// If the migrations table is missing, make it
		if ( ! $this->db->table_exists($this->_migration_table))
		{
			$this->dbforge->add_field(array(
				'version' => array('type' => 'BIGINT', 'constraint' => 20),
			));

			$this->dbforge->create_table($this->_migration_table, TRUE);

			$this->db->insert($this->_migration_table, array('version' => 0));
		}

		// Do we auto migrate to the latest migration?
		if ($this->_migration_auto_latest === TRUE && ! $this->latest())
		{
			show_error($this->error_string());
		}
	}

	// --------------------------------------------------------------------

	/**
	 * Migrate to a schema version
	 *
	 * Calls each migration step required to get to the schema version of
	 * choice
	 *
	 * @param	int	Target schema version
	 * @return	mixed	TRUE if already latest, FALSE if failed, int if upgraded
	 */
	public function version($target_version)
	{
		$current_version = (int) $this->_get_version();
		$target_version = (int) $target_version;
		
		$migrations = $this->find_migrations();
		
		if ($target_version > 0 && ! isset($migrations[$target_version]))
		{
			$this->_error_string = sprintf($this->lang->line('migration_not_found'), $target_version);
			return FALSE;
		}
		
		if ($target_version > $current_version)
		{
			// Moving Up
			$method = 'up';
		}
		else
		{
			// Moving Down, apply in reverse order
			$method = 'down';
			krsort($migrations);
		}

		if (empty($migrations))
		{
			return TRUE;
		}
		
		$previous = FALSE;

		// Validate all available migrations, and run the ones within our target range
		foreach ($migrations as $number => $file)
		{
			// Check for sequence gaps
			if ($this->_migration_type === 'sequential' && $previous !== FALSE && abs($number - $previous) > 1)
			{
				$this->_error_string = sprintf($this->lang->line('migration_sequence_gap'), $number);
				return FALSE;
			}
		
			include $file;
			$class = 'Migration_'.ucfirst(strtolower($this->_get_migration_name(basename($file, '.php'))));

			// Validate the migration file structure
			if ( ! class_exists($class))
			{
				$this->_error_string = sprintf($this->lang->line('migration_class_doesnt_exist'), $class);
				return FALSE;
			}
			elseif ( ! is_callable(array($class, $method)))
			{
				$this->_error_string = sprintf($this->lang->line('migration_missing_'.$method.'_method'), $class);
				return FALSE;
			}
			
			$previous = $number;

			// Run migrations that are inside the target range
			if (
				($method === 'up'   && $number > $current_version && $number <= $target_version) OR
				($method === 'down' && $number <= $current_version && $number > $target_version)
			)
			{
				log_message('debug', 'Migrating '.$method.' from version '.$current_version.' to version '.$number);
				call_user_func(array(new $class, $method));
				$current_version = $number;
				$this->_update_version($current_version);
			}
		}
		
		// This is necessary when moving down, since the the last migration applied
		// will be the down() method for the next migration up from the target
		if ($current_version <> $target_version)
		{
			$current_version = $target_version;
			$this->_update_version($current_version);
		}

		log_message('debug', 'Finished migrating to '.$current_version);

		return $current_version;
	}

	// --------------------------------------------------------------------

	/**
	 * Set's the schema to the latest migration
	 *
	 * @return	mixed	true if already latest, false if failed, int if upgraded
	 */
	public function latest()
	{
		$migrations = $this->find_migrations();
		
		if (empty($migrations))
		{
			$this->_error_string = $this->lang->line('migration_none_found');
			return FALSE;
		}

		$last_migration = basename(end($migrations));
		
		// Calculate the last migration step from existing migration
		// filenames and procceed to the standard version migration
		return $this->version($this->_get_migration_number($last_migration));
	}

	// --------------------------------------------------------------------

	/**
	 * Set's the schema to the migration version set in config
	 *
	 * @return	mixed	true if already current, false if failed, int if upgraded
	 */
	public function current()
	{
		return $this->version($this->_migration_version);
	}

	// --------------------------------------------------------------------

	/**
	 * Error string
	 *
	 * @return	string	Error message returned as a string
	 */
	public function error_string()
	{
		return $this->_error_string;
	}

	// --------------------------------------------------------------------

	/**
	 * Retrieves list of available migration scripts
	 *
	 * @return	array	list of migration file paths sorted by version
	 */
	public function find_migrations()
	{
		$migrations = array();
	
		// Load all *_*.php files in the migrations path
		foreach (glob($this->_migration_path.'*_*.php') as $file)
		{
			$name = basename($file, '.php');
		
			// Filter out non-migration files
			if (preg_match($this->_migration_regex, $name))
			{
				$number = $this->_get_migration_number($name);
				
				// There cannot be duplicate migration numbers
				if (isset($migrations[$number]))
				{
					$this->_error_string = sprintf($this->lang->line('migration_multiple_version'), $number);
					show_error($this->_error_string);
				}
				
				$migrations[$number] = $file;
			}
		}

		ksort($migrations);
		return $migrations;
	}

	// --------------------------------------------------------------------

	/**
	 * Extracts the migration number from a filename
	 *
	 * @return	int Numeric portion of a migration filename
	 */
	protected function _get_migration_number($migration)
	{
		$parts = explode('_', $migration);
		return (int) $parts[0];
	}

	// --------------------------------------------------------------------

	/**
	 * Extracts the migration class name from a filename
	 *
	 * @return	string text portion of a migration filename
	 */
	protected function _get_migration_name($migration)
	{
		$parts = explode('_', $migration);
		array_shift($parts);
		return implode('_', $parts);
	}

	// --------------------------------------------------------------------

	/**
	 * Retrieves current schema version
	 *
	 * @return	int	Current Migration
	 */
	protected function _get_version()
	{
		$row = $this->db->select('version')->get($this->_migration_table)->row();
		return $row ? $row->version : 0;
	}

	// --------------------------------------------------------------------

	/**
	 * Stores the current schema version
	 *
	 * @param	int	Migration reached
	 * @return	void	Outputs a report of the migration
	 */
	protected function _update_version($migration)
	{
		return $this->db->update($this->_migration_table, array(
			'version' => $migration
		));
	}

	// --------------------------------------------------------------------

	/**
	 * Enable the use of CI super-global
	 *
	 * @param	$var
	 * @return	mixed
	 */
	public function __get($var)
	{
		return get_instance()->$var;
	}

}

/* End of file Migration.php */
/* Location: ./system/libraries/Migration.php */