// The MIT License (MIT)
//
// Copyright (c) 2015-2017 Simon Ninon <simon.ninon@gmail.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#pragma once

#include <functional>
#include <memory>
#include <mutex>
#include <string>
#include <vector>

#include <cpp_redis/builders/reply_builder.hpp>
#include <cpp_redis/network/tcp_client_iface.hpp>

#ifndef __CPP_REDIS_READ_SIZE
#define __CPP_REDIS_READ_SIZE 4096
#endif /* __CPP_REDIS_READ_SIZE */

namespace cpp_redis {

	namespace network {

/**
 * tcp connection wrapper handling redis protocol
 *
 */
		class redis_connection {
		public:
#ifndef __CPP_REDIS_USE_CUSTOM_TCP_CLIENT

/**
 * ctor
 *
 */
				redis_connection();

#endif /* __CPP_REDIS_USE_CUSTOM_TCP_CLIENT */

/**
 * ctor allowing to specify custom tcp client (default ctor uses the default tacopie tcp client)
 *
 * @param tcp_client tcp client to be used for network communications
 *
 */
				explicit redis_connection(const std::shared_ptr<tcp_client_iface> &tcp_client);

/**
 * dtor
 *
 */
				~redis_connection();

/**
 * copy ctor
 *
 */
				redis_connection(const redis_connection &) = delete;

/**
 * assignment operator
 *
 */
				redis_connection &operator=(const redis_connection &) = delete;

		public:
/**
 * disconnection handler takes as parameter the instance of the redis_connection
 *
 */
				typedef std::function<void(redis_connection &)> disconnection_handler_t;

/**
 * reply handler takes as parameter the instance of the redis_connection and the built reply
 *
 */
				typedef std::function<void(redis_connection &, reply &)> reply_callback_t;

/**
 * connect to the given host and port, and set both disconnection and reply callbacks
 *
 * @param host host to be connected to
 * @param port port to be connected to
 * @param disconnection_handler handler to be called in case of disconnection
 * @param reply_callback handler to be called once a reply is ready
 * @param timeout_ms max time to connect (in ms)
 *
 */
				void connect(
						const std::string &host = "127.0.0.1",
						std::size_t port = 6379,
						const disconnection_handler_t &disconnection_handler = nullptr,
						const reply_callback_t &reply_callback = nullptr,
						std::uint32_t timeout_ms = 0);

/**
 * disconnect from redis server
 *
 * @param wait_for_removal when sets to true, disconnect blocks until the underlying TCP client has been effectively removed from the io_service and that all the underlying callbacks have completed.
 *
 */
				void disconnect(bool wait_for_removal = false);

/**
 * @return whether we are connected to the redis server or not
 *
 */
				bool is_connected() const;

/**
 * send the given command
 * the command is actually pipelined and only buffered, so nothing is sent to the network
 * please call commit() to flush the buffer
 *
 * @param redis_cmd command to be sent
 * @return current instance
 *
 */
				redis_connection &send(const std::vector<std::string> &redis_cmd);

/**
 * commit pipelined transaction
 * that is, send to the network all commands pipelined by calling send()
 *
 * @return current instance
 *
 */
				redis_connection &commit();

		private:
/**
 * tcp_client receive handler
 * called by the tcp_client whenever a read has completed
 *
 * @param result read result
 *
 */
				void tcp_client_receive_handler(const tcp_client_iface::read_result &result);

/**
 * tcp_client disconnection handler
 * called by the tcp_client whenever a disconnection occurred
 *
 */
				void tcp_client_disconnection_handler();

/**
 * transform a user command to a redis command using the redis protocol format
 * for example, transform {"GET", "HELLO"} to something like "*2\r\n+GET\r\n+HELLO\r\n"
 *
 */
				std::string build_command(const std::vector<std::string> &redis_cmd);

		private:
/**
 * simply call the disconnection handler (does nothing if disconnection handler is set to null)
 *
 */
				void call_disconnection_handler();

		private:
/**
 * tcp client for redis connection
 *
 */
				std::shared_ptr<cpp_redis::network::tcp_client_iface> m_client;

/**
 * reply callback called whenever a reply has been read
 *
 */
				reply_callback_t m_reply_callback;

/**
 * disconnection handler whenever a disconnection occurred
 *
 */
				disconnection_handler_t m_disconnection_handler;

/**
 * reply builder used to build replies
 *
 */
				builders::reply_builder m_builder;

/**
 * internal buffer used for pipelining (commands are buffered here and flushed to the tcp client when commit is called)
 *
 */
				std::string m_buffer;

/**
 * protect internal buffer against race conditions
 *
 */
				std::mutex m_buffer_mutex;
		};

	} // namespace network

} // namespace cpp_redis
