<?php
  
  /**
   * ownCloud - App Framework
   *
   * @author Bernhard Posselt
   * @author Morris Jobke
   * @copyright 2012 Bernhard Posselt dev@bernhard-posselt.com
   * @copyright 2013 Morris Jobke morris.jobke@gmail.com
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
   * License as published by the Free Software Foundation; either
   * version 3 of the License, or any later version.
   *
   * This library 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 AFFERO GENERAL PUBLIC LICENSE for more details.
   *
   * You should have received a copy of the GNU Affero General Public
   * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
   *
   */
  
  
  namespace OCP\AppFramework\Db;
  
  use \OCP\IDb;
  
  
  /**
   * Simple parent class for inheriting your data access layer from. This class
   * may be subject to change in the future
   */
  abstract class Mapper {
  
  	protected $tableName;
  	protected $entityClass;
  	protected $db;
  
  	/**
  	 * @param IDb $db Instance of the Db abstraction layer
  	 * @param string $tableName the name of the table. set this to allow entity 
  	 * @param string $entityClass the name of the entity that the sql should be
  	 * mapped to queries without using sql
  	 */
  	public function __construct(IDb $db, $tableName, $entityClass=null){
  		$this->db = $db;
  		$this->tableName = '*PREFIX*' . $tableName;
  
  		// if not given set the entity name to the class without the mapper part
  		// cache it here for later use since reflection is slow
  		if($entityClass === null) {
  			$this->entityClass = str_replace('Mapper', '', get_class($this));
  		} else {
  			$this->entityClass = $entityClass;
  		}
  	}
  
  
  	/**
  	 * @return string the table name
  	 */
  	public function getTableName(){
  		return $this->tableName;
  	}
  
  
  	/**
  	 * Deletes an entity from the table
  	 * @param Entity $entity the entity that should be deleted
  	 */
  	public function delete(Entity $entity){
  		$sql = 'DELETE FROM `' . $this->tableName . '` WHERE `id` = ?';
  		$this->execute($sql, array($entity->getId()));
  	}
  
  
  	/**
  	 * Creates a new entry in the db from an entity
  	 * @param Entity $entity the entity that should be created
  	 * @return Entity the saved entity with the set id
  	 */
  	public function insert(Entity $entity){
  		// get updated fields to save, fields have to be set using a setter to
  		// be saved
  		$properties = $entity->getUpdatedFields();
  		$values = '';
  		$columns = '';
  		$params = array();
  
  		// build the fields
  		$i = 0;
  		foreach($properties as $property => $updated) {
  			$column = $entity->propertyToColumn($property);
  			$getter = 'get' . ucfirst($property);
  			
  			$columns .= '`' . $column . '`';
  			$values .= '?';
  
  			// only append colon if there are more entries
  			if($i < count($properties)-1){
  				$columns .= ',';
  				$values .= ',';
  			}
  
  			array_push($params, $entity->$getter());
  			$i++;
  
  		}
  
  		$sql = 'INSERT INTO `' . $this->tableName . '`(' .
  				$columns . ') VALUES(' . $values . ')';
  		
  		$this->execute($sql, $params);
  
  		$entity->setId((int) $this->db->getInsertId($this->tableName));
  		return $entity;
  	}
  
  
  
  	/**
  	 * Updates an entry in the db from an entity
  	 * @throws \InvalidArgumentException if entity has no id
  	 * @param Entity $entity the entity that should be created
  	 */
  	public function update(Entity $entity){
  		// if entity wasn't changed it makes no sense to run a db query
  		$properties = $entity->getUpdatedFields();
  		if(count($properties) === 0) {
  			return $entity;
  		}
  
  		// entity needs an id
  		$id = $entity->getId();
  		if($id === null){
  			throw new \InvalidArgumentException(
  				'Entity which should be updated has no id');
  		}
  
  		// get updated fields to save, fields have to be set using a setter to
  		// be saved
  		// dont update the id field
  		unset($properties['id']);
  
  		$columns = '';
  		$params = array();
  
  		// build the fields
  		$i = 0;
  		foreach($properties as $property => $updated) {
  
  			$column = $entity->propertyToColumn($property);
  			$getter = 'get' . ucfirst($property);
  			
