/*
 * 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.blaze.base.async.executor;

import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.intellij.openapi.components.ServiceManager;
import com.intellij.openapi.progress.PerformInBackgroundOption;
import com.intellij.openapi.progress.ProgressManager;
import com.intellij.openapi.progress.Progressive;
import com.intellij.openapi.progress.impl.BackgroundableProcessIndicator;
import com.intellij.openapi.progress.util.AbstractProgressIndicatorExBase;
import com.intellij.openapi.progress.util.ProgressWindow;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.Computable;
import com.intellij.util.ui.UIUtil;
import java.util.concurrent.Callable;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/** Shared thread pool for blaze tasks. */
public abstract class BlazeExecutor {
  /** The type of modality used to launch tasks */
  public enum Modality {
    MODAL, // This task must start in the foreground and stay there.
    BACKGROUNDABLE, // This task will start in the foreground, but can be sent to the background.
    ALWAYS_BACKGROUND // This task will start in the background and stay there.
  }

  @NotNull
  public static BlazeExecutor getInstance() {
    return ServiceManager.getService(BlazeExecutor.class);
  }

  public abstract <T> ListenableFuture<T> submit(Callable<T> callable);

  public abstract ListeningExecutorService getExecutor();

  public static ListenableFuture<Void> submitTask(
      @Nullable final Project project, @NotNull final Progressive progressive) {
    return submitTask(project, "", progressive);
  }

  public static ListenableFuture<Void> submitTask(
      @Nullable final Project project,
      @NotNull final String title,
      @NotNull final Progressive progressive) {
    return submitTask(
        project, title, true /* cancelable */, Modality.ALWAYS_BACKGROUND, progressive);
  }

  public static ListenableFuture<Void> submitTask(
      @Nullable final Project project,
      @NotNull final String title,
      final boolean cancelable,
      final Modality modality,
      @NotNull final Progressive progressive) {

    // The progress indicator must be created on the UI thread.
    final ProgressWindow indicator =
        UIUtil.invokeAndWaitIfNeeded(
            new Computable<ProgressWindow>() {
              @Override
              public ProgressWindow compute() {
                if (modality == Modality.MODAL) {
                  ProgressWindow indicator = new ProgressWindow(cancelable, project);
                  indicator.setTitle(title);
                  return indicator;
                } else {
                  PerformInBackgroundOption backgroundOption =
                      modality == Modality.BACKGROUNDABLE
                          ? PerformInBackgroundOption.DEAF
                          : PerformInBackgroundOption.ALWAYS_BACKGROUND;
                  return new BackgroundableProcessIndicator(
                      project, title, backgroundOption, "Cancel", "Cancel", cancelable);
                }
              }
            });

    indicator.setIndeterminate(true);
    indicator.start();
    final Runnable process =
        new Runnable() {
          @Override
          public void run() {
            progressive.run(indicator);
          }
        };
    final ListenableFuture<Void> future =
        getInstance()
            .submit(
                new Callable<Void>() {
                  @Override
                  public Void call() throws Exception {
                    ProgressManager.getInstance().runProcess(process, indicator);
                    return null;
                  }
                });
    if (cancelable) {
      indicator.addStateDelegate(
          new AbstractProgressIndicatorExBase() {
            @Override
            public void cancel() {
              super.cancel();
              future.cancel(true);
            }
          });
    }
    return future;
  }
}