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<?php

/**

 * CodeIgniter

 *

 * An open source application development framework for PHP

 *

 * This content is released under the MIT License (MIT)

 *

 * Copyright (c) 2014 - 2019, British Columbia Institute of Technology

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 *

 * @package	CodeIgniter

 * @author	EllisLab Dev Team

 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)

 * @copyright	Copyright (c) 2014 - 2019, British Columbia Institute of Technology (https://bcit.ca/)

 * @license	https://opensource.org/licenses/MIT	MIT License

 * @link	https://codeigniter.com

 * @since	Version 3.0.0

 * @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 string

	 */

	protected $_migration_regex;

	/**

	 * Error message

	 *

	 * @var string

	 */

	protected $_error_string = '';

	/**

	 * Initialize Migration Class

	 *

	 * @param	array	$config

	 * @return	void

	 */

	public function __construct($config = array())

	{

		// Only run this constructor on main library load

		if ( ! in_array(get_class($this), array('CI_Migration', config_item('subclass_prefix').'Migration'), TRUE))

		{

			return;

		}

		foreach ($config as $key => $val)

		{

			$this->{'_'.$key} = $val;

		}

		log_message('info', '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	string	$target_version	Target schema version

	 * @return	mixed	TRUE if no migrations are found, current version string on success, FALSE on failure

	 */

	public function version($target_version)

	{

		// Note: We use strings, so that timestamp versions work on 32-bit systems

		$current_version = $this->_get_version();

		if ($this->_migration_type === 'sequential')

		{

			$target_version = sprintf('%03d', $target_version);

		}

		else

		{

			$target_version = (string) $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)

		{

			$method = 'up';

		}

		elseif ($target_version < $current_version)

		{

			$method = 'down';

			// We need this so that migrations are applied in reverse order

			krsort($migrations);

		}

		else

		{

			// Well, there's nothing to migrate then ...

			return TRUE;

		}

		// Validate all available migrations within our target range.

		//

		// Unfortunately, we'll have to use another loop to run them

		// in order to avoid leaving the procedure in a broken state.

		//

		// See https://github.com/bcit-ci/CodeIgniter/issues/4539

		$pending = array();

		foreach ($migrations as $number => $file)

		{

			// Ignore versions out of our range.

			//

			// Because we've previously sorted the $migrations array depending on the direction,

			// we can safely break the loop once we reach $target_version ...

			if ($method === 'up')

			{

				if ($number <= $current_version)

				{

					continue;

				}

				elseif ($number > $target_version)

				{

					break;

				}

			}

			else

			{

				if ($number > $current_version)

				{

					continue;

				}

				elseif ($number <= $target_version)

				{

					break;

				}

			}

			// Check for sequence gaps

			if ($this->_migration_type === 'sequential')

			{

				if (isset($previous) && abs($number - $previous) > 1)

				{

					$this->_error_string = sprintf($this->lang->line('migration_sequence_gap'), $number);

					return FALSE;

				}

				$previous = $number;

			}

			include_once($file);

			$class = 'Migration_'.ucfirst(strtolower($this->_get_migration_name(basename($file, '.php'))));

			// Validate the migration file structure

			if ( ! class_exists($class, FALSE))

			{

				$this->_error_string = sprintf($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;

			}

			$pending[$number] = array($class, $method);

		}

		// Now just run the necessary migrations

		foreach ($pending as $number => $migration)

		{

			log_message('debug', 'Migrating '.$method.' from version '.$current_version.' to version '.$number);

			$migration[0] = new $migration[0];

			call_user_func($migration);

			$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;

	}

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

	/**

	 * Sets the schema to the latest migration

	 *

	 * @return	mixed	Current version string on success, FALSE on failure

	 */

	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 proceed to the standard version migration

		return $this->version($this->_get_migration_number($last_migration));

	}

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

	/**

	 * Sets the schema to the migration version set in config

	 *

	 * @return	mixed	TRUE if no migrations are found, current version string on success, FALSE on failure

	 */

	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

	 *

	 * @param	string	$migration

	 * @return	string	Numeric portion of a migration filename

	 */

	protected function _get_migration_number($migration)

	{

		return sscanf($migration, '%[0-9]+', $number)

			? $number : '0';

	}

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

	/**

	 * Extracts the migration class name from a filename

	 *

	 * @param	string	$migration

	 * @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	string	Current migration version

	 */

	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	string	$migration	Migration reached

	 * @return	void

	 */

	protected function _update_version($migration)

	{

		$this->db->update($this->_migration_table, array(

			'version' => $migration

		));

	}

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

	/**

	 * Enable the use of CI super-global

	 *

	 * @param	string	$var

	 * @return	mixed

	 */

	public function __get($var)

	{

		return get_instance()->$var;

	}

}