/*
 * Copyright (C) 2024 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.server.appsearch.appsindexer;

import android.annotation.NonNull;
import android.annotation.WorkerThread;
import android.app.appsearch.AppSearchBatchResult;
import android.app.appsearch.AppSearchResult;
import android.app.appsearch.AppSearchSchema;
import android.app.appsearch.GenericDocument;
import android.app.appsearch.PackageIdentifier;
import android.app.appsearch.exceptions.AppSearchException;
import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.SystemClock;
import android.util.ArrayMap;
import android.util.ArraySet;
import android.util.Log;
import android.util.Pair;

import com.android.appsearch.flags.Flags;
import com.android.internal.annotations.VisibleForTesting;
import com.android.server.appsearch.appsindexer.appsearchtypes.AppFunctionDocument;
import com.android.server.appsearch.appsindexer.appsearchtypes.AppFunctionStaticMetadata;
import com.android.server.appsearch.appsindexer.appsearchtypes.MobileApplication;

import java.io.Closeable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;

/**
 * Interactions with PackageManager and AppSearch.
 *
 * <p>This class is NOT thread-safe.
 *
 * @hide
 */
public final class AppsIndexerImpl implements Closeable {
    static final String TAG = "AppSearchAppsIndexerImpl";

    private final Context mContext;
    private final AppSearchHelper mAppSearchHelper;
    private final AppsIndexerConfig mAppsIndexerConfig;

    public AppsIndexerImpl(@NonNull Context context, @NonNull AppsIndexerConfig appsIndexerConfig)
            throws AppSearchException {
        mContext = Objects.requireNonNull(context);
        mAppSearchHelper = new AppSearchHelper(context);
        mAppsIndexerConfig = Objects.requireNonNull(appsIndexerConfig);
    }

    /**
     * Checks PackageManager and AppSearch to sync the Apps Index in AppSearch.
     *
     * <p>It deletes removed apps, inserts newly-added ones, and updates existing ones in the App
     * corpus in AppSearch.
     *
     * @param settings contains update timestamps that help the indexer determine which apps were
     *     updated.
     * @param appsUpdateStats contains stats about the apps indexer update. This method will
     *     populate the fields of this {@link AppsUpdateStats} structure.
     * @param isFullUpdateRequired whether to re-index all apps irrespective of their last update
     *     timestamp.
     */
    @VisibleForTesting
    @WorkerThread
    public void doUpdateIncrementalPut(
            @NonNull AppsIndexerSettings settings,
            @NonNull AppsUpdateStats appsUpdateStats,
            boolean isFullUpdateRequired)
            throws AppSearchException {
        // TODO(b/357551503): Add metrics for app function indexing
        Objects.requireNonNull(settings);
        Objects.requireNonNull(appsUpdateStats);
        long currentTimeMillis = System.currentTimeMillis();

        // Search AppSearch for MobileApplication objects to get a "current" list of indexed apps.
        long beforeGetTimestamp = SystemClock.elapsedRealtime();
        Map<String, Long> appUpdatedTimestamps = mAppSearchHelper.getAppsFromAppSearch();

        appsUpdateStats.mAppSearchGetLatencyMillis =
                SystemClock.elapsedRealtime() - beforeGetTimestamp;

        long beforePackageManagerTimestamp = SystemClock.elapsedRealtime();
        PackageManager packageManager = mContext.getPackageManager();
        Map<PackageInfo, ResolveInfos> packagesToIndex =
                AppsUtil.getPackagesToIndex(packageManager);
        appsUpdateStats.mPackageManagerLatencyMillis =
                SystemClock.elapsedRealtime() - beforePackageManagerTimestamp;

        List<AppFunctionDocument> functionDocumentsToAddOrUpdate = new ArrayList<>();
        // To remove, we only need the id
        Set<String> functionIdsToRemove = new ArraySet<>();

        long mostRecentAppUpdatedTimestampMillis = settings.getLastAppUpdateTimestampMillis();

        // This boolean will be turned on if an app was added, an app was removed, all app
        // functions were removed from an app, or app functions were added to an app that
        // didn't have them previously. In all cases, we need to call setSchema to keep
        // AppSearch in sync with PackageManager.
        boolean addedOrRemovedFlag = false;

        Set<String> packagesToIndexIdSet = new ArraySet<>();

