#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/eventfd.h>
#include <string.h>
#include <stdint.h>
#include <poll.h>

#define SOCKET_PATH "/tmp/otp_socket"

#define CMD_ECHO 1
#define CMD_TIMER 2

struct request {
    int priority;
    int command;
    int value;
};

void send_fd(int socket, int fd) {
    struct msghdr msg = {0};

    char buf[CMSG_SPACE(sizeof(fd))];
    memset(buf, 0, sizeof(buf));

    struct iovec io = { .iov_base = (void*)"F", .iov_len = 1 };

    msg.msg_iov = &io;
    msg.msg_iovlen = 1;
    msg.msg_control = buf;
    msg.msg_controllen = sizeof(buf);

    struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
    cmsg->cmsg_level = SOL_SOCKET;
    cmsg->cmsg_type = SCM_RIGHTS;
    cmsg->cmsg_len = CMSG_LEN(sizeof(fd));

    memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));

    sendmsg(socket, &msg, 0);
}

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

    if (argc < 4) {
        printf("Usage: %s <priority> <command> <value>\n", argv[0]);
        return 1;
    }

    int sock = socket(AF_UNIX, SOCK_STREAM, 0);

    struct sockaddr_un addr;
    memset(&addr, 0, sizeof(addr));
    addr.sun_family = AF_UNIX;
    strcpy(addr.sun_path, SOCKET_PATH);

    connect(sock, (struct sockaddr*)&addr, sizeof(addr));

    int efd = eventfd(0, EFD_NONBLOCK);

    send_fd(sock, efd);

    struct request req;
    req.priority = atoi(argv[1]);
    req.command = atoi(argv[2]);
    req.value = atoi(argv[3]);

    write(sock, &req, sizeof(req));

    int response;
    read(sock, &response, sizeof(response));
    printf("Sync response: %d\n", response);

    struct pollfd pfd = { .fd = efd, .events = POLLIN };

    printf("Waiting for async notification...\n");

    poll(&pfd, 1, -1);

    uint64_t val;
    read(efd, &val, sizeof(val));
    printf("Async notification received!\n");

    close(sock);
    close(efd);
    return 0;
}