#include <errno.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/socket.h>
#include <unistd.h>
#include <poll.h>
#include "liburing.h"

#define BACKLOG 512

#define PORT 9700

struct io_uring ring;

char buf[100];

void add_poll(int fd, unsigned int poll_mask) {
    struct io_uring_sqe *sqe = io_uring_get_sqe(&ring);
    io_uring_prep_poll_add(sqe, fd, poll_mask);
    sqe->user_data = 1;
    sqe->flags |= IOSQE_IO_LINK;
}

void add_accept(int fd) {
    struct io_uring_sqe *sqe = io_uring_get_sqe(&ring);
    io_uring_prep_accept(sqe, fd, 0, 0, SOCK_NONBLOCK | SOCK_CLOEXEC);
    sqe->user_data = 2;
}

void add_read(int fd) {
    struct io_uring_sqe *sqe = io_uring_get_sqe(&ring);
    io_uring_prep_read(sqe, fd, &buf, 100, 0);
    sqe->user_data = 3;
}

int setup_io_uring() {
    int ret = io_uring_queue_init(16, &ring, 0);
    if (ret) {
        fprintf(stderr, "Unable to setup io_uring: %s\n", strerror(-ret));
        return 1;
    }
    return 0;
}

int main(int argc, char *argv[]) {

    struct sockaddr_in serv_addr;

    setup_io_uring();
    
    int sock_listen_fd = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);
    const int val = 1;
    setsockopt(sock_listen_fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));

    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);
    serv_addr.sin_addr.s_addr = INADDR_ANY;

    if (bind(sock_listen_fd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
         perror("Error binding socket\n");
         exit(1);
     }
    if (listen(sock_listen_fd, BACKLOG) < 0) {
         perror("Error listening on socket\n");
         exit(1);
    }

    setup_io_uring();

    add_poll(sock_listen_fd, POLLIN);
    add_accept(sock_listen_fd);
    io_uring_submit(&ring);

    while (1) {
        struct io_uring_cqe *cqe;
        io_uring_wait_cqe(&ring, &cqe);

        printf("Res: res: %d\n", cqe->res);
        
        if (cqe->user_data == 1) {
            printf("Poll Event\n");
        }
        
        if (cqe->user_data == 2 && cqe->res > 0) {
            printf("Accept Event\n");
                    
            add_poll(sock_listen_fd, POLLIN);
            add_accept(sock_listen_fd);

            add_poll(cqe->res, POLLIN);
            add_read(cqe->res);
        }

        if (cqe->user_data == 3) {
            printf("Read Buf: %s \n", buf);
        }
        io_uring_submit(&ring);

        io_uring_cqe_seen(&ring, cqe);
    }

    io_uring_queue_exit(&ring);

    return 0;
}