        // Prepare a list of newly added and updated packages. Added packages will have all
        // their app functions added to AppSearch, without checking what's in AppSearch. Updated
        // packages will require an additional call to AppSearch to see if we need to
        // add/update/remove individual app function documents. We don't do this for added apps as
        // we can just assume we need to add all of them. This saves a call to AppSearch. For both
        // added and updated packages, we parse xml. We don't check what functions are in AppSearch
        // for removed packages, as we can just remove the entire MobileApplication +
        // AppFunctionStaticMetadata schemas, which will in turn remove the documents.
        Map<PackageInfo, ResolveInfos> packagesToBeAddedOrUpdated = new ArrayMap<>();
        Set<String> updatedPackageIds = new ArraySet<>();

        // First loop, determine the status of apps
        for (Map.Entry<PackageInfo, ResolveInfos> packageEntry : packagesToIndex.entrySet()) {
            PackageInfo packageInfo = packageEntry.getKey();
            packagesToIndexIdSet.add(packageInfo.packageName);

            // Update the most recent timestamp as we iterate
            if (packageInfo.lastUpdateTime > mostRecentAppUpdatedTimestampMillis) {
                mostRecentAppUpdatedTimestampMillis = packageInfo.lastUpdateTime;
            }

            Long storedAppUpdateTime = appUpdatedTimestamps.get(packageInfo.packageName);

            if (storedAppUpdateTime == null) {
                // New app.
                addedOrRemovedFlag = true;
                appsUpdateStats.mNumberOfAppsAdded++;
                packagesToBeAddedOrUpdated.put(packageInfo, packageEntry.getValue());
            } else if (packageInfo.lastUpdateTime != storedAppUpdateTime || isFullUpdateRequired) {
                // Package last update timestamp discrepancy between AppSearch and PackageManager
                // or app indexer code was updated. Add this to the list of updated
                // apps so we can check what functions are indexed in AppSearch
                appsUpdateStats.mNumberOfAppsUpdated++;
                updatedPackageIds.add(packageInfo.packageName);
                packagesToBeAddedOrUpdated.put(packageInfo, packagesToIndex.get(packageInfo));
            } else {
                // Not updated.
                appsUpdateStats.mNumberOfAppsUnchanged++;
            }
        }

        // Now check for removed apps
        for (String appPackageId : appUpdatedTimestamps.keySet()) {
            if (!packagesToIndexIdSet.contains(appPackageId)) {
                // App was removed, remove all it's functions. This is simple because removing the
                // schema will remove all the functions. Do not add the app to the list of schemas
                // to set.
                appsUpdateStats.mNumberOfAppsRemoved++;
                addedOrRemovedFlag = true;
            }
        }

        Map<String, Map<String, AppSearchSchema>> dynamicAppFunctionSchemasForPackages = null;
        if (Flags.enableAppFunctionsSchemaParser()) {
            // TODO(b/382254638): Skip XML parsing for packages that were not updated by using
            // AppSearchSessio#getSchema.
            dynamicAppFunctionSchemasForPackages =
                    AppsUtil.getDynamicAppFunctionSchemasForPackages(
                            packageManager,
                            packagesToIndex,
                            mAppsIndexerConfig.getMaxAllowedAppFunctionSchemasPerPackage());
        }

        // Parse and build all necessary AppFunctionStaticMetadata from PackageManager.
        Map<String, Map<String, ? extends AppFunctionDocument>>
                currentAppFunctionsForAddedUpdatedPackages =
                        AppsUtil.buildAppFunctionDocumentsIntoMap(
                                packageManager,
                                packagesToBeAddedOrUpdated,
                                /* indexerPackageName= */ mContext.getPackageName(),
                                mAppsIndexerConfig,
                                dynamicAppFunctionSchemasForPackages);

        // Get all currently indexed AppFunctionStaticMetadata docs for the necessary packages.
        Map<String, Map<String, AppFunctionDocument>> appFunctionsFromAppSearch =
                mAppSearchHelper.getAppFunctionDocumentsFromAppSearch(updatedPackageIds);

        for (Map.Entry<String, Map<String, ? extends AppFunctionDocument>> packageEntry :
                currentAppFunctionsForAddedUpdatedPackages.entrySet()) {
            String packageName = packageEntry.getKey();
            Map<String, ? extends AppFunctionDocument> currentAppFunctionsPerApp =
                    packageEntry.getValue();

