AbstractUserComparator.java

/*
 * Copyright (C) 2015 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 xyz.klinker.blur.launcher3.model;

import android.content.Context;

import xyz.klinker.blur.launcher3.ItemInfo;
import xyz.klinker.blur.launcher3.compat.UserHandleCompat;
import xyz.klinker.blur.launcher3.compat.UserManagerCompat;

import java.util.Comparator;
import java.util.HashMap;

/**
 * A comparator to arrange items based on user profiles.
 */
public abstract class AbstractUserComparator<T extends ItemInfo> implements Comparator<T> {

    private HashMap<UserHandleCompat, Long> mUserSerialCache = new HashMap<>();
    private final UserManagerCompat mUserManager;
    private final UserHandleCompat mMyUser;

    public AbstractUserComparator(Context context) {
        mUserManager = UserManagerCompat.getInstance(context);
        mMyUser = UserHandleCompat.myUserHandle();
    }

    @Override
    public int compare(T lhs, T rhs) {
        if (mMyUser.equals(lhs.user)) {
            return -1;
        } else {
            Long aUserSerial = getAndCacheUserSerial(lhs.user);
            Long bUserSerial = getAndCacheUserSerial(rhs.user);
            return aUserSerial.compareTo(bUserSerial);
        }
    }

    /**
     * Returns the user serial for this user, using a cached serial if possible.
     */
    private Long getAndCacheUserSerial(UserHandleCompat user) {
        Long userSerial = mUserSerialCache.get(user);
        if (userSerial == null) {
            userSerial = mUserManager.getSerialNumberForUser(user);
            mUserSerialCache.put(user, userSerial);
        }
        return userSerial;
    }

    public void clearUserCache() {
        mUserSerialCache.clear();
    }
}