<?php
/*
** Zabbix
** Copyright (C) 2001-2021 Zabbix SIA
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program 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 General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
**/


class CJsonRpc {

	const VERSION = '2.0';

	/**
	 * API client to use for making requests.
	 *
	 * @var CApiClient
	 */
	protected $apiClient;

	private $_response;
	private $_error_list;
	private $_zbx2jsonErrors;
	private $_jsonDecoded;

	/**
	 * Constructor.
	 *
	 * @param CApiClient $apiClient
	 * @param string $data
	 */
	public function __construct(CApiClient $apiClient, $data) {
		$this->apiClient = $apiClient;

		$this->initErrors();

		$this->_response = [];
		$this->_jsonDecoded = json_decode($data, true);
	}

	/**
	 * Executes API requests.
	 *
	 * @return string JSON encoded value
	 */
	public function execute() {
		if (json_last_error()) {
			$this->jsonError([], '-32700', null, null, true);
			return json_encode($this->_response[0], JSON_UNESCAPED_SLASHES);
		}

		if (!is_array($this->_jsonDecoded) || $this->_jsonDecoded === []) {
			$this->jsonError([], '-32600', null, null, true);
			return json_encode($this->_response[0], JSON_UNESCAPED_SLASHES);
		}

		foreach (zbx_toArray($this->_jsonDecoded) as $call) {
			if (!$this->validate($call)) {
				continue;
			}

			list($api, $method) = explode('.', $call['method']) + [1 => ''];
			$result = $this->apiClient->callMethod($api, $method, $call['params'], $call['auth']);

			$this->processResult($call, $result);
		}

		if ($this->_response === array_fill(0, count($this->_response), null)) {
			return '';
		}

		if (is_array($this->_jsonDecoded)
				&& array_keys($this->_jsonDecoded) === range(0, count($this->_jsonDecoded) - 1)) {
			// Return response as encoded batch if $this->_jsonDecoded is associative array.
			return json_encode(array_values(array_filter($this->_response)), JSON_UNESCAPED_SLASHES);
		}

		return ($this->_response[0] !== null) ? json_encode($this->_response[0], JSON_UNESCAPED_SLASHES) : '';
	}

	public function validate(&$call) {
		if (is_array($call)) {
			$call = array_intersect_key($call, array_flip(['jsonrpc', 'method', 'params', 'auth', 'id']));
		}

		$api_input_rules = ['type' => API_OBJECT, 'fields' => [
			'jsonrpc' =>	['type' => API_STRING_UTF8, 'flags' => API_REQUIRED, 'in' => self::VERSION],
			'method' =>		['type' => API_STRING_UTF8, 'flags' => API_REQUIRED],
			'params' =>		['type' => API_JSONRPC_PARAMS, 'flags' => API_REQUIRED],
			'auth' =>		['type' => API_STRING_UTF8, 'flags' => API_NOT_EMPTY | API_ALLOW_NULL, 'default' => null],
			'id' =>			['type' => API_JSONRPC_ID]
		]];

		if (!CApiInputValidator::validate($api_input_rules, $call, '/', $error)) {
			$call_id = is_array($call) ? array_intersect_key($call, array_flip(['id'])) : [];
			$api_input_rules = ['type' => API_OBJECT, 'fields' => [
				'id' =>	['type' => API_JSONRPC_ID]
			]];

			if (!CApiInputValidator::validate($api_input_rules, $call_id, '', $err)) {
				$call_id = [];
			}

			$this->jsonError($call_id, '-32600', $error, null, true);

			return false;
		}

		return true;
	}

	public function processResult(array $call, CApiClientResponse $response) {
		if ($response->errorCode) {
			$errno = $this->_zbx2jsonErrors[$response->errorCode];

			$this->jsonError($call, $errno, $response->errorMessage, $response->debug);
		}
		else {
			// Notifications (request object without an "id" member) MUST NOT be answered.
			$this->_response[] = array_key_exists('id', $call)
				? [
					'jsonrpc' => self::VERSION,
					'result' => $response->data,
					'id' => $call['id']
				]
				: null;
		}
	}

	private function jsonError(array $call, $errno, $data = null, $debug = null, $force_err = false) {
		// Notifications MUST NOT be answered, but error MUST be generated on JSON parse error
		if (!$force_err && !array_key_exists('id', $call)) {
			$this->_response[] = null;
			return;
		}

		if (!array_key_exists($errno, $this->_error_list)) {
			$data = _s('JSON-RPC error generation failed. No such error "%1$s".', $errno);
			$errno = '-32400';
		}

		$error = $this->_error_list[$errno];

		if ($data !== null) {
			$error['data'] = $data;
		}

		if ($debug !== null) {
			$error['debug'] = $debug;
		}

		$this->_response[] = [
			'jsonrpc' => self::VERSION,
			'error' => $error,
			'id' => array_key_exists('id', $call) ? $call['id'] : null
		];
	}

	private function initErrors() {
		$this->_error_list = [
			'-32700' => [
				'code' => -32700,
				'message' => _('Parse error'),
				'data' => _('Invalid JSON. An error occurred on the server while parsing the JSON text.')
			],
			'-32600' => [
				'code' => -32600,
				'message' => _('Invalid Request.'),
				'data' => _('The received JSON is not a valid JSON-RPC Request.')
			],
			'-32601' => [
				'code' => -32601,
				'message' => _('Method not found.'),
				'data' => _('The requested remote-procedure does not exist / is not available')
			],
			'-32602' => [
				'code' => -32602,
				'message' => _('Invalid params.'),
				'data' => _('Invalid method parameters.')
			],
			'-32603' => [
				'code' => -32603,
				'message' => _('Internal error.'),
				'data' => _('Internal JSON-RPC error.')
			],
			'-32500' => [
				'code' => -32500,
				'message' => _('Application error.'),
				'data' => _('No details')
			],
			'-32400' => [
				'code' => -32400,
				'message' => _('System error.'),
				'data' => _('No details')
			],
			'-32300' => [
				'code' => -32300,
				'message' => _('Transport error.'),
				'data' => _('No details')
			]
		];

		$this->_zbx2jsonErrors = [
			ZBX_API_ERROR_NO_METHOD => '-32601',
			ZBX_API_ERROR_PARAMETERS => '-32602',
			ZBX_API_ERROR_NO_AUTH => '-32602',
			ZBX_API_ERROR_PERMISSIONS => '-32500',
			ZBX_API_ERROR_INTERNAL => '-32500'
		];
	}
}
