import Phaser from '../lib/phaser.js';

/**
 * Uses the Phaser 3 built in drag events to allow a game object to be moved around a Phaser 3 Scene instance.
 * The method will listen for the GameObject Destroy event and cleanup the various event listeners that
 * were registered.
 * @param {Phaser.GameObjects.Image} gameObject
 * @param {boolean} [enableLogs=false] enables logging for the various drag event callbacks. If the gameObject.name field
 *                                     is populated, this will be included in the log line.
 */
export function makeDraggable(gameObject, enableLogs = false) {
  gameObject.setInteractive();

  /**
   * @param {string} message
   * @returns {void}
   */
  function log(message) {
    if (enableLogs) {
      console.debug(message);
    }
  }

  /**
   * @param {Phaser.Input.Pointer} pointer
   * @returns {void}
   */
  function onDrag(pointer) {
    log(`[makeDraggable:onDrag] invoked for game object: ${gameObject.name}`);
    gameObject.x = pointer.x;
    gameObject.y = pointer.y;
  }

  /**
   * @returns {void}
   */
  function stopDrag() {
    log(`[makeDraggable:stopDrag] invoked for game object: ${gameObject.name}`);
    gameObject.on(Phaser.Input.Events.POINTER_DOWN, startDrag);
    gameObject.off(Phaser.Input.Events.POINTER_MOVE, onDrag);
    gameObject.off(Phaser.Input.Events.POINTER_UP, stopDrag);
    gameObject.x = Math.round(gameObject.x);
    gameObject.y = Math.round(gameObject.y);
  }

  /**
   * @returns {void}
   */
  function startDrag() {
    log(`[makeDraggable:startDrag] invoked for game object: ${gameObject.name}`);
    gameObject.off(Phaser.Input.Events.POINTER_DOWN, startDrag);
    gameObject.on(Phaser.Input.Events.POINTER_MOVE, onDrag);
    gameObject.on(Phaser.Input.Events.POINTER_UP, stopDrag);
  }

  /**
   * @returns {void}
   */
  function destroy() {
    log(`[makeDraggable:destroy] invoked for game object: ${gameObject.name}`);
    gameObject.off(Phaser.Input.Events.POINTER_DOWN, startDrag);
    gameObject.off(Phaser.Input.Events.POINTER_MOVE, onDrag);
    gameObject.off(Phaser.Input.Events.POINTER_UP, stopDrag);
  }

  gameObject.on(Phaser.Input.Events.POINTER_DOWN, startDrag);
  gameObject.once(Phaser.GameObjects.Events.DESTROY, destroy);
}