<?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
 */

require_once( dirname( __FILE__ ) . '/../../../maintenance/Maintenance.php' );

class ExportMathCache extends Maintenance {
	const DEFAULT_TABLE = 'mathoid';
	private static $allowedTables = array( 'mathoid' , 'mathlatexml');
	private static $inputColumns = array( 'mathoid' => 'math_input' , 'mathlatexml' => 'math_inputtex');

	public function __construct() {
		parent::__construct();
		$this->mDescription = 'Exports a json file that consists of the input hashes and the texvc input from the database cache.';
		$this->addArg( 'table', "The math table to be used (mathoid or latexml).", false );
		$this->addOption( 'offset', "If set the first n equations on the table are skipped", false, true, "o" );
		$this->addOption( 'length', "If set the only n equations are exported processed", false, true, "l" );
		$this->addOption( 'sort' , 'If set the result is sorted according to the input', false, false, 's' );
	}

	/**
	 * @param $table
	 * @param $offset
	 * @param $length
	 * @return bool|ResultWrapper
	 */
	private static function getMathTagsFromDatabase( $table , $offset , $length , $sort ) {
		$out = array();
		$dbr = wfGetDB( DB_SLAVE );
		$inputColumn = self::$inputColumns[ $table ];
		$options = array(
			'OFFSET'   => $offset,
			'LIMIT'    => $length );
		if ( $sort === true ) {
			$options['ORDER BY'] = $inputColumn;
		}
		$res =  $dbr->select(
			$table,
			array( 'math_inputhash', $inputColumn ),
			''
			, __METHOD__
			, $options	);
		if ( $res === false ) return false;
		// Convert result wrapper to array
		foreach ( $res as $row ){
			$out[] = array(
				// the binary encoded input-hash is no valid json output
				'inputhash' => MathRenderer::dbHash2md5($row->math_inputhash) ,
				'input'     => $row->$inputColumn );
		}
		return $out;
	}

	public function execute() {
		$table = $this->getArg( 0, self::DEFAULT_TABLE );
		if( !in_array( $table, self::$allowedTables ) ){
			echo "Error:  '$table' is not allowed.\n";
			return;
		}
		$offset = $this->getOption( 'offset', 0 );
		$length = $this->getOption( 'length', PHP_INT_MAX );
		$sort = $this->hasOption( 'sort' );
		$allEquations = self::getMathTagsFromDatabase( $table, $offset, $length, $sort );
		if ( !is_array( $allEquations ) ) {
			echo "Could not get equations from table '$table'\n";
			return;
		}
		$out = json_encode( $allEquations, JSON_PRETTY_PRINT );
		if( $out === false){
			echo "Could not encode result als json string '$table'\n";
		} else {
			echo $out;
		}
	}
}

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