/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License
 */

package com.android.internal.telephony;

import android.annotation.Nullable;
import android.content.ContentResolver;
import android.content.pm.ApplicationInfo;
import android.content.pm.IPackageManager;
import android.content.pm.PackageManager;
import android.content.res.Resources;
import android.os.RemoteException;
import android.provider.Settings;
import android.telephony.TelephonyManager;
import android.util.ArrayMap;
import android.util.Slog;

import com.android.internal.annotations.VisibleForTesting;
import com.android.server.SystemConfig;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * Utilities for handling carrier applications.
 * @hide
 */
public final class CarrierAppUtils {
    private static final String TAG = "CarrierAppUtils";

    private static final boolean DEBUG = false; // STOPSHIP if true

    private CarrierAppUtils() {}

    /**
     * Handle preinstalled carrier apps which should be disabled until a matching SIM is inserted.
     *
     * Evaluates the list of applications in config_disabledUntilUsedPreinstalledCarrierApps. We
     * want to disable each such application which is present on the system image until the user
     * inserts a SIM which causes that application to gain carrier privilege (indicating a "match"),
     * without interfering with the user if they opt to enable/disable the app explicitly.
     *
     * So, for each such app, we either disable until used IFF the app is not carrier privileged AND
     * in the default state (e.g. not explicitly DISABLED/DISABLED_BY_USER/ENABLED), or we enable if
     * the app is carrier privileged and in either the default state or DISABLED_UNTIL_USED.
     *
     * In addition, there is a list of carrier-associated applications in
     * {@link SystemConfig#getDisabledUntilUsedPreinstalledCarrierAssociatedApps}. Each app in this
     * list is associated with a carrier app. When the given carrier app is enabled/disabled per the
     * above, the associated applications are enabled/disabled to match.
     *
     * When enabling a carrier app we also grant it default permissions.
     *
     * This method is idempotent and is safe to be called at any time; it should be called once at
     * system startup prior to any application running, as well as any time the set of carrier
     * privileged apps may have changed.
     */
    public synchronized static void disableCarrierAppsUntilPrivileged(String callingPackage,
            IPackageManager packageManager, TelephonyManager telephonyManager,
            ContentResolver contentResolver, int userId) {
        if (DEBUG) {
            Slog.d(TAG, "disableCarrierAppsUntilPrivileged");
        }
        SystemConfig config = SystemConfig.getInstance();
        String[] systemCarrierAppsDisabledUntilUsed = Resources.getSystem().getStringArray(
                com.android.internal.R.array.config_disabledUntilUsedPreinstalledCarrierApps);
        ArrayMap<String, List<String>> systemCarrierAssociatedAppsDisabledUntilUsed =
                config.getDisabledUntilUsedPreinstalledCarrierAssociatedApps();
        disableCarrierAppsUntilPrivileged(callingPackage, packageManager, telephonyManager,
                contentResolver, userId, systemCarrierAppsDisabledUntilUsed,
                systemCarrierAssociatedAppsDisabledUntilUsed);
    }

    /**
     * Like {@link #disableCarrierAppsUntilPrivileged(String, IPackageManager, TelephonyManager,
     * ContentResolver, int)}, but assumes that no carrier apps have carrier privileges.
     *
     * This prevents a potential race condition on first boot - since the app's default state is
     * enabled, we will initially disable it when the telephony stack is first initialized as it has
     * not yet read the carrier privilege rules. However, since telephony is initialized later on
     * late in boot, the app being disabled may have already been started in response to certain
     * broadcasts. The app will continue to run (briefly) after being disabled, before the Package
     * Manager can kill it, and this can lead to crashes as the app is in an unexpected state.
     */
    public synchronized static void disableCarrierAppsUntilPrivileged(String callingPackage,
            IPackageManager packageManager, ContentResolver contentResolver, int userId) {
        if (DEBUG) {
            Slog.d(TAG, "disableCarrierAppsUntilPrivileged");
        }
        SystemConfig config = SystemConfig.getInstance();
        String[] systemCarrierAppsDisabledUntilUsed = Resources.getSystem().getStringArray(
                com.android.internal.R.array.config_disabledUntilUsedPreinstalledCarrierApps);
        ArrayMap<String, List<String>> systemCarrierAssociatedAppsDisabledUntilUsed =
                config.getDisabledUntilUsedPreinstalledCarrierAssociatedApps();
        disableCarrierAppsUntilPrivileged(callingPackage, packageManager,
                null /* telephonyManager */, contentResolver, userId,
                systemCarrierAppsDisabledUntilUsed, systemCarrierAssociatedAppsDisabledUntilUsed);
    }

