<?php

namespace Gedmo\Translatable\Query\TreeWalker;

use Gedmo\Translatable\Mapping\Event\Adapter\ORM as TranslatableEventAdapter;
use Gedmo\Translatable\TranslationListener;
use Doctrine\ORM\Query;
use Doctrine\ORM\Query\SqlWalker;
use Doctrine\ORM\Query\TreeWalkerAdapter;
use Doctrine\ORM\Query\AST\SelectStatement;
use Doctrine\ORM\Query\Exec\SingleSelectExecutor;

/**
 * The translation sql output walker makes it possible
 * to translate all query components during single query.
 * It works with any select query, any hydration method.
 *
 * Behind the scenes, during the object hydration it forces
 * custom hydrator in order to interact with TranslationListener
 * and skip postLoad event which would couse automatic retranslation
 * of the fields.
 *
 * @author Gediminas Morkevicius <gediminas.morkevicius@gmail.com>
 * @package Gedmo.Translatable.Query.TreeWalker
 * @subpackage TranslationWalker
 * @link http://www.gediminasm.org
 * @license MIT License (http://www.opensource.org/licenses/mit-license.php)
 */
class TranslationWalker extends SqlWalker
{
    /**
     * Name for translation fallback hint
     */
    const HINT_TRANSLATION_FALLBACKS = 'translation_fallbacks';

    /**
     * Name for translation listener hint
     */
    const HINT_TRANSLATION_LISTENER = 'translation_listener';

    /**
     * Customized object hydrator name
     */
    const HYDRATE_OBJECT_TRANSLATION = 'object_translation_hydrator';

    /**
     * Customized object hydrator name
     */
    const HYDRATE_ARRAY_TRANSLATION = 'array_translation_hydrator';

    /**
     * Customized object hydrator name
     */
    const HYDRATE_SIMPLE_OBJECT_TRANSLATION = 'simple_object_translation_hydrator';

    /**
     * Stores all component references from select clause
     *
     * @var array
     */
    private $translatedComponents = array();

    /**
     * Current TranslationListener instance used
     * in EntityManager
     *
     * @var TranslationListener
     */
    private $listener;

    /**
     * DBAL database platform
     *
     * @var Doctrine\DBAL\Platforms\AbstractPlatform
     */
    private $platform;

    /**
     * DBAL database connection
     *
     * @var Doctrine\DBAL\Connection
     */
    private $conn;

    /**
     * List of aliases to replace with translation
     * content reference
     *
     * @var array
     */
    private $replacements = array();

    /**
     * Translation joins on current query
     * components
     *
     * @var array
     */
    private $translationJoinSql = array();

    /**
     * Processed subselect number
     *
     * @var integer
     */
    private $processedNestingLevel = 0;

    /**
     * {@inheritDoc}
     */
    public function __construct($query, $parserResult, array $queryComponents)
    {
        parent::__construct($query, $parserResult, $queryComponents);
        $this->conn = $this->getConnection();
        $this->platform = $this->getConnection()->getDatabasePlatform();
        $this->listener = $this->getTranslationListener();
        $this->extractTranslatedComponents($queryComponents);
    }

    /**
     * {@inheritDoc}
     */
    public function getExecutor($AST)
    {
        if (!$AST instanceof SelectStatement) {
            throw new \Gedmo\Exception\UnexpectedValueException('Translation walker should be used only on select statement');
        }
        $this->translationJoinSql = $this->getTranslationJoinsSql();
        return new SingleSelectExecutor($AST, $this);
    }

    /**
     * {@inheritDoc}
     */
    public function walkSelectStatement(SelectStatement $AST)
    {
        $result = parent::walkSelectStatement($AST);
        if (!count($this->translatedComponents)) {
            return $result;
        }

        $hydrationMode = $this->getQuery()->getHydrationMode();
        if ($this->needsFallback()) {
            // in case if fallback is used and hydration is array, it needs custom hydrator
            if ($hydrationMode === Query::HYDRATE_ARRAY) {
                $this->getQuery()->setHydrationMode(self::HYDRATE_ARRAY_TRANSLATION);
                $this->getEntityManager()->getConfiguration()->addCustomHydrationMode(
                    self::HYDRATE_ARRAY_TRANSLATION,
                    'Gedmo\\Translatable\\Hydrator\\ORM\\ArrayHydrator'
                );
            }
        }

