/**
 * Relational pipes
 * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)
 *
 * 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, version 3 of the License.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */
#include <string>
#include <cstring>
#include <unistd.h>
#include <stdexcept>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <vector>
#include <memory>
#include <regex>
#include <iostream>
#include <netdb.h>

#include "Socket.h"

namespace relpipe {
namespace out {
namespace socket {

using namespace relpipe::out::socket::options;

static const std::string findOption(SocketOptions options, std::string name, bool required = false, const std::string defaultValue = "") {
	for (auto o : options) if (o.name == name) return o.value;
	if (required) throw std::invalid_argument("Option " + name + " is required but was not found");
	else return defaultValue;
}

class FD {
private:
	int fd;
public:

	FD(int fd) : fd(fd) {
	};

	virtual ~FD() {
		close(fd);
	}

	int getFD() {
		return fd;
	}
};

static void check(int result, std::string message) {
	if (result == 0); // OK
	else throw std::logic_error("Got error result: " + std::to_string(result) + " - " + message);
}

class AddressInfos {
private:
	std::shared_ptr<addrinfo> addrInfo;

	AddressInfos(addrinfo* addrInfo) : addrInfo(std::shared_ptr<addrinfo>(addrInfo, freeaddrinfo)) {
	}

public:

	virtual ~AddressInfos() {
	}

	class AddressInfo {
	private:
		std::shared_ptr<addrinfo> parent; // to avoid premature deletion of the whole structure
	public:
		const addrinfo * const ai;

		AddressInfo(const addrinfo * const ai, std::shared_ptr<addrinfo> parent) : ai(ai), parent(parent) {
		}

		const std::string toString() const {
			char buffer[INET6_ADDRSTRLEN] = {0};
			if (ai->ai_family == AF_INET) return inet_ntop(ai->ai_family, &((sockaddr_in const *) ai->ai_addr)->sin_addr, buffer, sizeof (buffer)); // TODO: check 0 result
			else if (ai->ai_family == AF_INET6) return inet_ntop(ai->ai_family, &((sockaddr_in6 const *) ai->ai_addr)->sin6_addr, buffer, sizeof (buffer)); // TODO: check 0 result
			else return "unknown address family: " + std::to_string(ai->ai_family);
		}
	};

	static AddressInfos getAddressInfos(const std::string& host, const std::string& port, int socketType = SOCK_STREAM, int protocol = IPPROTO_TCP) {
		struct addrinfo query;
		memset(&query, sizeof (query), 0);
		query.ai_family = AF_UNSPEC;
		query.ai_socktype = socketType;
		query.ai_protocol = protocol;
		query.ai_flags = AI_ALL;

		struct addrinfo* addrInfo;
		check(getaddrinfo(host.c_str(), port.c_str(), &query, &addrInfo), "getaddrinfo");

		return AddressInfos(addrInfo);
	}

	const std::size_t size() const {
		std::size_t size = 0;
		for (addrinfo* ai = addrInfo.get(); ai; ai = ai->ai_next) size++;
		return size;
	}

	const AddressInfo operator[](std::size_t index) const {
		for (addrinfo* ai = addrInfo.get(); ai; index--) {
			if (index == 0) return AddressInfo(ai, addrInfo);
			else ai = ai->ai_next;
		}

		throw std::out_of_range("invalid index for AddressInfo: " + std::to_string(index));
	}

};

template<class SocketClass, class... MoreArgs> static std::shared_ptr<SocketClass> openClientSocket(const SocketOptions& options, int socketType, int protocol, MoreArgs... moreArgs) {
	AddressInfos remoteAddresses = AddressInfos::getAddressInfos(
			findOption(options, OPTION_HOST, true),
			findOption(options, OPTION_PORT, true),
			socketType,
			protocol);

	return std::shared_ptr<SocketClass>(new SocketClass(remoteAddresses[0], moreArgs...));
}

class UDPClientSocket : public Socket {
private:
	AddressInfos::AddressInfo remoteAddress;
	useconds_t delay = 0;
	FD socket;

public:

	UDPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress), socket(::socket(remoteAddress.ai->ai_family, remoteAddress.ai->ai_socktype, remoteAddress.ai->ai_protocol)) {
	}

	static std::shared_ptr<Socket> open(const SocketOptions& options) {
		auto socket = openClientSocket<UDPClientSocket>(options, SOCK_DGRAM, IPPROTO_UDP);
		socket->delay = std::stol(findOption(options, OPTION_DELAY, false, "0")); // TODO: Move to SocketHandler? Or delete.
		return socket;
	}

	void send(const std::string& message) override {
		auto ai = remoteAddress.ai;
		sendto(socket.getFD(), message.c_str(), message.size(), 0, ai->ai_addr, ai->ai_addrlen);
		if (delay) usleep(delay);
	}

	const std::string receive() override {
		// TODO: UDP receive()
		return "TODO: receive() a message";
	}
};

class TCPClientSocket : public Socket {
private:
	AddressInfos::AddressInfo remoteAddress;

public:

	TCPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress) {
	}

	static std::shared_ptr<Socket> open(const SocketOptions& options) {
		return openClientSocket<TCPClientSocket>(options, SOCK_STREAM, IPPROTO_TCP);
	}

	void send(const std::string& message) override {
		auto ai = remoteAddress.ai;
		FD s(::socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol));
		check(::connect(s.getFD(), ai->ai_addr, ai->ai_addrlen), "connect socket");
		ssize_t written = ::write(s.getFD(), message.c_str(), message.size());
		if (written != message.size()) throw std::logic_error("writing to the socket failed");
		// TODO: partial writes, repeat
	}

	const std::string receive() override {
		// TODO: TCP receive()
		return "TODO: receive() a message";
	}
};

class SCTPClientSocket : public Socket {
private:
	AddressInfos::AddressInfo remoteAddress;
	FD socket;

public:

	SCTPClientSocket(AddressInfos::AddressInfo remoteAddress) : remoteAddress(remoteAddress), socket(::socket(remoteAddress.ai->ai_family, remoteAddress.ai->ai_socktype, remoteAddress.ai->ai_protocol)) {
	}

	static std::shared_ptr<Socket> open(const SocketOptions& options) {
		auto socket = openClientSocket<SCTPClientSocket>(options, SOCK_STREAM, IPPROTO_SCTP);
		check(::connect(socket->socket.getFD(), socket->remoteAddress.ai->ai_addr, socket->remoteAddress.ai->ai_addrlen), "connect socket");
		return socket;
	}

	void send(const std::string& message) override {
		iovec iov[1];
		msghdr msg = {};
		msg.msg_iov = iov;
		msg.msg_iov[0].iov_base = (void*) message.c_str();
		msg.msg_iov[0].iov_len = message.size();
		msg.msg_iovlen = sizeof (iov) / sizeof (iov[0]);
		ssize_t written = ::sendmsg(socket.getFD(), &msg, 0);
		if (written != message.size()) throw std::logic_error("writing to the socket failed");
	}

	const std::string receive() override {
		// TODO: SCTP receive()
		return "TODO: receive() a message";
	}
};

template<const char* protocol, const char* role, const char* mode, typename SocketClass>
class TemplateSocketFactory : public SocketFactory {
public:

	bool canHandle(const SocketOptions& options) override {
		return findOption(options, OPTION_PROTOCOL) == protocol
				&& findOption(options, OPTION_ROLE) == role
				&& findOption(options, OPTION_MODE) == mode;
	}

	std::shared_ptr<Socket> open(const SocketOptions& options) override {
		return SocketClass::open(options);
	}
};

static std::vector<std::shared_ptr<SocketFactory>> factories
{
	std::make_shared<TemplateSocketFactory<PROTOCOL_TCP, ROLE_CLIENT, MODE_STREAM, TCPClientSocket >> (),
			std::make_shared<TemplateSocketFactory<PROTOCOL_TCP, ROLE_SERVER, MODE_STREAM, TCPClientSocket >> (), // TODO: correct class
			std::make_shared<TemplateSocketFactory<PROTOCOL_UDP, ROLE_CLIENT, MODE_DATAGRAM, UDPClientSocket >> (),
			std::make_shared<TemplateSocketFactory<PROTOCOL_UDP, ROLE_SERVER, MODE_DATAGRAM, UDPClientSocket >> (), // TODO: correct class
			std::make_shared<TemplateSocketFactory<PROTOCOL_SCTP, ROLE_CLIENT, MODE_STREAM, SCTPClientSocket >> (),
			std::make_shared<TemplateSocketFactory<PROTOCOL_SCTP, ROLE_CLIENT, MODE_DATAGRAM, SCTPClientSocket >> (),
			std::make_shared<TemplateSocketFactory<PROTOCOL_SCTP, ROLE_SERVER, MODE_STREAM, UDPClientSocket >> (), // TODO: do we need a stream-mode SCTP?
			std::make_shared<TemplateSocketFactory<PROTOCOL_SCTP, ROLE_SERVER, MODE_DATAGRAM, UDPClientSocket >> (), // TODO: correct class
			std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_CLIENT, MODE_STREAM, UDPClientSocket >> (), // TODO: correct class
			std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_CLIENT, MODE_DATAGRAM, UDPClientSocket >> (), // TODO: correct class
			std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_SERVER, MODE_STREAM, UDPClientSocket >> (), // TODO: correct class
			std::make_shared<TemplateSocketFactory<PROTOCOL_UDS, ROLE_SERVER, MODE_DATAGRAM, UDPClientSocket >> (), // TODO: correct class
};

std::shared_ptr<SocketFactory> SocketFactory::find(const SocketOptions& options) {
	for (auto f : factories) if (f->canHandle(options)) return f;
	throw std::logic_error("Unable to find a SocketFactory"); // TODO: add relevant options?
}


}
}
}