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;