GcmManager.java

/*
 * The CroudTrip! application aims at revolutionizing the car-ride-sharing market with its easy,
 * user-friendly and highly automated way of organizing shared Trips. Copyright (C) 2015  Nazeeh Ammari,
 *  Philipp Eichhorn, Ricarda Hohn, Vanessa Lange, Alexander Popp, Frederik Simon, Michael Weber
 * This program is free software: you can redistribute it and/or modify  it under the terms of the GNU
 *  Affero General Public License as published by the Free Software Foundation, either version 3 of the
 *   License, or (at your option) any later version.
 *  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 *  even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Affero General Public License for more details.
 *  You should have received a copy of the GNU Affero General Public License along with this program.
 *    If not, see http://www.gnu.org/licenses/.
 */

package org.croudtrip.gcm;


import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;

import com.google.android.gms.gcm.GoogleCloudMessaging;

import org.croudtrip.R;
import org.croudtrip.api.GcmRegistrationResource;
import org.croudtrip.api.gcm.GcmRegistration;
import org.croudtrip.api.gcm.GcmRegistrationDescription;

import java.io.IOException;

import javax.inject.Inject;

import retrofit.client.Response;
import rx.Observable;
import rx.functions.Func0;
import rx.functions.Func1;

public class GcmManager {

	private static final String PREFS_NAME = GcmManager.class.getName();
	private static final String
			KEY_GCM_ID = "GCM_ID",
			KEY_APP_VERSION = "APP_VERSION";

	private final Context context;
	private final GoogleCloudMessaging googleCloudMessaging;
	private final GcmRegistrationResource registrationResource;

	@Inject
	GcmManager(Context context, GcmRegistrationResource registrationResource) {
		this.context = context;
		this.googleCloudMessaging = GoogleCloudMessaging.getInstance(context);
		this.registrationResource = registrationResource;
	}


	public boolean isRegistered() {
		return loadRegId() != null;
	}


	public Observable<Void> register() {
		return Observable.defer(new Func0<Observable<String>>() {
			@Override
			public Observable<String> call() {
				String regId = loadRegId();
				if (regId != null) {
					return Observable.just(regId);
				} else {
					try {
						regId = googleCloudMessaging.register(context.getString(R.string.gcm_sender_id));
						return Observable.just(regId);
					} catch (IOException ioe) {
						return Observable.error(ioe);
					}
				}
			}
		}).retry(5)
        .flatMap(new Func1<String, Observable<GcmRegistration>>() {
			@Override
			public Observable<GcmRegistration> call(String regId) {
				return registrationResource.register(new GcmRegistrationDescription(regId));
			}
		}).flatMap(new Func1<GcmRegistration, Observable<Void>>() {
			@Override
			public Observable<Void> call(GcmRegistration gcmRegistration) {
				storeRegId(gcmRegistration.getGcmId());
				return Observable.just(null);
			}
		});
	}


	public Observable<Void> unregister() {
		return Observable.defer(new Func0<Observable<Response>>() {
			@Override
			public Observable<Response> call() {
				try {
					clearRegId();
					googleCloudMessaging.unregister();
					return registrationResource.unregister();
				} catch (IOException ioe) {
					return Observable.error(ioe);
				}
			}
		}).flatMap(new Func1<Response, Observable<Void>>() {
			@Override
			public Observable<Void> call(Response response) {
				return Observable.just(null);
			}
		});
	}


	/**
	 * @return the last stored reg id or null if none was stored or the app version has changed since.
	 */
	private String loadRegId() {
		SharedPreferences prefs = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
		int storedAppVersion = prefs.getInt(KEY_APP_VERSION, -1);
		if (storedAppVersion == -1 || storedAppVersion != getAppVersion()) return null;
		return prefs.getString(KEY_GCM_ID, null);
	}


	private void storeRegId(String regId) {
		SharedPreferences.Editor editor = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE).edit();
		editor.putString(KEY_GCM_ID, regId);
		editor.putInt(KEY_APP_VERSION, getAppVersion());
		editor.commit();
	}


	private void clearRegId() {
		SharedPreferences.Editor editor = context.getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE).edit();
		editor.clear();
		editor.commit();
	}



	private int getAppVersion() {
		try {
			PackageInfo packageInfo = context.getPackageManager().getPackageInfo(context.getPackageName(), 0);
			return packageInfo.versionCode;
		} catch (PackageManager.NameNotFoundException e) {
			// should (tm) never happen
			throw new RuntimeException(e);
		}
	}

}