#include<stdio.h>
#define HOUR 3600
#define MINUTE 60
#if defined(WIN32) || defined(_WIN32) || defined(__WIN32) && !defined(__CYGWIN__)
#define IS_WINDOWS 1
#else
#define IS_WINDOWS 0
#endif

void scanf_int(char *q, int *n);
int shutdown(int h, int m, int s);
int calculate_seconds(int h, int m, int s);

int main() {

	int h = 0;
	int m = 0;
	int s = 0;

	printf("Simple Shutdown Timer for Windows.\n");
	printf("Written by: Joshua Paylaga\n\n");

	scanf_int("Hour(s): ", &h);
	scanf_int("Minute(s): ", &m);
	scanf_int("Seconds(s): ", &s);

	if ((h >= 0) && (m >= 0 && m < 60) && (s >= 0 && s < 60)) {
		if (shutdown(h, m, s) == 1) {
			printf("\nYour computer will shutdown in %d:%d:%d.\n\n", h, m, s);
			system("pause");
		}
		else {
			printf("\nThis program is intended only for Windows Machine.\n\n");
		}
	}
	else {
		printf("\nInvalid time provided.\n\n");
	}

	return 0;
}

/**
 * Accepts input from user and prevent run-time breakage
 * due to NULL input or wrong data type input.
 */
void scanf_int(char *q, int *n) {
	printf("%s", q);
	char buf[40];
	while (fgets(buf, sizeof buf, stdin) != NULL) {
		if (sscanf(buf, "%d", n) != 1) {
			printf("%s", q);
		}
		else {
			break;
		}
	}
}

/**
 * Shuts down your computer within the time given.
 * It utilizes the windows command shutdown /s /f /t {seconds}
 * to initialize shutdown. This will not work if compiled to
 * other operating systems.
 */
int shutdown(int h, int m, int s) {
	int success = 0;
	if (IS_WINDOWS == 1) {
		int seconds = calculate_seconds(h, m, s);
		char command[250];
		sprintf(command, "shutdown /s /f /t %d", seconds);
		system(command);
		success = 1;
	}
	else {
		int seconds = calculate_seconds(h, m, s);
		char command[250];
		sprintf(command, "shutdown +h %d", seconds);
		system(command);
		success = 1;
	}
	return success;
}

/**
 * Converts h:m:s time to seconds.
 */
int calculate_seconds(int h, int m, int s) {
	int h_to_s = HOUR * h;
	int m_to_s = MINUTE * m;
	return (h_to_s + m_to_s + s);
}