            // This might be null, in the case of functions newly added to a package
            Map<String, AppFunctionDocument> appSearchAppFunctionsPerApp =
                    appFunctionsFromAppSearch.get(packageName);

            if (appSearchAppFunctionsPerApp == null && !currentAppFunctionsPerApp.isEmpty()) {
                // Functions added to an app that didn't have them
                functionDocumentsToAddOrUpdate.addAll(currentAppFunctionsPerApp.values());
                addedOrRemovedFlag = true;
            }

            if (appSearchAppFunctionsPerApp != null) {
                if (currentAppFunctionsPerApp.isEmpty()) {
                    // All functions removed from an app that had them
                    addedOrRemovedFlag = true;
                } else {
                    // App updated that had packages, we should check
                    comparePackageFunctionDocuments(
                            currentAppFunctionsPerApp,
                            appSearchAppFunctionsPerApp,
                            functionDocumentsToAddOrUpdate,
                            functionIdsToRemove);
                }
            }
        }

        try {
            // TODO(b/382254638): Skip set schema calls if no packages have an updated schema.
            if (dynamicAppFunctionSchemasForPackages != null) {
                // Since dynamic schemas are enabled, we need to account for schema changes in
                // both updated packages and newly added packages.
                Pair<List<PackageIdentifier>, List<PackageIdentifier>>
                        mobileAppAndAppFunctionIdentifiers =
                                getPackageIdentifiers(
                                        packagesToIndex,
                                        currentAppFunctionsForAddedUpdatedPackages);

                long beforeSetSchemaTimestamp = SystemClock.elapsedRealtime();
                mAppSearchHelper.setSchemasForPackages(
                        /* mobileAppPkgs= */ mobileAppAndAppFunctionIdentifiers.first,
                        /* appFunctionPkgs= */ mobileAppAndAppFunctionIdentifiers.second,
                        dynamicAppFunctionSchemasForPackages);
                appsUpdateStats.mAppSearchSetSchemaLatencyMillis =
                        SystemClock.elapsedRealtime() - beforeSetSchemaTimestamp;
            } else if (addedOrRemovedFlag) {
                // This branch is executed when dynamic schemas are disabled and new packages are
                // added or removed to keep the AppSearch schema in sync with
                // PackageManager.
                Pair<List<PackageIdentifier>, List<PackageIdentifier>>
                        mobileAppAndAppFunctionIdentifiers =
                                getPackageIdentifiers(
                                        packagesToIndex,
                                        currentAppFunctionsForAddedUpdatedPackages);

                // The certificate is necessary along with the package name as it is used in
                // visibility settings.
                long beforeSetSchemaTimestamp = SystemClock.elapsedRealtime();
                mAppSearchHelper.setSchemasForPackages(
                        /* mobileAppPkgs= */ mobileAppAndAppFunctionIdentifiers.first,
                        /* appFunctionPkgs= */ mobileAppAndAppFunctionIdentifiers.second);
                appsUpdateStats.mAppSearchSetSchemaLatencyMillis =
                        SystemClock.elapsedRealtime() - beforeSetSchemaTimestamp;
            }

            if (!packagesToBeAddedOrUpdated.isEmpty()
                    || !functionDocumentsToAddOrUpdate.isEmpty()) {
                long beforePutTimestamp = SystemClock.elapsedRealtime();
                List<MobileApplication> mobileApplications =
                        AppsUtil.buildAppsFromPackageInfos(
                                packageManager, packagesToBeAddedOrUpdated);

                AppSearchBatchResult<String, Void> result =
                        mAppSearchHelper.indexApps(
                                mobileApplications, functionDocumentsToAddOrUpdate);
                if (result.isSuccess()) {
                    appsUpdateStats.mUpdateStatusCodes.add(AppSearchResult.RESULT_OK);
                } else {
                    Collection<AppSearchResult<Void>> values = result.getAll().values();

                    for (AppSearchResult<Void> putResult : values) {
                        appsUpdateStats.mUpdateStatusCodes.add(putResult.getResultCode());
                    }
                }

                appsUpdateStats.mAppSearchPutLatencyMillis =
                        SystemClock.elapsedRealtime() - beforePutTimestamp;
            }

