/*
 * Copyright (C) 2020 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;

import static android.app.appsearch.AppSearchResult.throwableToFailedResult;

import android.annotation.NonNull;
import android.annotation.UserIdInt;
import android.app.ActivityManager;
import android.app.appsearch.AppSearchBatchResult;
import android.app.appsearch.AppSearchMigrationHelper;
import android.app.appsearch.AppSearchResult;
import android.app.appsearch.AppSearchSchema;
import android.app.appsearch.GenericDocument;
import android.app.appsearch.GetSchemaResponse;
import android.app.appsearch.IAppSearchBatchResultCallback;
import android.app.appsearch.IAppSearchManager;
import android.app.appsearch.IAppSearchResultCallback;
import android.app.appsearch.PackageIdentifier;
import android.app.appsearch.SearchResultPage;
import android.app.appsearch.SearchSpec;
import android.app.appsearch.SetSchemaResponse;
import android.content.Context;
import android.content.pm.PackageManagerInternal;
import android.os.Binder;
import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.os.ParcelableException;
import android.os.RemoteException;
import android.os.UserHandle;
import android.os.UserManager;
import android.util.ArrayMap;
import android.util.ArraySet;
import android.util.Log;

import com.android.internal.annotations.GuardedBy;
import com.android.internal.util.Preconditions;
import com.android.server.LocalServices;
import com.android.server.SystemService;
import com.android.server.appsearch.external.localstorage.AppSearchImpl;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;

/** TODO(b/142567528): add comments when implement this class */
public class AppSearchManagerService extends SystemService {
    private static final String TAG = "AppSearchManagerService";
    private PackageManagerInternal mPackageManagerInternal;
    private ImplInstanceManager mImplInstanceManager;
    private UserManager mUserManager;

    // Cache of unlocked user ids so we don't have to query UserManager service each time. The
    // "locked" suffix refers to the fact that access to the field should be locked; unrelated to
    // the unlocked status of user ids.
    @GuardedBy("mUnlockedUserIdsLocked")
    private final Set<Integer> mUnlockedUserIdsLocked = new ArraySet<>();

    public AppSearchManagerService(Context context) {
        super(context);
    }

    @Override
    public void onStart() {
        publishBinderService(Context.APP_SEARCH_SERVICE, new Stub());
        mPackageManagerInternal = LocalServices.getService(PackageManagerInternal.class);
        mImplInstanceManager = ImplInstanceManager.getInstance(getContext());
        mUserManager = getContext().getSystemService(UserManager.class);
    }

    @Override
    public void onUserUnlocking(@NonNull TargetUser user) {
        synchronized (mUnlockedUserIdsLocked) {
            mUnlockedUserIdsLocked.add(user.getUserIdentifier());
        }
    }

