car-ui-lib/car-ui-lib/src/main/java/com/android/car/ui/utils/CarUxRestrictionsUtil.java

/*
 * Copyright (C) 2019 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 com.android.car.ui.utils;

import static android.car.drivingstate.CarUxRestrictions.UX_RESTRICTIONS_LIMIT_STRING_LENGTH;

import android.car.Car;
import android.car.drivingstate.CarUxRestrictions;
import android.car.drivingstate.CarUxRestrictions.CarUxRestrictionsInfo;
import android.car.drivingstate.CarUxRestrictionsManager;
import android.content.Context;
import android.os.Build;
import android.util.Log;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.VisibleForTesting;

import com.android.car.ui.R;

import java.util.Collections;
import java.util.Set;
import java.util.WeakHashMap;

/**
 * Utility class to access Car Restriction Manager.
 *
 * <p>This class must be a singleton because only one listener can be registered with {@link
 * CarUxRestrictionsManager} at a time, as documented in
 * {@link CarUxRestrictionsManager#registerListener}.
 */
public class CarUxRestrictionsUtil {
    private static final String TAG = "CarUxRestrictionsUtil";

    @NonNull
    private CarUxRestrictions mCarUxRestrictions = getDefaultRestrictions();

    private final Set<OnUxRestrictionsChangedListener> mObservers =
            Collections.newSetFromMap(new WeakHashMap<>());
    private final CarUxRestrictionsManager.OnUxRestrictionsChangedListener mListener =
            (carUxRestrictions) -> {
                if (carUxRestrictions == null) {
                    mCarUxRestrictions = getDefaultRestrictions();
                } else {
                    mCarUxRestrictions = carUxRestrictions;
                }

                for (OnUxRestrictionsChangedListener observer : mObservers) {
                    observer.onRestrictionsChanged(mCarUxRestrictions);
                }
            };
    private static CarUxRestrictionsUtil sInstance = null;

    private CarUxRestrictionsUtil(Context context) {
        try {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
                Car.createCar(context.getApplicationContext(), null,
                        Car.CAR_WAIT_TIMEOUT_DO_NOT_WAIT,
                        (Car car, boolean ready) -> {
                            if (ready) {
                                registerCarUxRestrictionsListener(car, mListener);
                            } else {
                                Log.w(TAG, "Car service disconnected, assuming fully"
                                        + " restricted uxr");
                                mListener.onUxRestrictionsChanged(null);
                            }
                        });
            } else {
                Car car = Car.createCar(context.getApplicationContext());
                registerCarUxRestrictionsListener(car, mListener);
            }
        } catch (RuntimeException e) {
            // Can't catch more specific exception, because
            // Car class literally throws RuntimeException or SecurityException on error.
            Log.w(TAG, "Unable to connect to car service, assuming unrestricted", e);
            mListener.onUxRestrictionsChanged(new CarUxRestrictions.Builder(
                    false, CarUxRestrictions.UX_RESTRICTIONS_BASELINE, 0)
                    .build());
        }
    }

    @NonNull
    private static CarUxRestrictions getDefaultRestrictions() {
        return new CarUxRestrictions.Builder(
                true, CarUxRestrictions.UX_RESTRICTIONS_FULLY_RESTRICTED, 0)
                .build();
    }

    /**
     * Listener interface used to update clients on UxRestrictions changes
     */
    public interface OnUxRestrictionsChangedListener {
        /**
         * Called when CarUxRestrictions changes
         */
        void onRestrictionsChanged(@NonNull CarUxRestrictions carUxRestrictions);
    }

    /**
     * Returns the singleton sInstance of this class
     */
    @NonNull
    public static CarUxRestrictionsUtil getInstance(Context context) {
        if (sInstance == null) {
            sInstance = new CarUxRestrictionsUtil(context);
        }

        return sInstance;
    }

    /**
     * Registers a listener on this class for updates to CarUxRestrictions. Multiple listeners may
     * be registered. Note that this class will only hold a weak reference to the listener, you must
     * maintain a strong reference to it elsewhere.
     */
    public void register(OnUxRestrictionsChangedListener listener) {
        mObservers.add(listener);
        listener.onRestrictionsChanged(mCarUxRestrictions);
    }

    /**
     * Unregisters a registered listener
     */
    public void unregister(OnUxRestrictionsChangedListener listener) {
        mObservers.remove(listener);
    }

    @NonNull
    public CarUxRestrictions getCurrentRestrictions() {
        return mCarUxRestrictions;
    }

    /**
     * Returns whether any of the given flags are blocked by the specified restrictions. If null is
     * given, the method returns true for safety.
     */
    public static boolean isRestricted(
            @CarUxRestrictionsInfo int restrictionFlags, @Nullable CarUxRestrictions uxr) {
        return (uxr == null) || ((uxr.getActiveRestrictions() & restrictionFlags) != 0);
    }

    /**
     * Complies the input string with the given UX restrictions. Returns the original string if
     * already compliant, otherwise a shortened ellipsized string.
     */
    public static String complyString(Context context, String str, CarUxRestrictions uxr) {

        if (isRestricted(UX_RESTRICTIONS_LIMIT_STRING_LENGTH, uxr)) {
            int maxLength =
                    uxr == null
                            ? context.getResources().getInteger(
                            R.integer.car_ui_default_max_string_length)
                            : uxr.getMaxRestrictedStringLength();

            if (str.length() > maxLength) {
                return str.substring(0, maxLength) + context.getString(R.string.car_ui_ellipsis);
            }
        }

        return str;
    }

    /**
     * Sets car UX restrictions. Only used for testing.
     */
    @VisibleForTesting
    public void setUxRestrictions(CarUxRestrictions carUxRestrictions) {
        mCarUxRestrictions = carUxRestrictions;
        mListener.onUxRestrictionsChanged(mCarUxRestrictions);
    }

    private static void registerCarUxRestrictionsListener(
            @NonNull Car car,
            @NonNull CarUxRestrictionsManager.OnUxRestrictionsChangedListener listener) {
        try {
            CarUxRestrictionsManager carUxRestrictionsManager =
                    (CarUxRestrictionsManager) car.getCarManager(
                            Car.CAR_UX_RESTRICTION_SERVICE);
            carUxRestrictionsManager.registerListener(listener);
            listener.onUxRestrictionsChanged(
                    carUxRestrictionsManager.getCurrentCarUxRestrictions());
        } catch (NullPointerException e) {
            Log.e(TAG, "Car not connected", e);
            // mCarUxRestrictions will be the default
        }
    }
}