// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

part of dart.html;

/**
 * Helper class to implement custom events which wrap DOM events.
 */
class _WrappedEvent implements Event {
  /** Needed because KeyboardEvent is implements.
   *  TODO(terry): Consider making blink_jsObject private (add underscore) for
   *               all blink_jsObject.  Then needed private wrap/unwrap_jso
   *               functions that delegate to a public wrap/unwrap_jso.
   */
  js.JsObject blink_jsObject;

  final Event wrapped;

  /** The CSS selector involved with event delegation. */
  String _selector;

  _WrappedEvent(this.wrapped);

  bool get bubbles => wrapped.bubbles;

  bool get cancelable => wrapped.cancelable;

  DataTransfer get clipboardData => wrapped.clipboardData;

  EventTarget get currentTarget => wrapped.currentTarget;

  bool get defaultPrevented => wrapped.defaultPrevented;

  int get eventPhase => wrapped.eventPhase;

  EventTarget get target => wrapped.target;

  int get timeStamp => wrapped.timeStamp;

  String get type => wrapped.type;

  void _initEvent(String eventTypeArg, bool canBubbleArg,
      bool cancelableArg) {
    throw new UnsupportedError(
        'Cannot initialize this Event.');
  }

  void preventDefault() {
    wrapped.preventDefault();
  }

  void stopImmediatePropagation() {
    wrapped.stopImmediatePropagation();
  }

  void stopPropagation() {
    wrapped.stopPropagation();
  }

  /**
   * A pointer to the element whose CSS selector matched within which an event
   * was fired. If this Event was not associated with any Event delegation,
   * accessing this value will throw an [UnsupportedError].
   */
  Element get matchingTarget {
    if (_selector == null) {
      throw new UnsupportedError('Cannot call matchingTarget if this Event did'
          ' not arise as a result of event delegation.');
    }
    var currentTarget = this.currentTarget;
    var target = this.target;
    var matchedTarget;
    do {
      if (target.matches(_selector)) return target;
      target = target.parent;
    } while (target != null && target != currentTarget.parent);
    throw new StateError('No selector matched for populating matchedTarget.');
  }

  /**
   * This event's path, taking into account shadow DOM.
   *
   * ## Other resources
   *
   * * [Shadow DOM extensions to Event]
   * (http://w3c.github.io/webcomponents/spec/shadow/#extensions-to-event) from
   * W3C.
   */
  // https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#extensions-to-event
  @Experimental()
  List<Node> get path => wrapped.path;
}