import android.app.AppOpsManager;
import android.app.NotificationManager;
import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.os.Build;
import android.support.annotation.RequiresApi;
import android.support.v4.app.NotificationManagerCompat;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class NotificationsCheckUtil {
    public static boolean areNotificationsEnabled(Context context) {
        NotificationManagerCompat.from(context).areNotificationsEnabled();
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
            return true;
        }
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O){
            return isEnableV19(context);
        }else {
            return isEnableV26(context);
        }
    }


    @RequiresApi(api = Build.VERSION_CODES.KITKAT)
    private static boolean isEnableV19(Context context) {
        final String CHECK_OP_NO_THROW = "checkOpNoThrow";
        final String OP_POST_NOTIFICATION = "OP_POST_NOTIFICATION";
        AppOpsManager mAppOps = (AppOpsManager) context.getSystemService(Context.APP_OPS_SERVICE);
        ApplicationInfo appInfo = context.getApplicationInfo();
        String pkg = context.getApplicationContext().getPackageName();
        int uid = appInfo.uid;
        Class appOpsClass = null; /* Context.APP_OPS_MANAGER */
        try {
            appOpsClass = Class.forName(AppOpsManager.class.getName());
            Method checkOpNoThrowMethod = appOpsClass.getMethod(CHECK_OP_NO_THROW, Integer.TYPE, Integer.TYPE, String.class);
            Field opPostNotificationValue = appOpsClass.getDeclaredField(OP_POST_NOTIFICATION);
            int value = (int) opPostNotificationValue.get(Integer.class);
            return ((int) checkOpNoThrowMethod.invoke(mAppOps, value, uid, pkg) == AppOpsManager.MODE_ALLOWED);
        } catch (ClassNotFoundException e) {
        } catch (NoSuchMethodException e) {
        } catch (NoSuchFieldException e) {
        } catch (InvocationTargetException e) {
        } catch (IllegalAccessException e) {
        } catch (Exception e) {
        }
        return false;
    }


    private static boolean isEnableV26(Context context) {
        ApplicationInfo appInfo = context.getApplicationInfo();
        String pkg = context.getApplicationContext().getPackageName();
        int uid = appInfo.uid;
        try {
            NotificationManager notificationManager = (NotificationManager)
                    context.getSystemService(Context.NOTIFICATION_SERVICE);
            Method sServiceField = notificationManager.getClass().getDeclaredMethod("getService");
            sServiceField.setAccessible(true);
            Object sService = sServiceField.invoke(notificationManager);

            Method method = sService.getClass().getDeclaredMethod("areNotificationsEnabledForPackage"
                    , String.class, Integer.TYPE);
            method.setAccessible(true);
            return (boolean) method.invoke(sService, pkg, uid);
        } catch (Exception e) {
            return true;
        }
    }
}