/*
 * Copyright 2000-2009 JetBrains s.r.o.
 *
 * 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.intellij.util.ui.update;

import com.intellij.openapi.Disposable;
import com.intellij.openapi.application.Application;
import com.intellij.openapi.application.ApplicationManager;
import com.intellij.openapi.application.ModalityState;
import com.intellij.openapi.project.DumbAwareRunnable;
import com.intellij.openapi.util.Disposer;
import org.jetbrains.annotations.NotNull;

import javax.swing.*;
import java.awt.*;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
import java.lang.ref.WeakReference;

public class UiNotifyConnector implements Disposable, HierarchyListener{

  @NotNull
  private final WeakReference<Component> myComponent;
  private Activatable myTarget;

  public UiNotifyConnector(@NotNull final Component component, @NotNull final Activatable target) {
    myComponent = new WeakReference<Component>(component);
    myTarget = target;
    if (component.isShowing()) {
      showNotify();
    } else {
      hideNotify();
    }
    component.addHierarchyListener(this);
  }

  public void hierarchyChanged(HierarchyEvent e) {
    if (isDisposed()) return;

    if ((e.getChangeFlags() & HierarchyEvent.SHOWING_CHANGED) > 0) {
      final Runnable runnable = new DumbAwareRunnable() {
        public void run() {
          final Component c = myComponent.get();
          if (isDisposed() || c == null) return;

          if (c.isShowing()) {
            showNotify();
          }
          else {
            hideNotify();
          }
        }
      };
      final Application app = ApplicationManager.getApplication();
      if (app != null && app.isDispatchThread()) {
        app.invokeLater(runnable, ModalityState.current());
      } else {
        //noinspection SSBasedInspection
        SwingUtilities.invokeLater(runnable);
      }
    }
  }

  protected void hideNotify() {
    myTarget.hideNotify();
  }

  protected void showNotify() {
    myTarget.showNotify();
  }

  public void dispose() {
    if (isDisposed()) return;

    myTarget.hideNotify();
    final Component c = myComponent.get();
    if (c != null) {
      c.removeHierarchyListener(this);
    }

    myTarget = null;
    myComponent.clear();
  }

  private boolean isDisposed() {
    return myTarget == null;
  }

  public static class Once extends UiNotifyConnector {

    private boolean myShown;
    private boolean myHidden;

    public Once(final Component component, final Activatable target) {
      super(component, target);
    }

    protected final void hideNotify() {
      super.hideNotify();
      myHidden = true;
      disposeIfNeeded();
    }

    protected final void showNotify() {
      super.showNotify();
      myShown = true;
      disposeIfNeeded();
    }

    private void disposeIfNeeded() {
      if (myShown && myHidden) {
        Disposer.dispose(this);
      }
    }
  }

  public static void doWhenFirstShown(@NotNull JComponent c, @NotNull final Runnable runnable) {
    new Once(c, new Activatable() {
      public void showNotify() {
        runnable.run();        
      }

      public void hideNotify() {
      }
    });
  }

}