  			$columns .= '`' . $column . '` = ?';
  
  			// only append colon if there are more entries
  			if($i < count($properties)-1){
  				$columns .= ',';
  			}
  
  			array_push($params, $entity->$getter());
  			$i++;
  		}
  
  		$sql = 'UPDATE `' . $this->tableName . '` SET ' . 
  				$columns . ' WHERE `id` = ?';
  		array_push($params, $id);
  
  		$this->execute($sql, $params);
  	}
  
  
  	/**
  	 * Runs an sql query
  	 * @param string $sql the prepare string
  	 * @param array $params the params which should replace the ? in the sql query
  	 * @param int $limit the maximum number of rows
  	 * @param int $offset from which row we want to start
  	 * @return \PDOStatement the database query result
  	 */
  	protected function execute($sql, array $params=array(), $limit=null, $offset=null){
  		$query = $this->db->prepareQuery($sql, $limit, $offset);
  
  		$index = 1;  // bindParam is 1 indexed
  		foreach($params as $param) {
  
  			switch (gettype($param)) {
  				case 'integer':
  					$pdoConstant = \PDO::PARAM_INT;
  					break;
  
  				case 'boolean':
  					$pdoConstant = \PDO::PARAM_BOOL;
  					break;
  				
  				default:
  					$pdoConstant = \PDO::PARAM_STR;
  					break;
  			}
  			
  			$query->bindValue($index, $param, $pdoConstant);
  
  			$index++;
  		}
  
  		return $query->execute();
  	}
  
  
  	/**
  	 * Returns an db result and throws exceptions when there are more or less
  	 * results
  	 * @see findEntity
  	 * @param string $sql the sql query
  	 * @param array $params the parameters of the sql query
  	 * @param int $limit the maximum number of rows
  	 * @param int $offset from which row we want to start
  	 * @throws DoesNotExistException if the item does not exist
  	 * @throws MultipleObjectsReturnedException if more than one item exist
  	 * @return array the result as row
  	 */
  	protected function findOneQuery($sql, array $params=array(), $limit=null, $offset=null){
  		$result = $this->execute($sql, $params, $limit, $offset);
  		$row = $result->fetch();
  
  		if($row === false || $row === null){
  			throw new DoesNotExistException('No matching entry found');
  		}
  		$row2 = $result->fetch();
  		//MDB2 returns null, PDO and doctrine false when no row is available
  		if( ! ($row2 === false || $row2 === null )) {
  			throw new MultipleObjectsReturnedException('More than one result');
  		} else {
  			return $row;
  		}
  	}
  
  
  	/**
  	 * Creates an entity from a row. Automatically determines the entity class
  	 * from the current mapper name (MyEntityMapper -> MyEntity)
  	 * @param array $row the row which should be converted to an entity
  	 * @return Entity the entity
  	 */
  	protected function mapRowToEntity($row) {
  		return call_user_func($this->entityClass .'::fromRow', $row);
  	}
  
  
  	/**
  	 * Runs a sql query and returns an array of entities
  	 * @param string $sql the prepare string
  	 * @param array $params the params which should replace the ? in the sql query
  	 * @param int $limit the maximum number of rows
  	 * @param int $offset from which row we want to start
  	 * @return array all fetched entities
  	 */
  	protected function findEntities($sql, array $params=array(), $limit=null, $offset=null) {
  		$result = $this->execute($sql, $params, $limit, $offset);
  
  		$entities = array();
  		
  		while($row = $result->fetch()){
  			$entities[] = $this->mapRowToEntity($row);
  		}
  
  		return $entities;
  	}
  
  
  	/**
  	 * Returns an db result and throws exceptions when there are more or less
  	 * results
  	 * @param string $sql the sql query
  	 * @param array $params the parameters of the sql query
  	 * @param int $limit the maximum number of rows
  	 * @param int $offset from which row we want to start
  	 * @throws DoesNotExistException if the item does not exist
  	 * @throws MultipleObjectsReturnedException if more than one item exist
  	 * @return Entity the entity
  	 */
  	protected function findEntity($sql, array $params=array(), $limit=null, $offset=null){
  		return $this->mapRowToEntity($this->findOneQuery($sql, $params, $limit, $offset));
  	}
  
  
  }