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

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

#define ERR(a) fprintf(stderr, "Error: %s\n", a)

uint32_t fib(uint32_t n)
{
	if (n <= 2)
		return 1;
	else
		return fib(n-1) + fib(n-2);
}

int main()
{
	// server variables
	int server;
	struct addrinfo hints, *info;

	// client variables
	int client;
	struct sockaddr_in client_addr;
	socklen_t addr_size;

	// calculation variables
	uint32_t n, fib_n;


	// Get the address & some socket information
	memset((void *) &hints, 0, sizeof(hints));		// zero out the structure
	hints.ai_family = AF_INET; 			// use IPv4
	hints.ai_socktype = SOCK_STREAM;		// give me a "stream socket" rather than a "datagram socket"
	hints.ai_flags = AI_PASSIVE;			// fill in my IP for me

	getaddrinfo(NULL, "4000", &hints, &info);		// Get me the information for that address, and let the port be 4000

	// Get an actual network socket
	server = socket(info->ai_family, info->ai_socktype, info->ai_protocol);
	if (server < 0)
	{
		ERR("could not get a socket!");
		return -1;
	}

	// Bind the socket to the desired address to be able to listen for incoming connections
	if (bind(server, info->ai_addr, info->ai_addrlen) < 0)
	{
		ERR("could not bind to socket!");
		return -1;
	}

	// Start listening for incoming connections and allow 5 connections at a time
	// in the backlog
	if (listen(server, 5) < 0)
	{
		ERR("problem in listening!");
		return -1;
	}

	// Set things up for the incoming client
	addr_size = sizeof(client_addr);

	// Accept a single client
	client = accept(server, (struct sockaddr *) &client_addr, &addr_size);
	if (client < 0)
	{
		ERR("could not accept client socket!");
		return -1;
	}

	do
	{
		recv(client, (void *) &n, sizeof(uint32_t), 0);		// receive a message from the client
		// NOTE: you should check the reutrn result of recv to see how many bytes
		// were received or if there was an error. But we will skip that for now

		// NOTE: usually the data received is in "network order" and should be
		// changed to "host order". This will be explained in the next lecture,
		// and is skipped for now

		printf("Received %d from the client\n", n);

		fib_n = fib(n);
		send(client, (void *) &fib_n, sizeof(uint32_t), 0);	// send a message to the client
		// NOTE: as before, you should check the return of send to see how many
		// bytes were sent and if there were any errors. But we will skip that now

		printf("Sent fib(%d) = %d to the client\n", n, fib_n);
	} while(n > 0);

	// We are done! Close things up
	close(client);
	close(server);

	return 0;
}