<?php

/**

 * LICENSE

 *

 * This source file is subject to the new BSD license that is bundled

 * with this package in the file LICENSE.txt.

 * It is also available through the world-wide-web at this URL:

 * http://framework.zend.com/license/new-bsd

 * If you did not receive a copy of the license and are unable to

 * obtain it through the world-wide-web, please send an email

 * to license@zend.com so we can send you a copy immediately.

 *

 * @category   Zend

 * @package    Zend_Cloud

 * @subpackage DocumentService

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

/*

 * @see Zend_Cloud_DocumentService_Query

 */

require_once 'Zend/Cloud/DocumentService/Query.php';

/**

 * Class implementing Query adapter for working with SimpleDb queries in a 

 * structured way

 *

 * @category   Zend

 * @package    Zend_Cloud

 * @subpackage DocumentService

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_Cloud_DocumentService_Adapter_SimpleDb_Query

    extends Zend_Cloud_DocumentService_Query

{

    /**

     * @var Zend_Cloud_DocumentService_Adapter_SimpleDb

     */

    protected $_adapter;

    /**

     * Constructor

     * 

     * @param  Zend_Cloud_DocumentService_Adapter_SimpleDb $adapter 

     * @param  null|string $collectionName

     * @return void

     */

    public function __construct(Zend_Cloud_DocumentService_Adapter_SimpleDb $adapter, $collectionName = null)

    {

        $this->_adapter = $adapter;

        if (null !== $collectionName) {

            $this->from($collectionName);

        }

    }

    /**

     * Get adapter

     * 

     * @return Zend_Cloud_DocumentService_Adapter_SimpleDb

     */

    public function getAdapter()

    {

        return $this->_adapter;

    }

    /**

     * Assemble the query into a format the adapter can utilize

     * 

     * @var    string $collectionName Name of collection from which to select

     * @return string

     */

    public function assemble($collectionName = null)

    {

        $adapter = $this->getAdapter()->getClient();

        $select  = null;

        $from    = null;

        $where   = null;

        $order   = null;

        $limit   = null;

        foreach ($this->getClauses() as $clause) {

            list($name, $args) = $clause;

            switch ($name) {

                case self::QUERY_SELECT:

                    $select = $args[0];

                    break;

                case self::QUERY_FROM:

                    if (null === $from) {

                        // Only allow setting FROM clause once

                        $from = $adapter->quoteName($args);

                    }

                    break;

                case self::QUERY_WHERE:

                    $statement = $this->_parseWhere($args[0], $args[1]);

                    if (null === $where) {

                        $where = $statement;

                    } else {

                        $operator = empty($args[2]) ? 'AND' : $args[2];

                        $where .= ' ' . $operator . ' ' . $statement;

                    }

                    break;

                case self::QUERY_WHEREID:

                    $statement = $this->_parseWhere('ItemName() = ?', array($args));

                    if (null === $where) {

                        $where = $statement;

                    } else {

                        $operator = empty($args[2]) ? 'AND' : $args[2];

                        $where .= ' ' . $operator . ' ' . $statement;

                    }

                    break;

                case self::QUERY_ORDER:

                    $order = $adapter->quoteName($args[0]);

                    if (isset($args[1])) {

                        $order .= ' ' . $args[1];

                    }

                    break;

                case self::QUERY_LIMIT:

                    $limit = $args;

                    break;

                default:

                    // Ignore unknown clauses

                    break;

            }

        }

        if (empty($select)) {

            $select = "*";

        }

        if (empty($from)) {

            if (null === $collectionName) {

                require_once 'Zend/Cloud/DocumentService/Exception.php';

                throw new Zend_Cloud_DocumentService_Exception("Query requires a FROM clause");

            }

            $from = $adapter->quoteName($collectionName);

        }

        $query = "select $select from $from";

        if (!empty($where)) {

            $query .= " where $where";

        }

        if (!empty($order)) {

            $query .= " order by $order";

        }

        if (!empty($limit)) {

            $query .= " limit $limit";

        }

        return $query;

    }

    /**

     * Parse a where statement into service-specific language

     * 

     * @todo   Ensure this fulfills the entire SimpleDB query specification for WHERE

     * @param  string $where 

     * @param  array $args 

     * @return string

     */

    protected function _parseWhere($where, $args)

    {

        if (!is_array($args)) {

            $args = (array) $args;

        }

        $adapter = $this->getAdapter()->getClient();

        $i = 0;

        while (false !== ($pos = strpos($where, '?'))) {

           $where = substr_replace($where, $adapter->quote($args[$i]), $pos);

           ++$i;

        }

        if (('(' != $where[0]) || (')' != $where[strlen($where) - 1])) {

            $where = '(' . $where . ')';

        }

        return $where;

    }

 }