com.esminis.server.library.permission.PermissionRequester.java Source code

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Here is the source code for com.esminis.server.library.permission.PermissionRequester.java

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/**
 * Copyright 2016 Tautvydas Andrikys
 *
 * 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.esminis.server.library.permission;

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;

import java.lang.ref.WeakReference;

import javax.inject.Inject;

import rx.Observable;
import rx.Subscriber;
import rx.android.schedulers.AndroidSchedulers;

public class PermissionRequester {

    static private final int REQUEST_CODE_PERMISSION = 1;

    private final Object lock = new Object();
    private Subscriber<? super Void> subscriberInProgress = null;
    private boolean showExplanation = false;

    @Inject
    public PermissionRequester() {
    }

    public boolean hasPermission(Context context, String permission) {
        return context != null
                && ContextCompat.checkSelfPermission(context, permission) == PackageManager.PERMISSION_GRANTED;
    }

    public Observable<Void> request(Activity activity, final String permission) {
        final WeakReference<Activity> activityReference = new WeakReference<>(activity);
        return Observable.create(new Observable.OnSubscribe<Void>() {
            @Override
            public void call(Subscriber<? super Void> subscriber) {
                final Activity activity = activityReference.get();
                if (activity == null) {
                    subscriber.onError(new PermissionRequestFailed(PermissionRequestFailed.ACTIVITY_NOT_AVAILABLE));
                } else if (permission == null) {
                    subscriber.onError(
                            new PermissionRequestFailed(PermissionRequestFailed.DENIED_INVALID_PERMISSION));
                } else if (hasPermission(activity, permission)) {
                    subscriber.onNext(null);
                    subscriber.onCompleted();
                } else {
                    synchronized (lock) {
                        if (subscriberInProgress != null) {
                            subscriber.onError(new PermissionRequestFailed(
                                    PermissionRequestFailed.DENIED_ANOTHER_REQUEST_IN_PROGRESS));
                            return;
                        }
                        showExplanation = ActivityCompat.shouldShowRequestPermissionRationale(activity, permission);
                        subscriberInProgress = subscriber;
                    }
                    ActivityCompat.requestPermissions(activity, new String[] { permission },
                            REQUEST_CODE_PERMISSION);
                }
            }
        }).subscribeOn(AndroidSchedulers.mainThread()).observeOn(AndroidSchedulers.mainThread());
    }

    public void onRequestPermissionsResult(int requestCode, int[] grantResults) {
        if (requestCode != REQUEST_CODE_PERMISSION) {
            return;
        }
        final Subscriber<? super Void> subscriber;
        final boolean showExplanation;
        synchronized (lock) {
            subscriber = subscriberInProgress;
            showExplanation = this.showExplanation;
            subscriberInProgress = null;
            this.showExplanation = false;
        }
        if (subscriber == null) {
            return;
        }
        if (grantResults != null && grantResults.length > 0
                && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            subscriber.onNext(null);
        } else {
            subscriber.onError(
                    new PermissionRequestFailed(showExplanation ? PermissionRequestFailed.DENIED_EXPLANATION_NEEDED
                            : PermissionRequestFailed.DENIED));
        }
        subscriber.onCompleted();
    }

    public void cleanup() {
        synchronized (lock) {
            subscriberInProgress = null;
            showExplanation = false;
        }
    }

}