/*
 * Copyright (C) 2022 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.settings.fuelgauge.batteryusage;

import static com.android.settings.fuelgauge.batteryusage.ConvertUtils.getEffectivePackageName;
import static com.android.settings.fuelgauge.batteryusage.ConvertUtils.isSystemConsumer;
import static com.android.settings.fuelgauge.batteryusage.ConvertUtils.isUidConsumer;
import static com.android.settingslib.fuelgauge.BatteryStatus.BATTERY_LEVEL_UNKNOWN;

import android.app.usage.IUsageStatsManager;
import android.app.usage.UsageEvents;
import android.app.usage.UsageEvents.Event;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.BatteryConsumer;
import android.os.BatteryStatsManager;
import android.os.BatteryUsageStats;
import android.os.BatteryUsageStatsQuery;
import android.os.Process;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.UidBatteryConsumer;
import android.os.UserBatteryConsumer;
import android.os.UserHandle;
import android.os.UserManager;
import android.text.TextUtils;
import android.text.format.DateUtils;
import android.util.ArrayMap;
import android.util.ArraySet;
import android.util.Log;
import android.util.SparseArray;

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

import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.os.PowerProfile;
import com.android.settings.fuelgauge.BatteryUtils;
import com.android.settings.overlay.FeatureFactory;
import com.android.settingslib.fuelgauge.BatteryStatus;
import com.android.settingslib.spaprivileged.model.app.AppListRepositoryUtil;

import com.google.common.base.Preconditions;

import java.time.Duration;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * A utility class to process data loaded from database and make the data easy to use for battery
 * usage UI.
 */
public final class DataProcessor {
    private static final String TAG = "DataProcessor";
    private static final int POWER_COMPONENT_SYSTEM_SERVICES = 7;
    private static final int POWER_COMPONENT_WAKELOCK = 12;
    private static final int MIN_AVERAGE_POWER_THRESHOLD_MILLI_AMP = 10;
    private static final int MIN_DAILY_DATA_SIZE = 2;
    private static final int MAX_DIFF_SECONDS_OF_UPPER_TIMESTAMP = 5;
    private static final String MEDIASERVER_PACKAGE_NAME = "mediaserver";
    private static final String ANDROID_CORE_APPS_SHARED_USER_ID = "android.uid.shared";
    private static final Map<String, BatteryHistEntry> EMPTY_BATTERY_MAP = new ArrayMap<>();
    private static final BatteryHistEntry EMPTY_BATTERY_HIST_ENTRY =
            new BatteryHistEntry(new ContentValues());

    @VisibleForTesting
    static final long DEFAULT_USAGE_DURATION_FOR_INCOMPLETE_INTERVAL =
            DateUtils.SECOND_IN_MILLIS * 30;

    @VisibleForTesting
    static final int SELECTED_INDEX_ALL = BatteryChartViewModel.SELECTED_INDEX_ALL;

    @VisibleForTesting
    static final Comparator<AppUsageEvent> APP_USAGE_EVENT_TIMESTAMP_COMPARATOR =
            Comparator.comparing(AppUsageEvent::getTimestamp);

    @VisibleForTesting
    static final Comparator<BatteryEvent> BATTERY_EVENT_TIMESTAMP_COMPARATOR =
            Comparator.comparing(BatteryEvent::getTimestamp);

    @VisibleForTesting static boolean sDebug = false;

    @VisibleForTesting static long sTestCurrentTimeMillis = 0;

    @VisibleForTesting static Set<String> sTestSystemAppsPackageNames;

    @VisibleForTesting
    static IUsageStatsManager sUsageStatsManager =
            IUsageStatsManager.Stub.asInterface(
                    ServiceManager.getService(Context.USAGE_STATS_SERVICE));

    public static final String CURRENT_TIME_BATTERY_HISTORY_PLACEHOLDER =
            "CURRENT_TIME_BATTERY_HISTORY_PLACEHOLDER";

    /** A callback listener when battery usage loading async task is executed. */
    public interface UsageMapAsyncResponse {
        /** The callback function when batteryUsageMap is loaded. */
        void onBatteryCallbackDataLoaded(
                Map<Integer, Map<Integer, BatteryDiffData>> batteryCallbackData);
    }

    private DataProcessor() {}

    /**
     * @return Returns battery usage data of different entries. <br>
     *     Returns null if the input is invalid or there is no enough data.
     */
    @Nullable
    public static Map<Integer, Map<Integer, BatteryDiffData>> getBatteryUsageData(
            Context context,
            UserIdsSeries userIdsSeries,
            @Nullable final Map<Long, Map<String, BatteryHistEntry>> batteryHistoryMap) {
        if (batteryHistoryMap == null || batteryHistoryMap.isEmpty()) {
            Log.d(TAG, "getBatteryLevelData() returns null");
            return null;
        }
        // Process raw history map data into hourly timestamps.
        final Map<Long, Map<String, BatteryHistEntry>> processedBatteryHistoryMap =
                getHistoryMapWithExpectedTimestamps(context, batteryHistoryMap);
        // Wrap and processed history map into easy-to-use format for UI rendering.
        final BatteryLevelData batteryLevelData =
                getLevelDataThroughProcessedHistoryMap(context, processedBatteryHistoryMap);
        // Loads the current battery usage data from the battery stats service.
        final Map<String, BatteryHistEntry> currentBatteryHistoryMap =
                getCurrentBatteryHistoryMapFromStatsService(context);
        // Replaces the placeholder in processedBatteryHistoryMap.
        for (Map.Entry<Long, Map<String, BatteryHistEntry>> mapEntry :
                processedBatteryHistoryMap.entrySet()) {
            if (mapEntry.getValue().containsKey(CURRENT_TIME_BATTERY_HISTORY_PLACEHOLDER)) {
                mapEntry.setValue(currentBatteryHistoryMap);
            }
        }
        return batteryLevelData == null
                ? null
                : generateBatteryUsageMap(
                        context,
                        getBatteryDiffDataMap(
                                context,
                                userIdsSeries,
                                batteryLevelData.getHourlyBatteryLevelsPerDay(),
                                processedBatteryHistoryMap,
                                /* appUsagePeriodMap= */ null,
                                getSystemAppsPackageNames(context),
                                getSystemAppsUids(context)),
                        batteryLevelData);
    }

    /** Gets the {@link BatteryUsageStats} from system service. */
    @Nullable
    public static BatteryUsageStats getBatteryUsageStats(final Context context) {
        final BatteryUsageStatsQuery batteryUsageStatsQuery =
                new BatteryUsageStatsQuery.Builder()
                        .includeBatteryHistory()
                        .includeProcessStateData()
                        .build();
        return context.getSystemService(BatteryStatsManager.class)
                .getBatteryUsageStats(batteryUsageStatsQuery);
    }

    /** Gets the {@link UsageEvents} from system service for all unlocked users. */
    @Nullable
    public static Map<Long, UsageEvents> getAppUsageEvents(
            Context context, UserIdsSeries userIdsSeries) {
        final long start = System.currentTimeMillis();
        context = DatabaseUtils.getParentContext(context);
        if (context == null) {
            return null;
        }
        final Map<Long, UsageEvents> resultMap = new ArrayMap();
        final long sixDaysAgoTimestamp =
                DatabaseUtils.getTimestampSixDaysAgo(Calendar.getInstance());
        for (final int userId : userIdsSeries.getVisibleUserIds()) {
            final UsageEvents events =
                    getAppUsageEventsForUser(context, userIdsSeries, userId, sixDaysAgoTimestamp);
            if (events != null) {
                resultMap.put(Long.valueOf(userId), events);
            }
        }
        final long elapsedTime = System.currentTimeMillis() - start;
        Log.d(
                TAG,
                String.format("getAppUsageEvents() for all unlocked users in %d/ms", elapsedTime));
        return resultMap.isEmpty() ? null : resultMap;
    }

    /** Gets the {@link UsageEvents} from system service for the specific user. */
    @Nullable
    public static UsageEvents getCurrentAppUsageEventsForUser(
            Context context,
            final UserIdsSeries userIdsSeries,
            final int userID,
            final long startTimestampOfLevelData) {
        final long start = System.currentTimeMillis();
        context = DatabaseUtils.getParentContext(context);
        if (context == null) {
            return null;
        }
        final long sixDaysAgoTimestamp =
                DatabaseUtils.getTimestampSixDaysAgo(Calendar.getInstance());
        final long earliestTimestamp = Math.max(sixDaysAgoTimestamp, startTimestampOfLevelData);
        final UsageEvents events =
                getAppUsageEventsForUser(context, userIdsSeries, userID, earliestTimestamp);
        final long elapsedTime = System.currentTimeMillis() - start;
        Log.d(
                TAG,
                String.format(
                        "getAppUsageEventsForUser() for user %d in %d/ms", userID, elapsedTime));
        return events;
    }

    /** Closes the {@link BatteryUsageStats} after using it. */
    public static void closeBatteryUsageStats(BatteryUsageStats batteryUsageStats) {
        if (batteryUsageStats != null) {
            try {
                batteryUsageStats.close();
            } catch (Exception e) {
                Log.e(TAG, "BatteryUsageStats.close() failed", e);
            }
        }
    }

