/*
	Copyright 2022 flyinghead

	This file is part of Flycast.

    Flycast 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.

    Flycast 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 Flycast.  If not, see <https://www.gnu.org/licenses/>.
 */
#include "hw/sh4/modules/modules.h"
#include "net_platform.h"
#include "cfg/option.h"
#include "miniupnp.h"
#include "hw/sh4/sh4_sched.h"
#include <deque>

struct MaxSpeedNetPipe : public SerialPipe
{
	class Exception : public FlycastException
	{
	public:
		Exception(const std::string& reason) : FlycastException(reason) {}
	};

	// Serial TX
	void write(u8 data) override
	{
		txBuffer.push_back(data);
		parseMaxspeedPacket(data);
		if (txPacketSize != 0 && txBuffer.size() == txPacketSize)
		{
			sendto(sock, (const char *)&txBuffer[0], txPacketSize, 0, (const sockaddr *)&peerAddress, sizeof(peerAddress));
			txBuffer.clear();
		}
	}

	// RX buffer Size
	int available() override {
		poll();
		return rxBuffer.size();
	}

	// Serial RX
	u8 read() override
	{
		poll();
		if (rxBuffer.empty()) {
			WARN_LOG(NETWORK, "NetPipe: empty read");
			return 0;
		}
		u8 b = rxBuffer.front();
		rxBuffer.pop_front();

		return b;
	}

	~MaxSpeedNetPipe() {
		shutdown();
	}

	bool init()
	{
		if (!config::NetworkEnable)
			return false;
#ifdef _WIN32
		WSADATA wsaData;
		if (WSAStartup(MAKEWORD(2, 0), &wsaData) != 0)
		{
			ERROR_LOG(NETWORK, "WSAStartup failed. errno=%d", get_last_error());
			throw Exception("WSAStartup failed");
		}
#endif
		if (config::EnableUPnP)
		{
			miniupnp.Init();
			miniupnp.AddPortMapping(config::LocalPort, true);
		}

		createSocket();

		return true;
	}

	void shutdown()
	{
		enableNetworkBroadcast(false);
		if (VALID(sock))
			closesocket(sock);
		sock = INVALID_SOCKET;
	}

private:
	void parseMaxspeedPacket(u8 b)
	{
		switch (txPacketState)
		{
		case 0:
			if (b == 0x4d)
				txPacketState = 1;
			else
				txPacketSize = 1;
			break;
		case 1:
			if (b == 0x41)
				txPacketState = 2;
			else {
				txPacketState = 0;
				txPacketSize = 2;
			}
			break;
		case 2:
			if (b == 0x58)
				txPacketState = 3;
			else {
				txPacketState = 0;
				txPacketSize = 3;
			}
			break;
		case 3:
			txPacketSize = b;
			if (txPacketSize < 3)
			{
				// invalid size
				txPacketState = 0;
				txPacketSize = 4;
			}
			else
			{
				txPacketState = 4;
				txPacketSize += 4;
			}
			break;
		case 4:	// payload then crc (lsb), crc (msb), 1
			if (txPacketSize == txBuffer.size())
				txPacketState = 0;
			break;
		}
	}

	void poll()
	{
		if (lastPoll == sh4_sched_now64())
			return;
		lastPoll = sh4_sched_now64();
		u8 data[0x100];
		sockaddr_in addr;
		while (true)
		{
			socklen_t len = sizeof(addr);
			int rc = recvfrom(sock, (char *)data, sizeof(data), 0, (sockaddr *)&addr, &len);
			if (rc == -1)
			{
				int error = get_last_error();
				if (error == L_EWOULDBLOCK || error == L_EAGAIN)
					break;
#ifdef _WIN32
				if (error == WSAECONNRESET)
					// Happens if the previous send resulted in an ICMP Port Unreachable message
					break;
#endif
				throw Exception("Receive error: errno " + std::to_string(error));
			}
			rxBuffer.insert(rxBuffer.end(), &data[0], &data[rc]);

			if (peerAddress.sin_addr.s_addr == INADDR_BROADCAST
					&& (addr.sin_port != htons(config::LocalPort) || !is_local_address(addr.sin_addr.s_addr)))
			{
				peerAddress.sin_addr.s_addr = addr.sin_addr.s_addr;
				peerAddress.sin_port = addr.sin_port;
				enableNetworkBroadcast(false);
			}
		}
	}

	void createSocket()
	{
		sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
		if (sock == INVALID_SOCKET)
		{
			ERROR_LOG(NETWORK, "Socket creation failed: errno %d", get_last_error());
			throw Exception("Socket creation failed");
		}
		int option = 1;
		setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const char *)&option, sizeof(option));

		sockaddr_in serveraddr{};
		serveraddr.sin_family = AF_INET;
		serveraddr.sin_port = htons(config::LocalPort);

		if (::bind(sock, (sockaddr *)&serveraddr, sizeof(serveraddr)) < 0)
		{
			ERROR_LOG(NETWORK, "NaomiServer: bind() failed. errno=%d", get_last_error());
			closesocket(sock);

			throw Exception("Socket bind failed");
		}
		set_non_blocking(sock);

	    // Allow broadcast packets to be sent
	    int broadcast = 1;
	    if (setsockopt(sock, SOL_SOCKET, SO_BROADCAST, (const char *)&broadcast, sizeof(broadcast)) == -1)
	        WARN_LOG(NETWORK, "setsockopt(SO_BROADCAST) failed. errno=%d", get_last_error());

	    peerAddress.sin_family = AF_INET;
	    peerAddress.sin_addr.s_addr = INADDR_BROADCAST;
	    peerAddress.sin_port = htons(config::LocalPort);
		if (!config::NetworkServer.get().empty())
		{
			auto pos = config::NetworkServer.get().find_last_of(':');
			std::string server;
			if (pos != std::string::npos)
			{
				peerAddress.sin_port = htons(atoi(config::NetworkServer.get().substr(pos + 1).c_str()));
				server = config::NetworkServer.get().substr(0, pos);
			}
			else
				server = config::NetworkServer;
			addrinfo *resultAddr;
			if (getaddrinfo(server.c_str(), 0, nullptr, &resultAddr))
				WARN_LOG(NETWORK, "Server %s is unknown", server.c_str());
			else
			{
				for (addrinfo *ptr = resultAddr; ptr != nullptr; ptr = ptr->ai_next)
					if (ptr->ai_family == AF_INET)
					{
						peerAddress.sin_addr.s_addr = ((sockaddr_in *)ptr->ai_addr)->sin_addr.s_addr;
						break;
					}
				freeaddrinfo(resultAddr);
			}
		}
		else
			enableNetworkBroadcast(true);

		serial_setPipe(this);
	}

	sock_t sock = INVALID_SOCKET;
	MiniUPnP miniupnp;
	std::deque<u8> rxBuffer;
	std::vector<u8> txBuffer;
	u32 txPacketSize = 0;
	int txPacketState = 0;
	sockaddr_in peerAddress{};
	u64 lastPoll = 0;
};