/*
 * Copyright 2008 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.dom.client;

/**
 * Internet Explorer 6 implementation of
 * {@link com.google.gwt.user.client.impl.DOMImpl}.
 */
class DOMImplIE6 extends DOMImplTrident {

  @Override
  public int getAbsoluteLeft(Element elem) {
    Document doc = elem.getOwnerDocument();
    return (int) Math.floor(getBoundingClientRectLeft(elem)
        / getZoomMultiple(doc) + doc.getScrollLeft());
  }

  @Override
  public int getAbsoluteTop(Element elem) {
    Document doc = elem.getOwnerDocument();
    return (int) Math.floor(getBoundingClientRectTop(elem)
        / getZoomMultiple(doc) + doc.getScrollTop());
  }

  @Override
  public int getScrollLeft(Element elem) {
    if (isRTL(elem)) {
      return super.getScrollLeft(elem) - (elem.getScrollWidth() - elem.getClientWidth());
    }
    return super.getScrollLeft(elem);
  }

  public native boolean hasAttribute(Element elem, String name) /*-{
    var node = elem.getAttributeNode(name);
    return !!(node && node.specified);
  }-*/;

  /*
   * The src may not be set yet because of funky logic in setImgSrc(). See
   * setImgSrc().
   */
  @Override
  public String imgGetSrc(Element img) {
    return ImageSrcIE6.getImgSrc(img);
  }

  /**
   * Works around an IE problem where multiple images trying to load at the same
   * time will generate a request per image. We fix this by only allowing the
   * first image of a given URL to set its source immediately, but simultaneous
   * requests for the same URL don't actually get their source set until the
   * original load is complete.
   */
  @Override
  public void imgSetSrc(Element img, String src) {
    ImageSrcIE6.setImgSrc(img, src);
  }

  @Override
  public void setScrollLeft(Element elem, int left) {
    if (isRTL(elem)) {
      left += elem.getScrollWidth() - elem.getClientWidth();
    }
    super.setScrollLeft(elem, left);
  }

  /**
   * Get the zoom multiple based on the current IE zoom level. A multiple of 2.0
   * means that the user has zoomed in to 200%.
   * 
   * @return the zoom multiple
   */
  private double getZoomMultiple(Document doc) {
    if (doc.getCompatMode().equals("CSS1Compat")) {
      return 1;
    } else {
      // TODO(FINDBUGS): is integer division correct?
      int bodyOffset = doc.getBody().getOffsetWidth();
      return bodyOffset == 0 ? 1
          : doc.getBody().getParentElement().getOffsetWidth() / bodyOffset;
    }
  }
}