    /**
     * Generates the indexed {@link AppUsagePeriod} list data for each corresponding time slot.
     * Attributes the list of {@link AppUsageEvent} into hourly time slots and reformat them into
     * {@link AppUsagePeriod} for easier use in the following process.
     *
     * <p>There could be 2 cases of the returned value:
     *
     * <ul>
     *   <li>null: empty or invalid data.
     *   <li>non-null: must be a 2d map and composed by:
     *       <p>[0][0] ~ [maxDailyIndex][maxHourlyIndex]
     * </ul>
     *
     * <p>The structure is consistent with the battery usage map returned by {@code
     * generateBatteryUsageMap}.
     *
     * <p>{@code Long} stands for the userId.
     *
     * <p>{@code String} stands for the packageName.
     */
    @Nullable
    public static Map<Integer, Map<Integer, Map<Long, Map<String, List<AppUsagePeriod>>>>>
            generateAppUsagePeriodMap(
                    Context context,
                    final List<BatteryLevelData.PeriodBatteryLevelData> hourlyBatteryLevelsPerDay,
                    final List<AppUsageEvent> appUsageEventList,
                    final List<BatteryEvent> batteryEventList) {
        if (appUsageEventList.isEmpty()) {
            Log.w(TAG, "appUsageEventList is empty");
            return null;
        }
        // Sorts the appUsageEventList and batteryEventList in ascending order based on the
        // timestamp before distribution.
        Collections.sort(appUsageEventList, APP_USAGE_EVENT_TIMESTAMP_COMPARATOR);
        Collections.sort(batteryEventList, BATTERY_EVENT_TIMESTAMP_COMPARATOR);
        final Map<Integer, Map<Integer, Map<Long, Map<String, List<AppUsagePeriod>>>>> resultMap =
                new ArrayMap<>();

        for (int dailyIndex = 0; dailyIndex < hourlyBatteryLevelsPerDay.size(); dailyIndex++) {
            final Map<Integer, Map<Long, Map<String, List<AppUsagePeriod>>>> dailyMap =
                    new ArrayMap<>();
            resultMap.put(dailyIndex, dailyMap);
            if (hourlyBatteryLevelsPerDay.get(dailyIndex) == null) {
                continue;
            }
            final List<Long> timestamps = hourlyBatteryLevelsPerDay.get(dailyIndex).getTimestamps();
            for (int hourlyIndex = 0; hourlyIndex < timestamps.size() - 1; hourlyIndex++) {
                final long startTimestamp = timestamps.get(hourlyIndex);
                final long endTimestamp = timestamps.get(hourlyIndex + 1);
                // Gets the app usage event list for this hourly slot first.
                final List<AppUsageEvent> hourlyAppUsageEventList =
                        getAppUsageEventListWithinTimeRangeWithBuffer(
                                appUsageEventList, startTimestamp, endTimestamp);

                // The value could be null when there is no data in the hourly slot.
                dailyMap.put(
                        hourlyIndex,
                        buildAppUsagePeriodList(
                                context,
                                hourlyAppUsageEventList,
                                batteryEventList,
                                startTimestamp,
                                endTimestamp));
            }
        }
        return resultMap;
    }

    /** Generates the list of {@link AppUsageEvent} from the supplied {@link UsageEvents}. */
    public static List<AppUsageEvent> generateAppUsageEventListFromUsageEvents(
            Context context, Map<Long, UsageEvents> usageEventsMap) {
        final List<AppUsageEvent> appUsageEventList = new ArrayList<>();
        long numEventsFetched = 0;
        long numAllEventsFetched = 0;
        final Set<String> ignoreScreenOnTimeTaskRootSet =
                FeatureFactory.getFeatureFactory()
                        .getPowerUsageFeatureProvider()
                        .getIgnoreScreenOnTimeTaskRootSet();
        for (final long userId : usageEventsMap.keySet()) {
            final UsageEvents usageEvents = usageEventsMap.get(userId);
            while (usageEvents.hasNextEvent()) {
                final Event event = new Event();
                usageEvents.getNextEvent(event);
                numAllEventsFetched++;
                switch (event.getEventType()) {
                    case Event.ACTIVITY_RESUMED:
                    case Event.ACTIVITY_STOPPED:
                    case Event.DEVICE_SHUTDOWN:
                        final String taskRootClassName = event.getTaskRootClassName();
                        if (!TextUtils.isEmpty(taskRootClassName)
                                && ignoreScreenOnTimeTaskRootSet.contains(taskRootClassName)) {
                            Log.w(
                                    TAG,
                                    String.format(
                                            "Ignoring a usage event with task root class name %s, "
                                                    + "(timestamp=%d, type=%d)",
                                            taskRootClassName,
                                            event.getTimeStamp(),
                                            event.getEventType()));
                            break;
                        }
                        final AppUsageEvent appUsageEvent =
                                ConvertUtils.convertToAppUsageEvent(
                                        context, sUsageStatsManager, event, userId);
                        if (appUsageEvent != null) {
                            numEventsFetched++;
                            appUsageEventList.add(appUsageEvent);
                        }
                        break;
                    default:
                        break;
                }
            }
        }
        Log.w(
                TAG,
                String.format(
                        "Read %d relevant events (%d total) from UsageStatsManager",
                        numEventsFetched, numAllEventsFetched));
        return appUsageEventList;
    }

    /** Generates the list of {@link BatteryEntry} from the supplied {@link BatteryUsageStats}. */
    @Nullable
    public static List<BatteryEntry> generateBatteryEntryListFromBatteryUsageStats(
            final Context context, @Nullable final BatteryUsageStats batteryUsageStats) {
        if (batteryUsageStats == null) {
            Log.w(TAG, "batteryUsageStats is null content");
            return null;
        }
        if (!shouldShowBatteryAttributionList(context)) {
            return null;
        }
        final BatteryUtils batteryUtils = BatteryUtils.getInstance(context);
        final int dischargePercentage = Math.max(0, batteryUsageStats.getDischargePercentage());
        final List<BatteryEntry> usageList =
                getCoalescedUsageList(
                        context,
                        batteryUtils,
                        batteryUsageStats,
                        /* loadDataInBackground= */ false);
        final double totalPower = batteryUsageStats.getConsumedPower();
        for (int i = 0; i < usageList.size(); i++) {
            final BatteryEntry entry = usageList.get(i);
            final double percentOfTotal =
                    batteryUtils.calculateBatteryPercent(
                            entry.getConsumedPower(), totalPower, dischargePercentage);
            entry.mPercent = percentOfTotal;
        }
        return usageList;
    }

    /**
     * @return Returns the latest battery history map loaded from the battery stats service.
     */
    public static Map<String, BatteryHistEntry> getCurrentBatteryHistoryMapFromStatsService(
            final Context context) {
        final List<BatteryHistEntry> batteryHistEntryList =
                getBatteryHistListFromFromStatsService(context);
        return batteryHistEntryList == null
                ? new ArrayMap<>()
                : batteryHistEntryList.stream().collect(Collectors.toMap(e -> e.getKey(), e -> e));
    }

    /**
     * @return Returns the processed history map which has interpolated to every hour data.
     *     <p>The start timestamp is the first timestamp in batteryHistoryMap. The end timestamp is
     *     current time. The keys of processed history map should contain every hour between the
     *     start and end timestamp. If there's no data in some key, the value will be the empty map.
     */
    static Map<Long, Map<String, BatteryHistEntry>> getHistoryMapWithExpectedTimestamps(
            Context context, final Map<Long, Map<String, BatteryHistEntry>> batteryHistoryMap) {
        final long startTime = System.currentTimeMillis();
        final List<Long> rawTimestampList = new ArrayList<>(batteryHistoryMap.keySet());
        final Map<Long, Map<String, BatteryHistEntry>> resultMap = new ArrayMap();
        if (rawTimestampList.isEmpty()) {
            Log.d(TAG, "empty batteryHistoryMap in getHistoryMapWithExpectedTimestamps()");
            return resultMap;
        }
        Collections.sort(rawTimestampList);
        final long currentTime = getCurrentTimeMillis();
        final List<Long> expectedTimestampList = getTimestampSlots(rawTimestampList, currentTime);
        interpolateHistory(
                context, rawTimestampList, expectedTimestampList, batteryHistoryMap, resultMap);
        Log.d(
                TAG,
                String.format(
                        "getHistoryMapWithExpectedTimestamps() size=%d in %d/ms",
                        resultMap.size(), (System.currentTimeMillis() - startTime)));
        return resultMap;
    }

    @Nullable
    static BatteryLevelData getLevelDataThroughProcessedHistoryMap(
            Context context,
            final Map<Long, Map<String, BatteryHistEntry>> processedBatteryHistoryMap) {
        // There should be at least the start and end timestamps. Otherwise, return null to not show
        // data in usage chart.
        if (processedBatteryHistoryMap.size() < MIN_DAILY_DATA_SIZE) {
            return null;
        }
        Map<Long, Integer> batteryLevelMap = new ArrayMap<>();
        for (Long timestamp : processedBatteryHistoryMap.keySet()) {
            batteryLevelMap.put(
                    timestamp, getLevel(context, processedBatteryHistoryMap, timestamp));
        }
        return new BatteryLevelData(batteryLevelMap);
    }

    /**
     * Computes expected timestamp slots. The start timestamp is the first timestamp in
     * rawTimestampList. The end timestamp is current time. The middle timestamps are the sharp hour
     * timestamps between the start and end timestamps.
     */
    @VisibleForTesting
    static List<Long> getTimestampSlots(final List<Long> rawTimestampList, final long currentTime) {
        final List<Long> timestampSlots = new ArrayList<>();
        if (rawTimestampList.isEmpty()) {
            return timestampSlots;
        }
        final long startTimestamp = rawTimestampList.get(0);
        final long endTimestamp = currentTime;
        // If the start timestamp is later or equal the end one, return the empty list.
        if (startTimestamp >= endTimestamp) {
            return timestampSlots;
        }
        timestampSlots.add(startTimestamp);
        for (long timestamp = TimestampUtils.getNextHourTimestamp(startTimestamp);
                timestamp < endTimestamp;
                timestamp += DateUtils.HOUR_IN_MILLIS) {
            timestampSlots.add(timestamp);
        }
        timestampSlots.add(endTimestamp);
        return timestampSlots;
    }

    @VisibleForTesting
    static boolean isFromFullCharge(@Nullable final Map<String, BatteryHistEntry> entryList) {
        if (entryList == null) {
            Log.d(TAG, "entryList is null in isFromFullCharge()");
            return false;
        }
        final List<String> entryKeys = new ArrayList<>(entryList.keySet());
        if (entryKeys.isEmpty()) {
            Log.d(TAG, "empty entryList in isFromFullCharge()");
            return false;
        }
        // The hist entries in the same timestamp should have same battery status and level.
        // Checking the first one should be enough.
        final BatteryHistEntry firstHistEntry = entryList.get(entryKeys.get(0));
        return BatteryStatus.isCharged(firstHistEntry.mBatteryStatus, firstHistEntry.mBatteryLevel);
    }

