<?php

namespace SilverStripe\ORM\Connect;

use Config;
use Exception;
use PaginatedList;
use SilverStripe\Framework\Core\Configurable;
use SilverStripe\ORM\DataList;
use SilverStripe\ORM\ArrayList;

/**
 * MySQL connector class.
 *
 * Supported indexes for {@link requireTable()}:
 *
 * @package framework
 * @subpackage orm
 */
class MySQLDatabase extends SS_Database {

	/**
	 * Default connection charset (may be overridden in $databaseConfig)
	 *
	 * @config
	 * @var String
	 */
	private static $connection_charset = null;

	public function connect($parameters) {
		// Ensure that driver is available (required by PDO)
		if(empty($parameters['driver'])) {
			$parameters['driver'] = $this->getDatabaseServer();
		}

		// Set charset
		if( empty($parameters['charset'])
			&& ($charset = Config::inst()->get('SilverStripe\ORM\Connect\MySQLDatabase', 'connection_charset'))
		) {
			$parameters['charset'] = $charset;
		}

		// Set collation
		if( empty($parameters['collation'])
			&& ($collation = Config::inst()->get('SilverStripe\ORM\Connect\MySQLDatabase', 'connection_collation'))
		) {
			$parameters['collation'] = $collation;
		}

		// Notify connector of parameters
		$this->connector->connect($parameters);

		// This is important!
		$this->setSQLMode('ANSI');

		if (isset($parameters['timezone'])) {
			$this->selectTimezone($parameters['timezone']);
		}

		// SS_Database subclass maintains responsibility for selecting database
		// once connected in order to correctly handle schema queries about
		// existence of database, error handling at the correct level, etc
		if (!empty($parameters['database'])) {
			$this->selectDatabase($parameters['database'], false, false);
		}
	}

	/**
	 * Sets the SQL mode
	 *
	 * @param string $mode Connection mode
	 */
	public function setSQLMode($mode) {
		if (empty($mode)) return;
		$this->preparedQuery("SET sql_mode = ?", array($mode));
	}

	/**
	 * Sets the system timezone for the database connection
	 *
	 * @param string $timezone
	 */
	public function selectTimezone($timezone) {
		if (empty($timezone)) return;
		$this->preparedQuery("SET SESSION time_zone = ?", array($timezone));
	}

	public function supportsCollations() {
		return true;
	}

	public function supportsTimezoneOverride() {
		return true;
	}

	public function getDatabaseServer() {
		return "mysql";
	}

	/**
	 * The core search engine, used by this class and its subclasses to do fun stuff.
	 * Searches both SiteTree and File.
	 *
	 * @param string $keywords Keywords as a string.
	 */
	public function searchEngine($classesToSearch, $keywords, $start, $pageLength, $sortBy = "Relevance DESC",
		$extraFilter = "", $booleanSearch = false, $alternativeFileFilter = "", $invertedMatch = false
	) {
		if (!class_exists('SiteTree'))
				throw new Exception('MySQLDatabase->searchEngine() requires "SiteTree" class');
		if (!class_exists('File'))
				throw new Exception('MySQLDatabase->searchEngine() requires "File" class');

		$keywords = $this->escapeString($keywords);
		$htmlEntityKeywords = htmlentities($keywords, ENT_NOQUOTES, 'UTF-8');

		$extraFilters = array('SiteTree' => '', 'File' => '');

		if ($booleanSearch) $boolean = "IN BOOLEAN MODE";

		if ($extraFilter) {
			$extraFilters['SiteTree'] = " AND $extraFilter";

			if ($alternativeFileFilter)
					$extraFilters['File'] = " AND $alternativeFileFilter";
			else $extraFilters['File'] = $extraFilters['SiteTree'];
		}

		// Always ensure that only pages with ShowInSearch = 1 can be searched
		$extraFilters['SiteTree'] .= " AND ShowInSearch <> 0";

		// File.ShowInSearch was added later, keep the database driver backwards compatible
		// by checking for its existence first
		$fields = $this->fieldList('File');
		if (array_key_exists('ShowInSearch', $fields))
				$extraFilters['File'] .= " AND ShowInSearch <> 0";

