#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <pthread.h>
#include <limits.h>

#define SERVER_IP "127.0.0.1"
#define SERVER_PORT 6667
#define BUFFER_SIZE 512

int sock;
pthread_t recv_thread;

void *receive_handler(void *arg) {
    char buffer[BUFFER_SIZE];
    while (1) {
        ssize_t bytes = recv(sock, buffer, sizeof(buffer) - 1, 0);
        if (bytes <= 0) {
            puts("Disconnected from server.");
            close(sock);
            exit(0);
        }
        buffer[bytes] = '\0';
        printf("%s", buffer);
        fflush(stdout);
    }
    return NULL;
}

void get_nickname(char *nickname, size_t size) {
    char *user = getlogin();
    if (!user) user = getenv("USER");

    char hostname[HOST_NAME_MAX + 1];
    if (gethostname(hostname, sizeof(hostname)) != 0) {
        strncpy(hostname, "unknown", sizeof(hostname));
    }

    snprintf(nickname, size, "%s@%s", user ? user : "user", hostname);
}

int main() {
    struct sockaddr_in server_addr;
    char buffer[BUFFER_SIZE];
    char nickname[100];

    get_nickname(nickname, sizeof(nickname));

    sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock < 0) {
        perror("socket");
        return 1;
    }

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, SERVER_IP, &server_addr.sin_addr);

    if (connect(sock, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("connect");
        return 1;
    }

    // Send NICK and USER commands
    char init[BUFFER_SIZE];
    snprintf(init, sizeof(init), "NICK %s\r\nUSER %s 0 * :realname\r\n", nickname, nickname);
    send(sock, init, strlen(init), 0);

    puts("Connected to chat server.");
    pthread_create(&recv_thread, NULL, receive_handler, NULL);

    while (1) {
        fgets(buffer, sizeof(buffer), stdin);
        if (strcmp(buffer, "/quit\n") == 0) {
            break;
        }
        send(sock, buffer, strlen(buffer), 0);
    }

    close(sock);
    return 0;
}