CommonUtils.java

package org.grakovne.mds.android.utils;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.text.TextUtils;
import android.widget.Toast;

import org.grakovne.mds.android.R;
import org.grakovne.mds.android.common.BroadcastActionNames.Application;
import org.grakovne.mds.android.manager.BroadcastManager;
import org.grakovne.mds.android.manager.SettingsManager;

import static java.util.Arrays.asList;
import static org.grakovne.mds.android.manager.BroadcastManager.subscribeTo;
import static org.grakovne.mds.android.manager.BroadcastManager.unSubscribeFrom;

public class CommonUtils {

    public static boolean isVkAppInstalled(Context context) {
        return isAppInstalled(context, "com.vkontakte.android");
    }

    private static boolean isAppInstalled(Context context, String packageName) {
        try {
            context.getPackageManager().getApplicationInfo(packageName, 0);
            return true;
        }
        catch (PackageManager.NameNotFoundException e) {
            return false;
        }
    }

    public static void ifUserLogged(Context context, Action positiveAction, Action negativeAction) {
        if (SettingsManager.getManager(context).isUserLogged()){
            positiveAction.apply();
        } else {
            negativeAction.apply();
        }
    }

    public static void ifUserLogged(Context context, Action action) {
        ifUserLogged(context, action, new Action() {
            @Override
            public void apply() {
                BroadcastReceiver receiver = new BroadcastReceiver() {
                    @Override
                    public void onReceive(Context context, Intent intent) {
                        String requiredAction = intent.getAction();
                        if (TextUtils.isEmpty(requiredAction)) {
                            return;
                        }

                        unSubscribeFrom(context, this);
                        switch (requiredAction) {
                            case Application.USER_LOGIN_EVENT:
                                action.apply();
                                break;
                        }
                    }
                };

                subscribeTo(context,
                        receiver,
                        asList(Application.USER_LOGIN_EVENT, Application.USER_LOGIN_CANCELLED_EVENT));

                Toast.makeText(context, R.string.sign_in_reqiured_toast, Toast.LENGTH_LONG).show();
                BroadcastManager.send(context, Application.USER_LOGIN_INTENT);
            }
        });
    }

    public static <T> void ifNotNull(T value, Action action) {
        if (null != value) {
            action.apply();
        }
    }

    public interface Action {
        void apply();
    }
}