// ui/VirtualJoystick.js
export class VirtualJoystick {
  constructor(scene, enabled = true) {
    this.scene = scene;
    this.isActive = false;
    this.base = null;
    this.knob = null;
    this.activePointer = null; // 保持单一激活指针，但允许不同指针触发
    this.centerX = 0;
    this.centerY = 0;
    this.radius = 50;
    this.enabled = enabled;

    // 仅在启用时创建摇杆
    if (this.enabled) {
      // 在所有设备上都显示摇杆
      this.create();
      this.bindEvents();
    }
  }

  create() {
    const x = 200;
    const y = this.scene.scale.height - 200;
    this.centerX = x;
    this.centerY = y;

    this.base = this.scene.add.circle(x, y, this.radius, 0x444444, 0.5);
    this.knob = this.scene.add.circle(x, y, this.radius * 0.5, 0xff0000, 0.8);

    this.base.setScrollFactor(0); // 不随相机移动
    this.knob.setScrollFactor(0);
  }

  bindEvents() {
    this.scene.input.on('pointerdown', (ptr) => {
      if (this.isInBase(ptr)) {
        // 只有在没有激活指针时才设置新指针
        // 这样可以避免不同触摸点之间的干扰
        if (!this.isActive) {
          this.activePointer = ptr;
          this.isActive = true;
        }
      }
    });

    this.scene.input.on('pointermove', (ptr) => {
      if (this.isActive && this.activePointer === ptr) {
        const dx = ptr.x - this.centerX;
        const dy = ptr.y - this.centerY;
        const distance = Math.sqrt(dx * dx + dy * dy);

        if (distance > this.radius) {
          // 限制在圆内
          const angle = Math.atan2(dy, dx);
          const knobX = this.centerX + Math.cos(angle) * this.radius;
          const knobY = this.centerY + Math.sin(angle) * this.radius;
          this.knob.setPosition(knobX, knobY);
        } else {
          this.knob.setPosition(ptr.x, ptr.y);
        }

        // 发送相对方向（归一化）
        const dirX = dx / this.radius;
        const dirY = dy / this.radius;
        this.scene.events.emit('move-relative', { x: dirX, y: dirY });
      }
    });

    this.scene.input.on('pointerup', (ptr) => {
      if (this.activePointer === ptr) {
        this.isActive = false;
        this.activePointer = null;
        this.knob.setPosition(this.centerX, this.centerY);
        this.scene.events.emit('move-relative', { x: 0, y: 0 }); // 停止
      }
    });

    // 处理指针离开屏幕的情况
    this.scene.input.on('pointerout', (ptr) => {
      if (this.activePointer === ptr) {
        this.isActive = false;
        this.activePointer = null;
        this.knob.setPosition(this.centerX, this.centerY);
        this.scene.events.emit('move-relative', { x: 0, y: 0 }); // 停止
      }
    });
  }

  isInBase(pointer) {
    const dx = pointer.x - this.centerX;
    const dy = pointer.y - this.centerY;
    return Math.sqrt(dx * dx + dy * dy) <= this.radius + 20; // 容差
  }

  /**
   * 更新方法，用于在游戏循环中持续发送移动指令
   */
  update() {
    // 仅在启用时更新
    if (this.enabled && this.isActive && this.activePointer) {
      const dx = this.activePointer.x - this.centerX;
      const dy = this.activePointer.y - this.centerY;
      
      // 发送相对方向（归一化）
      const dirX = dx / this.radius;
      const dirY = dy / this.radius;
      this.scene.events.emit('move-relative', { x: dirX, y: dirY });
    }
  }
}