#include <cstdio>
#include <cstdlib>
#include <unistd.h>
#include <arpa/inet.h>
#include <signal.h>
#include <string.h>

#include "UdpVpn.hpp"
#include "UdpVpnServer.hpp"
#include "UdpVpnClient.hpp"
#include "util.hpp"

struct ProgOptions {
    bool listen;
    in6_addr bind_addr;
    in_port_t bind_port;

    bool has_peer;
    in6_addr server_addr;
    in_port_t server_port;
};

static UdpVpn* vpn_instance = nullptr;

void stop_sig_handler(int signal) {
    printf("Received signal %d. Stopping.\n", signal);
    if(vpn_instance != nullptr)
        vpn_instance->stop();
}

void dump_sig_handler(int /*signal*/) {
    vpn_instance->dump_requested();
}

bool parse_options(int argc, char** argv, ProgOptions& opts) {
    int option;
    memset(&opts, 0, sizeof(opts));

    while((option = getopt(argc, argv, ":d:l:b:s:p:")) >= 0) {
        switch(option) {
            case 'd': // debug
                debug = atoi(optarg);
                break;
            case 'l': // listen, aka "call bind()"
                opts.listen = true;
                opts.bind_port = atoi(optarg);
                break;
            case 'b': // bind to address
                inet_pton(AF_INET6, optarg, &opts.bind_addr);
                break;
            case 's': // server -- initial peer
                opts.has_peer = true;
                inet_pton(AF_INET6, optarg, &opts.server_addr);
                break;
            case 'p': // port -- initial peer address
                opts.server_port = atoi(optarg);
                break;
            case ':':
                fprintf(stderr, "Option %c requires a value.\n", optopt);
                return false;
            default:
            case '?':
                fprintf(stderr, "Unknown option %c.\n", optopt);
                return false;
        }
    }

    return true;
}

int main(int argc, char** argv) {
    debug = 0;
    ProgOptions program_options;
    parse_options(argc, argv, program_options);

    printf("==== Options ====\n");
    printf("Debug level: %d\n", debug);
    printf("Bind socket: %d\n", program_options.listen);
    if(program_options.listen) {
        char bind_addr_str[INET6_ADDRSTRLEN];
        inet_ntop(
                AF_INET6, &(program_options.bind_addr),
                bind_addr_str, INET6_ADDRSTRLEN);
        printf("\taddr: %s\n", bind_addr_str);
        printf("\tport: %d\n", program_options.bind_port);
    }
    printf("Start with peer: %d\n", program_options.has_peer);
    if(program_options.has_peer) {
        char peer_addr_str[INET6_ADDRSTRLEN];
        inet_ntop(
                AF_INET6, &(program_options.server_addr),
                peer_addr_str, INET6_ADDRSTRLEN);
        printf("\taddr: %s\n", peer_addr_str);
        printf("\tport: %d\n", program_options.server_port);
    }
    printf("=== END OPTIONS ==\n\n");

    srand(time(NULL));  // FIXME something more secure if we ever need crypto

    signal(SIGINT, stop_sig_handler);
    signal(SIGUSR1, dump_sig_handler);

    try {
        if(program_options.listen && program_options.has_peer) {
            fprintf(stderr,
                    "ERROR: Cannot be a server and a client at the same time "
                    "-- provide either -l or -s.\n");
            return 1;
        }
        if(program_options.listen) {
            vpn_instance = new UdpVpnServer(
                program_options.bind_addr, program_options.bind_port);
        } else if(program_options.has_peer) {
            if(program_options.server_port == 0) {
                fprintf(stderr,
                        "ERROR: A client instance must be given a server port "
                        "-- please provide -p.\n");
                return 1;
            }

            struct sockaddr_in6 server_addr;
            server_addr.sin6_family = AF_INET6; memcpy(&server_addr.sin6_addr, &program_options.server_addr,
                    sizeof(server_addr.sin6_addr));
            server_addr.sin6_port = htons(program_options.server_port);

            vpn_instance = new UdpVpnClient(server_addr);
        } else {
            fprintf(stderr,
                    "ERROR: Must be either a server or a client "
                    "-- provide either -l or -s.\n");
            return 1;
        }

        printf("Starting to listen...\n");
        vpn_instance->run();

        delete vpn_instance;

        printf("Shutting down.\n");
    } catch(const TunDevice::InitializationError& exn) {
        fprintf(stderr, "TUN INIT ERROR: %s\n", exn.what());
    } catch(const TunDevice::NetError& exn) {
        fprintf(stderr, "TUN NET ERROR: %s\n", exn.what());
    } catch(const UdpVpn::InitializationError& exn) {
        fprintf(stderr, "VPN INIT ERROR: %s\n", exn.what());
    } catch(const UdpVpn::NetError& exn) {
        fprintf(stderr, "VPN NET ERROR: %s\n", exn.what());
    }

    return 0;
}