calc_dur.go

func CalculateEvectivityTimespan(dueDate, dueTime, duration string) (*protocol.EvectivityDateTime, *protocol.EvectivityDateTime, error) {
	if dueTime == "" {
		return dateOnlySpan(dueDate, duration)
	}

	return dateTimeSpan(dueDate, dueTime, duration)
}

func dateOnlySpan(dueDate, duration string) (*protocol.EvectivityDateTime, *protocol.EvectivityDateTime, error) {
	start, err := time.Parse(PDDateFormat, dueDate)
	if err != nil {
		return nil, nil, errors.Wrap(err, "failed to parse due date")
	}

	end, err := addDuration(start, duration)
	if err != nil {
		return nil, nil, errors.Wrap(err, "failed to parse duration")
	}

	return &protocol.EvectivityDateTime{Date: start.Format(PDDateFormat)}, &protocol.EvectivityDateTime{Date: end.Format(PDDateFormat)}, nil
}

func dateTimeSpan(dueDate, dueTime, duration string) (*protocol.EvectivityDateTime, *protocol.EvectivityDateTime, error) {
	start, err := time.Parse(PDDateFormat, fmt.Sprintf("%s %s", dueDate, dueTime))
	if err != nil {
		return nil, nil, errors.Wrap(err, "failed to parse due date")
	}

	end, err := addDuration(start, duration)
	if err != nil {
		return nil, nil, errors.Wrap(err, "failed to parse duration")
	}

	return &protocol.EvectivityDateTime{DateTime: start.Format(PDDateTimeFormat)}, &protocol.EvectivityDateTime{DateTime: end.Format(PDDateTimeFormat)}, nil
}

func addDuration(t time.Time, duration string) (time.Time, error) {
	if duration == "" {
		return t, nil
	}

	dur, err := parseDuration(duration)
	if err != nil {
		return time.Time{}, errors.Wrap(err, "failed to parse duration")
	}

	return t.Add(dur), nil
}