#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
using namespace std;
// Don't forget to include "Ws2_32.lib" in the library list.
#include <winsock2.h>
#include <string.h>
#include <time.h>
#include <Windows.h>

#define TIME_PORT	27015

void main()
{
	// Initialize Winsock (Windows Sockets).

	// Create a WSADATA object called wsaData.
	// The WSADATA structure contains information about the Windows
	// Sockets implementation.
	WSAData wsaData;

	// Call WSAStartup and return its value as an integer and check for errors.
	// The WSAStartup function initiates the use of WS2_32.DLL by a process.
	// First parameter is the version number 2.2.
	// The WSACleanup function destructs the use of WS2_32.DLL by a process.
	if (NO_ERROR != WSAStartup(MAKEWORD(2, 2), &wsaData))
	{
		cout << "Time Server: Error at WSAStartup()\n";
	}

	// Server side:
	// Create and bind a socket to an internet address.

	// After initialization, a SOCKET object is ready to be instantiated.

	// Create a SOCKET object called m_socket.
	// For this application:	use the Internet address family (AF_INET),
	//							datagram sockets (SOCK_DGRAM),
	//							and the UDP/IP protocol (IPPROTO_UDP).
	SOCKET m_socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

	// Check for errors to ensure that the socket is a valid socket.
	// Error detection is a key part of successful networking code.
	// If the socket call fails, it returns INVALID_SOCKET.
	// The "if" statement in the previous code is used to catch any errors that
	// may have occurred while creating the socket. WSAGetLastError returns an
	// error number associated with the last error that occurred.
	if (INVALID_SOCKET == m_socket)
	{
		cout << "Time Server: Error at socket(): " << WSAGetLastError() << endl;
		WSACleanup();
		return;
	}

	// For a server to communicate on a network, it must first bind the socket to
	// a network address.

	// Need to assemble the required data for connection in sockaddr structure.

	// Create a sockaddr_in object called serverService.
	sockaddr_in serverService;
	// Address family (must be AF_INET - Internet address family).
	serverService.sin_family = AF_INET;
	// IP address. The sin_addr is a union (s_addr is a unsigdned long (4 bytes) data type).
	// INADDR_ANY means to listen on all interfaces.
	// inet_addr (Internet address) is used to convert a string (char *) into unsigned int.
	// inet_ntoa (Internet address) is the reverse function (converts unsigned int to char *)
	// The IP address 127.0.0.1 is the host itself, it's actually a loop-back.
	serverService.sin_addr.s_addr = INADDR_ANY;	//inet_addr("127.0.0.1");
	// IP Port. The htons (host to network - short) function converts an
	// unsigned short from host to TCP/IP network byte order (which is big-endian).
	serverService.sin_port = htons(TIME_PORT);

	// Bind the socket for client's requests.

	// The bind function establishes a connection to a specified socket.
	// The function uses the socket handler, the sockaddr structure (which
	// defines properties of the desired connection) and the length of the
	// sockaddr structure (in bytes).
	if (SOCKET_ERROR == bind(m_socket, (SOCKADDR *)&serverService, sizeof(serverService)))
	{
		cout << "Time Server: Error at bind(): " << WSAGetLastError() << endl;
		closesocket(m_socket);
		WSACleanup();
		return;
	}

	// Waits for incoming requests from clients.

	// Send and receive data.
	sockaddr client_addr;
	int client_addr_len = sizeof(client_addr);
	int bytesSent = 0;
	int bytesRecv = 0;
	char sendBuff[255];
	char recvBuff[255];