		$limit = $start . ", " . (int) $pageLength;

		$notMatch = $invertedMatch
				? "NOT "
				: "";
		if ($keywords) {
			$match['SiteTree'] = "
				MATCH (Title, MenuTitle, Content, MetaDescription) AGAINST ('$keywords' $boolean)
				+ MATCH (Title, MenuTitle, Content, MetaDescription) AGAINST ('$htmlEntityKeywords' $boolean)
			";
			$match['File'] = "MATCH (Name, Title) AGAINST ('$keywords' $boolean) AND ClassName = 'File'";

			// We make the relevance search by converting a boolean mode search into a normal one
			$relevanceKeywords = str_replace(array('*', '+', '-'), '', $keywords);
			$htmlEntityRelevanceKeywords = str_replace(array('*', '+', '-'), '', $htmlEntityKeywords);
			$relevance['SiteTree'] = "MATCH (Title, MenuTitle, Content, MetaDescription) "
					. "AGAINST ('$relevanceKeywords') "
					. "+ MATCH (Title, MenuTitle, Content, MetaDescription) AGAINST ('$htmlEntityRelevanceKeywords')";
			$relevance['File'] = "MATCH (Name, Title) AGAINST ('$relevanceKeywords')";
		} else {
			$relevance['SiteTree'] = $relevance['File'] = 1;
			$match['SiteTree'] = $match['File'] = "1 = 1";
		}

		// Generate initial DataLists and base table names
		$lists = array();
		$baseClasses = array('SiteTree' => '', 'File' => '');
		foreach ($classesToSearch as $class) {
			$lists[$class] = DataList::create($class)->where($notMatch . $match[$class] . $extraFilters[$class], "");
			$baseClasses[$class] = '"' . $class . '"';
		}

		$charset = Config::inst()->get('SilverStripe\ORM\Connect\MySQLDatabase', 'charset');

		// Make column selection lists
		$select = array(
			'SiteTree' => array(
				"ClassName", "$baseClasses[SiteTree].\"ID\"", "ParentID",
				"Title", "MenuTitle", "URLSegment", "Content",
				"LastEdited", "Created",
				"Name" => "_{$charset}''",
				"Relevance" => $relevance['SiteTree'], "CanViewType"
			),
			'File' => array(
				"ClassName", "$baseClasses[File].\"ID\"", "ParentID",
				"Title", "MenuTitle" => "_{$charset}''", "URLSegment" => "_{$charset}''", "Content" => "_{$charset}''",
				"LastEdited", "Created",
				"Name",
				"Relevance" => $relevance['File'], "CanViewType" => "NULL"
			),
		);

		// Process and combine queries
		$querySQLs = array();
		$queryParameters = array();
		$totalCount = 0;
		foreach ($lists as $class => $list) {
			$query = $list->dataQuery()->query();

			// There's no need to do all that joining
			$query->setFrom(array(str_replace(array('"', '`'), '', $baseClasses[$class]) => $baseClasses[$class]));
			$query->setSelect($select[$class]);
			$query->setOrderBy(array());

			$querySQLs[] = $query->sql($parameters);
			$queryParameters = array_merge($queryParameters, $parameters);

			$totalCount += $query->unlimitedRowCount();
		}
		$fullQuery = implode(" UNION ", $querySQLs) . " ORDER BY $sortBy LIMIT $limit";

		// Get records
		$records = $this->preparedQuery($fullQuery, $queryParameters);

		$objects = array();

		foreach ($records as $record) {
			$objects[] = new $record['ClassName']($record);
		}

		$list = new PaginatedList(new ArrayList($objects));
		$list->setPageStart($start);
		$list->setPageLength($pageLength);
		$list->setTotalItems($totalCount);

		// The list has already been limited by the query above
		$list->setLimitItems(false);

		return $list;
	}

	public function supportsTransactions() {
		return true;
	}

	public function transactionStart($transactionMode = false, $sessionCharacteristics = false) {
		// This sets the isolation level for the NEXT transaction, not the current one.
		if ($transactionMode) {
			$this->query('SET TRANSACTION ' . $transactionMode);
		}

