src/hebrew/lib/setYear.ts

import {
  getMonthCode,
  isHebrewLeapYear,
  monthsInHebrewYear,
} from "../utils/calendarMath.js";
import { toGregorianDate, toHebrewDate } from "../utils/dateConversion.js";
import { clampHebrewDay } from "../utils/serial.js";

import { findMonthIndexByCode } from "./findMonthIndexByCode.js";

export function setYear(date: Date, year: number): Date {
  const hebrew = toHebrewDate(date);
  const targetYear = year;
  const originalCode = getMonthCode(hebrew.year, hebrew.monthIndex);
  let targetMonthIndex = findMonthIndexByCode(targetYear, originalCode);

  if (targetMonthIndex === -1) {
    if (originalCode === "adarI") {
      targetMonthIndex = findMonthIndexByCode(targetYear, "adar");
    } else if (originalCode === "adar" && !isHebrewLeapYear(targetYear)) {
      targetMonthIndex = findMonthIndexByCode(targetYear, "adar");
    } else {
      const monthsCount = monthsInHebrewYear(targetYear);
      targetMonthIndex = Math.min(hebrew.monthIndex, monthsCount - 1);
    }
  }

  const day = clampHebrewDay(targetYear, targetMonthIndex, hebrew.day);
  return toGregorianDate({
    year: targetYear,
    monthIndex: targetMonthIndex,
    day,
  });
}