        $this->getQuery()->setHint(self::HINT_TRANSLATION_LISTENER, $this->listener);
        if ($hydrationMode === Query::HYDRATE_OBJECT) {
            $this->getQuery()->setHydrationMode(self::HYDRATE_OBJECT_TRANSLATION);
            $this->getEntityManager()->getConfiguration()->addCustomHydrationMode(
                self::HYDRATE_OBJECT_TRANSLATION,
                'Gedmo\\Translatable\\Hydrator\\ORM\\ObjectHydrator'
            );
            $this->getQuery()->setHint(Query::HINT_REFRESH, true);
        } elseif ($hydrationMode === Query::HYDRATE_SIMPLEOBJECT) {
            $this->getQuery()->setHydrationMode(self::HYDRATE_SIMPLE_OBJECT_TRANSLATION);
            $this->getEntityManager()->getConfiguration()->addCustomHydrationMode(
                self::HYDRATE_SIMPLE_OBJECT_TRANSLATION,
                'Gedmo\\Translatable\\Hydrator\\ORM\\SimpleObjectHydrator'
            );
            $this->getQuery()->setHint(Query::HINT_REFRESH, true);
        }
        return $result;
    }

    /**
     * {@inheritDoc}
     */
    public function walkSelectClause($selectClause)
    {
        $result = parent::walkSelectClause($selectClause);
        $fallbackSql = '';
        if ($this->needsFallback() && count($this->translatedComponents)) {
            $fallbackAliases = array();
            foreach ($this->replacements as $dqlAlias => $trans) {
                if (preg_match("/{$dqlAlias} AS ([^\s]+)/smi", $result, $m)) {
                    list($tblAlias, $colName) = explode('.', $dqlAlias);
                    $fallback = $this->getSQLColumnAlias($colName.'_fallback');
                    $fallbackSql .= ', '.$dqlAlias.' AS '.$fallback;
                    $fallbackAliases[$fallback] = rtrim($m[1], ',');
                }
            }
            $this->getQuery()->setHint(self::HINT_TRANSLATION_FALLBACKS, $fallbackAliases);
        }
        $result = str_replace(
            array_keys($this->replacements),
            array_values($this->replacements),
            $result
        );
        $result .= $fallbackSql;
        return $result;
    }

    /**
     * {@inheritDoc}
     */
    public function walkFromClause($fromClause)
    {
        $result = parent::walkFromClause($fromClause);
        $result .= $this->translationJoinSql[0];
        return $result;
    }

    /**
     * {@inheritDoc}
     */
    public function walkWhereClause($whereClause)
    {
        $result = parent::walkWhereClause($whereClause);
        return str_replace(
            array_keys($this->replacements),
            array_values($this->replacements),
            $result
        );
    }

    /**
     * {@inheritDoc}
     */
    public function walkHavingClause($havingClause)
    {
        $result = parent::walkHavingClause($havingClause);
        return str_replace(
            array_keys($this->replacements),
            array_values($this->replacements),
            $result
        );
    }

    /**
     * {@inheritDoc}
     */
    public function walkOrderByClause($orderByClause)
    {
        $result = parent::walkOrderByClause($orderByClause);
        return str_replace(
            array_keys($this->replacements),
            array_values($this->replacements),
            $result
        );
    }

    /**
     * {@inheritDoc}
     */
    public function walkSubselect($subselect)
    {
        $this->processedNestingLevel++;
        $result = parent::walkSubselect($subselect);
        return $result;
    }

    /**
     * {@inheritDoc}
     */
    public function walkSubselectFromClause($subselectFromClause)
    {
        $result = parent::walkSubselectFromClause($subselectFromClause);
        if (isset($this->translationJoinSql[$this->processedNestingLevel])) {
            $result .= $this->translationJoinSql[$this->processedNestingLevel];
        }
        return $result;
    }

