#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <stdlib.h>
#include <signal.h>
#include <netinet/tcp.h>

int server;

void timespec_diff(const struct timespec *start, const struct timespec *stop, struct timespec *result)
{
	if ((stop->tv_nsec - start->tv_nsec) < 0) {
		result->tv_sec = stop->tv_sec - start->tv_sec - 1;
		result->tv_nsec = stop->tv_nsec - start->tv_nsec + 1000000000L;
	} else {
		result->tv_sec = stop->tv_sec - start->tv_sec;
		result->tv_nsec = stop->tv_nsec - start->tv_nsec;
	}
}

double timespec_conv(const struct timespec *ts)
{
	return ts->tv_sec + (double) ts->tv_nsec / 1000000000L;
}

void recieve(int sock)
{
	struct timespec start, stop, result;
	char buffer[1024 * 10];
	ssize_t bc;

	int bytes;
	bc = recv(sock, &bytes, sizeof(int), 0);
	if (bc <= 0) {
		printf("Failed to receive file size\n");
		close(sock);
		return;
	}
	printf("File size: %i\n", bytes);

    bc = send(sock, buffer, sizeof(char), 0);
    if (bc <= 0) {
        printf("Failed to send ack\n");
        close(sock);
        return;
    }

	int count = 0;
	FILE *fp = fopen("/tmp/TEST", "w");

	timespec_get(&start, TIME_UTC);
	while (count < bytes) {
	    int temp = 0;
	    gtrecv:
		bc = recv(sock, buffer, sizeof(buffer), 0);
		if (bc <= 0) {
			printf("Failed to receive file\n");
			close(sock);
			return;
		}
        temp += (int) bc;
		fwrite(buffer, sizeof(char), bc, fp);
		printf("Received: %zi bytes, total: %i\n", bc, count);
		if (temp < 512)
		    goto gtrecv;
		count += temp;
		bc = send(sock, buffer, sizeof(char), 0);
		if (bc <= 0) {
			printf("Failed to send ack\n");
			close(sock);
			return;
		}
	}
	timespec_get(&stop, TIME_UTC);
	timespec_diff(&start, &stop, &result);
	printf("time: %g\n", timespec_conv(&result));
	printf("speed: %g\n", (count / timespec_conv(&result)) / (1024 * 1024 / 8));
	fclose(fp);

	close(sock);
}

void cli()
{
	int conn;
	struct sockaddr_in server_addr, cl;

	memset(&server_addr, 0, sizeof(server_addr));
	server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(5005);

	server = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
	if (server == -1) {
		printf("Failed creating socket\n");
		close(server);
		return;
	}

	int err;
	int opt = 1;
    err = setsockopt(server, IPPROTO_TCP, TCP_QUICKACK, (void *) &opt, sizeof(opt));
    if (err == -1) {
        printf("Failed to set socket to TCP_QUICKACK\n");
        close(server);
        return;
    }

    int opt2 = 1;
    err = setsockopt(server, IPPROTO_TCP, TCP_NODELAY, (void *) &opt2, sizeof(opt2));
    if (err == -1) {
        printf("Failed to set socket to TCP_NODELAY\n");
        close(server);
        return;
    }

	if ((bind(server, (struct sockaddr *) &server_addr, sizeof(server_addr))) != 0) {
		printf("Failed binding socket\n");
		close(server);
		return;
	}

	if ((listen(server, 5)) != 0) {
		printf("Failed to start listening socket\n");
		close(server);
		return;
	}

	socklen_t len = sizeof(cl);
	conn = accept(server, (struct sockaddr *) &cl, &len);
	if (conn <= 0) {
		printf("Failed to accept client\n");
		close(server);
		return;
	}

	recieve(conn);

	close(server);
}

void handler(int c)
{
	close(server);
	exit(EXIT_SUCCESS);
}

int main(void)
{
	struct sigaction act;
	act.sa_handler = handler;
	sigaction(SIGINT, &act, NULL);
	sigaction(SIGTERM, &act, NULL);

	cli();
	handler(0);
	return 0;
}