            if (!functionIdsToRemove.isEmpty()) {
                AppSearchBatchResult<String, Void> result =
                        mAppSearchHelper.removeAppFunctionsById(functionIdsToRemove);
                if (result.isSuccess()) {
                    appsUpdateStats.mUpdateStatusCodes.add(AppSearchResult.RESULT_OK);
                }
            }

            settings.setLastAppUpdateTimestampMillis(mostRecentAppUpdatedTimestampMillis);
            settings.setLastUpdateTimestampMillis(currentTimeMillis);

            appsUpdateStats.mLastAppUpdateTimestampMillis = mostRecentAppUpdatedTimestampMillis;
        } catch (AppSearchException e) {
            // Reset the last update time stamp and app update timestamp so we can try again later.
            settings.reset();
            appsUpdateStats.mUpdateStatusCodes.clear();
            appsUpdateStats.mUpdateStatusCodes.add(e.getResultCode());
            throw e;
        }
    }

    /**
     * Return a pair of lists of {@link PackageIdentifier}s, the first list representing all
     * packages, and the second list representing packages with app functions.
     *
     * <p>The second list is always a subset of the first list.
     *
     * @param packagesToIndex a mapping of {@link PackageInfo}s with their corresponding {@link
     *     ResolveInfos} for the packages launch activity and maybe app function resolve info.
     * @param currentAppFunctionsForAddedUpdatedPackages a mapping of package name to a map of all
     *     app functions for the packages that were either updated or added.
     * @return a pair of lists of {@link PackageIdentifier}s, the first list representing all
     *     packages, and the second list representing packages with app functions.
     */
    private Pair<List<PackageIdentifier>, List<PackageIdentifier>> getPackageIdentifiers(
            @NonNull Map<PackageInfo, ResolveInfos> packagesToIndex,
            Map<String, Map<String, ? extends AppFunctionDocument>>
                    currentAppFunctionsForAddedUpdatedPackages) {
        List<PackageIdentifier> packageIdentifiers = new ArrayList<>();
        List<PackageIdentifier> packageIdentifiersWithAppFunctions = new ArrayList<>();
        for (Map.Entry<PackageInfo, ResolveInfos> entry : packagesToIndex.entrySet()) {
            // We get certificates here as getting the certificates during the previous for
            // loop would be wasteful if we end up not needing to call set schema
            PackageInfo packageInfo = entry.getKey();
            byte[] certificate = AppsUtil.getCertificate(packageInfo);
            if (certificate == null) {
                Log.e(TAG, "Certificate not found for package: " + packageInfo.packageName);
                continue;
            }
            PackageIdentifier packageIdentifier =
                    new PackageIdentifier(packageInfo.packageName, certificate);
            packageIdentifiers.add(packageIdentifier);
            // Check if the package was updated and all app functions were removed. The map only
            // contains entries for packages that updated or newly added, for packages with no
            // change we would rely solely on presence of AppFunctionServiceInfo to decide if it's
            // an app function package.
            boolean appFunctionsRemoved =
                    currentAppFunctionsForAddedUpdatedPackages.containsKey(packageInfo.packageName)
                            && currentAppFunctionsForAddedUpdatedPackages
                                    .get(packageInfo.packageName)
                                    .isEmpty();
            if (entry.getValue().getAppFunctionServiceInfo() != null && !appFunctionsRemoved) {
                packageIdentifiersWithAppFunctions.add(packageIdentifier);
            }
        }
        return new Pair<>(packageIdentifiers, packageIdentifiersWithAppFunctions);
    }

    /**
     * Compares the app function documents in PackageManager vs those in AppSearch, and updates
     * functionDocumentsToAddOrUpdate and functionDocumentIdsToRemove accordingly.
     *
     * @param currentAppFunctionDocumentsPerApp the mapping of function ids to documents
     *     corresponding to what is in the apps metadata.
     * @param appSearchAppFunctionDocumentsPerApp the mapping of function ids to documents
     *     corresponding to what is in AppSearch
     * @param functionDocumentsToAddOrUpdate the List of {@link AppFunctionDocument} that will be
     *     sent to a put call to AppSearch
     * @param functionDocumentIdsToRemove the set of ids that will be sent to a remove call in
     *     AppSearch
     */
    private void comparePackageFunctionDocuments(
            @NonNull Map<String, ? extends AppFunctionDocument> currentAppFunctionDocumentsPerApp,
            @NonNull Map<String, AppFunctionDocument> appSearchAppFunctionDocumentsPerApp,
            @NonNull List<AppFunctionDocument> functionDocumentsToAddOrUpdate,
            @NonNull Set<String> functionDocumentIdsToRemove) {
        Objects.requireNonNull(currentAppFunctionDocumentsPerApp);
        Objects.requireNonNull(appSearchAppFunctionDocumentsPerApp);
        Objects.requireNonNull(functionDocumentsToAddOrUpdate);
        Objects.requireNonNull(functionDocumentIdsToRemove);