    private class Stub extends IAppSearchManager.Stub {
        @Override
        public void setSchema(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull List<Bundle> schemaBundles,
                @NonNull List<String> schemasNotDisplayedBySystem,
                @NonNull Map<String, List<Bundle>> schemasPackageAccessibleBundles,
                boolean forceOverride,
                @UserIdInt int userId,
                int schemaVersion,
                @NonNull IAppSearchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(databaseName);
            Preconditions.checkNotNull(schemaBundles);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                List<AppSearchSchema> schemas = new ArrayList<>(schemaBundles.size());
                for (int i = 0; i < schemaBundles.size(); i++) {
                    schemas.add(new AppSearchSchema(schemaBundles.get(i)));
                }
                Map<String, List<PackageIdentifier>> schemasPackageAccessible =
                        new ArrayMap<>(schemasPackageAccessibleBundles.size());
                for (Map.Entry<String, List<Bundle>> entry :
                        schemasPackageAccessibleBundles.entrySet()) {
                    List<PackageIdentifier> packageIdentifiers =
                            new ArrayList<>(entry.getValue().size());
                    for (int i = 0; i < entry.getValue().size(); i++) {
                        packageIdentifiers.add(new PackageIdentifier(entry.getValue().get(i)));
                    }
                    schemasPackageAccessible.put(entry.getKey(), packageIdentifiers);
                }
                AppSearchImpl impl = mImplInstanceManager.getAppSearchImpl(callingUserId);
                SetSchemaResponse setSchemaResponse = impl.setSchema(
                        packageName,
                        databaseName,
                        schemas,
                        schemasNotDisplayedBySystem,
                        schemasPackageAccessible,
                        forceOverride,
                        schemaVersion);
                invokeCallbackOnResult(callback,
                        AppSearchResult.newSuccessfulResult(setSchemaResponse.getBundle()));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void getSchema(
                @NonNull String packageName,
                @NonNull String databaseName,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(databaseName);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUidOrThrow();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                GetSchemaResponse response = impl.getSchema(packageName, databaseName);
                invokeCallbackOnResult(
                        callback, AppSearchResult.newSuccessfulResult(response.getBundle()));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void getNamespaces(
                @NonNull String packageName,
                @NonNull String databaseName,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(databaseName);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUidOrThrow();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                List<String> namespaces = impl.getNamespaces(packageName, databaseName);
                invokeCallbackOnResult(callback, AppSearchResult.newSuccessfulResult(namespaces));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void putDocuments(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull List<Bundle> documentBundles,
                @UserIdInt int userId,
                @NonNull IAppSearchBatchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(databaseName);
            Preconditions.checkNotNull(documentBundles);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                AppSearchBatchResult.Builder<String, Void> resultBuilder =
                        new AppSearchBatchResult.Builder<>();
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                for (int i = 0; i < documentBundles.size(); i++) {
                    GenericDocument document = new GenericDocument(documentBundles.get(i));
                    try {
                        // TODO(b/173451571): reduce burden of binder thread by enqueue request onto
                        // a separate thread.
                        impl.putDocument(packageName, databaseName, document, /*logger=*/ null);
                        resultBuilder.setSuccess(document.getUri(), /*result=*/ null);
                    } catch (Throwable t) {
                        resultBuilder.setResult(document.getUri(), throwableToFailedResult(t));
                    }
                }
                invokeCallbackOnResult(callback, resultBuilder.build());
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void getDocuments(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull String namespace,
                @NonNull List<String> uris,
                @NonNull Map<String, List<String>> typePropertyPaths,
                @UserIdInt int userId,
                @NonNull IAppSearchBatchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(databaseName);
            Preconditions.checkNotNull(namespace);
            Preconditions.checkNotNull(uris);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                AppSearchBatchResult.Builder<String, Bundle> resultBuilder =
                        new AppSearchBatchResult.Builder<>();
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                for (int i = 0; i < uris.size(); i++) {
                    String uri = uris.get(i);
                    try {
                        GenericDocument document =
                                impl.getDocument(
                                        packageName,
                                        databaseName,
                                        namespace,
                                        uri,
                                        typePropertyPaths);
                        resultBuilder.setSuccess(uri, document.getBundle());
                    } catch (Throwable t) {
                        resultBuilder.setResult(uri, throwableToFailedResult(t));
                    }
                }
                invokeCallbackOnResult(callback, resultBuilder.build());
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        // TODO(sidchhabra): Do this in a threadpool.
        @Override
        public void query(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull String queryExpression,
                @NonNull Bundle searchSpecBundle,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(databaseName);
            Preconditions.checkNotNull(queryExpression);
            Preconditions.checkNotNull(searchSpecBundle);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                SearchResultPage searchResultPage =
                        impl.query(
                                packageName,
                                databaseName,
                                queryExpression,
                                new SearchSpec(searchSpecBundle));
                invokeCallbackOnResult(
                        callback,
                        AppSearchResult.newSuccessfulResult(searchResultPage.getBundle()));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void globalQuery(
                @NonNull String packageName,
                @NonNull String queryExpression,
                @NonNull Bundle searchSpecBundle,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(queryExpression);
            Preconditions.checkNotNull(searchSpecBundle);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                SearchResultPage searchResultPage =
                        impl.globalQuery(
                                queryExpression,
                                new SearchSpec(searchSpecBundle),
                                packageName,
                                callingUid);
                invokeCallbackOnResult(
                        callback,
                        AppSearchResult.newSuccessfulResult(searchResultPage.getBundle()));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void getNextPage(
                long nextPageToken,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            // TODO(b/162450968) check nextPageToken is being advanced by the same uid as originally
            // opened it
            try {
                verifyUserUnlocked(callingUserId);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                SearchResultPage searchResultPage = impl.getNextPage(nextPageToken);
                invokeCallbackOnResult(
                        callback,
                        AppSearchResult.newSuccessfulResult(searchResultPage.getBundle()));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void invalidateNextPageToken(long nextPageToken, @UserIdInt int userId) {
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                impl.invalidateNextPageToken(nextPageToken);
            } catch (Throwable t) {
                Log.e(TAG, "Unable to invalidate the query page token", t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void writeQueryResultsToFile(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull ParcelFileDescriptor fileDescriptor,
                @NonNull String queryExpression,
                @NonNull Bundle searchSpecBundle,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyCallingPackage(callingUid, packageName);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                // we don't need to append the file. The file is always brand new.
                try (DataOutputStream outputStream = new DataOutputStream(
                        new FileOutputStream(fileDescriptor.getFileDescriptor()))) {
                    SearchResultPage searchResultPage = impl.query(
                            packageName,
                            databaseName,
                            queryExpression,
                            new SearchSpec(searchSpecBundle));
                    while (!searchResultPage.getResults().isEmpty()) {
                        for (int i = 0; i < searchResultPage.getResults().size(); i++) {
                            AppSearchMigrationHelper.writeBundleToOutputStream(
                                    outputStream, searchResultPage.getResults().get(i)
                                            .getGenericDocument().getBundle());
                        }
                        searchResultPage = impl.getNextPage(searchResultPage.getNextPageToken());
                    }
                }
                invokeCallbackOnResult(callback, AppSearchResult.newSuccessfulResult(null));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void putDocumentsFromFile(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull ParcelFileDescriptor fileDescriptor,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyCallingPackage(callingUid, packageName);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);

