<?php
/**
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @ingroup Maintenance
 */

/**
 * When using shared tables that are referenced by foreign keys on local
 * tables you have to change the constraints on local tables.
 * 
 * The shared tables have to have GRANT REFERENCE on shared tables to local schema
 * i.e.: GRANT REFERENCES (user_id) ON mwuser TO hubclient;
 */

require_once( __DIR__ . '/../Maintenance.php' );

class AlterSharedConstraints extends Maintenance {
	public function __construct() {
		parent::__construct();
		$this->mDescription = "Alter foreign key to reference master tables in shared database setup.";
	}

	public function getDbType() {
		return Maintenance::DB_ADMIN;
	}

	public function execute() {
		global $wgSharedDB, $wgSharedTables, $wgSharedPrefix, $wgDBprefix;
		
		if ( $wgSharedDB == null ) {
			$this->output( "Database sharing is not enabled\n" );
			return;
		}
		
		$dbw = wfGetDB( DB_MASTER );
		foreach ( $wgSharedTables as $table ) {
			$stable = $dbw->tableNameInternal($table);
			if ( $wgSharedPrefix != null ) {
				$ltable = preg_replace( "/^$wgSharedPrefix(.*)/i", "$wgDBprefix\\1", $stable );
			} else {
				$ltable = "{$wgDBprefix}{$stable}" ;
			}
			
			$result = $dbw->query( "SELECT uc.constraint_name, uc.table_name, ucc.column_name, uccpk.table_name pk_table_name, uccpk.column_name pk_column_name, uc.delete_rule, uc.deferrable, uc.deferred
					  FROM user_constraints uc, user_cons_columns ucc, user_cons_columns uccpk
					 WHERE uc.constraint_type = 'R'
					   AND ucc.constraint_name = uc.constraint_name
					   AND uccpk.constraint_name = uc.r_constraint_name
					   AND uccpk.table_name = '$ltable'" );
			while (($row = $result->fetchRow()) !== false) {
				
					$this->output( "Altering {$row['constraint_name']} ...");
					
					try {
						$dbw->query( "ALTER TABLE {$row['table_name']} DROP CONSTRAINT {$wgDBprefix}{$row['constraint_name']}" );
					} catch (DBQueryError $exdb) {
						if ($exdb->errno != 2443) {
							throw $exdb;
						}
					}
					
					$deleteRule = $row['delete_rule'] == 'NO ACTION' ? '' : "ON DELETE {$row['delete_rule']}";
					$dbw->query( "ALTER TABLE {$row['table_name']} ADD CONSTRAINT {$wgDBprefix}{$row['constraint_name']} 
						FOREIGN KEY ({$row['column_name']}) 
						REFERENCES {$wgSharedDB}.$stable({$row['pk_column_name']}) 
						{$deleteRule} {$row['deferrable']} INITIALLY {$row['deferred']}" );
					
					$this->output( "DONE\n" );
			}
		}
	}

}

$maintClass = "AlterSharedConstraints";
require_once( RUN_MAINTENANCE_IF_MAIN );
