#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <unistd.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/ioctl.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>


#define SCREEN_FILE "/dev/fb0"

#define SERVER_IP "192.168.1.50"
#define SERVER_PORT 8080
#define TCP_PACKET_SIZE 1024 // 1KB chunks for sending




typedef struct DisplayInfo {
    int framebuffer;
    int width;
    int height;
    int bpp;
    size_t screensize;
} DisplayInfo;


int get_display_info(DisplayInfo *info) {
    // Open fb0 file descriptor and get display information. Saves them in the struct
    char *fb_path = SCREEN_FILE;

    int fb = open(fb_path, O_RDONLY);
    if (fb < 0) {
        perror("Can't open framebuffer");
        return -1;
    }

    
    struct fb_var_screeninfo vinfo;
    if (ioctl(fb, FBIOGET_VSCREENINFO, &vinfo)) {
        perror("ioctl failed");
        close(fb);
        return -1;
    }
    

    info->framebuffer = fb;
    info->width = vinfo.xres;
    info->height = vinfo.yres;
    info->bpp = vinfo.bits_per_pixel;
    info->screensize = info->width * info->height * (info->bpp / 8);

    return 0;
}

int TakeScreenshot(DisplayInfo *info, unsigned char *buffer){
    // Set the cursor at the start of framebuffer (fb0), then copy it on buffer
    if (lseek(info->framebuffer, 0, SEEK_SET) < 0) {
        perror("lseek failed");
        close(info->framebuffer);
        return -1;
    }

    if (read(info->framebuffer, buffer, info->screensize) != info->screensize) {
        perror("read failed");
        close(info->framebuffer);
        return -1;
    }
    return 0;
}

int TCP_connect() {
    int socketfd;
    struct sockaddr_in server_addr;

    // Create TCP socket
    socketfd = socket(AF_INET, SOCK_STREAM, 0);
    if (socketfd < 0) {
        perror("Can't create socket");
        return -1;
    }

    // Configure server address
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    server_addr.sin_addr.s_addr = inet_addr(SERVER_IP);

    // Connect to server
    if (connect(socketfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        perror("Can't connect");
        close(socketfd);
        return -1;
    }

    printf("Connected to %s:%d\n", SERVER_IP, SERVER_PORT);    
    return socketfd;
}

int TCP_disconnect(int socketfd) {
    close(socketfd);
}

int TCP_send_data(int socketfd, DisplayInfo *info, unsigned char *buffer) {
    int buffer_size = info->screensize;
    
    int total_sent = 0;
    while (total_sent < buffer_size) {
        // Calculate how many byte i still have to send (could be TCP_PACKET_SIZE or less)
        int to_send = 0;
        if (buffer_size - total_sent > TCP_PACKET_SIZE) {
            to_send = TCP_PACKET_SIZE;
        } else {
            to_send = (buffer_size - total_sent);
        }
        
        // Send the package and update the total_sent value
        int sent = send(socketfd, buffer + total_sent, to_send, 0);        
        total_sent += sent;
    }
    
    return 0;
}


int main (){
    // Use display information to allocate the correct size of memory
    DisplayInfo info;
    get_display_info(&info);
    
    unsigned char *buffer = malloc(info.screensize);
    if (!buffer) {
        perror("malloc failed");
        close(info.framebuffer);
    }


    // Create TCP connection and returns socket file descriptor
    int socketfd = TCP_connect();
    // Send the display information to the server
    send(socketfd, &(info.width), sizeof(int), 0);
    send(socketfd, &(info.height), sizeof(int), 0);
    send(socketfd, &(info.bpp), sizeof(int), 0);
    
    printf("width = %d\n", info.width);
    printf("height = %d\n", info.height);
    printf("bpp = %d\n", info.bpp);
    printf("buffer_size = %zu\n", info.screensize);


    int i=0;
    while (1) {
        // Copy the framebuffer fb0 into buffer
        TakeScreenshot(&info, buffer);

        // Send the data in chunks of TCP_BUFFER_SIZE
        printf("Start transmission[%d]\n", i);
        TCP_send_data(socketfd, &info, buffer);
        printf("Buffer sent[%d]\n", i);

        // Wait a second
        sleep(0.5);
        i++;
    }
    

    // Clean
    TCP_disconnect(socketfd);
    close(info.framebuffer);
    free(buffer);
    return 0;
    
}