<?php


/**
 * Provides a set of utility functions for managing migrations
 *
 * @author Matt Button <matthew@sigswitch.com>
 **/
class Minion_Migration_Util {

	/**
	 * Parses a set of files generated by Kohana::find_files and compiles it 
	 * down into an array of migrations
	 *
	 * @param  array Available files
	 * @return array Available Migrations
	 */
	public static function compile_migrations_from_files(array $files)
	{
		$migrations = array();

		foreach($files as $file => $path)
		{
			// If this is a directory we're dealing with
			if(is_array($path))
			{
				$migrations += Minion_Migration_Util::compile_migrations_from_files($path);
			}
			else
			{
				$migration = Minion_Migration_Util::get_migration_from_filename($file);

				$migrations[$migration['id']] = array(
					'file'     => $file, 
					'location' => $migration['location']
				);
			}
		}

		return $migrations;
	}

	/**
	 * Extracts information about a migration from its filename.
	 *
	 * Returns an array like:
	 *
	 *     array(
	 *        'location'      => 'mylocation',
	 *        'id'          => '1293214439_initial-setup',
	 *        'file'        => 'migrations/mylocation/1293214439_initial-setup.php',
	 *        'timestamp'   => '1293214439',
	 *        'description' => 'initial-setup',
	 *     );
	 *
	 * @param  string The migration's filename
	 * @return array  Array of components about the migration
	 */
	public static function get_migration_from_filename($file)
	{
		$migration = array();

		// Get rid of the file's "migrations/" prefix, the file extension and then 
		// the filename itself.  The "location" is essentially a slash delimited 
		// path from the migrations folder to the migration file
		$migration['location'] = dirname(substr($file, 11, -strlen(EXT)));
		$migration['id']     = basename($file, EXT);
		$migration['file']   = $file;

		list($migration['timestamp'], $migration['description']) 
			= explode('_', $migration['id'], 2);

		return $migration;
	}

	/**
	 * Gets a migration file from its timestamp, description and location
	 *
	 * @param  integer|array The migration's ID or an array of timestamp, description
	 * @param  string        The migration location
	 * @return string        Path to the migration file
	 */
	public static function get_filename_from_migration($migration, $location)
	{
		if(is_array($migration))
		{
			$location  = $migration['location'];
			$migration = $migration['id'];
		}

		$location = ! empty($location) ? rtrim($location, '/').'/' : '';

		return $location.$migration.EXT;
	}
}