#include "UDP.h"

#include <memory>
#include <mutex>

void UDPSocketBase::create_socket() {
	while (true) {
		sockfd_ = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
#if defined(_WIN32)
		if (sockfd_ != INVALID_SOCKET_VALUE) {
			break;
		}
#else
		if (sockfd_ >= 0) {
			break;
		}
#endif
	}
}

void UDPSocketBase::create_socket(socket_t socket) {
	sockfd_ = socket;
}

void UDPSocketBase::set_nonblock(bool enable) {
	u_long ctl = enable ? 1 : 0;
#if defined(_WIN32)
	ioctlsocket(sockfd_, FIONBIO, &ctl) == 0;
#else
	ioctl(sockfd_, FIONBIO, &ctl) == 0;
#endif
	is_nonblock_ = enable;
}

void UDPSocketBase::bind_socket(const sockaddr_in &addr) const {
	if (bind(sockfd_, (struct sockaddr *) &addr, sizeof(addr)) != 0) {
		throw std::runtime_error("Bind failed");
	}
}

UDPSocketBase::~UDPSocketBase() {
	if (sockfd_ != INVALID_SOCKET_VALUE) {
#ifdef _WIN32
		closesocket(sockfd_);
#else
		close(sockfd_);
#endif
	}
}

UDPSender::UDPSender(socket_t socket, bool nonblock) {
	if (socket != INVALID_SOCKET_VALUE) {
		create_socket(socket);
	}
	else {
		create_socket();
	}
	set_nonblock(nonblock);
}

void UDPSender::set_destination(const std::string &ip, uint16_t port) {
	dstIp = ip;
	dstPort = port;
	dest_addr_.sin_family = AF_INET;
	dest_addr_.sin_port = htons(port);
#if defined(_WIN32_WINNT) && _WIN32_WINNT < 0x600
	dest_addr_.sin_addr.S_un.S_addr = inet_addr(ip.c_str());
#else
	inet_pton(AF_INET, ip.c_str(), &dest_addr_.sin_addr);
#endif
}

void UDPSender::set_source(const std::string &ip, uint16_t port) {
	sockaddr_in addr{};
	addr.sin_family = AF_INET;
	addr.sin_port = htons(port);
#if defined(_WIN32_WINNT) && _WIN32_WINNT < 0x600
	addr.sin_addr.S_un.S_addr = inet_addr(ip.c_str());
#else
	inet_pton(AF_INET, ip.c_str(), &addr.sin_addr);
#endif
	bind_socket(addr);
}

size_t UDPSender::send(const std::vector<uint8_t> &data) {
	auto sent = sendto(sockfd_,
	                   reinterpret_cast<const char *>(data.data()),
	                   static_cast<int>(data.size()),
	                   0,
	                   (struct sockaddr *) &dest_addr_,
	                   sizeof(dest_addr_));
	
	if (sent == SOCKET_ERROR) {
		throw std::runtime_error("Send failed");
	}
	return static_cast<size_t>(sent);
}

size_t UDPSender::send(const std::string &data) {
	auto sent = sendto(sockfd_,
	                   reinterpret_cast<const char *>(data.data()),
	                   static_cast<int>(data.size()),
	                   0,
	                   (struct sockaddr *) &dest_addr_,
	                   sizeof(dest_addr_));
	
	if (sent == SOCKET_ERROR) {
		throw std::runtime_error("Send failed");
	}
	return static_cast<size_t>(sent);
}

size_t UDPSender::send(uint8_t *data, size_t size) {
	int nleft, nwritten;
	const char *ptr;
	
	ptr = (char *) data;    /* can't do pointer arithmetic on void* */
	nleft = size;
	while (nleft > 0) {
#if defined(_WIN32)
		if ((nwritten = sendto(sockfd_, ptr, nleft, 0, (const struct sockaddr *) &dest_addr_, sizeof(dest_addr_))) <= 0)
#else
			if ((nwritten = sendto(sockfd_, ptr, nleft, MSG_NOSIGNAL, (const struct sockaddr *) &dest_addr_,
								   sizeof(struct sockaddr))) <= 0)
#endif
		{
			if (!(errno == EWOULDBLOCK || errno == EAGAIN || errno == EINTR))
				return -1;        /* error */
			else
				continue;
		}
		
		nleft -= nwritten;
		ptr += nwritten;
	}
	
	return (size);
}


UDPReceiver::UDPReceiver(uint16_t port, bool nonblock, size_t buffer_size)
		: buffer_(buffer_size), running_(false), srcPort(port) {
	create_socket();
	
	sockaddr_in addr{};
	addr.sin_family = AF_INET;
	addr.sin_port = htons(port);
	addr.sin_addr.s_addr = INADDR_ANY;
	
	bind_socket(addr);
	set_nonblock(nonblock);
}

void UDPReceiver::start_receiving(const UDPReceiver::ReceiveCallback &callback) {
	running_ = true;
	receiver_thread_ = std::thread([this, callback]() {
		while (running_.load(std::memory_order_relaxed)) {
			try {
				auto result = receive();
				ssize_t size = result.first;
				auto &from = result.second;
				if (size > 0) {
					std::vector<uint8_t> data(buffer_.begin(),
					                          buffer_.begin() + size);
					callback(data, from.first, from.second);
				}
			}
			catch (const std::runtime_error &e) {
				if (is_nonblock_) continue;
				throw;
			}
		}
	});
}

void UDPReceiver::stop_receiving() {
	running_.store(false);
	if (receiver_thread_.joinable()) {
		receiver_thread_.join();
	}
}

std::pair<ssize_t, std::pair<sockaddr_in, socklen_t>> UDPReceiver::receive() {
	sockaddr_in from_addr{};
	socklen_t from_len = sizeof(from_addr);
#ifdef _WIN32
	DWORD timeout = UDPTimeout * 1000; // 3秒(单位：毫秒)
	setsockopt(sockfd_, SOL_SOCKET, SO_RCVTIMEO, (const char *) &timeout, sizeof(timeout));
#else
	struct timeval tv;
	tv.tv_sec = UDPTimeout;    // 秒
	tv.tv_usec = 0;   // 微秒
	setsockopt(sockfd_, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
#endif
	auto size = recvfrom(sockfd_,
	                     reinterpret_cast<char *>(buffer_.data()),
	                     static_cast<int>(buffer_.size()),
	                     0,
	                     (struct sockaddr *) &from_addr,
	                     &from_len);
	
	if (size == SOCKET_ERROR) {
		throw std::runtime_error("Receive Timeout");
	}
	
	return {size, {from_addr, from_len}};
}