    @VisibleForTesting
    static long[] findNearestTimestamp(final List<Long> timestamps, final long target) {
        final long[] results = new long[] {Long.MIN_VALUE, Long.MAX_VALUE};
        // Searches the nearest lower and upper timestamp value.
        timestamps.forEach(
                timestamp -> {
                    if (timestamp <= target && timestamp > results[0]) {
                        results[0] = timestamp;
                    }
                    if (timestamp >= target && timestamp < results[1]) {
                        results[1] = timestamp;
                    }
                });
        // Uses zero value to represent invalid searching result.
        results[0] = results[0] == Long.MIN_VALUE ? 0 : results[0];
        results[1] = results[1] == Long.MAX_VALUE ? 0 : results[1];
        return results;
    }

    static Map<Long, BatteryDiffData> getBatteryDiffDataMap(
            Context context,
            final UserIdsSeries userIdsSeries,
            final List<BatteryLevelData.PeriodBatteryLevelData> hourlyBatteryLevelsPerDay,
            final Map<Long, Map<String, BatteryHistEntry>> batteryHistoryMap,
            final Map<Integer, Map<Integer, Map<Long, Map<String, List<AppUsagePeriod>>>>>
                    appUsagePeriodMap,
            final @NonNull Set<String> systemAppsPackageNames,
            final @NonNull Set<Integer> systemAppsUids) {
        final Map<Long, BatteryDiffData> batteryDiffDataMap = new ArrayMap<>();
        // Each time slot usage diff data =
        //     sum(Math.abs(timestamp[i+1] data - timestamp[i] data));
        // since we want to aggregate every hour usage diff data into a single time slot.
        for (int dailyIndex = 0; dailyIndex < hourlyBatteryLevelsPerDay.size(); dailyIndex++) {
            if (hourlyBatteryLevelsPerDay.get(dailyIndex) == null) {
                continue;
            }
            final List<Long> hourlyTimestamps =
                    hourlyBatteryLevelsPerDay.get(dailyIndex).getTimestamps();
            for (int hourlyIndex = 0; hourlyIndex < hourlyTimestamps.size() - 1; hourlyIndex++) {
                final Long startTimestamp = hourlyTimestamps.get(hourlyIndex);
                final Long endTimestamp = hourlyTimestamps.get(hourlyIndex + 1);
                final int startBatteryLevel =
                        hourlyBatteryLevelsPerDay.get(dailyIndex).getLevels().get(hourlyIndex);
                final int endBatteryLevel =
                        hourlyBatteryLevelsPerDay.get(dailyIndex).getLevels().get(hourlyIndex + 1);
                final long slotDuration = endTimestamp - startTimestamp;
                List<Map<String, BatteryHistEntry>> slotBatteryHistoryList = new ArrayList<>();
                slotBatteryHistoryList.add(
                        batteryHistoryMap.getOrDefault(startTimestamp, EMPTY_BATTERY_MAP));
                for (Long timestamp = TimestampUtils.getNextHourTimestamp(startTimestamp);
                        timestamp < endTimestamp;
                        timestamp += DateUtils.HOUR_IN_MILLIS) {
                    slotBatteryHistoryList.add(
                            batteryHistoryMap.getOrDefault(timestamp, EMPTY_BATTERY_MAP));
                }
                slotBatteryHistoryList.add(
                        batteryHistoryMap.getOrDefault(endTimestamp, EMPTY_BATTERY_MAP));

                final BatteryDiffData hourlyBatteryDiffData =
                        insertHourlyUsageDiffDataPerSlot(
                                context,
                                startTimestamp,
                                endTimestamp,
                                startBatteryLevel,
                                endBatteryLevel,
                                userIdsSeries,
                                slotDuration,
                                systemAppsPackageNames,
                                systemAppsUids,
                                appUsagePeriodMap == null
                                                || appUsagePeriodMap.get(dailyIndex) == null
                                        ? null
                                        : appUsagePeriodMap.get(dailyIndex).get(hourlyIndex),
                                slotBatteryHistoryList);
                batteryDiffDataMap.put(startTimestamp, hourlyBatteryDiffData);
            }
        }
        return batteryDiffDataMap;
    }

    /**
     * @return Returns the indexed battery usage data for each corresponding time slot.
     *     <p>There could be 2 cases of the returned value:
     *     <ul>
     *       <li>null: empty or invalid data.
     *       <li>1 part: if batteryLevelData is null.
     *           <p>[SELECTED_INDEX_ALL][SELECTED_INDEX_ALL]
     *       <li>3 parts: if batteryLevelData is not null.
     *           <p>1 - [SELECTED_INDEX_ALL][SELECTED_INDEX_ALL]
     *           <p>2 - [0][SELECTED_INDEX_ALL] ~ [maxDailyIndex][SELECTED_INDEX_ALL]
     *           <p>3 - [0][0] ~ [maxDailyIndex][maxHourlyIndex]
     *     </ul>
     */
    static Map<Integer, Map<Integer, BatteryDiffData>> generateBatteryUsageMap(
            final Context context,
            final Map<Long, BatteryDiffData> batteryDiffDataMap,
            final @Nullable BatteryLevelData batteryLevelData) {
        final Map<Integer, Map<Integer, BatteryDiffData>> resultMap = new ArrayMap<>();
        if (batteryLevelData == null) {
            Preconditions.checkArgument(batteryDiffDataMap.size() == 1);
            BatteryDiffData batteryDiffData = batteryDiffDataMap.values().stream().toList().get(0);
            final Map<Integer, BatteryDiffData> allUsageMap = new ArrayMap<>();
            allUsageMap.put(SELECTED_INDEX_ALL, batteryDiffData);
            resultMap.put(SELECTED_INDEX_ALL, allUsageMap);
            return resultMap;
        }
        List<BatteryLevelData.PeriodBatteryLevelData> hourlyBatteryLevelsPerDay =
                batteryLevelData.getHourlyBatteryLevelsPerDay();
        // Insert diff data from [0][0] to [maxDailyIndex][maxHourlyIndex].
        insertHourlyUsageDiffData(hourlyBatteryLevelsPerDay, batteryDiffDataMap, resultMap);
        // Insert diff data from [0][SELECTED_INDEX_ALL] to [maxDailyIndex][SELECTED_INDEX_ALL].
        insertDailyUsageDiffData(context, hourlyBatteryLevelsPerDay, resultMap);
        // Insert diff data [SELECTED_INDEX_ALL][SELECTED_INDEX_ALL].
        insertAllUsageDiffData(context, resultMap);
        if (!isUsageMapValid(resultMap, hourlyBatteryLevelsPerDay)) {
            return null;
        }
        return resultMap;
    }

    @VisibleForTesting
    @Nullable
    static BatteryDiffData generateBatteryDiffData(
            final Context context,
            final UserIdsSeries userIdsSeries,
            final long startTimestamp,
            final List<BatteryHistEntry> batteryHistEntryList,
            final @NonNull Set<String> systemAppsPackageNames,
            final @NonNull Set<Integer> systemAppsUids) {
        final List<BatteryDiffEntry> appEntries = new ArrayList<>();
        final List<BatteryDiffEntry> systemEntries = new ArrayList<>();
        if (batteryHistEntryList == null || batteryHistEntryList.isEmpty()) {
            Log.w(TAG, "batteryHistEntryList is null or empty in generateBatteryDiffData()");
            return new BatteryDiffData(
                    context,
                    startTimestamp,
                    getCurrentTimeMillis(),
                    /* startBatteryLevel= */ 100,
                    getCurrentLevel(context),
                    /* screenOnTime= */ 0L,
                    appEntries,
                    systemEntries,
                    systemAppsPackageNames,
                    systemAppsUids,
                    /* isAccumulated= */ false);
        }
        for (BatteryHistEntry entry : batteryHistEntryList) {
            final boolean isFromOtherUsers =
                    isConsumedFromOtherUsers(userIdsSeries, entry);
            // Not show other users' battery usage data.
            if (isFromOtherUsers) {
                continue;
            } else {
                final BatteryDiffEntry currentBatteryDiffEntry =
                        new BatteryDiffEntry(
                                context,
                                entry.mUid,
                                entry.mUserId,
                                entry.getKey(),
                                entry.mIsHidden,
                                entry.mDrainType,
                                entry.mPackageName,
                                entry.mAppLabel,
                                entry.mConsumerType,
                                entry.mForegroundUsageTimeInMs,
                                entry.mForegroundServiceUsageTimeInMs,
                                entry.mBackgroundUsageTimeInMs,
                                /* screenOnTimeInMs= */ 0,
                                entry.mConsumePower,
                                entry.mForegroundUsageConsumePower,
                                entry.mForegroundServiceUsageConsumePower,
                                entry.mBackgroundUsageConsumePower,
                                entry.mCachedUsageConsumePower);
                if (currentBatteryDiffEntry.isSystemEntry()) {
                    systemEntries.add(currentBatteryDiffEntry);
                } else {
                    appEntries.add(currentBatteryDiffEntry);
                }
            }
        }
        return new BatteryDiffData(
                context,
                startTimestamp,
                getCurrentTimeMillis(),
                /* startBatteryLevel= */ 100,
                getCurrentLevel(context),
                /* screenOnTime= */ 0L,
                appEntries,
                systemEntries,
                systemAppsPackageNames,
                systemAppsUids,
                /* isAccumulated= */ false);
    }

    /**
     * {@code Long} stands for the userId.
     *
     * <p>{@code String} stands for the packageName.
     */
    @VisibleForTesting
    @Nullable
    static Map<Long, Map<String, List<AppUsagePeriod>>> buildAppUsagePeriodList(
            Context context,
            final List<AppUsageEvent> appUsageEvents,
            final List<BatteryEvent> batteryEventList,
            final long startTime,
            final long endTime) {
        if (appUsageEvents.isEmpty()) {
            return null;
        }

