src/ethiopic/lib/newDate.ts

import { toGregorianDate } from "../utils/index.js";
import { isEthiopicDateValid } from "../utils/isEthiopicDateValid.js";

/**
 * Creates a new Ethiopic date
 *
 * @param {number} year - The year of the Ethiopic date
 * @param {number} monthIndex - The zero-based month index of the Ethiopic date
 * @param {number} date - The day of the month of the Ethiopic date
 * @returns {Date} The corresponding Gregorian date
 */
export function newDate(year: number, monthIndex: number, date: number): Date {
  // Convert from 0-based month index to 1-based Ethiopic month
  const month = monthIndex + 1;

  if (!isEthiopicDateValid({ year, month, day: date })) {
    throw new Error("Invalid Ethiopic date");
  }
  return toGregorianDate({
    year: year,
    month: month,
    day: date,
  });
}