		$this->query('START TRANSACTION');

		if ($sessionCharacteristics) {
			$this->query('SET SESSION TRANSACTION ' . $sessionCharacteristics);
		}
	}

	public function transactionSavepoint($savepoint) {
		$this->query("SAVEPOINT $savepoint");
	}

	public function transactionRollback($savepoint = false) {
		if ($savepoint) {
			$this->query('ROLLBACK TO ' . $savepoint);
		} else {
			$this->query('ROLLBACK');
		}
	}

	public function transactionEnd($chain = false) {
		$this->query('COMMIT AND ' . ($chain ? '' : 'NO ') . 'CHAIN');
	}

	public function comparisonClause($field, $value, $exact = false, $negate = false, $caseSensitive = null,
		$parameterised = false
	) {
		if ($exact && $caseSensitive === null) {
			$comp = ($negate) ? '!=' : '=';
		} else {
			$comp = ($caseSensitive) ? 'LIKE BINARY' : 'LIKE';
			if ($negate) $comp = 'NOT ' . $comp;
		}

		if($parameterised) {
			return sprintf("%s %s ?", $field, $comp);
		} else {
			return sprintf("%s %s '%s'", $field, $comp, $value);
		}
	}

	public function formattedDatetimeClause($date, $format) {
		preg_match_all('/%(.)/', $format, $matches);
		foreach ($matches[1] as $match)
			if (array_search($match, array('Y', 'm', 'd', 'H', 'i', 's', 'U')) === false) {
				user_error('formattedDatetimeClause(): unsupported format character %' . $match, E_USER_WARNING);
			}

		if (preg_match('/^now$/i', $date)) {
			$date = "NOW()";
		} else if (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date)) {
			$date = "'$date'";
		}

		if ($format == '%U') return "UNIX_TIMESTAMP($date)";

		return "DATE_FORMAT($date, '$format')";
	}

	public function datetimeIntervalClause($date, $interval) {
		$interval = preg_replace('/(year|month|day|hour|minute|second)s/i', '$1', $interval);

		if (preg_match('/^now$/i', $date)) {
			$date = "NOW()";
		} else if (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date)) {
			$date = "'$date'";
		}

		return "$date + INTERVAL $interval";
	}

	public function datetimeDifferenceClause($date1, $date2) {
		// First date format
		if (preg_match('/^now$/i', $date1)) {
			$date1 = "NOW()";
		} else if (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date1)) {
			$date1 = "'$date1'";
		}
		// Second date format
		if (preg_match('/^now$/i', $date2)) {
			$date2 = "NOW()";
		} else if (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/i', $date2)) {
			$date2 = "'$date2'";
		}

		return "UNIX_TIMESTAMP($date1) - UNIX_TIMESTAMP($date2)";
	}

	public function supportsLocks() {
		return true;
	}

	public function canLock($name) {
		$id = $this->getLockIdentifier($name);
		return (bool) $this->query(sprintf("SELECT IS_FREE_LOCK('%s')", $id))->value();
	}

	public function getLock($name, $timeout = 5) {
		$id = $this->getLockIdentifier($name);

		// MySQL auto-releases existing locks on subsequent GET_LOCK() calls,
		// in contrast to PostgreSQL and SQL Server who stack the locks.
		return (bool) $this->query(sprintf("SELECT GET_LOCK('%s', %d)", $id, $timeout))->value();
	}

	public function releaseLock($name) {
		$id = $this->getLockIdentifier($name);
		return (bool) $this->query(sprintf("SELECT RELEASE_LOCK('%s')", $id))->value();
	}

	protected function getLockIdentifier($name) {
		// Prefix with database name
		$dbName = $this->connector->getSelectedDatabase() ;
		return $this->escapeString("{$dbName}_{$name}");
	}

	public function now() {
		// MySQL uses NOW() to return the current date/time.
		return 'NOW()';
	}

	public function random() {
		return 'RAND()';
	}
}