import today from './today';
import { BS, DATES } from './config';
import { BsDateSanitizer } from './utils/dateSanitizer';
import Errors from './constants/errors';
import { splitDate } from './utils/date';

function ageCalculator(bsDate: string) {
	const selectedDate = BsDateSanitizer(bsDate);
	const [year, month, day] = splitDate(selectedDate);

	const { currentYear, currentMonth, currentDay } = today();
	// validate user input date not exceed today
	if (
		year > currentYear ||
		(year === currentYear && month > currentMonth) ||
		(year === currentYear && month === currentMonth && day > currentDay)
	) {
		throw new Error(Errors.DATE_GREATER_THAN_TODAY);
	}
	let ageDate = {
		year: 0,
		month: 0,
		day: BS[year][month] - day,
	};
	for (let i = year; i <= currentYear; i++) {
		if (i === year) {
			if (currentDay >= day) {
				ageDate.day = currentDay - day;
				if (currentMonth >= month) ageDate.month = currentMonth - month;
				else {
					ageDate.month = DATES.MAX_MONTH - month + currentMonth;
					ageDate.year--;
				}
			} else {
				ageDate.day += currentDay;
				if (currentMonth > month) ageDate.month = currentMonth - month - 1;
				else {
					ageDate.month = DATES.MAX_MONTH - month + currentMonth - 1;
					ageDate.year--;
				}
			}
		} else ageDate.year++;
	}
	return ageDate;
}

export default ageCalculator;