        for (Map.Entry<String, ? extends AppFunctionDocument> currentFunctionEntry :
                currentAppFunctionDocumentsPerApp.entrySet()) {
            String functionId = currentFunctionEntry.getKey();
            AppFunctionDocument currentFunctionDocument = currentFunctionEntry.getValue();
            AppFunctionDocument appSearchFunctionDocument =
                    appSearchAppFunctionDocumentsPerApp.get(functionId);
            // appSearchFunctionDocument == null means it's a new document, document inequality
            // means
            // updated document. Both mean we need to call put with this document.
            if (appSearchFunctionDocument == null
                    || !areFunctionDocumentsEqual(
                            appSearchFunctionDocument, currentFunctionDocument)) {
                functionDocumentsToAddOrUpdate.add(currentFunctionDocument);
            }
        }

        for (Map.Entry<String, AppFunctionDocument> appSearchFunctionEntry :
                appSearchAppFunctionDocumentsPerApp.entrySet()) {
            if (!currentAppFunctionDocumentsPerApp.containsKey(appSearchFunctionEntry.getKey())) {
                functionDocumentIdsToRemove.add(appSearchFunctionEntry.getValue().getId());
            }
        }
    }

    /**
     * Checks if two AppFunction documents are equal. It isn't enough to call equals. We also need
     * to ignore creation timestamp and parent types. These are set in AppSearch, but aren't set for
     * the "about to be indexed" docs
     *
     * @return true if the documents are equal, false otherwise.
     */
    private boolean areFunctionDocumentsEqual(
            @NonNull GenericDocument document1, @NonNull GenericDocument document2) {
        Objects.requireNonNull(document1);
        Objects.requireNonNull(document2);

        document1 = clearTimestampsAndParentTypesInDocument(document1);
        document2 = clearTimestampsAndParentTypesInDocument(document2);

        return document1.equals(document2);
    }

    private GenericDocument clearTimestampsAndParentTypesInDocument(
            @NonNull GenericDocument document) {
        GenericDocument.Builder<?> builder =
                new GenericDocument.Builder<>(document)
                        .setCreationTimestampMillis(0)
                        // GenericDocument#PARENT_TYPES_SYNTHETIC_PROPERTY is hidden
                        .clearProperty("$$__AppSearch__parentTypes");

        for (String propertyName : document.getPropertyNames()) {
            Object property = document.getProperty(propertyName);
            if (property instanceof GenericDocument[] nestedDocuments) {
                GenericDocument[] clearedNestedDocuments =
                        new GenericDocument[nestedDocuments.length];

                for (int i = 0; i < nestedDocuments.length; i++) {
                    clearedNestedDocuments[i] =
                            clearTimestampsAndParentTypesInDocument(nestedDocuments[i]);
                }

                builder.setPropertyDocument(propertyName, clearedNestedDocuments);
            }
        }

        return builder.build();
    }

    /**
     * Checks PackageManager and AppSearch to sync the Apps Index in AppSearch.
     *
     * <p>It deletes removed apps, inserts newly-added ones, and updates existing ones in the App
     * corpus in AppSearch.
     *
     * @param settings contains update timestamps that help the indexer determine which apps were
     *     updated.
     * @param appsUpdateStats contains stats about the apps indexer update. This method will
     *     populate the fields of this {@link AppsUpdateStats} structure.
     */
    @VisibleForTesting
    @WorkerThread
    public void doUpdate(
            @NonNull AppsIndexerSettings settings, @NonNull AppsUpdateStats appsUpdateStats)
            throws AppSearchException {
        Objects.requireNonNull(settings);
        Objects.requireNonNull(appsUpdateStats);
        long currentTimeMillis = System.currentTimeMillis();