        // Attributes the list of AppUsagePeriod into device events and instance events for further
        // use.
        final List<AppUsageEvent> deviceEvents = new ArrayList<>();
        final ArrayMap<Integer, List<AppUsageEvent>> usageEventsByInstanceId = new ArrayMap<>();
        for (final AppUsageEvent event : appUsageEvents) {
            final AppUsageEventType eventType = event.getType();
            if (eventType == AppUsageEventType.ACTIVITY_RESUMED
                    || eventType == AppUsageEventType.ACTIVITY_STOPPED) {
                final int instanceId = event.getInstanceId();
                if (usageEventsByInstanceId.get(instanceId) == null) {
                    usageEventsByInstanceId.put(instanceId, new ArrayList<>());
                }
                usageEventsByInstanceId.get(instanceId).add(event);
            } else if (eventType == AppUsageEventType.DEVICE_SHUTDOWN) {
                // Track device-wide events in their own list as they affect any app.
                deviceEvents.add(event);
            }
        }
        if (usageEventsByInstanceId.isEmpty()) {
            return null;
        }

        final Map<Long, Map<String, List<AppUsagePeriod>>> allUsagePeriods = new ArrayMap<>();

        for (int i = 0; i < usageEventsByInstanceId.size(); i++) {
            // The usage periods for an instance are determined by the usage events with its
            // instance id and any device-wide events such as device shutdown.
            final List<AppUsageEvent> usageEvents = usageEventsByInstanceId.valueAt(i);
            if (usageEvents == null || usageEvents.isEmpty()) {
                continue;
            }
            // The same instance must have same userId and packageName.
            final AppUsageEvent firstEvent = usageEvents.get(0);
            final long eventUserId = firstEvent.getUserId();
            final String packageName =
                    getEffectivePackageName(
                            context,
                            sUsageStatsManager,
                            firstEvent.getPackageName(),
                            firstEvent.getTaskRootPackageName());
            usageEvents.addAll(deviceEvents);
            // Sorts the usageEvents in ascending order based on the timestamp before computing the
            // period.
            Collections.sort(usageEvents, APP_USAGE_EVENT_TIMESTAMP_COMPARATOR);

            // A package might have multiple instances. Computes the usage period per instance id
            // and then merges them into the same user-package map.
            final List<AppUsagePeriod> usagePeriodList =
                    excludePowerConnectedTimeFromAppUsagePeriodList(
                            buildAppUsagePeriodListPerInstance(usageEvents, startTime, endTime),
                            batteryEventList);
            if (!usagePeriodList.isEmpty()) {
                addToUsagePeriodMap(allUsagePeriods, usagePeriodList, eventUserId, packageName);
            }
        }

        // Sorts all usage periods by start time.
        for (final long userId : allUsagePeriods.keySet()) {
            if (allUsagePeriods.get(userId) == null) {
                continue;
            }
            for (final String packageName : allUsagePeriods.get(userId).keySet()) {
                Collections.sort(
                        allUsagePeriods.get(userId).get(packageName),
                        Comparator.comparing(AppUsagePeriod::getStartTime));
            }
        }
        return allUsagePeriods.isEmpty() ? null : allUsagePeriods;
    }

    @VisibleForTesting
    static List<AppUsagePeriod> buildAppUsagePeriodListPerInstance(
            final List<AppUsageEvent> usageEvents, final long startTime, final long endTime) {
        final List<AppUsagePeriod> usagePeriodList = new ArrayList<>();
        AppUsagePeriod.Builder pendingUsagePeriod = AppUsagePeriod.newBuilder();

        for (final AppUsageEvent event : usageEvents) {
            final long eventTime = event.getTimestamp();

            if (event.getType() == AppUsageEventType.ACTIVITY_RESUMED) {
                // If there is an existing start time, simply ignore this start event.
                // If there was no start time, then start a new period.
                if (!pendingUsagePeriod.hasStartTime()) {
                    pendingUsagePeriod.setStartTime(eventTime);
                }
            } else if (event.getType() == AppUsageEventType.ACTIVITY_STOPPED) {
                pendingUsagePeriod.setEndTime(eventTime);
                if (!pendingUsagePeriod.hasStartTime()) {
                    pendingUsagePeriod.setStartTime(
                            getStartTimeForIncompleteUsagePeriod(pendingUsagePeriod));
                }
                // If we already have start time, add it directly.
                validateAndAddToPeriodList(
                        usagePeriodList, pendingUsagePeriod.build(), startTime, endTime);
                pendingUsagePeriod.clear();
            } else if (event.getType() == AppUsageEventType.DEVICE_SHUTDOWN) {
                // The end event might be lost when device is shutdown. Use the estimated end
                // time for the period.
                if (pendingUsagePeriod.hasStartTime()) {
                    pendingUsagePeriod.setEndTime(
                            getEndTimeForIncompleteUsagePeriod(pendingUsagePeriod, eventTime));
                    validateAndAddToPeriodList(
                            usagePeriodList, pendingUsagePeriod.build(), startTime, endTime);
                    pendingUsagePeriod.clear();
                }
            }
        }
        // If there exists unclosed period, the stop event might happen in the next time
        // slot. Use the endTime for the period.
        if (pendingUsagePeriod.hasStartTime() && pendingUsagePeriod.getStartTime() < endTime) {
            pendingUsagePeriod.setEndTime(endTime);
            validateAndAddToPeriodList(
                    usagePeriodList, pendingUsagePeriod.build(), startTime, endTime);
            pendingUsagePeriod.clear();
        }
        return usagePeriodList;
    }

    @VisibleForTesting
    static List<AppUsagePeriod> excludePowerConnectedTimeFromAppUsagePeriodList(
            final List<AppUsagePeriod> usagePeriodList, final List<BatteryEvent> batteryEventList) {
        final List<AppUsagePeriod> resultList = new ArrayList<>();
        int index = 0;
        for (AppUsagePeriod inputPeriod : usagePeriodList) {
            long lastStartTime = inputPeriod.getStartTime();
            while (index < batteryEventList.size()) {
                BatteryEvent batteryEvent = batteryEventList.get(index);
                if (batteryEvent.getTimestamp() < inputPeriod.getStartTime()) {
                    // Because the batteryEventList has been sorted, here is to mark the power
                    // connection state when the usage period starts. If power is connected when
                    // the usage period starts, the starting period will be ignored; otherwise it
                    // will be added.
                    if (batteryEvent.getType() == BatteryEventType.POWER_CONNECTED) {
                        lastStartTime = 0;
                    } else if (batteryEvent.getType() == BatteryEventType.POWER_DISCONNECTED) {
                        lastStartTime = inputPeriod.getStartTime();
                    }
                    index++;
                    continue;
                }
                if (batteryEvent.getTimestamp() > inputPeriod.getEndTime()) {
                    // Because the batteryEventList has been sorted, if any event is already after
                    // the end time, all the following events should be able to drop directly.
                    break;
                }

                if (batteryEvent.getType() == BatteryEventType.POWER_CONNECTED
                        && lastStartTime != 0) {
                    resultList.add(
                            AppUsagePeriod.newBuilder()
                                    .setStartTime(lastStartTime)
                                    .setEndTime(batteryEvent.getTimestamp())
                                    .build());
                    lastStartTime = 0;
                } else if (batteryEvent.getType() == BatteryEventType.POWER_DISCONNECTED) {
                    lastStartTime = batteryEvent.getTimestamp();
                }
                index++;
            }
            if (lastStartTime != 0) {
                resultList.add(
                        AppUsagePeriod.newBuilder()
                                .setStartTime(lastStartTime)
                                .setEndTime(inputPeriod.getEndTime())
                                .build());
            }
        }
        return resultList;
    }

    @VisibleForTesting
    static long getScreenOnTime(
            final Map<Long, Map<String, List<AppUsagePeriod>>> appUsageMap,
            final long userId,
            final String packageName) {
        if (appUsageMap == null || appUsageMap.get(userId) == null) {
            return 0;
        }

        return getScreenOnTime(appUsageMap.get(userId).get(packageName));
    }

    static Map<Long, BatteryDiffData> getBatteryDiffDataMapFromStatsService(
            final Context context,
            final UserIdsSeries userIdsSeries,
            final long startTimestamp,
            @NonNull final Set<String> systemAppsPackageNames,
            @NonNull final Set<Integer> systemAppsUids) {
        Map<Long, BatteryDiffData> batteryDiffDataMap = new ArrayMap<>(1);
        batteryDiffDataMap.put(
                startTimestamp,
                generateBatteryDiffData(
                        context,
                        userIdsSeries,
                        startTimestamp,
                        getBatteryHistListFromFromStatsService(context),
                        systemAppsPackageNames,
                        systemAppsUids));
        return batteryDiffDataMap;
    }

    static void loadLabelAndIcon(
            @Nullable final Map<Integer, Map<Integer, BatteryDiffData>> batteryUsageMap) {
        if (batteryUsageMap == null) {
            return;
        }
        // Pre-loads each BatteryDiffEntry relative icon and label for all slots.
        final BatteryDiffData batteryUsageMapForAll =
                batteryUsageMap.get(SELECTED_INDEX_ALL).get(SELECTED_INDEX_ALL);
        if (batteryUsageMapForAll != null) {
            batteryUsageMapForAll.getAppDiffEntryList().forEach(entry -> entry.loadLabelAndIcon());
            batteryUsageMapForAll
                    .getSystemDiffEntryList()
                    .forEach(entry -> entry.loadLabelAndIcon());
        }
    }

    static Set<String> getSystemAppsPackageNames(Context context) {
        return sTestSystemAppsPackageNames != null
                ? sTestSystemAppsPackageNames
                : AppListRepositoryUtil.getSystemPackageNames(context, context.getUserId());
    }

    static Set<Integer> getSystemAppsUids(Context context) {
        Set<Integer> result = new ArraySet<>(1);
        try {
            result.add(
                    context.getPackageManager()
                            .getUidForSharedUser(ANDROID_CORE_APPS_SHARED_USER_ID));
        } catch (PackageManager.NameNotFoundException e) {
            // No Android Core Apps
        }
        return result;
    }

