/**
 * Copyright 2010 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.wavepanel.impl.focus;

import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.event.dom.client.MouseDownEvent;

import org.waveprotocol.wave.client.common.util.KeyCombo;
import org.waveprotocol.wave.client.wavepanel.WavePanel;
import org.waveprotocol.wave.client.wavepanel.event.EventHandlerRegistry;
import org.waveprotocol.wave.client.wavepanel.event.KeySignalHandler;
import org.waveprotocol.wave.client.wavepanel.event.KeySignalRouter;
import org.waveprotocol.wave.client.wavepanel.event.WaveMouseDownHandler;
import org.waveprotocol.wave.client.wavepanel.view.View.Type;
import org.waveprotocol.wave.client.wavepanel.view.dom.DomAsViewProvider;
import org.waveprotocol.wave.client.wavepanel.view.dom.full.TypeCodes;

import java.util.EnumSet;

/**
 * Interpets user gestures as focus-frame actions.
 *
 */
public final class FocusFrameController implements WaveMouseDownHandler, KeySignalHandler {
  private final FocusFramePresenter focus;
  private final DomAsViewProvider panel;

  /**
   * Creates a focus controller.
   */
  private FocusFrameController(FocusFramePresenter focus, DomAsViewProvider panel) {
    this.focus = focus;
    this.panel = panel;
  }

  /**
   * Installs the focus-frame feature in a wave panel.
   */
  public static void install(FocusFramePresenter focus, WavePanel panel) {
    new FocusFrameController(focus, panel.getViewProvider()).install(
        panel.getHandlers(), panel.getKeyRouter());
  }

  private void install(EventHandlerRegistry handlers, KeySignalRouter keys) {
    handlers.registerMouseDownHandler(TypeCodes.kind(Type.BLIP), this);
    keys.register(
        EnumSet.of(KeyCombo.UP, KeyCombo.DOWN, KeyCombo.SPACE, KeyCombo.SHIFT_SPACE), this);
  }

  @Override
  public boolean onMouseDown(MouseDownEvent event, Element source) {
    if (event.getNativeButton() != NativeEvent.BUTTON_LEFT) {
      return false;
    }
    focus.focusWithoutScroll(panel.asBlip(source));
    // Cancel bubbling, so that other blips do not grab focus.
    return true;
  }

  @Override
  public boolean onKeySignal(KeyCombo key) {
    switch (key) {
      case UP:
        focus.moveUp();
        return true;
      case DOWN:
        focus.moveDown();
        return true;
      case SPACE:
        focus.focusNext();
        return true;
      case SHIFT_SPACE:
        focus.focusPrevious();
        return true;
      default:
        return false;
    }
  }
}