        // Search AppSearch for MobileApplication objects to get a "current" list of indexed apps.
        long beforeGetTimestamp = SystemClock.elapsedRealtime();
        Map<String, Long> appUpdatedTimestamps = mAppSearchHelper.getAppsFromAppSearch();
        appsUpdateStats.mAppSearchGetLatencyMillis =
                SystemClock.elapsedRealtime() - beforeGetTimestamp;

        long beforePackageManagerTimestamp = SystemClock.elapsedRealtime();
        PackageManager packageManager = mContext.getPackageManager();
        Map<PackageInfo, ResolveInfos> packagesToIndex =
                AppsUtil.getPackagesToIndex(packageManager);
        appsUpdateStats.mPackageManagerLatencyMillis =
                SystemClock.elapsedRealtime() - beforePackageManagerTimestamp;
        Set<PackageInfo> packageInfos = packagesToIndex.keySet();

        Map<PackageInfo, ResolveInfos> packagesToBeAddedOrUpdated = new ArrayMap<>();
        long mostRecentAppUpdatedTimestampMillis = settings.getLastAppUpdateTimestampMillis();

        // Prepare a set of current app IDs for efficient lookup
        Set<String> currentAppIds = new ArraySet<>();
        for (PackageInfo packageInfo : packageInfos) {
            currentAppIds.add(packageInfo.packageName);

            // Update the most recent timestamp as we iterate
            if (packageInfo.lastUpdateTime > mostRecentAppUpdatedTimestampMillis) {
                mostRecentAppUpdatedTimestampMillis = packageInfo.lastUpdateTime;
            }

            Long storedUpdateTime = appUpdatedTimestamps.get(packageInfo.packageName);

            boolean added = storedUpdateTime == null;
            boolean updated =
                    storedUpdateTime != null && packageInfo.lastUpdateTime != storedUpdateTime;

            if (added) {
                appsUpdateStats.mNumberOfAppsAdded++;
            }
            if (updated) {
                appsUpdateStats.mNumberOfAppsUpdated++;
            }
            if (added || updated) {
                packagesToBeAddedOrUpdated.put(packageInfo, packagesToIndex.get(packageInfo));
            } else {
                appsUpdateStats.mNumberOfAppsUnchanged++;
            }
        }

        List<GenericDocument> appSearchAppFunctions =
                mAppSearchHelper.getAppFunctionsFromAppSearch();

        try {
            if (!currentAppIds.equals(appUpdatedTimestamps.keySet())
                    || requiresInsertSchemaForAppFunction(packagesToIndex, appSearchAppFunctions)) {
                // The current list of apps/app functions in AppSearch does not match what is in
                // PackageManager. This means this is the first sync, an app/app function was
                // removed, or an app/app function was added. In all cases, we need to call
                // setSchema to keep AppSearch in sync with PackageManager.

                // currentAppIds comes from PackageManager, appUpdatedTimestamps comes from
                // AppSearch. Deleted apps are those in appUpdateTimestamps and NOT in currentAppIds
                appsUpdateStats.mNumberOfAppsRemoved = 0;
                for (String appSearchApp : appUpdatedTimestamps.keySet()) {
                    if (!currentAppIds.contains(appSearchApp)) {
                        appsUpdateStats.mNumberOfAppsRemoved++;
                    }
                }

                List<PackageIdentifier> packageIdentifiers = new ArrayList<>();
                List<PackageIdentifier> packageIdentifiersWithAppFunctions = new ArrayList<>();
                for (Map.Entry<PackageInfo, ResolveInfos> entry : packagesToIndex.entrySet()) {
                    // We get certificates here as getting the certificates during the previous for
                    // loop would be wasteful if we end up not needing to call set schema
                    PackageInfo packageInfo = entry.getKey();
                    byte[] certificate = AppsUtil.getCertificate(packageInfo);
                    if (certificate == null) {
                        Log.e(TAG, "Certificate not found for package: " + packageInfo.packageName);
                        continue;
                    }
                    PackageIdentifier packageIdentifier =
                            new PackageIdentifier(packageInfo.packageName, certificate);
                    packageIdentifiers.add(packageIdentifier);
                    if (entry.getValue().getAppFunctionServiceInfo() != null) {
                        packageIdentifiersWithAppFunctions.add(packageIdentifier);
                    }
                }
                // The certificate is necessary along with the package name as it is used in
                // visibility settings.
                long beforeSetSchemaTimestamp = SystemClock.elapsedRealtime();
                mAppSearchHelper.setSchemasForPackages(
                        packageIdentifiers, packageIdentifiersWithAppFunctions);
                appsUpdateStats.mAppSearchSetSchemaLatencyMillis =
                        SystemClock.elapsedRealtime() - beforeSetSchemaTimestamp;
            }