    /**
     * Generates the list of {@link AppUsageEvent} within the specific time range. The buffer is
     * added to make sure the app usage calculation near the boundaries is correct.
     *
     * <p>Note: The appUsageEventList should have been sorted when calling this function.
     */
    private static List<AppUsageEvent> getAppUsageEventListWithinTimeRangeWithBuffer(
            final List<AppUsageEvent> appUsageEventList, final long startTime, final long endTime) {
        final long start = startTime - DatabaseUtils.USAGE_QUERY_BUFFER_HOURS;
        final long end = endTime + DatabaseUtils.USAGE_QUERY_BUFFER_HOURS;
        final List<AppUsageEvent> resultList = new ArrayList<>();
        for (final AppUsageEvent event : appUsageEventList) {
            final long eventTime = event.getTimestamp();
            // Because the appUsageEventList has been sorted, if any event is already after the end
            // time, all the following events should be able to drop directly.
            if (eventTime > end) {
                break;
            }
            // If the event timestamp is in [start, end], add it into the result list.
            if (eventTime >= start) {
                resultList.add(event);
            }
        }
        return resultList;
    }

    private static void validateAndAddToPeriodList(
            final List<AppUsagePeriod> appUsagePeriodList,
            final AppUsagePeriod appUsagePeriod,
            final long startTime,
            final long endTime) {
        final long periodStartTime =
                trimPeriodTime(appUsagePeriod.getStartTime(), startTime, endTime);
        final long periodEndTime = trimPeriodTime(appUsagePeriod.getEndTime(), startTime, endTime);
        // Only when the period is valid, add it into the list.
        if (periodStartTime < periodEndTime) {
            final AppUsagePeriod period =
                    AppUsagePeriod.newBuilder()
                            .setStartTime(periodStartTime)
                            .setEndTime(periodEndTime)
                            .build();
            appUsagePeriodList.add(period);
        }
    }

    private static long trimPeriodTime(
            final long originalTime, final long startTime, final long endTime) {
        long finalTime = Math.max(originalTime, startTime);
        finalTime = Math.min(finalTime, endTime);
        return finalTime;
    }

    private static void addToUsagePeriodMap(
            final Map<Long, Map<String, List<AppUsagePeriod>>> usagePeriodMap,
            final List<AppUsagePeriod> usagePeriodList,
            final long userId,
            final String packageName) {
        usagePeriodMap.computeIfAbsent(userId, key -> new ArrayMap<>());
        final Map<String, List<AppUsagePeriod>> packageNameMap = usagePeriodMap.get(userId);
        packageNameMap.computeIfAbsent(packageName, key -> new ArrayList<>());
        packageNameMap.get(packageName).addAll(usagePeriodList);
    }

    /** Returns the start time that gives {@code usagePeriod} the default usage duration. */
    private static long getStartTimeForIncompleteUsagePeriod(
            final AppUsagePeriodOrBuilder usagePeriod) {
        return usagePeriod.getEndTime() - DEFAULT_USAGE_DURATION_FOR_INCOMPLETE_INTERVAL;
    }

    /** Returns the end time that gives {@code usagePeriod} the default usage duration. */
    private static long getEndTimeForIncompleteUsagePeriod(
            final AppUsagePeriodOrBuilder usagePeriod, final long eventTime) {
        return Math.min(
                usagePeriod.getStartTime() + DEFAULT_USAGE_DURATION_FOR_INCOMPLETE_INTERVAL,
                eventTime);
    }

    @Nullable
    private static UsageEvents getAppUsageEventsForUser(
            Context context,
            final UserIdsSeries userIdsSeries,
            final int userID,
            final long earliestTimestamp) {
        final String callingPackage = context.getPackageName();
        final long now = System.currentTimeMillis();
        // When the user is not unlocked, UsageStatsManager will return null, so bypass the
        // following data loading logics directly.
        if (userIdsSeries.isUserLocked(userID)) {
            Log.w(TAG, "fail to load app usage event for user :" + userID + " because locked");
            return null;
        }
        final long startTime =
                DatabaseUtils.getAppUsageStartTimestampOfUser(context, userID, earliestTimestamp);
        return loadAppUsageEventsForUserFromService(
                sUsageStatsManager, startTime, now, userID, callingPackage);
    }

    @Nullable
    private static UsageEvents loadAppUsageEventsForUserFromService(
            final IUsageStatsManager usageStatsManager,
            final long startTime,
            final long endTime,
            final int userId,
            final String callingPackage) {
        final long start = System.currentTimeMillis();
        UsageEvents events = null;
        try {
            events =
                    usageStatsManager.queryEventsForUser(
                            startTime, endTime, userId, callingPackage);
        } catch (RemoteException e) {
            Log.e(TAG, "Error fetching usage events: ", e);
        }
        final long elapsedTime = System.currentTimeMillis() - start;
        Log.d(
                TAG,
                String.format(
                        "getAppUsageEventsForUser(): %d from %d to %d in %d/ms",
                        userId, startTime, endTime, elapsedTime));
        return events;
    }

    @Nullable
    private static List<BatteryHistEntry> getBatteryHistListFromFromStatsService(
            final Context context) {
        List<BatteryHistEntry> batteryHistEntryList = null;
        try {
            final BatteryUsageStats batteryUsageStats = getBatteryUsageStats(context);
            final List<BatteryEntry> batteryEntryList =
                    generateBatteryEntryListFromBatteryUsageStats(context, batteryUsageStats);
            batteryHistEntryList = convertToBatteryHistEntry(batteryEntryList, batteryUsageStats);
            closeBatteryUsageStats(batteryUsageStats);
        } catch (RuntimeException e) {
            Log.e(TAG, "load batteryUsageStats:", e);
        }

        return batteryHistEntryList;
    }

    @VisibleForTesting
    @Nullable
    static List<BatteryHistEntry> convertToBatteryHistEntry(
            @Nullable final List<BatteryEntry> batteryEntryList,
            final BatteryUsageStats batteryUsageStats) {
        if (batteryEntryList == null || batteryEntryList.isEmpty()) {
            Log.w(TAG, "batteryEntryList is null or empty in convertToBatteryHistEntry()");
            return null;
        }
        return batteryEntryList.stream()
                .filter(
                        entry -> {
                            final long foregroundMs = entry.getTimeInForegroundMs();
                            final long backgroundMs = entry.getTimeInBackgroundMs();
                            return entry.getConsumedPower() > 0
                                    || (entry.getConsumedPower() == 0
                                            && (foregroundMs != 0 || backgroundMs != 0));
                        })
                .map(entry -> ConvertUtils.convertToBatteryHistEntry(entry, batteryUsageStats))
                .collect(Collectors.toList());
    }

    /**
     * Interpolates history map based on expected timestamp slots and processes the corner case when
     * the expected start timestamp is earlier than what we have.
     */
    private static void interpolateHistory(
            Context context,
            final List<Long> rawTimestampList,
            final List<Long> expectedTimestampSlots,
            final Map<Long, Map<String, BatteryHistEntry>> batteryHistoryMap,
            final Map<Long, Map<String, BatteryHistEntry>> resultMap) {
        if (rawTimestampList.isEmpty() || expectedTimestampSlots.isEmpty()) {
            return;
        }
        final int expectedTimestampSlotsSize = expectedTimestampSlots.size();
        final long startTimestamp = expectedTimestampSlots.get(0);
        final long endTimestamp = expectedTimestampSlots.get(expectedTimestampSlotsSize - 1);

        resultMap.put(startTimestamp, batteryHistoryMap.get(startTimestamp));
        for (int index = 1; index < expectedTimestampSlotsSize - 1; index++) {
            interpolateHistoryForSlot(
                    context,
                    expectedTimestampSlots.get(index),
                    rawTimestampList,
                    batteryHistoryMap,
                    resultMap);
        }
        resultMap.put(
                endTimestamp,
                Map.of(CURRENT_TIME_BATTERY_HISTORY_PLACEHOLDER, EMPTY_BATTERY_HIST_ENTRY));
    }

    private static void interpolateHistoryForSlot(
            Context context,
            final long currentSlot,
            final List<Long> rawTimestampList,
            final Map<Long, Map<String, BatteryHistEntry>> batteryHistoryMap,
            final Map<Long, Map<String, BatteryHistEntry>> resultMap) {
        final long[] nearestTimestamps = findNearestTimestamp(rawTimestampList, currentSlot);
        final long lowerTimestamp = nearestTimestamps[0];
        final long upperTimestamp = nearestTimestamps[1];
        // Case 1: upper timestamp is zero since scheduler is delayed!
        if (upperTimestamp == 0) {
            log(context, "job scheduler is delayed", currentSlot, null);
            resultMap.put(currentSlot, new ArrayMap<>());
            return;
        }
        // Case 2: upper timestamp is closed to the current timestamp.
        if ((upperTimestamp - currentSlot)
                < MAX_DIFF_SECONDS_OF_UPPER_TIMESTAMP * DateUtils.SECOND_IN_MILLIS) {
            log(context, "force align into the nearest slot", currentSlot, null);
            resultMap.put(currentSlot, batteryHistoryMap.get(upperTimestamp));
            return;
        }
        // Case 3: lower timestamp is zero before starting to collect data.
        if (lowerTimestamp == 0) {
            log(context, "no lower timestamp slot data", currentSlot, null);
            resultMap.put(currentSlot, new ArrayMap<>());
            return;
        }
        interpolateHistoryForSlot(
                context, currentSlot, lowerTimestamp, upperTimestamp, batteryHistoryMap, resultMap);
    }

