namespace ClassLibrary;

public class Calculations
{
    static void AvailablePeriods(TimeSpan[] startTimes, int[] durations, TimeSpan beginWorkingTime, TimeSpan endWorkingTime, int consultationTime)
    {
        DateTime[] startTimesAsDateTime = new DateTime[startTimes.Length];
        for (int i = 0; i < startTimes.Length; i++)
        {
            startTimesAsDateTime[i] = DateTime.Today.Add(startTimes[i]);
        }

        DateTime beginWorkingDateTime = DateTime.Today.Add(beginWorkingTime);
        DateTime endWorkingDateTime = DateTime.Today.Add(endWorkingTime);

        string[] result = DatesBumBum(beginWorkingDateTime, endWorkingDateTime, startTimesAsDateTime, durations, consultationTime);

        int count = 0;
        foreach (string date in result)
        {
            if (!string.IsNullOrEmpty(date))
            {
                Console.WriteLine(date);
                count++;
            }
        }
        Console.WriteLine(count);
    }

    static string[] DatesBumBum(DateTime beginWorkingTime, DateTime endWorkingTime, DateTime[] startTimes, int[] durations, int consultationTime)
    {
        int maxIntervals = (int)((endWorkingTime - beginWorkingTime).TotalMinutes / consultationTime);
        string[] availablePeriods = new string[maxIntervals];
        int index = 0;
        DateTime workTime = beginWorkingTime;
        int i = 0;

        while (workTime < endWorkingTime)
        {
            DateTime nextBusyStart = (i < startTimes.Length) ? startTimes[i] : endWorkingTime;
            TimeSpan availableTime = nextBusyStart - workTime;
            int availableMinutes = (int)availableTime.TotalMinutes;

            while (availableMinutes >= consultationTime)
            {
                DateTime nextAvailableEnd = workTime.AddMinutes(consultationTime);
                
                if (nextAvailableEnd > endWorkingTime)
                {
                    nextAvailableEnd = endWorkingTime;
                }
                
                availablePeriods[index++] = $"{workTime:HH:mm}-{nextAvailableEnd:HH:mm}";
                
                workTime = nextAvailableEnd;
                availableMinutes -= consultationTime;
            }

            if (i < startTimes.Length)
            {
                workTime = startTimes[i].AddMinutes(durations[i]);
                i++;
            }
            else
            {
                break;
            }
        }
        return availablePeriods;
    }
}