const HP_BAR_WIDTH = 30;
const HP_BAR_HEIGHT = 4;
const HP_BAR_OFFSET_Y = -20;

export class BaseEnemy {
  /**
   * @param {Phaser.Scene} scene
   * @param {number} x
   * @param {number} y
   * @param {object} player - Player instance
   * @param {object} config - { color, radius, hp, speed, xp, contactDamage }
   */
  constructor(scene, x, y, player, config) {
    this.scene = scene;
    this.player = player;

    this.maxHp = config.hp;
    this.hp = config.hp;
    this.speed = config.speed;
    this.xp = config.xp;
    this.contactDamage = config.contactDamage ?? 10;
    this.radius = config.radius ?? 14;

    this.body = scene.add.circle(x, y, this.radius, config.color ?? 0xff4444);
    scene.physics.add.existing(this.body);
    this.body.body.setCircle(this.radius);

    // HP bar
    this._hpBg = scene.add.rectangle(x, y + HP_BAR_OFFSET_Y, HP_BAR_WIDTH, HP_BAR_HEIGHT, 0x333333);
    this._hpFill = scene.add.rectangle(x, y + HP_BAR_OFFSET_Y, HP_BAR_WIDTH, HP_BAR_HEIGHT, 0x00ff44);

    this._contactTimer = 0;
  }

  get x() { return this.body.x; }
  get y() { return this.body.y; }
  get active() { return this.body?.active ?? false; }

  takeDamage(amount) {
    this.hp -= amount;
    this._updateHpBar();
    if (this.hp <= 0) this._die();
  }

  _updateHpBar() {
    const ratio = Math.max(0, this.hp / this.maxHp);
    this._hpFill.width = HP_BAR_WIDTH * ratio;
    this._hpFill.x = this.x - (HP_BAR_WIDTH * (1 - ratio)) / 2;
  }

  _syncBarPosition() {
    this._hpBg.setPosition(this.x, this.y + HP_BAR_OFFSET_Y);
    this._hpFill.setPosition(
      this.x - (HP_BAR_WIDTH * (1 - Math.max(0, this.hp / this.maxHp))) / 2,
      this.y + HP_BAR_OFFSET_Y
    );
  }

  _die() {
    this.scene.events.emit('enemy-killed', { xp: this.xp, x: this.x, y: this.y });
    this.destroy();
  }

  /** Check contact damage with player. Call from subclass update(). */
  _checkContact(delta) {
    this._contactTimer -= delta;
    if (this._contactTimer > 0) return;

    const dist = Phaser.Math.Distance.Between(this.x, this.y, this.player.x, this.player.y);
    if (dist < this.radius + 16) {
      this.player.takeDamage(this.contactDamage);
      this._contactTimer = 800; // ms between contact hits
    }
  }

  update(delta) {
    this._syncBarPosition();
    this._checkContact(delta);
  }

  destroy() {
    this.body?.destroy();
    this._hpBg?.destroy();
    this._hpFill?.destroy();
  }
}