<?php
/**
 * @author Robin J. Rogge <rrogge@bigpoint.net>
 * @link http://www.pradosoft.com/
 * @copyright 2010 Bigpoint GmbH
 * @license http://www.pradosoft.com/license/
 * @since 3.2
 * @package Prado\Web\Services
 */

namespace Prado\Web\Services;
use Prado\Exceptions\THttpException;

/**
 * TJsonRpcProtocol class
 *
 * TJsonRpcProtocol is a class that implements JSON-Rpc protocol in {@link TRpcService}.
 * Both version 1.0 and 2.0 of the specification are implemented, and the server will try
 * to answer using the same version of the protocol used by the requesting client.
 *
 * @author Robin J. Rogge <rrogge@bigpoint.net>
 * @author Fabio Bas <ctrlaltca@gmail.com>
 * @package Prado\Web\Services
 * @since 3.2
 */
class TJsonRpcProtocol extends TRpcProtocol
{
	protected $_id=null;
	protected $_specificationVersion=1.0;

	/**
	 * Handles the RPC request
	 * @param string $requestPayload
	 * @return string JSON RPC response
	 */
	public function callMethod($requestPayload)
	{
		try
		{
			$_request = $this->decode($requestPayload);

			if(isset($_request['jsonrpc']))
			{
				$this->_specificationVersion=$_request['jsonrpc'];
				if($this->_specificationVersion > 2.0)
					throw new TRpcException('Unsupported specification version', '-32600');
			}

			if(isset($_request['id']))
				$this->_id=$_request['id'];

			if(!isset($_request['method']))
					throw new TRpcException('Missing request method', '-32600');

			if(!isset($_request['params']))
				$parameters = array();
			else
				$parameters = $_request['params'];

			if(!is_array($parameters))
				$parameters = array($parameters);

			// a request without an id is a notification that doesn't need a response
			if($this->_id !== null)
			{
				if($this->_specificationVersion==2.0)
				{
					return $this->encode(array(
						'jsonrpc' => '2.0',
						'id' => $this->_id,
						'result' => $this->callApiMethod($_request['method'], $parameters),
					));
				} else {
					return $this->encode(array(
						'id' => $this->_id,
						'result' => $this->callApiMethod($_request['method'], $_request['params']),
						'error' => null
					));
				}
			}
		}
		catch(TRpcException $e)
		{
			return $this->createErrorResponse($e);
		}
		catch(THttpException $e)
		{
			throw $e;
		}
		catch(\Exception $e)
		{
			return $this->createErrorResponse(new TRpcException('An internal error occured', '-32603'));
		}
	}

	/**
	 * Turns the given exception into an JSON RPC fault
	 * @param TRpcException $exception
	 * @return string JSON RPC fault
	 */
	public function createErrorResponse(TRpcException $exception)
	{
		if($this->_specificationVersion==2.0)
		{
			return $this->encode(array(
				'id' => $this->_id,
				'result' => null,
				'error'=> array(
					'code' => $exception->getCode(),
					'message'=> $exception->getMessage(),
					'data' => null,
					)
			));
		} else {
			return $this->encode(array(
				'id' => $this->_id,
				'error'=> array(
					'code' => $exception->getCode(),
					'message'=> $exception->getMessage(),
					'data' => null,
					)
			));			
		}
	}

	/**
	 * Sets the correct response headers
	 * @param THttpResponse $response
	 */
	public function createResponseHeaders($response)
	{
		$response->setContentType('application/json');
		$response->setCharset('UTF-8');
	}

	/**
	 * Decodes JSON encoded data into PHP data
	 * @param string $data in JSON format
	 * @return array PHP data
	 */
	public function decode($data)
	{
		$s = json_decode($data, true);
		self::checkJsonError();
		return $s;
	}

	/**
	 * Encodes PHP data into JSON data
	 * @param mixed PHP data
	 * @return string JSON encoded PHP data
	 */
	public function encode($data)
	{
		$s = json_encode($data);
		self::checkJsonError();
		return $s;		
	}

	private static function checkJsonError()
	{
		$errnum = json_last_error();
		if($errnum != JSON_ERROR_NONE)
			throw new \Exception("JSON error: $msg", $err);
	}

	/**
	 * Calls the callback handler for the given method
	 * Overrides parent implementation to correctly handle error codes
	 * @param string $methodName of the RPC
	 * @param array $parameters for the callback handler as provided by the client
	 * @return mixed whatever the callback handler returns
	 */
	public function callApiMethod($methodName, $parameters)
	{
		if(!isset($this->rpcMethods[$methodName]))
			throw new TRpcException('Method "'.$methodName.'" not found', '-32601');

		return call_user_func_array($this->rpcMethods[$methodName]['method'], $parameters);
	}
}