/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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.googlecode.android_scripting;

import android.app.Notification;
import android.app.NotificationManager;
import android.app.Service;

import java.lang.reflect.Method;

public abstract class ForegroundService extends Service {
  private static final Class<?>[] mStartForegroundSignature =
      new Class[] { int.class, Notification.class };
  private static final Class<?>[] mStopForegroundSignature = new Class[] { boolean.class };

  private final int mNotificationId;

  private NotificationManager mNotificationManager;
  private Method mStartForeground;
  private Method mStopForeground;
  private Object[] mStartForegroundArgs = new Object[2];
  private Object[] mStopForegroundArgs = new Object[1];

  public ForegroundService(int id) {
    mNotificationId = id;
  }

  protected abstract Notification createNotification();

  /**
   * @return The NotificationManager for this Context.
   */
  protected NotificationManager getNotificationManager() {
    if (mNotificationManager == null) {
      mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
    }
    return mNotificationManager;
  }

  /**
   * This is a wrapper around the new startForeground method, using the older APIs if it is not
   * available.
   */
  private void startForegroundCompat(Notification notification) {
    // If we have the new startForeground API, then use it.
    if (mStartForeground != null) {
      mStartForegroundArgs[0] = Integer.valueOf(mNotificationId);
      mStartForegroundArgs[1] = notification;
      try {
        mStartForeground.invoke(this, mStartForegroundArgs);
      } catch (Exception e) {
        Log.e(e);
      }
      return;
    }

    // Fall back on the old API.
    setForeground(true);
    if (notification != null) {
      getNotificationManager().notify(mNotificationId, notification);
    }
  }

  /**
   * This is a wrapper around the new stopForeground method, using the older APIs if it is not
   * available.
   */
  private void stopForegroundCompat() {
    // If we have the new stopForeground API, then use it.
    if (mStopForeground != null) {
      mStopForegroundArgs[0] = Boolean.TRUE;
      try {
        mStopForeground.invoke(this, mStopForegroundArgs);
      } catch (Exception e) {
        Log.e(e);
      }
      return;
    }

    // Fall back on the old API. Note to cancel BEFORE changing the
    // foreground state, since we could be killed at that point.
    getNotificationManager().cancel(mNotificationId);
    setForeground(false);
  }

  @Override
  public void onCreate() {
    try {
      mStartForeground = getClass().getMethod("startForeground", mStartForegroundSignature);
      mStopForeground = getClass().getMethod("stopForeground", mStopForegroundSignature);
    } catch (NoSuchMethodException e) {
      // Running on an older platform.
      mStartForeground = mStopForeground = null;
    }
    startForegroundCompat(createNotification());
  }

  @Override
  public void onDestroy() {
    // Make sure our notification is gone.
    stopForegroundCompat();
  }
}