// Copyright (c) 2011, 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 touch;

/**
 * Common effects related helpers.
 */
class FxUtil {
  /** On transition end event. */
  static const TRANSITION_END_EVENT = 'webkitTransitionEnd';

  /** The translate3d transform function. */
  static const TRANSLATE_3D = 'translate3d';

  /** The rotate transform function. */
  static const ROTATE = 'rotate';

  /** The scale transform function. */
  static const SCALE = 'scale';

  /** Stops and clears the transition on an element. */
  static void clearWebkitTransition(Element el) {
    el.style.transition = '';
  }

  static void setPosition(Element el, Coordinate point) {
    num x = point.x;
    num y = point.y;
    el.style.transform = '${TRANSLATE_3D}(${x}px,${y}px,0px)';
  }

  /** Apply a transform using translate3d to an HTML element. */
  static void setTranslate(Element el, num x, num y, num z) {
    el.style.transform = '${TRANSLATE_3D}(${x}px,${y}px,${z}px)';
  }

  /** Apply a -webkit-transform using translate3d to an HTML element. */
  static void setWebkitTransform(Element el, num x, num y,
      [num z = 0,
      num rotation = null,
      num scale = null,
      num originX = null,
      num originY = null]) {
    final style = el.style;
    // TODO(jacobr): create a helper class that simplifies building
    // transformation matricies that will be set as CSS styles. We should
    // consider using CSSMatrix although that may be overkill.
    String transform = '${TRANSLATE_3D}(${x}px,${y}px,${z}px)';
    if (rotation != null) {
      transform += ' ${ROTATE}(${rotation}deg)';
    }
    if (scale != null) {
      transform += ' ${SCALE}(${scale})';
    }
    style.transform = transform;
    if (originX != null || originY != null) {
      assert(originX != null && originY != null);
      style.transformOrigin = '${originX}px ${originY}px';
    }
  }

  /**
   * Determine the position of an [element] relative to a [target] element.
   * Moving the [element] to be a child of [target] and setting the
   * [element]'s top and left values to the returned coordinate should result
   * in the [element]'s position remaining unchanged while its parent is
   * changed.
   */
  static Coordinate computeRelativePosition(Element element, Element target) {
    final testPoint = new Point(0, 0);
    /*
    final pagePoint =
        window.convertPointFromNodeToPage(element, testPoint);
    final pointRelativeToTarget =
        window.convertPointFromPageToNode(target, pagePoint);
    return new Coordinate(pointRelativeToTarget.x, pointRelativeToTarget.y);
    */
    // TODO(sra): Test this version that avoids the nonstandard
    // `convertPointFromPageToNode`.
    var eRect = element.getBoundingClientRect();
    var tRect = target.getBoundingClientRect();
    return new Coordinate(eRect.left - tRect.left, eRect.top - tRect.top);
  }

  /** Clear a -webkit-transform from an element. */
  static void clearWebkitTransform(Element el) {
    el.style.transform = '';
  }

  /**
   * Checks whether an element has a translate3d webkit transform applied.
   */
  static bool hasWebkitTransform(Element el) {
    return el.style.transform.indexOf(TRANSLATE_3D, 0) != -1;
  }

  /**
   * Translates [el], an HTML element that has a relative CSS
   * position, by setting its left and top CSS styles.
   */
  static void setLeftAndTop(Element el, num x, num y) {
    final style = el.style;
    style.left = '${x}px';
    style.top = '${y}px';
  }
}

class TransitionTimingFunction {
  static const EASE_IN = 'ease-in';
  static const EASE_OUT = 'ease-out';
  static const EASE_IN_OUT = 'ease-in-out';
}