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



struct Time
{
	int seconds;
	int minutes;
	int hours;
};

int		IsTimeValid(const struct Time* timePtr);
void	AddOneSecond(struct Time* timePtr);
void	AddSeconds(struct Time* timePtr, int seconds);

// === main ====================================================================
//  
// =============================================================================

int main(void)
{
	struct Time smallTime;
	int num;
	
	printf("Enter the start time in HH:MM:SS format: ");
	
	if (3 != scanf("%d:%d:%d", &smallTime.hours, &smallTime.minutes
				   , &smallTime.seconds))
		{
		puts("Error reading input...");
		exit(1);
		}
	
	// check if time entered is valid
	auto	int	notvalid = IsTimeValid(&smallTime);
	
	if (notvalid)
		{
		exit(1);
		}
	
	printf("How many seconds would you like to add? ");
	scanf("%d", &num);
	
	while (num--)
		{
		AddOneSecond(&smallTime);
		printf("%02d:%02d:%02d\n", smallTime.hours, smallTime.minutes,
					smallTime.seconds);
		}
		
	return 0;
} // end of "main"


// === IsTimeValid =============================================================
//  
// =============================================================================

int		IsTimeValid(const struct Time* timePtr)
{
	int invalidMask = 0;
	// 000
	// hms

	if ((timePtr->seconds > 59) || (timePtr->seconds < 0))
		{
		invalidMask |= 1;
		}
	
	if ((timePtr->minutes > 59) || (timePtr->minutes < 0))
		{
		invalidMask |= 2;
		}

	if ((timePtr->hours > 23) || (timePtr->hours < 0))
		{
		invalidMask |= 4;
		}

	// print error mesasge
	if (invalidMask)
		{
		printf("Invalid data: the ");
		if (invalidMask & 4)
			{
			printf("hours ");
			invalidMask ^= 4;
			if (invalidMask)
				{
				printf("and ");
				}
			}
		if (invalidMask & 2)
			{
			printf("minutes ");
			invalidMask ^= 2;
			if (invalidMask)
				{
				printf("and ");
				}
			}
		if (invalidMask & 1)
			{
			printf("seconds ");
			}
		puts("are out of range...");
		}
	return invalidMask;
} // end of "IsTimeValid"


void	AddOneSecond(struct Time* timePtr)
{
	char 	timeStr[10];
	
	// Store the current time in the myTime tm structure (from stdlib)
	// so that it's valid when passed to mktime.
	time_t	myTime_t = time(&myTime_t);	
	struct	tm *myTime = localtime(&myTime_t);
	
	myTime->tm_sec = timePtr->seconds + 1;
	myTime->tm_min = timePtr->minutes;
	myTime->tm_hour = timePtr->hours;
	
	// corrects the values of myTime
	mktime(myTime);
	
	timePtr->seconds = myTime->tm_sec;
	timePtr->minutes = myTime->tm_min;
	timePtr->hours = myTime->tm_hour;
	
	/* print
	strftime(timeStr, 10, "%H:%M:%S", myTime);
	printf("%s\n", timeStr);
	*/
}



void	AddSeconds(struct Time* timePtr, int num)
{
	char 	timeStr[10];
	time_t	myTime_t;
	myTime_t = time(&myTime_t);	
	struct tm *myTime = localtime(&myTime_t);
	
	myTime->tm_sec = timePtr->seconds + num;
	myTime->tm_min = timePtr->minutes;
	myTime->tm_hour = timePtr->hours;
	
	// corrects time
	mktime(myTime);
	
	timePtr->seconds = myTime->tm_sec;
	timePtr->minutes = myTime->tm_min;
	timePtr->hours = myTime->tm_hour;
	
	/* print
	strftime(timeStr, 10, "%H:%M:%S", myTime);
	printf("myTime: %s\n", timeStr);
	*/
}