/*
 * Copyright 2016 The Bazel Authors. All rights reserved.
 *
 * 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.idea.testing;


import com.intellij.lang.LanguageExtensionPoint;
import com.intellij.openapi.Disposable;
import com.intellij.openapi.application.Application;
import com.intellij.openapi.application.ApplicationManager;
import com.intellij.openapi.components.impl.ComponentManagerImpl;
import com.intellij.openapi.extensions.ExtensionPoint;
import com.intellij.openapi.extensions.ExtensionPointName;
import com.intellij.openapi.extensions.Extensions;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.Disposer;
import org.picocontainer.MutablePicoContainer;

/** Utility class for registering project services, application services and extensions. */
public class ServiceHelper {

  public static <T> void registerExtension(
      ExtensionPointName<T> name, T instance, Disposable parentDisposable) {
    ExtensionPoint<T> ep = Extensions.getRootArea().getExtensionPoint(name);
    ep.registerExtension(instance);
    Disposer.register(parentDisposable, () -> ep.unregisterExtension(instance));
  }

  /** Unregister all extensions of the given class, for the given extension point. */
  public static <T> void unregisterLanguageExtensionPoint(
      String extensionPointKey, Class<T> clazz, Disposable parentDisposable) {
    ExtensionPoint<LanguageExtensionPoint<T>> ep =
        Extensions.getRootArea().getExtensionPoint(extensionPointKey);
    LanguageExtensionPoint<T>[] existingExtensions = ep.getExtensions();
    for (LanguageExtensionPoint<T> ext : existingExtensions) {
      if (clazz.getName().equals(ext.implementationClass)) {
        ep.unregisterExtension(ext);
        Disposer.register(parentDisposable, () -> ep.registerExtension(ext));
      }
    }
  }

  public static <T> void registerApplicationService(
      Class<T> key, T implementation, Disposable parentDisposable) {
    registerComponentInstance(
        (MutablePicoContainer) ApplicationManager.getApplication().getPicoContainer(),
        key,
        implementation,
        parentDisposable);
  }

  public static <T> void registerApplicationComponent(
      Class<T> key, T implementation, Disposable parentDisposable) {
    Application application = ApplicationManager.getApplication();
    if (application instanceof ComponentManagerImpl) {
      replaceComponentInstance(
          (ComponentManagerImpl) application, key, implementation, parentDisposable);
    } else {
      registerComponentInstance(
          (MutablePicoContainer) application.getPicoContainer(),
          key,
          implementation,
          parentDisposable);
    }
  }

  public static <T> void registerProjectService(
      Project project, Class<T> key, T implementation, Disposable parentDisposable) {
    registerComponentInstance(
        (MutablePicoContainer) project.getPicoContainer(), key, implementation, parentDisposable);
  }

  private static <T> void registerComponentInstance(
      MutablePicoContainer container, Class<T> key, T implementation, Disposable parentDisposable) {
    Object old = container.getComponentInstance(key);
    container.unregisterComponent(key.getName());
    container.registerComponentInstance(key.getName(), implementation);
    Disposer.register(
        parentDisposable,
        () -> {
          container.unregisterComponent(key.getName());
          if (old != null) {
            container.registerComponentInstance(key.getName(), old);
          }
        });
  }

  private static <T> void replaceComponentInstance(
      ComponentManagerImpl componentManager,
      Class<T> key,
      T implementation,
      Disposable parentDisposable) {
    T old = componentManager.registerComponentInstance(key, implementation);
    Disposer.register(parentDisposable, () -> componentManager.registerComponentInstance(key, old));
  }
}