                GenericDocument document;
                ArrayList<Bundle> migrationFailureBundles = new ArrayList<>();
                try (DataInputStream inputStream = new DataInputStream(
                        new FileInputStream(fileDescriptor.getFileDescriptor()))) {
                    while (true) {
                        try {
                            document = AppSearchMigrationHelper
                                    .readDocumentFromInputStream(inputStream);
                        } catch (EOFException e) {
                            // nothing wrong, we just finish the reading.
                            break;
                        }
                        try {
                            impl.putDocument(packageName, databaseName, document, /*logger=*/ null);
                        } catch (Throwable t) {
                            migrationFailureBundles.add(
                                    new SetSchemaResponse.MigrationFailure.Builder()
                                            .setNamespace(document.getNamespace())
                                            .setSchemaType(document.getSchemaType())
                                            .setUri(document.getUri())
                                            .setAppSearchResult(
                                                    AppSearchResult.throwableToFailedResult(t))
                                            .build().getBundle());
                        }
                    }
                }
                impl.persistToDisk();
                invokeCallbackOnResult(callback,
                        AppSearchResult.newSuccessfulResult(migrationFailureBundles));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void reportUsage(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull String namespace,
                @NonNull String uri,
                long usageTimeMillis,
                boolean systemUsage,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            Objects.requireNonNull(databaseName);
            Objects.requireNonNull(namespace);
            Objects.requireNonNull(uri);
            Objects.requireNonNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);

                if (systemUsage) {
                    // TODO(b/183031844): Validate that the call comes from the system
                }

                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                impl.reportUsage(
                        packageName, databaseName, namespace, uri,
                        usageTimeMillis, systemUsage);
                invokeCallbackOnResult(
                        callback, AppSearchResult.newSuccessfulResult(/*result=*/ null));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void removeByUri(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull String namespace,
                @NonNull List<String> uris,
                @UserIdInt int userId,
                @NonNull IAppSearchBatchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(databaseName);
            Preconditions.checkNotNull(uris);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                AppSearchBatchResult.Builder<String, Void> resultBuilder =
                        new AppSearchBatchResult.Builder<>();
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                for (int i = 0; i < uris.size(); i++) {
                    String uri = uris.get(i);
                    try {
                        impl.remove(packageName, databaseName, namespace, uri);
                        resultBuilder.setSuccess(uri, /*result= */ null);
                    } catch (Throwable t) {
                        resultBuilder.setResult(uri, throwableToFailedResult(t));
                    }
                }
                invokeCallbackOnResult(callback, resultBuilder.build());
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void removeByQuery(
                @NonNull String packageName,
                @NonNull String databaseName,
                @NonNull String queryExpression,
                @NonNull Bundle searchSpecBundle,
                @UserIdInt int userId,
                @NonNull IAppSearchResultCallback callback) {
            Preconditions.checkNotNull(packageName);
            Preconditions.checkNotNull(databaseName);
            Preconditions.checkNotNull(queryExpression);
            Preconditions.checkNotNull(searchSpecBundle);
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                verifyCallingPackage(callingUid, packageName);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                impl.removeByQuery(
                        packageName,
                        databaseName,
                        queryExpression,
                        new SearchSpec(searchSpecBundle));
                invokeCallbackOnResult(callback, AppSearchResult.newSuccessfulResult(null));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void persistToDisk(@UserIdInt int userId) {
            int callingUid = Binder.getCallingUidOrThrow();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                AppSearchImpl impl =
                        mImplInstanceManager.getAppSearchImpl(callingUserId);
                impl.persistToDisk();
            } catch (Throwable t) {
                Log.e(TAG, "Unable to persist the data to disk", t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        @Override
        public void initialize(@UserIdInt int userId, @NonNull IAppSearchResultCallback callback) {
            Preconditions.checkNotNull(callback);
            int callingUid = Binder.getCallingUid();
            int callingUserId = handleIncomingUser(userId, callingUid);
            final long callingIdentity = Binder.clearCallingIdentity();
            try {
                verifyUserUnlocked(callingUserId);
                mImplInstanceManager.getOrCreateAppSearchImpl(getContext(), callingUserId);
                invokeCallbackOnResult(callback, AppSearchResult.newSuccessfulResult(null));
            } catch (Throwable t) {
                invokeCallbackOnError(callback, t);
            } finally {
                Binder.restoreCallingIdentity(callingIdentity);
            }
        }