    private static void interpolateHistoryForSlot(
            Context context,
            final long currentSlot,
            final long lowerTimestamp,
            final long upperTimestamp,
            final Map<Long, Map<String, BatteryHistEntry>> batteryHistoryMap,
            final Map<Long, Map<String, BatteryHistEntry>> resultMap) {
        final Map<String, BatteryHistEntry> lowerEntryDataMap =
                batteryHistoryMap.get(lowerTimestamp);
        final Map<String, BatteryHistEntry> upperEntryDataMap =
                batteryHistoryMap.get(upperTimestamp);
        // Verifies whether the lower data is valid to use or not by checking boot time.
        final BatteryHistEntry upperEntryDataFirstEntry =
                upperEntryDataMap.values().stream().findFirst().get();
        final long upperEntryDataBootTimestamp =
                upperEntryDataFirstEntry.mTimestamp - upperEntryDataFirstEntry.mBootTimestamp;
        // Lower data is captured before upper data corresponding device is booting.
        // Skips the booting-specific logics and always does interpolation for daily chart level
        // data.
        if (lowerTimestamp < upperEntryDataBootTimestamp
                && !TimestampUtils.isMidnight(currentSlot)) {
            // Provides an opportunity to force align the slot directly.
            if ((upperTimestamp - currentSlot) < 10 * DateUtils.MINUTE_IN_MILLIS) {
                log(context, "force align into the nearest slot", currentSlot, null);
                resultMap.put(currentSlot, upperEntryDataMap);
            } else {
                log(context, "in the different booting section", currentSlot, null);
                resultMap.put(currentSlot, new ArrayMap<>());
            }
            return;
        }
        log(context, "apply interpolation arithmetic", currentSlot, null);
        final Map<String, BatteryHistEntry> newHistEntryMap = new ArrayMap<>();
        final double timestampLength = upperTimestamp - lowerTimestamp;
        final double timestampDiff = currentSlot - lowerTimestamp;
        // Applies interpolation arithmetic for each BatteryHistEntry.
        for (String entryKey : upperEntryDataMap.keySet()) {
            final BatteryHistEntry lowerEntry = lowerEntryDataMap.get(entryKey);
            final BatteryHistEntry upperEntry = upperEntryDataMap.get(entryKey);
            // Checks whether there is any abnormal battery reset conditions.
            if (lowerEntry != null) {
                final boolean invalidForegroundUsageTime =
                        lowerEntry.mForegroundUsageTimeInMs > upperEntry.mForegroundUsageTimeInMs;
                final boolean invalidBackgroundUsageTime =
                        lowerEntry.mBackgroundUsageTimeInMs > upperEntry.mBackgroundUsageTimeInMs;
                if (invalidForegroundUsageTime || invalidBackgroundUsageTime) {
                    newHistEntryMap.put(entryKey, upperEntry);
                    log(context, "abnormal reset condition is found", currentSlot, upperEntry);
                    continue;
                }
            }
            final BatteryHistEntry newEntry =
                    BatteryHistEntry.interpolate(
                            currentSlot,
                            upperTimestamp,
                            /* ratio= */ timestampDiff / timestampLength,
                            lowerEntry,
                            upperEntry);
            newHistEntryMap.put(entryKey, newEntry);
            if (lowerEntry == null) {
                log(context, "cannot find lower entry data", currentSlot, upperEntry);
                continue;
            }
        }
        resultMap.put(currentSlot, newHistEntryMap);
    }

    private static Integer getLevel(
            Context context,
            final Map<Long, Map<String, BatteryHistEntry>> processedBatteryHistoryMap,
            final long timestamp) {
        final Map<String, BatteryHistEntry> entryMap = processedBatteryHistoryMap.get(timestamp);
        if (entryMap == null || entryMap.isEmpty()) {
            Log.e(
                    TAG,
                    "abnormal entry list in the timestamp:"
                            + ConvertUtils.utcToLocalTimeForLogging(timestamp));
            return BATTERY_LEVEL_UNKNOWN;
        }
        // The current time battery history hasn't been loaded yet, returns the current battery
        // level.
        if (entryMap.containsKey(CURRENT_TIME_BATTERY_HISTORY_PLACEHOLDER)) {
            return getCurrentLevel(context);
        }
        // Averages the battery level in each time slot to avoid corner conditions.
        float batteryLevelCounter = 0;
        for (BatteryHistEntry entry : entryMap.values()) {
            batteryLevelCounter += entry.mBatteryLevel;
        }
        return Math.round(batteryLevelCounter / entryMap.size());
    }

    private static int getCurrentLevel(Context context) {
        final Intent intent = BatteryUtils.getBatteryIntent(context);
        return BatteryStatus.getBatteryLevel(intent);
    }

    private static void insertHourlyUsageDiffData(
            final List<BatteryLevelData.PeriodBatteryLevelData> hourlyBatteryLevelsPerDay,
            final Map<Long, BatteryDiffData> batteryDiffDataMap,
            final Map<Integer, Map<Integer, BatteryDiffData>> resultMap) {
        // Each time slot usage diff data =
        //     sum(Math.abs(timestamp[i+1] data - timestamp[i] data));
        // since we want to aggregate every hour usage diff data into a single time slot.
        for (int dailyIndex = 0; dailyIndex < hourlyBatteryLevelsPerDay.size(); dailyIndex++) {
            final Map<Integer, BatteryDiffData> dailyDiffMap = new ArrayMap<>();
            resultMap.put(dailyIndex, dailyDiffMap);
            if (hourlyBatteryLevelsPerDay.get(dailyIndex) == null) {
                continue;
            }
            final List<Long> hourlyTimestamps =
                    hourlyBatteryLevelsPerDay.get(dailyIndex).getTimestamps();
            for (int hourlyIndex = 0; hourlyIndex < hourlyTimestamps.size() - 1; hourlyIndex++) {
                final Long startTimestamp = hourlyTimestamps.get(hourlyIndex);
                dailyDiffMap.put(hourlyIndex, batteryDiffDataMap.get(startTimestamp));
            }
        }
    }

    private static void insertDailyUsageDiffData(
            final Context context,
            final List<BatteryLevelData.PeriodBatteryLevelData> hourlyBatteryLevelsPerDay,
            final Map<Integer, Map<Integer, BatteryDiffData>> resultMap) {
        for (int index = 0; index < hourlyBatteryLevelsPerDay.size(); index++) {
            Map<Integer, BatteryDiffData> dailyUsageMap = resultMap.get(index);
            if (dailyUsageMap == null) {
                dailyUsageMap = new ArrayMap<>();
                resultMap.put(index, dailyUsageMap);
            }
            dailyUsageMap.put(
                    SELECTED_INDEX_ALL,
                    getAccumulatedUsageDiffData(context, dailyUsageMap.values()));
        }
    }

    private static void insertAllUsageDiffData(
            final Context context, final Map<Integer, Map<Integer, BatteryDiffData>> resultMap) {
        final List<BatteryDiffData> diffDataList = new ArrayList<>();
        resultMap
                .keySet()
                .forEach(key -> diffDataList.add(resultMap.get(key).get(SELECTED_INDEX_ALL)));
        final Map<Integer, BatteryDiffData> allUsageMap = new ArrayMap<>();
        allUsageMap.put(SELECTED_INDEX_ALL, getAccumulatedUsageDiffData(context, diffDataList));
        resultMap.put(SELECTED_INDEX_ALL, allUsageMap);
    }

    @Nullable
    private static BatteryDiffData insertHourlyUsageDiffDataPerSlot(
            final Context context,
            final long startTimestamp,
            final long endTimestamp,
            final int startBatteryLevel,
            final int endBatteryLevel,
            final UserIdsSeries userIdsSeries,
            final long slotDuration,
            final Set<String> systemAppsPackageNames,
            final Set<Integer> systemAppsUids,
            final Map<Long, Map<String, List<AppUsagePeriod>>> appUsageMap,
            final List<Map<String, BatteryHistEntry>> slotBatteryHistoryList) {
        long slotScreenOnTime = 0L;
        if (appUsageMap != null) {
            final List<AppUsagePeriod> flatAppUsagePeriodList = new ArrayList<>();
            for (final long userId : appUsageMap.keySet()) {
                if (userIdsSeries.isFromOtherUsers(userId) || appUsageMap.get(userId) == null) {
                    continue;
                }
                for (final String packageName : appUsageMap.get(userId).keySet()) {
                    final List<AppUsagePeriod> appUsagePeriodList =
                            appUsageMap.get(userId).get(packageName);
                    if (appUsagePeriodList != null) {
                        flatAppUsagePeriodList.addAll(appUsagePeriodList);
                    }
                }
            }
            slotScreenOnTime = Math.min(slotDuration, getScreenOnTime(flatAppUsagePeriodList));
        }

        final List<BatteryDiffEntry> appEntries = new ArrayList<>();
        final List<BatteryDiffEntry> systemEntries = new ArrayList<>();

        // Collects all keys in these three time slot records as all populations.
        final Set<String> allBatteryHistEntryKeys = new ArraySet<>();
        for (Map<String, BatteryHistEntry> slotBatteryHistMap : slotBatteryHistoryList) {
            if (slotBatteryHistMap.isEmpty()) {
                // We should not get the empty list since we have at least one fake data to record
                // the battery level and status in each time slot, the empty list is used to
                // represent there is no enough data to apply interpolation arithmetic.
                return new BatteryDiffData(
                        context,
                        startTimestamp,
                        endTimestamp,
                        startBatteryLevel,
                        endBatteryLevel,
                        /* screenOnTime= */ 0L,
                        appEntries,
                        systemEntries,
                        systemAppsPackageNames,
                        systemAppsUids,
                        /* isAccumulated= */ false);
            }
            allBatteryHistEntryKeys.addAll(slotBatteryHistMap.keySet());
        }

        // Calculates all packages diff usage data in a specific time slot.
        for (String key : allBatteryHistEntryKeys) {
            if (key == null) {
                continue;
            }

            BatteryHistEntry selectedBatteryEntry = null;
            final List<BatteryHistEntry> batteryHistEntries = new ArrayList<>();
            for (Map<String, BatteryHistEntry> slotBatteryHistMap : slotBatteryHistoryList) {
                BatteryHistEntry entry =
                        slotBatteryHistMap.getOrDefault(key, EMPTY_BATTERY_HIST_ENTRY);
                batteryHistEntries.add(entry);
                if (selectedBatteryEntry == null && entry != EMPTY_BATTERY_HIST_ENTRY) {
                    selectedBatteryEntry = entry;
                }
            }
            if (selectedBatteryEntry == null) {
                continue;
            }

            // Not show other users' battery usage data.
            final boolean isFromOtherUsers =
                    isConsumedFromOtherUsers(userIdsSeries, selectedBatteryEntry);
            if (isFromOtherUsers) {
                continue;
            }

