/**
 * Copyright 2009 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 org.waveprotocol.wave.client.editor.selection.content;

import org.waveprotocol.wave.client.editor.content.ContentElement;
import org.waveprotocol.wave.client.editor.content.ContentNode;
import org.waveprotocol.wave.client.editor.content.ContentTextNode;
import org.waveprotocol.wave.model.document.ReadableDocument;
import org.waveprotocol.wave.model.document.util.FocusedPointRange;
import org.waveprotocol.wave.model.document.util.Point;
import org.waveprotocol.wave.model.document.util.TextLocator;

/**
 * Implementation of CaretMovement that manually traverses the document.
 *
 * TODO(user): Add an IE specific implementation that uses native methods.
 *
 */
public final class CaretMovementHelperImpl implements CaretMovementHelper {
  // We use the persistent view here rather than renderedView because
  // the word boundary detection code works on contiguous text nodes. We want to
  // ignore rendered nodes such as formatting.
  private final ReadableDocument<ContentNode, ContentElement, ContentTextNode> persistentView;
  private final SelectionHelper selectionHelper;

  public CaretMovementHelperImpl(
      ReadableDocument<ContentNode, ContentElement, ContentTextNode> persistentView,
      SelectionHelper selectionHelper) {
    this.persistentView = persistentView;
    this.selectionHelper = selectionHelper;
  }

  @Override
  public Point<ContentNode> getWordBoundary(boolean forward) {
    FocusedPointRange<ContentNode> range = selectionHelper.getSelectionPoints();
    if (range == null) {
      return null;
    }
    return TextLocator.getWordBoundary(range.getFocus(), persistentView, forward);
  }
}