        private void verifyUserUnlocked(int callingUserId) {
            synchronized (mUnlockedUserIdsLocked) {
                // First, check the local copy.
                if (mUnlockedUserIdsLocked.contains(callingUserId)) {
                    return;
                }
                // If the local copy says the user is locked, check with UM for the actual state,
                // since the user might just have been unlocked.
                if (!mUserManager.isUserUnlockingOrUnlocked(UserHandle.of(callingUserId))) {
                    throw new IllegalStateException(
                            "User " + callingUserId + " is locked or not running.");
                }
            }
        }

        private void verifyCallingPackage(int callingUid, @NonNull String callingPackage) {
            Preconditions.checkNotNull(callingPackage);
            if (mPackageManagerInternal.getPackageUid(
                            callingPackage, /*flags=*/ 0, UserHandle.getUserId(callingUid))
                    != callingUid) {
                throw new SecurityException(
                        "Specified calling package ["
                                + callingPackage
                                + "] does not match the calling uid "
                                + callingUid);
            }
        }

        /** Invokes the {@link IAppSearchResultCallback} with the result. */
        private void invokeCallbackOnResult(
                IAppSearchResultCallback callback, AppSearchResult<?> result) {
            try {
                callback.onResult(result);
            } catch (RemoteException e) {
                Log.e(TAG, "Unable to send result to the callback", e);
            }
        }

        /** Invokes the {@link IAppSearchBatchResultCallback} with the result. */
        private void invokeCallbackOnResult(
                IAppSearchBatchResultCallback callback, AppSearchBatchResult<?, ?> result) {
            try {
                callback.onResult(result);
            } catch (RemoteException e) {
                Log.e(TAG, "Unable to send result to the callback", e);
            }
        }

        /**
         * Invokes the {@link IAppSearchResultCallback} with an throwable.
         *
         * <p>The throwable is convert to a {@link AppSearchResult};
         */
        private void invokeCallbackOnError(IAppSearchResultCallback callback, Throwable throwable) {
            try {
                callback.onResult(throwableToFailedResult(throwable));
            } catch (RemoteException e) {
                Log.e(TAG, "Unable to send result to the callback", e);
            }
        }

        /**
         * Invokes the {@link IAppSearchBatchResultCallback} with an unexpected internal throwable.
         *
         * <p>The throwable is converted to {@link ParcelableException}.
         */
        private void invokeCallbackOnError(
                IAppSearchBatchResultCallback callback, Throwable throwable) {
            try {
                //TODO(b/175067650) verify ParcelableException could propagate throwable correctly.
                callback.onSystemError(new ParcelableException(throwable));
            } catch (RemoteException e) {
                Log.e(TAG, "Unable to send error to the callback", e);
            }
        }
    }

    // TODO(b/173553485) verifying that the caller has permission to access target user's data
    // TODO(b/173553485) Handle ACTION_USER_REMOVED broadcast
    // TODO(b/173553485) Implement SystemService.onUserStopping()
    private static int handleIncomingUser(@UserIdInt int userId, int callingUid) {
        int callingPid = Binder.getCallingPid();
        return ActivityManager.handleIncomingUser(
                callingPid,
                callingUid,
                userId,
                /*allowAll=*/ false,
                /*requireFull=*/ false,
                /*name=*/ null,
                /*callerPackage=*/ null);
    }
}