            // Cumulative values is a specific time slot for a specific app.
            long foregroundUsageTimeInMs = 0;
            long foregroundServiceUsageTimeInMs = 0;
            long backgroundUsageTimeInMs = 0;
            double consumePower = 0;
            double foregroundUsageConsumePower = 0;
            double foregroundServiceUsageConsumePower = 0;
            double backgroundUsageConsumePower = 0;
            double cachedUsageConsumePower = 0;
            for (int i = 0; i < batteryHistEntries.size() - 1; i++) {
                final BatteryHistEntry currentEntry = batteryHistEntries.get(i);
                final BatteryHistEntry nextEntry = batteryHistEntries.get(i + 1);
                foregroundUsageTimeInMs +=
                        getDiffValue(
                                currentEntry.mForegroundUsageTimeInMs,
                                nextEntry.mForegroundUsageTimeInMs);
                foregroundServiceUsageTimeInMs +=
                        getDiffValue(
                                currentEntry.mForegroundServiceUsageTimeInMs,
                                nextEntry.mForegroundServiceUsageTimeInMs);
                backgroundUsageTimeInMs +=
                        getDiffValue(
                                currentEntry.mBackgroundUsageTimeInMs,
                                nextEntry.mBackgroundUsageTimeInMs);
                consumePower += getDiffValue(currentEntry.mConsumePower, nextEntry.mConsumePower);
                foregroundUsageConsumePower +=
                        getDiffValue(
                                currentEntry.mForegroundUsageConsumePower,
                                nextEntry.mForegroundUsageConsumePower);
                foregroundServiceUsageConsumePower +=
                        getDiffValue(
                                currentEntry.mForegroundServiceUsageConsumePower,
                                nextEntry.mForegroundServiceUsageConsumePower);
                backgroundUsageConsumePower +=
                        getDiffValue(
                                currentEntry.mBackgroundUsageConsumePower,
                                nextEntry.mBackgroundUsageConsumePower);
                cachedUsageConsumePower +=
                        getDiffValue(
                                currentEntry.mCachedUsageConsumePower,
                                nextEntry.mCachedUsageConsumePower);
            }
            if (isSystemConsumer(selectedBatteryEntry.mConsumerType)
                    && selectedBatteryEntry.mDrainType == BatteryConsumer.POWER_COMPONENT_SCREEN) {
                // Replace Screen system component time with screen on time.
                foregroundUsageTimeInMs = slotScreenOnTime;
            }
            // Excludes entry since we don't have enough data to calculate.
            if (foregroundUsageTimeInMs == 0
                    && foregroundServiceUsageTimeInMs == 0
                    && backgroundUsageTimeInMs == 0
                    && consumePower == 0) {
                continue;
            }
            // Forces refine the cumulative value since it may introduce deviation error since we
            // will apply the interpolation arithmetic.
            final float totalUsageTimeInMs =
                    foregroundUsageTimeInMs
                            + backgroundUsageTimeInMs
                            + foregroundServiceUsageTimeInMs;
            if (totalUsageTimeInMs > slotDuration) {
                final float ratio = slotDuration / totalUsageTimeInMs;
                if (sDebug) {
                    Log.w(
                            TAG,
                            String.format(
                                    "abnormal usage time %d|%d|%d for:\n%s",
                                    Duration.ofMillis(foregroundUsageTimeInMs).getSeconds(),
                                    Duration.ofMillis(foregroundServiceUsageTimeInMs).getSeconds(),
                                    Duration.ofMillis(backgroundUsageTimeInMs).getSeconds(),
                                    selectedBatteryEntry));
                }
                foregroundUsageTimeInMs = Math.round(foregroundUsageTimeInMs * ratio);
                foregroundServiceUsageTimeInMs = Math.round(foregroundServiceUsageTimeInMs * ratio);
                backgroundUsageTimeInMs = Math.round(backgroundUsageTimeInMs * ratio);
                consumePower = consumePower * ratio;
                foregroundUsageConsumePower = foregroundUsageConsumePower * ratio;
                foregroundServiceUsageConsumePower = foregroundServiceUsageConsumePower * ratio;
                backgroundUsageConsumePower = backgroundUsageConsumePower * ratio;
                cachedUsageConsumePower = cachedUsageConsumePower * ratio;
            }

            // Compute the screen on time and make sure it won't exceed the threshold.
            final long screenOnTime =
                    Math.min(
                            (long) slotDuration,
                            getScreenOnTime(
                                    appUsageMap,
                                    selectedBatteryEntry.mUserId,
                                    selectedBatteryEntry.mPackageName));
            // Ensure the following value will not exceed the threshold.
            // value = background + foregroundService + screen-on
            backgroundUsageTimeInMs =
                    Math.min(backgroundUsageTimeInMs, (long) slotDuration - screenOnTime);
            foregroundServiceUsageTimeInMs =
                    Math.min(
                            foregroundServiceUsageTimeInMs,
                            (long) slotDuration - screenOnTime - backgroundUsageTimeInMs);
            final BatteryDiffEntry currentBatteryDiffEntry =
                    new BatteryDiffEntry(
                            context,
                            selectedBatteryEntry.mUid,
                            selectedBatteryEntry.mUserId,
                            selectedBatteryEntry.getKey(),
                            selectedBatteryEntry.mIsHidden,
                            selectedBatteryEntry.mDrainType,
                            selectedBatteryEntry.mPackageName,
                            selectedBatteryEntry.mAppLabel,
                            selectedBatteryEntry.mConsumerType,
                            foregroundUsageTimeInMs,
                            foregroundServiceUsageTimeInMs,
                            backgroundUsageTimeInMs,
                            screenOnTime,
                            consumePower,
                            foregroundUsageConsumePower,
                            foregroundServiceUsageConsumePower,
                            backgroundUsageConsumePower,
                            cachedUsageConsumePower);
            if (currentBatteryDiffEntry.isSystemEntry()) {
                systemEntries.add(currentBatteryDiffEntry);
            } else {
                appEntries.add(currentBatteryDiffEntry);
            }
        }
        return new BatteryDiffData(
                context,
                startTimestamp,
                endTimestamp,
                startBatteryLevel,
                endBatteryLevel,
                slotScreenOnTime,
                appEntries,
                systemEntries,
                systemAppsPackageNames,
                systemAppsUids,
                /* isAccumulated= */ false);
    }

    private static long getScreenOnTime(@Nullable final List<AppUsagePeriod> appUsagePeriodList) {
        if (appUsagePeriodList == null || appUsagePeriodList.isEmpty()) {
            return 0;
        }
        // Create a list of endpoints (the beginning or the end) of usage periods and order the list
        // chronologically.
        final List<AppUsageEndPoint> endPoints =
                appUsagePeriodList.stream()
                        .flatMap(
                                foregroundUsage ->
                                        Stream.of(
                                                AppUsageEndPoint.newBuilder()
                                                        .setTimestamp(
                                                                foregroundUsage.getStartTime())
                                                        .setType(AppUsageEndPointType.START)
                                                        .build(),
                                                AppUsageEndPoint.newBuilder()
                                                        .setTimestamp(foregroundUsage.getEndTime())
                                                        .setType(AppUsageEndPointType.END)
                                                        .build()))
                        .sorted((x, y) -> (int) (x.getTimestamp() - y.getTimestamp()))
                        .collect(Collectors.toList());

        // Traverse the list of endpoints in order to determine the non-overlapping usage duration.
        int numberOfActiveAppUsagePeriods = 0;
        long startOfCurrentContiguousAppUsagePeriod = 0;
        long totalScreenOnTime = 0;
        for (final AppUsageEndPoint endPoint : endPoints) {
            if (endPoint.getType() == AppUsageEndPointType.START) {
                if (numberOfActiveAppUsagePeriods++ == 0) {
                    startOfCurrentContiguousAppUsagePeriod = endPoint.getTimestamp();
                }
            } else {
                if (--numberOfActiveAppUsagePeriods == 0) {
                    totalScreenOnTime +=
                            (endPoint.getTimestamp() - startOfCurrentContiguousAppUsagePeriod);
                }
            }
        }

        return totalScreenOnTime;
    }

    private static boolean isConsumedFromOtherUsers(
            final UserIdsSeries userIdsSeries,
            final BatteryHistEntry batteryHistEntry) {
        return isUidConsumer(batteryHistEntry.mConsumerType)
                && userIdsSeries.isFromOtherUsers(batteryHistEntry.mUserId);
    }

    @Nullable
    private static BatteryDiffData getAccumulatedUsageDiffData(
            final Context context, final Collection<BatteryDiffData> batteryDiffDataList) {
        final Map<String, BatteryDiffEntry> diffEntryMap = new ArrayMap<>();
        final List<BatteryDiffEntry> appEntries = new ArrayList<>();
        final List<BatteryDiffEntry> systemEntries = new ArrayList<>();

        long startTimestamp = Long.MAX_VALUE;
        long endTimestamp = 0;
        int startBatteryLevel = BATTERY_LEVEL_UNKNOWN;
        int endBatteryLevel = BATTERY_LEVEL_UNKNOWN;
        long totalScreenOnTime = 0;
        for (BatteryDiffData batteryDiffData : batteryDiffDataList) {
            if (batteryDiffData == null) {
                continue;
            }
            if (startTimestamp > batteryDiffData.getStartTimestamp()) {
                startTimestamp = batteryDiffData.getStartTimestamp();
                startBatteryLevel = batteryDiffData.getStartBatteryLevel();
            }
            if (endTimestamp > batteryDiffData.getEndTimestamp()) {
                endTimestamp = batteryDiffData.getEndTimestamp();
                endBatteryLevel = batteryDiffData.getEndBatteryLevel();
            }
            totalScreenOnTime += batteryDiffData.getScreenOnTime();
            for (BatteryDiffEntry entry : batteryDiffData.getAppDiffEntryList()) {
                computeUsageDiffDataPerEntry(entry, diffEntryMap);
            }
            for (BatteryDiffEntry entry : batteryDiffData.getSystemDiffEntryList()) {
                computeUsageDiffDataPerEntry(entry, diffEntryMap);
            }
        }

        final Collection<BatteryDiffEntry> diffEntryList = diffEntryMap.values();
        for (BatteryDiffEntry entry : diffEntryList) {
            if (entry.isSystemEntry()) {
                systemEntries.add(entry);
            } else {
                appEntries.add(entry);
            }
        }

        return new BatteryDiffData(
                context,
                startTimestamp,
                endTimestamp,
                startBatteryLevel,
                endBatteryLevel,
                totalScreenOnTime,
                appEntries,
                systemEntries,
                /* systemAppsPackageNames= */ new ArraySet<>(),
                /* systemAppsUids= */ new ArraySet<>(),
                /* isAccumulated= */ true);
    }

