/*
 * Copyright (C) 2013 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 android.service.notification;

import android.annotation.SdkConstant;
import android.app.INotificationManager;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.IBinder;
import android.os.ServiceManager;
import android.util.Log;

/**
 * A service that receives calls from the system when new notifications are posted or removed.
 * <p>To extend this class, you must declare the service in your manifest file with
 * the {@link android.Manifest.permission#BIND_NOTIFICATION_LISTENER_SERVICE} permission
 * and include an intent filter with the {@link #SERVICE_INTERFACE} action. For example:</p>
 * <pre>
 * &lt;service android:name=".NotificationListener"
 *          android:label="&#64;string/service_name"
 *          android:permission="android.permission.BIND_NOTIFICATION_LISTENER_SERVICE">
 *     &lt;intent-filter>
 *         &lt;action android:name="android.service.notification.NotificationListenerService" />
 *     &lt;/intent-filter>
 * &lt;/service></pre>
 */
public abstract class NotificationListenerService extends Service {
    // TAG = "NotificationListenerService[MySubclass]"
    private final String TAG = NotificationListenerService.class.getSimpleName()
            + "[" + getClass().getSimpleName() + "]";

    private INotificationListenerWrapper mWrapper = null;

    private INotificationManager mNoMan;

    /**
     * The {@link Intent} that must be declared as handled by the service.
     */
    @SdkConstant(SdkConstant.SdkConstantType.SERVICE_ACTION)
    public static final String SERVICE_INTERFACE
            = "android.service.notification.NotificationListenerService";

    /**
     * Implement this method to learn about new notifications as they are posted by apps.
     *
     * @param sbn A data structure encapsulating the original {@link android.app.Notification}
     *            object as well as its identifying information (tag and id) and source
     *            (package name).
     */
    public abstract void onNotificationPosted(StatusBarNotification sbn);

    /**
     * Implement this method to learn when notifications are removed.
     * <P>
     * This might occur because the user has dismissed the notification using system UI (or another
     * notification listener) or because the app has withdrawn the notification.
     * <P>
     * NOTE: The {@link StatusBarNotification} object you receive will be "light"; that is, the
     * result from {@link StatusBarNotification#getNotification} may be missing some heavyweight
     * fields such as {@link android.app.Notification#contentView} and
     * {@link android.app.Notification#largeIcon}. However, all other fields on
     * {@link StatusBarNotification}, sufficient to match this call with a prior call to
     * {@link #onNotificationPosted(StatusBarNotification)}, will be intact.
     *
     * @param sbn A data structure encapsulating at least the original information (tag and id)
     *            and source (package name) used to post the {@link android.app.Notification} that
     *            was just removed.
     */
    public abstract void onNotificationRemoved(StatusBarNotification sbn);

    private final INotificationManager getNotificationInterface() {
        if (mNoMan == null) {
            mNoMan = INotificationManager.Stub.asInterface(
                    ServiceManager.getService(Context.NOTIFICATION_SERVICE));
        }
        return mNoMan;
    }

    /**
     * Inform the notification manager about dismissal of a single notification.
     * <p>
     * Use this if your listener has a user interface that allows the user to dismiss individual
     * notifications, similar to the behavior of Android's status bar and notification panel.
     * It should be called after the user dismisses a single notification using your UI;
     * upon being informed, the notification manager will actually remove the notification
     * and you will get an {@link #onNotificationRemoved(StatusBarNotification)} callback.
     * <P>
     * <b>Note:</b> If your listener allows the user to fire a notification's
     * {@link android.app.Notification#contentIntent} by tapping/clicking/etc., you should call
     * this method at that time <i>if</i> the Notification in question has the
     * {@link android.app.Notification#FLAG_AUTO_CANCEL} flag set.
     *
     * @param pkg Package of the notifying app.
     * @param tag Tag of the notification as specified by the notifying app in
     *     {@link android.app.NotificationManager#notify(String, int, android.app.Notification)}.
     * @param id  ID of the notification as specified by the notifying app in
     *     {@link android.app.NotificationManager#notify(String, int, android.app.Notification)}.
     */
    public final void cancelNotification(String pkg, String tag, int id) {
        try {
            getNotificationInterface().cancelNotificationFromListener(mWrapper, pkg, tag, id);
        } catch (android.os.RemoteException ex) {
            Log.v(TAG, "Unable to contact notification manager", ex);
        }
    }

    /**
     * Inform the notification manager about dismissal of all notifications.
     * <p>
     * Use this if your listener has a user interface that allows the user to dismiss all
     * notifications, similar to the behavior of Android's status bar and notification panel.
     * It should be called after the user invokes the "dismiss all" function of your UI;
     * upon being informed, the notification manager will actually remove all active notifications
     * and you will get multiple {@link #onNotificationRemoved(StatusBarNotification)} callbacks.
     *
     * {@see #cancelNotification(String, String, int)}
     */
    public final void cancelAllNotifications() {
        try {
            getNotificationInterface().cancelAllNotificationsFromListener(mWrapper);
        } catch (android.os.RemoteException ex) {
            Log.v(TAG, "Unable to contact notification manager", ex);
        }
    }

    /**
     * Request the list of outstanding notifications (that is, those that are visible to the
     * current user). Useful when starting up and you don't know what's already been posted.
     *
     * @return An array of active notifications.
     */
    public StatusBarNotification[] getActiveNotifications() {
        try {
            return getNotificationInterface().getActiveNotificationsFromListener(mWrapper);
        } catch (android.os.RemoteException ex) {
            Log.v(TAG, "Unable to contact notification manager", ex);
        }
        return null;
    }

    @Override
    public IBinder onBind(Intent intent) {
        if (mWrapper == null) {
            mWrapper = new INotificationListenerWrapper();
        }
        return mWrapper;
    }

    private class INotificationListenerWrapper extends INotificationListener.Stub {
        @Override
        public void onNotificationPosted(StatusBarNotification sbn) {
            NotificationListenerService.this.onNotificationPosted(sbn);
        }
        @Override
        public void onNotificationRemoved(StatusBarNotification sbn) {
            NotificationListenerService.this.onNotificationRemoved(sbn);
        }
    }
}