extern "C" {
#include <arpa/inet.h>
}

#include <expected>
#include <string>
#include <thread>
#include <chrono>
#include <cstring>

#include <tservice.hpp>
#include <uxlogger.hpp>
#include <networkaux.hpp>

using namespace std::chrono_literals;

TunService::TunService(int svcport, std::string itunnelnet, std::vector<std::string> ilocalnets) {
        listenport = svcport;
        tunnelnet = itunnelnet;
        localnets = ilocalnets;
}

TunService::~TunService() {
        close(listenport);
}

std::expected<void, std::string> TunService::Bind(void) {
        struct sockaddr_in address;
        int srvsock;
        if ((srvsock = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
                int errnocopy = errno;
                std::string error = std::strerror(errnocopy);
                return std::unexpected("Create socker error: " + error);
        }
        int opt = 1;
        if (setsockopt(srvsock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
                int errnocopy = errno;
                std::string error = std::strerror(errnocopy);
                return std::unexpected("Set socket option error: " + error);
        }
        address.sin_family = AF_INET;
        address.sin_addr.s_addr = INADDR_ANY;
        address.sin_port = htons(listenport);
        if (bind(srvsock, (struct sockaddr *)&address, sizeof(address)) < 0) {
                int errnocopy = errno;
                std::string error = std::strerror(errnocopy);
                return std::unexpected("Bind error: " + error);
        }
        if (listen(srvsock, 3) < 0) {
                int errnocopy = errno;
                std::string error = std::strerror(errnocopy);
                return std::unexpected("Listen error: " + error);
        }
        sock = srvsock;
        return {};
}

std::expected<void, std::string> TunService::Listen(void) {
        struct sockaddr_in address;
        int addrlen = sizeof(address);
        int newsock = 0;
        for (;;) {
                if ((newsock = accept(sock, (struct sockaddr *)&address, (socklen_t *)&addrlen)) < 0) {
                        int errnocopy = errno;
                        std::string error = std::strerror(errnocopy);
                        return std::unexpected("Accept error: " + error);
                }

                std::jthread t(&TunService::Handle, this, newsock);
                t.detach();
        }
        return {};
}


void TunService::Handle(int sock) {
        auto prefixRes = netprefix(tunnelnet);
        if (!prefixRes) {
                uxlogger.Error(prefixRes.error());
                return;
        }
        auto networkRes = network(tunnelnet);
        if (!networkRes) {
                uxlogger.Error(networkRes.error());
                return;
        }
        int num = (sock - 2) * 2;
        auto localaddrRes = nethost(networkRes.value(), prefixRes.value(), num);
        if (!networkRes) {
                uxlogger.Error(networkRes.error());
                return;
        }
        auto remoteaddrRes = nethost(networkRes.value(), prefixRes.value(), num + 1);
        if (!remoteaddrRes) {
                uxlogger.Error(remoteaddrRes.error());
                return;
        }
        uxlogger.Debug("Start socker handler");
        SocketHandler handler;
        std::string laddr = localaddrRes.value();
        std::string raddr = remoteaddrRes.value();
        auto prefix = prefixRes.value();
        handler.Handle(sock, laddr, raddr, prefix);
        uxlogger.Debug("Stop socker handler");
        close(sock);
}