/**
 * Copyright 2011 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.toolbar;

import org.waveprotocol.wave.client.editor.Editor;
import org.waveprotocol.wave.client.wavepanel.WavePanel;
import org.waveprotocol.wave.client.wavepanel.impl.edit.EditSession;
import org.waveprotocol.wave.client.wavepanel.view.BlipView;

/**
 * Switches between two toolbars, a "view" and "edit" toolbar, as the client
 * moves in and out of edit mode.
 *
 * @author kalman@google.com (Benjamin Kalman)
 */
public final class ToolbarSwitcher implements EditSession.Listener {

  private final WavePanel panel;
  private final EditSession editSession;
  private final ViewToolbar viewToolbar;
  private final EditToolbar editToolbar;

  private ToolbarSwitcher(WavePanel panel, EditSession editSession,
      ViewToolbar viewToolbar, EditToolbar editToolbar) {
    this.panel = panel;
    this.editSession = editSession;
    this.viewToolbar = viewToolbar;
    this.editToolbar = editToolbar;
  }

  /**
   * Creates a new {@link ToolbarSwitcher} and initialises it.
   */
  public static ToolbarSwitcher install(WavePanel panel, EditSession editSession,
      ViewToolbar viewToolbar, EditToolbar editToolbar) {
    ToolbarSwitcher switcher = new ToolbarSwitcher(panel, editSession, viewToolbar, editToolbar);
    switcher.init();
    return switcher;
  }

  private void init() {
    viewToolbar.init();
    editToolbar.init();
    editSession.addListener(this);
    if (editSession.isEditing()) {
      startEditSession(editSession.getEditor());
    } else if (panel.hasContents()) {
      startViewSession();
    }
  }

  @Override
  public void onSessionStart(Editor editor, BlipView blipUi) {
    viewToolbar.getWidget().removeFromParent();
    startEditSession(editor);
  }

  private void startEditSession(Editor editor) {
    panel.getContents().setToolbar(editToolbar.getWidget().getElement());
    panel.getGwtPanel().doAdopt(editToolbar.getWidget());
    editToolbar.enable(editor);
  }

  @Override
  public void onSessionEnd(Editor editor, BlipView blipUi) {
    editToolbar.disable(editor);
    editToolbar.getWidget().removeFromParent();
    startViewSession();
  }

  private void startViewSession() {
    panel.getContents().setToolbar(viewToolbar.getWidget().getElement());
    panel.getGwtPanel().doAdopt(viewToolbar.getWidget());
  }
}