/**
 * MagicalObject — shared base for all magical items in the game.
 *
 * Invariants enforced at construction:
 * - Health is non-negative
 * - Health never exceeds maxHealth
 * - Status derived from health (0 = destroyed, > 0 = alive)
 */

export type MagicalObjectStatus = { readonly kind: 'alive' } | { readonly kind: 'destroyed' };

export class MagicalObject {
  readonly #health: number;
  readonly #maxHealth: number;
  readonly #status: MagicalObjectStatus;

  protected constructor(health: number, maxHealth: number, status: MagicalObjectStatus) {
    this.#health = health;
    this.#maxHealth = maxHealth;
    this.#status = status;
  }

  get health(): number {
    return this.#health;
  }

  get maxHealth(): number {
    return this.#maxHealth;
  }

  get status(): MagicalObjectStatus {
    return this.#status;
  }

  /** Create a destroyed object (health = 0). */
  static createDestroyed(maxHealth: number): MagicalObject {
    if (maxHealth < 0) throw new Error('MaxHealth cannot be negative');
    return new MagicalObject(0, maxHealth, { kind: 'destroyed' });
  }

  /** Check if this object is alive. */
  isAlive(): boolean {
    return this.#status.kind === 'alive';
  }
}