/*
 * Copyright (C) 2015 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.android.mtp;

import android.annotation.NonNull;
import android.annotation.Nullable;
import android.app.Notification;
import android.app.Service;
import android.app.NotificationManager;
import android.content.Intent;
import android.os.IBinder;
import android.os.Parcelable;
import android.service.notification.StatusBarNotification;
import android.util.Log;
import com.android.internal.util.Preconditions;
import java.util.HashSet;
import java.util.Set;

Service to manage lifetime of DocumentsProvider's process.
The service prevents the system from killing the process that holds USB connections. The service
starts to run when the first MTP device is opened, and stops when the last MTP device is closed.
/**
 * Service to manage lifetime of DocumentsProvider's process.
 * The service prevents the system from killing the process that holds USB connections. The service
 * starts to run when the first MTP device is opened, and stops when the last MTP device is closed.
 */
public class MtpDocumentsService extends Service {
    static final String ACTION_UPDATE_NOTIFICATION = "com.android.mtp.UPDATE_NOTIFICATION";
    static final String EXTRA_DEVICE_IDS = "deviceIds";
    static final String EXTRA_DEVICE_NOTIFICATIONS = "deviceNotifications";

    private NotificationManager mNotificationManager;

    @Override
    public IBinder onBind(Intent intent) {
        // The service is used via intents.
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mNotificationManager = getSystemService(NotificationManager.class);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        // If intent is null, the service was restarted.
        if (intent == null || ACTION_UPDATE_NOTIFICATION.equals(intent.getAction())) {
            final int[] ids = intent.hasExtra(EXTRA_DEVICE_IDS) ?
                    intent.getExtras().getIntArray(EXTRA_DEVICE_IDS) : null;
            final Notification[] notifications = intent.hasExtra(EXTRA_DEVICE_NOTIFICATIONS) ?
                    castToNotifications(intent.getExtras().getParcelableArray(
                            EXTRA_DEVICE_NOTIFICATIONS)) : null;
            return updateForegroundState(ids, notifications) ? START_STICKY : START_NOT_STICKY;
        }
        return START_NOT_STICKY;
    }

    
Updates the foreground state of the service.
Returns:
Whether the service is foreground or not./**
     * Updates the foreground state of the service.
     * @return Whether the service is foreground or not.
     */
    private boolean updateForegroundState(
            @Nullable int[] ids, @Nullable Notification[] notifications) {
        final Set<Integer> openedNotification = new HashSet<>();
        final int size = ids != null ? ids.length : 0;
        if (size != 0) {
            Preconditions.checkArgument(ids != null);
            Preconditions.checkArgument(notifications != null);
            Preconditions.checkArgument(ids.length == notifications.length);
        }

        for (int i = 0; i < size; i++) {
            if (i == 0) {
                // Mark this service as foreground with the notification so that the process is
                // not killed by the system while a MTP device is opened.
                startForeground(ids[i], notifications[i]);
            } else {
                // Only one notification can be shown as a foreground notification. We need to
                // show the rest as normal notification.
                mNotificationManager.notify(ids[i], notifications[i]);
            }
            openedNotification.add(ids[i]);
        }

        final StatusBarNotification[] activeNotifications =
                mNotificationManager.getActiveNotifications();
        for (final StatusBarNotification notification : activeNotifications) {
            if (!openedNotification.contains(notification.getId())) {
                mNotificationManager.cancel(notification.getId());
            }
        }

        if (size == 0) {
            // There is no opened device.
            stopForeground(true /* removeNotification */);
            stopSelf();
            return false;
        }

        return true;
    }

    private static @NonNull Notification[] castToNotifications(@NonNull Parcelable[] src) {
        Preconditions.checkNotNull(src);
        final Notification[] notifications = new Notification[src.length];
        for (int i = 0; i < src.length; i++) {
            notifications[i] = (Notification) src[i];
        }
        return notifications;
    }
}