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

#define SOCKET_PATH "/tmp/unix_dgram_demo"

int main() {
    int sock_fd;
    struct sockaddr_un server_addr, client_addr;
    socklen_t client_len;
    char buffer[256];
    
    // Create socket
    sock_fd = socket(AF_UNIX, SOCK_DGRAM, 0);
    if (sock_fd == -1) {
        perror("socket");
        exit(EXIT_FAILURE);
    }
    
    // Remove socket file if it already exists
    unlink(SOCKET_PATH);
    
    // Configure server address
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sun_family = AF_UNIX;
    strncpy(server_addr.sun_path, SOCKET_PATH, sizeof(server_addr.sun_path) - 1);
    
    // Bind socket to address
    if (bind(sock_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("bind");
        close(sock_fd);
        exit(EXIT_FAILURE);
    }
    
    printf("Receiver is waiting for messages on %s...\n", SOCKET_PATH);
    
    // Receive message
    client_len = sizeof(client_addr);
    ssize_t num_bytes = recvfrom(sock_fd, buffer, sizeof(buffer) - 1, 0,
                                (struct sockaddr *)&client_addr, &client_len);
    if (num_bytes == -1) {
        perror("recvfrom");
    } else {
        buffer[num_bytes] = '\0';
        printf("Received message: %s\n", buffer);
        
        // Send response
        const char *response = "Hello from receiver!";
        if (sendto(sock_fd, response, strlen(response), 0,
                  (struct sockaddr *)&client_addr, client_len) == -1) {
            perror("sendto");
        }
    }
    
    // Clean up
    close(sock_fd);
    unlink(SOCKET_PATH);
    
    return 0;
}