/**
 * Character entity — value-object-driven.
 *
 * "I can't believe it's not Haskell": invariants at boundaries.
 * State is encapsulated in a CharacterState record type.
 */
import { Health } from './Health.ts';
import type { Level } from './Level.ts';
import type { Status } from './Status.ts';
import { StatusAlive, StatusDead } from './Status.ts';
import { CharacterState } from './CharacterState.ts';
import type { Faction } from './Faction.ts';

export interface CharacterCtor {
  name: string;
  level: Level;
}

export interface CharacterCtorWithHealth {
  name: string;
  level: Level;
  health: number;
}

export class Character {
  #state: CharacterState;

  private constructor(state: CharacterState) {
    this.#state = state;
  }

  /** Create a new character with default health (1000) and alive status. */
  static create({ name, level }: CharacterCtor): Character {
    const state = new CharacterState(name, Health.create(1000), StatusAlive, level, new Set());
    return new Character(state);
  }

  /** Create a character with a specific health value (for testing). */
  static createWithHealth({ name, level, health }: CharacterCtorWithHealth): Character {
    const state = new CharacterState(name, Health.create(health), StatusAlive, level, new Set());
    return new Character(state);
  }

  get name(): string {
    return this.#state.name;
  }

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

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

  get level(): Level {
    return this.#state.level;
  }

  get factions(): ReadonlySet<Faction> {
    return this.#state.factions;
  }

  /** Deal damage to another character. Mutates target in place. */
  dealDamage(target: Character, damage: number): void {
    // Self-damage is forbidden
    if (this.name === target.name) return;
    // Dead characters cannot take damage
    if (target.status.kind === 'dead') return;
    // Reduce health
    const newHealth = target.health.sub(damage);
    const newStatus = newHealth.value === 0 ? StatusDead : StatusAlive;
    target.#state = new CharacterState(
      target.name,
      newHealth,
      newStatus,
      target.level,
      target.factions,
    );
  }
}