var Hammer = require('./module/hammer');

/**
 * Register a touch event, taking place before a gesture
 * @param {Hammer} hammer       A hammer instance
 * @param {function} callback   Callback, called as callback(event)
 */
exports.onTouch = function (hammer, callback) {
  callback.inputHandler = function (event) {
    if (event.isFirst) {
      callback(event);
    }
  };

  hammer.on('hammer.input', callback.inputHandler);
};

/**
 * Register a release event, taking place after a gesture
 * @param {Hammer} hammer       A hammer instance
 * @param {function} callback   Callback, called as callback(event)
 */
exports.onRelease = function (hammer, callback) {
  callback.inputHandler = function (event) {
    if (event.isFinal) {
      callback(event);
    }
  };

  return hammer.on('hammer.input', callback.inputHandler);
};


/**
 * Unregister a touch event, taking place before a gesture
 * @param {Hammer} hammer       A hammer instance
 * @param {function} callback   Callback, called as callback(event)
 */
exports.offTouch = function (hammer, callback) {
  hammer.off('hammer.input', callback.inputHandler);
};

/**
 * Unregister a release event, taking place before a gesture
 * @param {Hammer} hammer       A hammer instance
 * @param {function} callback   Callback, called as callback(event)
 */
exports.offRelease = exports.offTouch;

/**
 * Hack the PinchRecognizer such that it doesn't prevent default behavior
 * for vertical panning.
 * @param {Hammer.Pinch} pinchRecognizer
 * @return {Hammer.Pinch} returns the pinchRecognizer
 */
exports.disablePreventDefaultVertically = function (pinchRecognizer) {
  var TOUCH_ACTION_PAN_Y = 'pan-y';

  pinchRecognizer.getTouchAction = function() {
    // default method returns [TOUCH_ACTION_NONE]
    return [TOUCH_ACTION_PAN_Y];
  };

  return pinchRecognizer;
};