	// Get client's requests and answer them.
	// The recvfrom function receives a datagram and stores the source address.
	// The buffer for data to be received and its available size are
	// returned by recvfrom. The fourth argument is an idicator
	// specifying the way in which the call is made (0 for default).
	// The two last arguments are optional and will hold the details of the client for further communication.
	// NOTE: the last argument should always be the actual size of the client's data-structure (i.e. sizeof(sockaddr)).
	cout << "Time Server: Wait for clients' requests.\n";

	while (true)
	{
		bytesRecv = recvfrom(m_socket, recvBuff, 255, 0, &client_addr, &client_addr_len);
		if (SOCKET_ERROR == bytesRecv)
		{
			cout << "Time Server: Error at recvfrom(): " << WSAGetLastError() << endl;
			closesocket(m_socket);
			WSACleanup();
			return;
		}

		recvBuff[bytesRecv] = '\0'; //add the null-terminating to make it a string
		cout << "Time Server: Recieved: " << bytesRecv << " bytes of \"" << recvBuff << "\" message.\n";

		// Answer client's request by the current time.

		if (strcmp(recvBuff, "GetTime") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Parse the current time to printable string.
			strcpy(sendBuff, ctime(&timer));
			sendBuff[strlen(sendBuff) - 1] = '\0'; //to remo
		}
		else if (strcmp(recvBuff, "GetTimeWithoutDate") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Parse the current time to printable string.
			struct tm * t = localtime(&timer);
			sprintf(sendBuff, "%02d:%02d:%02d", t->tm_hour, t->tm_min, t->tm_sec);
		}
		else if (strcmp(recvBuff, "GetTimeSinceEpoch") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Parse the current time to printable string.
			struct tm * t = localtime(&timer);
			sprintf(sendBuff, "%d", timer);
		}
		else if (strcmp(recvBuff, "GetClientToServerDelayEstimation") == 0) {
			sprintf(sendBuff, "%d", GetTickCount());
		}
		else if (strcmp(recvBuff, "MeasureRTT") == 0) {
			sprintf(sendBuff, "%d", GetTickCount());
		}
		else if (strcmp(recvBuff, "GetTimeWithoutDateOrSeconds") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Parse the current time to printable string.
			struct tm * t = localtime(&timer);
			sprintf(sendBuff, "%02d:%02d", t->tm_hour, t->tm_min);
		}
		else if (strcmp(recvBuff, "GetYear") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Parse the current time to printable string.
			struct tm * t = localtime(&timer);
			sprintf(sendBuff, "%d", t->tm_year + 1900);
		}
		else if (strcmp(recvBuff, "GetMonthAndDay") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Parse the current time to printable string.
			struct tm * t = localtime(&timer);
			strftime(sendBuff, 254, "%B %d", t);
		}
		else if (strcmp(recvBuff, "GetSecondsSinceBeginingOfMonth") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Getting the beginning of the month.
			struct tm * t = localtime(&timer);
			t->tm_sec = 0;
			t->tm_min = 0;
			t->tm_hour = 0;
			t->tm_mday = 1;
			// Parse the current time to printable string.
			sprintf(sendBuff, "%.f", difftime(timer, mktime(t)));
		}
		else if (strcmp(recvBuff, "GetDayOfYear") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Parse the current time to printable string.t
			struct tm * t = localtime(&timer);
			sprintf(sendBuff, "%d", t->tm_yday);
		}
		else if (strcmp(recvBuff, "GetDaylightSavings") == 0) {
			// Get the current time.
			time_t timer;
			time(&timer);
			// Parse the current time to printable string.
			struct tm * t = localtime(&timer);
			sprintf(sendBuff, "%d", t->tm_isdst);
		}

		// Sends the answer to the client, using the client address gathered
		// by recvfrom.
		bytesSent = sendto(m_socket, sendBuff, (int)strlen(sendBuff), 0, (const sockaddr *)&client_addr, client_addr_len);
		if (SOCKET_ERROR == bytesSent)
		{
			cout << "Time Server: Error at sendto(): " << WSAGetLastError() << endl;
			closesocket(m_socket);
			WSACleanup();
			return;
		}

		cout << "Time Server: Sent: " << bytesSent << "\\" << strlen(sendBuff) << " bytes of \"" << sendBuff << "\" message.\n";
	}

	// Closing connections and Winsock.
	cout << "Time Server: Closing Connection.\n";
	closesocket(m_socket);
	WSACleanup();
}