    private static void computeUsageDiffDataPerEntry(
            final BatteryDiffEntry entry, final Map<String, BatteryDiffEntry> diffEntryMap) {
        final String key = entry.getKey();
        final BatteryDiffEntry oldBatteryDiffEntry = diffEntryMap.get(key);
        // Creates new BatteryDiffEntry if we don't have it.
        if (oldBatteryDiffEntry == null) {
            diffEntryMap.put(key, entry.clone());
        } else {
            // Sums up some field data into the existing one.
            oldBatteryDiffEntry.mForegroundUsageTimeInMs += entry.mForegroundUsageTimeInMs;
            oldBatteryDiffEntry.mForegroundServiceUsageTimeInMs +=
                    entry.mForegroundServiceUsageTimeInMs;
            oldBatteryDiffEntry.mBackgroundUsageTimeInMs += entry.mBackgroundUsageTimeInMs;
            oldBatteryDiffEntry.mScreenOnTimeInMs += entry.mScreenOnTimeInMs;
            oldBatteryDiffEntry.mConsumePower += entry.mConsumePower;
            oldBatteryDiffEntry.mForegroundUsageConsumePower += entry.mForegroundUsageConsumePower;
            oldBatteryDiffEntry.mForegroundServiceUsageConsumePower +=
                    entry.mForegroundServiceUsageConsumePower;
            oldBatteryDiffEntry.mBackgroundUsageConsumePower += entry.mBackgroundUsageConsumePower;
            oldBatteryDiffEntry.mCachedUsageConsumePower += entry.mCachedUsageConsumePower;
        }
    }

    private static boolean shouldShowBatteryAttributionList(final Context context) {
        final PowerProfile powerProfile = new PowerProfile(context);
        // Cheap hack to try to figure out if the power_profile.xml was populated.
        final double averagePowerForOrdinal =
                powerProfile.getAveragePowerForOrdinal(
                        PowerProfile.POWER_GROUP_DISPLAY_SCREEN_FULL, 0);
        final boolean shouldShowBatteryAttributionList =
                averagePowerForOrdinal >= MIN_AVERAGE_POWER_THRESHOLD_MILLI_AMP;
        if (!shouldShowBatteryAttributionList) {
            Log.w(TAG, "shouldShowBatteryAttributionList(): " + averagePowerForOrdinal);
        }
        return shouldShowBatteryAttributionList;
    }

    /**
     * We want to coalesce some UIDs. For example, dex2oat runs under a shared gid that exists for
     * all users of the same app. We detect this case and merge the power use for dex2oat to the
     * device OWNER's use of the app.
     *
     * @return A sorted list of apps using power.
     */
    private static List<BatteryEntry> getCoalescedUsageList(
            final Context context,
            final BatteryUtils batteryUtils,
            final BatteryUsageStats batteryUsageStats,
            final boolean loadDataInBackground) {
        final PackageManager packageManager = context.getPackageManager();
        final UserManager userManager = context.getSystemService(UserManager.class);
        final SparseArray<BatteryEntry> batteryEntryList = new SparseArray<>();
        final ArrayList<BatteryEntry> results = new ArrayList<>();
        final List<UidBatteryConsumer> uidBatteryConsumers =
                batteryUsageStats.getUidBatteryConsumers();

        // Sort to have all apps with "real" UIDs first, followed by apps that are supposed
        // to be combined with the real ones.
        uidBatteryConsumers.sort(
                Comparator.comparingInt(
                        consumer -> consumer.getUid() == getRealUid(consumer) ? 0 : 1));

        for (int i = 0, size = uidBatteryConsumers.size(); i < size; i++) {
            final UidBatteryConsumer consumer = uidBatteryConsumers.get(i);
            final int uid = getRealUid(consumer);

            final String[] packages = packageManager.getPackagesForUid(uid);
            if (batteryUtils.shouldHideUidBatteryConsumerUnconditionally(consumer, packages)) {
                continue;
            }

            final boolean isHidden = batteryUtils.shouldHideUidBatteryConsumer(consumer, packages);
            final int index = batteryEntryList.indexOfKey(uid);
            if (index < 0) {
                // New entry.
                batteryEntryList.put(
                        uid,
                        new BatteryEntry(
                                context,
                                userManager,
                                consumer,
                                isHidden,
                                uid,
                                packages,
                                null,
                                loadDataInBackground));
            } else {
                // Combine BatterySippers if we already have one with this UID.
                final BatteryEntry existingSipper = batteryEntryList.valueAt(index);
                existingSipper.add(consumer);
            }
        }

        final BatteryConsumer deviceConsumer =
                batteryUsageStats.getAggregateBatteryConsumer(
                        BatteryUsageStats.AGGREGATE_BATTERY_CONSUMER_SCOPE_DEVICE);

        for (int componentId = 0;
                componentId < BatteryConsumer.POWER_COMPONENT_COUNT;
                componentId++) {
            results.add(
                    new BatteryEntry(
                            context,
                            componentId,
                            deviceConsumer.getConsumedPower(componentId),
                            deviceConsumer.getUsageDurationMillis(componentId),
                            componentId == POWER_COMPONENT_SYSTEM_SERVICES
                                    || componentId == POWER_COMPONENT_WAKELOCK));
        }

        for (int componentId = BatteryConsumer.FIRST_CUSTOM_POWER_COMPONENT_ID;
                componentId
                        < BatteryConsumer.FIRST_CUSTOM_POWER_COMPONENT_ID
                                + deviceConsumer.getCustomPowerComponentCount();
                componentId++) {
            results.add(
                    new BatteryEntry(
                            context,
                            componentId,
                            deviceConsumer.getCustomPowerComponentName(componentId),
                            deviceConsumer.getConsumedPowerForCustomComponent(componentId)));
        }

        final List<UserBatteryConsumer> userBatteryConsumers =
                batteryUsageStats.getUserBatteryConsumers();
        for (int i = 0, size = userBatteryConsumers.size(); i < size; i++) {
            final UserBatteryConsumer consumer = userBatteryConsumers.get(i);
            results.add(
                    new BatteryEntry(
                            context,
                            userManager,
                            consumer, /* isHidden */
                            true,
                            Process.INVALID_UID,
                            null,
                            null,
                            loadDataInBackground));
        }

        final int numUidSippers = batteryEntryList.size();

        for (int i = 0; i < numUidSippers; i++) {
            results.add(batteryEntryList.valueAt(i));
        }

        // The sort order must have changed, so re-sort based on total power use.
        results.sort(BatteryEntry.COMPARATOR);
        return results;
    }

    private static int getRealUid(final UidBatteryConsumer consumer) {
        int realUid = consumer.getUid();

        // Check if this UID is a shared GID. If so, we combine it with the OWNER's
        // actual app UID.
        if (isSharedGid(consumer.getUid())) {
            realUid =
                    UserHandle.getUid(
                            UserHandle.USER_SYSTEM,
                            UserHandle.getAppIdFromSharedAppGid(consumer.getUid()));
        }

        // Check if this UID is a system UID (mediaserver, logd, nfc, drm, etc).
        if (isSystemUid(realUid)
                && !MEDIASERVER_PACKAGE_NAME.equals(consumer.getPackageWithHighestDrain())) {
            // Use the system UID for all UIDs running in their own sandbox that
            // are not apps. We exclude mediaserver because we already are expected to
            // report that as a separate item.
            realUid = Process.SYSTEM_UID;
        }
        return realUid;
    }

    private static boolean isSharedGid(final int uid) {
        return UserHandle.getAppIdFromSharedAppGid(uid) > 0;
    }

    private static boolean isSystemUid(final int uid) {
        final int appUid = UserHandle.getAppId(uid);
        return appUid >= Process.SYSTEM_UID && appUid < Process.FIRST_APPLICATION_UID;
    }

    private static boolean isUsageMapValid(
            final Map<Integer, Map<Integer, BatteryDiffData>> batteryUsageMap,
            final List<BatteryLevelData.PeriodBatteryLevelData> hourlyBatteryLevelsPerDay) {
        if (batteryUsageMap.get(SELECTED_INDEX_ALL) == null
                || !batteryUsageMap.get(SELECTED_INDEX_ALL).containsKey(SELECTED_INDEX_ALL)) {
            Log.e(TAG, "no [SELECTED_INDEX_ALL][SELECTED_INDEX_ALL] in batteryUsageMap");
            return false;
        }
        for (int dailyIndex = 0; dailyIndex < hourlyBatteryLevelsPerDay.size(); dailyIndex++) {
            if (batteryUsageMap.get(dailyIndex) == null
                    || !batteryUsageMap.get(dailyIndex).containsKey(SELECTED_INDEX_ALL)) {
                Log.e(
                        TAG,
                        "no ["
                                + dailyIndex
                                + "][SELECTED_INDEX_ALL] in batteryUsageMap, "
                                + "daily size is: "
                                + hourlyBatteryLevelsPerDay.size());
                return false;
            }
            if (hourlyBatteryLevelsPerDay.get(dailyIndex) == null) {
                continue;
            }
            final List<Long> timestamps = hourlyBatteryLevelsPerDay.get(dailyIndex).getTimestamps();
            // Length of hourly usage map should be the length of hourly level data - 1.
            for (int hourlyIndex = 0; hourlyIndex < timestamps.size() - 1; hourlyIndex++) {
                if (!batteryUsageMap.get(dailyIndex).containsKey(hourlyIndex)) {
                    Log.e(
                            TAG,
                            "no ["
                                    + dailyIndex
                                    + "]["
                                    + hourlyIndex
                                    + "] in batteryUsageMap, "
                                    + "hourly size is: "
                                    + (timestamps.size() - 1));
                    return false;
                }
            }
        }
        return true;
    }

    private static long getDiffValue(long v1, long v2) {
        return v2 > v1 ? v2 - v1 : 0;
    }

    private static double getDiffValue(double v1, double v2) {
        return v2 > v1 ? v2 - v1 : 0;
    }

    private static long getCurrentTimeMillis() {
        return sTestCurrentTimeMillis > 0 ? sTestCurrentTimeMillis : System.currentTimeMillis();
    }

    private static void log(
            Context context,
            final String content,
            final long timestamp,
            final BatteryHistEntry entry) {
        if (sDebug) {
            Log.d(
                    TAG,
                    String.format(
                            entry != null ? "%s %s:\n%s" : "%s %s:%s",
                            ConvertUtils.utcToLocalTimeForLogging(timestamp),
                            content,
                            entry));
        }
    }
}