export class DateOnly {
  private readonly _ticks: number;

  constructor(year: number, month: number, day: number);
  constructor(date: Date);
  constructor(date: string);
  constructor(yearOrDate: number | Date | string, month?: number, day?: number) {
    if (yearOrDate instanceof Date) {
      this._ticks = yearOrDate.getTime();
    } else if (typeof yearOrDate === 'number' && month !== undefined && day !== undefined) {
      this._ticks = new Date(yearOrDate, month - 1, day).getTime();
    } else if (typeof yearOrDate === 'string') {
      const [year, month, day] = yearOrDate.split('-').map(Number);
      this._ticks = new Date(year, month - 1, day).getTime();
    } else {
      throw new Error('Invalid constructor arguments');
    }
  }

  get year(): number {
    return new Date(this._ticks).getFullYear();
  }

  get month(): number {
    return new Date(this._ticks).getMonth() + 1;
  }

  get day(): number {
    return new Date(this._ticks).getDate();
  }

  get date(): Date {
    return new Date(this._ticks);
  }

  toString(): string {
    return `${this.year}-${String(this.month).padStart(2, '0')}-${String(this.day).padStart(2, '0')}`;
  }
}