    /**
     * {@inheritDoc}
     */
    public function walkSimpleSelectClause($simpleSelectClause)
    {
        $result = parent::walkSimpleSelectClause($simpleSelectClause);
        return str_replace(
            array_keys($this->replacements),
            array_values($this->replacements),
            $result
        );
    }

    /**
     * Creates a left join list for translations
     * on used query components
     *
     * @todo: make it cleaner
     * @return string
     */
    private function getTranslationJoinsSql()
    {
        $result = array();
        $em = $this->getEntityManager();
        $ea = new TranslatableEventAdapter;
        $locale = $this->listener->getListenerLocale();

        foreach ($this->translatedComponents as $dqlAlias => $comp) {
            if (!isset($result[$comp['nestingLevel']])) {
                $result[$comp['nestingLevel']] = '';
            }
            $meta = $comp['metadata'];
            $config = $this->listener->getConfiguration($em, $meta->name);
            $transClass = $this->listener->getTranslationClass($ea, $meta->name);
            $transMeta = $em->getClassMetadata($transClass);
            $transTable = $transMeta->getQuotedTableName($this->platform);
            foreach ($config['fields'] as $field) {
                $compTableName = $meta->getQuotedTableName($this->platform);
                $compTblAlias = $this->getSQLTableAlias($compTableName, $dqlAlias);
                $tblAlias = $this->getSQLTableAlias('trans'.$compTblAlias.$field);
                $sql = ' LEFT JOIN '.$transTable.' '.$tblAlias;
                $sql .= ' ON '.$tblAlias.'.'.$transMeta->getQuotedColumnName('locale', $this->platform)
                    .' = '.$this->conn->quote($locale);
                $sql .= ' AND '.$tblAlias.'.'.$transMeta->getQuotedColumnName('objectClass', $this->platform)
                    .' = '.$this->conn->quote($meta->name);
                $sql .= ' AND '.$tblAlias.'.'.$transMeta->getQuotedColumnName('field', $this->platform)
                    .' = '.$this->conn->quote($field);
                $identifier = $meta->getSingleIdentifierFieldName();
                $colName = $meta->getQuotedColumnName($identifier, $this->platform);
                $colAlias = $this->getSQLColumnAlias($colName);
                $sql .= ' AND '.$tblAlias.'.'.$transMeta->getQuotedColumnName('foreignKey', $this->platform)
                    .' = '.$compTblAlias.'.'.$colName;
                $result[$comp['nestingLevel']] .= $sql;
                $this->replacements[$compTblAlias.'.'.$meta->getQuotedColumnName($field, $this->platform)]
                    = $tblAlias.'.'.$transMeta->getQuotedColumnName('content', $this->platform);
            }
        }
        return $result;
    }

    /**
     * Checks if translation fallbacks are needed
     *
     * @return boolean
     */
    private function needsFallback()
    {
        $q = $this->getQuery();
        return $this->listener->getTranslationFallback()
            && $q->getHydrationMode() !== Query::HYDRATE_SCALAR
            && $q->getHydrationMode() !== Query::HYDRATE_SINGLE_SCALAR;
    }

    /**
     * Search for translated components in the select clause
     *
     * @param array $queryComponents
     * @return void
     */
    private function extractTranslatedComponents(array $queryComponents)
    {
        $em = $this->getEntityManager();
        foreach ($queryComponents as $alias => $comp) {
            $meta = $comp['metadata'];
            $config = $this->listener->getConfiguration($em, $meta->name);
            if ($config && isset($config['fields'])) {
                $this->translatedComponents[$alias] = $comp;
            }
        }
    }

    /**
     * Get the currently used TranslationListener
     *
     * @throws \Gedmo\Exception\RuntimeException - if listener is not found
     * @return TranslationListener
     */
    private function getTranslationListener()
    {
        $translationListener = null;
        $em = $this->getEntityManager();
        foreach ($em->getEventManager()->getListeners() as $event => $listeners) {
            foreach ($listeners as $hash => $listener) {
                if ($listener instanceof TranslationListener) {
                    $translationListener = $listener;
                    break;
                }
            }
            if ($translationListener) {
                break;
            }
        }

        if (is_null($translationListener)) {
            throw new \Gedmo\Exception\RuntimeException('The translation listener could not be found');
        }
        return $translationListener;
    }
}