            if (!packagesToBeAddedOrUpdated.isEmpty()) {
                long beforePutTimestamp = SystemClock.elapsedRealtime();
                List<MobileApplication> mobileApplications =
                        AppsUtil.buildAppsFromPackageInfos(
                                packageManager, packagesToBeAddedOrUpdated);
                List<AppFunctionStaticMetadata> appFunctions =
                        AppsUtil.buildAppFunctionStaticMetadata(
                                packageManager,
                                packagesToBeAddedOrUpdated,
                                /* indexerPackageName= */ mContext.getPackageName(),
                                mAppsIndexerConfig);

                AppSearchBatchResult<String, Void> result =
                        mAppSearchHelper.indexApps(
                                mobileApplications,
                                appFunctions,
                                appSearchAppFunctions,
                                appsUpdateStats);
                // Here we log all of these functions as "updated". However, some of these may be
                // added or unchanged.
                // TODO(b/357551503): Log function counts more accurately
                appsUpdateStats.mNumberOfFunctionsUpdated = appFunctions.size();
                if (result.isSuccess()) {
                    appsUpdateStats.mUpdateStatusCodes.add(AppSearchResult.RESULT_OK);
                } else {
                    Collection<AppSearchResult<Void>> values = result.getAll().values();

                    for (AppSearchResult<Void> putResult : values) {
                        appsUpdateStats.mUpdateStatusCodes.add(putResult.getResultCode());
                    }
                }
                appsUpdateStats.mAppSearchPutLatencyMillis =
                        SystemClock.elapsedRealtime() - beforePutTimestamp;
            }

            settings.setLastAppUpdateTimestampMillis(mostRecentAppUpdatedTimestampMillis);
            settings.setLastUpdateTimestampMillis(currentTimeMillis);

            appsUpdateStats.mLastAppUpdateTimestampMillis = mostRecentAppUpdatedTimestampMillis;
        } catch (AppSearchException e) {
            // Reset the last update time stamp and app update timestamp so we can try again later.
            settings.reset();
            appsUpdateStats.mUpdateStatusCodes.clear();
            appsUpdateStats.mUpdateStatusCodes.add(e.getResultCode());
            throw e;
        }
    }

    /** Returns whether the indexer should insert schema for app functions. */
    private boolean requiresInsertSchemaForAppFunction(
            @NonNull Map<PackageInfo, ResolveInfos> targetedPackages,
            List<GenericDocument> appSearchAppFunctions)
            throws AppSearchException {
        // Should re-insert the schema as long as the indexed packages does not match the current
        // set of packages.
        Set<String> indexedAppFunctionPackages = new ArraySet<>();
        for (int i = 0; i < appSearchAppFunctions.size(); i++) {
            indexedAppFunctionPackages.add(
                    appSearchAppFunctions
                            .get(i)
                            .getPropertyString(AppFunctionDocument.PROPERTY_PACKAGE_NAME));
        }
        Set<String> currentAppFunctionPackages = getCurrentAppFunctionPackages(targetedPackages);
        return !indexedAppFunctionPackages.equals(currentAppFunctionPackages);
    }

    /** Returns a set of currently installed packages that have app functions. */
    private Set<String> getCurrentAppFunctionPackages(
            @NonNull Map<PackageInfo, ResolveInfos> targetedPackages) {
        Set<String> currentAppFunctionPackages = new ArraySet<>();
        for (Map.Entry<PackageInfo, ResolveInfos> entry : targetedPackages.entrySet()) {
            PackageInfo packageInfo = entry.getKey();
            ResolveInfos resolveInfos = entry.getValue();
            if (resolveInfos.getAppFunctionServiceInfo() != null) {
                currentAppFunctionPackages.add(packageInfo.packageName);
            }
        }
        return currentAppFunctionPackages;
    }

    /** Shuts down the {@link AppsIndexerImpl} and its {@link AppSearchHelper}. */
    @Override
    public void close() {
        mAppSearchHelper.close();
    }
}