// Server for chatty
#include "common.h"
#include <arpa/inet.h>
#include <errno.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

#define MAX_CONNECTIONS 5
#define FD_MAX MAX_CONNECTIONS + 1

static const char *filename = "history.dat";

enum { FD_SERVER = 0 };
u32 serverfd;

void err_exit(const char *msg)
{
    if (serverfd)
        if (close(serverfd))
            writef("Error while closing server socket. errno: %d\n", errno);
    fprintf(stderr, "%s errno: %d\n", msg, errno);
    _exit(1);
}

int main(void)
{
    u32 clientfd;
    u16 nclient             = 0;
    u8 on                  = 1;
    struct message msg_recv = {0};

    serverfd = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
    if (setsockopt(serverfd, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on)))
        err_exit("Error while setting socket option.");

    const struct sockaddr_in address = {
        AF_INET,
        htons(PORT),
        {0},
    };

    if (bind(serverfd, (struct sockaddr *)&address, sizeof(address)))
        err_exit("Error while binding.");

    if (listen(serverfd, BUF_MAX))
        err_exit("Error while listening");

    writef("Listening on localhost:%d\n", PORT);

    struct pollfd fds[MAX_CONNECTIONS + 1] = {
        {serverfd, POLLIN, 0}, // FD_SERVER
        {      -1, POLLIN, 0},
        {      -1, POLLIN, 0},
        {      -1, POLLIN, 0},
        {      -1, POLLIN, 0},
        {      -1, POLLIN, 0},
    };

    for (;;) {
        u32 ret = poll(fds, FD_MAX, 50000);
        if (ret == -1)
            err_exit("Error while polling");
        else if (ret == 0) {
            writef("polling timed out.\n");
            continue;
        }

        // New client tries to connect to serverfd
        if (fds[FD_SERVER].revents & POLLIN) {
            clientfd = accept(serverfd, NULL, NULL);

            // When MAX_CONNECTIONS is reached, close new clients trying to connect.
            if (nclient == MAX_CONNECTIONS) {
                writef("Max connections reached.\n");
                if (send(clientfd, 0, 0, 0) == -1)
                    err_exit("Error while sending EOF to client socket.");
                if (shutdown(clientfd, SHUT_RDWR))
                    err_exit("Error while shutting down client socket.");
                if (close(clientfd))
                    err_exit("Error while closing client socket.");
            } else if (clientfd != -1) {
                nclient++;

                // get a new available spot in the fds array
                u32 i;
                for (i = 0; i < MAX_CONNECTIONS; i++)
                    if (fds[i].fd == -1)
                        break;
                fds[i].fd = clientfd;
                writef("New client: %d, %d\n", i, clientfd);

            } else {
                writef("Could not accept client errno: %d\n", errno);
            }
        }

        // Check for events on connected clients
        for (u32 i = 1; i <= nclient; i++) {
            if (!(fds[i].revents & POLLIN))
                continue;

            u32 nrecv;

            clientfd = fds[i].fd;

            nrecv = receive_message(&msg_recv, clientfd);
            if (nrecv == 0) {
                printf("client %d disconnected.\n", i);
                fds[i].fd      = -1;
                fds[i].revents = 0;
                if (shutdown(clientfd, SHUT_RDWR))
                    err_exit("Error while shutting down client %d socket.");
                if (close(clientfd))
                    err_exit("Error while cloing client socket.");
                nclient--;
                break;
            } else if (nrecv == -1) {
                // TODO: this can happen when connect is reset by pear
                err_exit("Error while receiving from client socket.");
            }

            // TODO:
            for (u32 j = 1; j <= nclient; j++) {
                // skip the client that sent the message
                if (j == i)
                    continue;
                if (send(fds[j].fd, &msg_recv, nrecv, 0) == -1)
                    printf("Error while sendig message to client %d. errno: %d\n", j, errno);
                else
                    printf("Retransmitted message to client %d.\n", j);
            }

            // // TODO: Serialize received message
            // FILE *f = fopen(filename, "wb");
            // save_message(&msg_recv, f);
            // fclose(f);
            // // return 0;

        }
    }

    return 0;
}