#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/stat.h>

#define PORT htons(12221)

void ServeConnection(int sock)
{
    char path[512];
    long dl_of_the_file, sent, sent_in_total, read;
    struct stat fileinfo;
    unsigned char buffer[1024];
    FILE* file;

    printf("Give the path to the file: \n");
    memset(path, 0, 512);
    scanf("%s",path);

    if (stat(path, &fileinfo) < 0)
    {
        printf("Child: I can't obtain information about a file\n");
        return;
    }
    if (fileinfo.st_size == 0)
    {
        printf("Child: filesize 0\n");
        return;
    }

    printf("Child: filesize : %d\n", fileinfo.st_size);

    dl_of_the_file = fileinfo.st_size;
    sent_in_total = 0;
    file = fopen(path, "rb");

    if (file == NULL)
    {
        printf("Child: error at opening a file\n");
        return;
    }

    while (sent_in_total < dl_of_the_file)
    {
        read = fread(buffer, 1, 1024, file);
        sent = send(sock, buffer, read, 0);
        if (read != sent)
            break;
        sent_in_total += sent;
        printf("Child: total sent %ld\n", sent_in_total);
    }

    if (sent_in_total == dl_of_the_file)
    {
        printf("Child: file sent ok\n");
    }
    else
    {
        printf("Child: error at sending a file\n");
    }

    fclose(file);
    return;
}


int main()
{
    struct sockaddr_in adr;
    socklen_t dladr = sizeof(struct sockaddr_in);
    int sock_listen, sock_client;
    sock_listen = socket(PF_INET, SOCK_STREAM, 0);
    adr.sin_family = AF_INET;
    adr.sin_port = PORT;
    adr.sin_addr.s_addr = INADDR_ANY;
    memset(adr.sin_zero, 0, sizeof(adr.sin_zero));


    if (bind(sock_listen, (struct sockaddr*) &adr, dladr) < 0)
    {
        printf("Parent: bind failed\n");
        return 1;
    }

    listen(sock_listen, 10);
    printf("Server running...\n");

    while(1)
    {
        dladr = sizeof(struct sockaddr_in);
        sock_client = accept(sock_listen, (struct sockaddr*) &adr, &dladr);

        if (sock_client < 0)
        {
            printf("Parent: accept error\n");
            continue;
        }

        printf("Parent: connection from %s:%u\n",
            inet_ntoa(adr.sin_addr),
            ntohs(adr.sin_port));
        printf("Parent: I'm creating child process\n");


        if (fork() == 0)
        {
            //child
            printf("Child: start serving)\n");
            ServeConnection(sock_client);
            printf("Child: closing socket\n");
            close(sock_client);
            printf("Child: end of the process\n");
            exit(0);
        }
        else
        {
            //parent
            printf("Parent: return to listening)\n");
            continue;
        }

    }
    return 0;
}