#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/time.h>

#include "common.h"

#define LOCAL_PORT 9000
#define PEER_PORT  9001
#define TIMEOUT_MS 500

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <Windows IPv6>\n", argv[0]);
        return 1;
    }

    int sock = socket(AF_INET6, SOCK_DGRAM, 0);
    if (sock < 0) {
        perror("socket");
        return 1;
    }

    struct sockaddr_in6 local = {0};
    local.sin6_family = AF_INET6;
    local.sin6_port = htons(LOCAL_PORT);
    local.sin6_addr = in6addr_any;

    bind(sock, (struct sockaddr*)&local, sizeof(local));

    struct sockaddr_in6 peer = {0};
    peer.sin6_family = AF_INET6;
    peer.sin6_port = htons(PEER_PORT);
    inet_pton(AF_INET6, argv[1], &peer.sin6_addr);

    struct timeval tv;
    tv.tv_sec = 0;
    tv.tv_usec = TIMEOUT_MS * 1000;
    setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));

    uint8_t seq = 0;
    char input[DATA_LEN];

    while (1) {
        printf("You: ");
        fflush(stdout);
        fgets(input, sizeof(input), stdin);

        packet_t pkt = {0};
        pkt.type = TYPE_DATA;
        pkt.seq = seq;
        pkt.length = strlen(input);
        memcpy(pkt.data, input, pkt.length);

        while (1) {
            sendto(sock, &pkt, sizeof(pkt), 0,
                   (struct sockaddr*)&peer, sizeof(peer));

            packet_t ack;
            struct sockaddr_in6 from;
            socklen_t fromlen = sizeof(from);

            int n = recvfrom(sock, &ack, sizeof(ack), 0,
                             (struct sockaddr*)&from, &fromlen);

            if (n > 0 && ack.type == TYPE_ACK && ack.seq == seq) {
                break;
            }

            usleep(TIMEOUT_MS * 1000);
        }

        seq ^= 1;
    }

    close(sock);
    return 0;
}