    // Must be public b/c framework unit tests can't access package-private methods.
    @VisibleForTesting
    public static void disableCarrierAppsUntilPrivileged(String callingPackage,
            IPackageManager packageManager, @Nullable TelephonyManager telephonyManager,
            ContentResolver contentResolver, int userId,
            String[] systemCarrierAppsDisabledUntilUsed,
            ArrayMap<String, List<String>> systemCarrierAssociatedAppsDisabledUntilUsed) {
        List<ApplicationInfo> candidates = getDefaultCarrierAppCandidatesHelper(packageManager,
                userId, systemCarrierAppsDisabledUntilUsed);
        if (candidates == null || candidates.isEmpty()) {
            return;
        }

        Map<String, List<ApplicationInfo>> associatedApps = getDefaultCarrierAssociatedAppsHelper(
                packageManager,
                userId,
                systemCarrierAssociatedAppsDisabledUntilUsed);

        List<String> enabledCarrierPackages = new ArrayList<>();

        boolean hasRunOnce = Settings.Secure.getIntForUser(
                contentResolver, Settings.Secure.CARRIER_APPS_HANDLED, 0, userId) == 1;

        try {
            for (ApplicationInfo ai : candidates) {
                String packageName = ai.packageName;
                boolean hasPrivileges = telephonyManager != null &&
                        telephonyManager.checkCarrierPrivilegesForPackageAnyPhone(packageName) ==
                                TelephonyManager.CARRIER_PRIVILEGE_STATUS_HAS_ACCESS;

                if (hasPrivileges) {
                    // Only update enabled state for the app on /system. Once it has been
                    // updated we shouldn't touch it.
                    if (!ai.isUpdatedSystemApp()
                            && (ai.enabledSetting ==
                            PackageManager.COMPONENT_ENABLED_STATE_DEFAULT
                            || ai.enabledSetting ==
                            PackageManager.COMPONENT_ENABLED_STATE_DISABLED_UNTIL_USED)) {
                        Slog.i(TAG, "Update state(" + packageName + "): ENABLED for user "
                                + userId);
                        packageManager.setApplicationEnabledSetting(
                                packageName,
                                PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
                                PackageManager.DONT_KILL_APP,
                                userId,
                                callingPackage);
                    }

                    // Also enable any associated apps for this carrier app.
                    List<ApplicationInfo> associatedAppList = associatedApps.get(packageName);
                    if (associatedAppList != null) {
                        for (ApplicationInfo associatedApp : associatedAppList) {
                            if (associatedApp.enabledSetting ==
                                    PackageManager.COMPONENT_ENABLED_STATE_DEFAULT
                                    || associatedApp.enabledSetting ==
                                    PackageManager.COMPONENT_ENABLED_STATE_DISABLED_UNTIL_USED) {
                                Slog.i(TAG, "Update associated state(" + associatedApp.packageName
                                        + "): ENABLED for user " + userId);
                                packageManager.setApplicationEnabledSetting(
                                        associatedApp.packageName,
                                        PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
                                        PackageManager.DONT_KILL_APP,
                                        userId,
                                        callingPackage);
                            }
                        }
                    }

                    // Always re-grant default permissions to carrier apps w/ privileges.
                    enabledCarrierPackages.add(ai.packageName);
                } else {  // No carrier privileges
                    // Only update enabled state for the app on /system. Once it has been
                    // updated we shouldn't touch it.
                    if (!ai.isUpdatedSystemApp()
                            && ai.enabledSetting ==
                            PackageManager.COMPONENT_ENABLED_STATE_DEFAULT) {
                        Slog.i(TAG, "Update state(" + packageName
                                + "): DISABLED_UNTIL_USED for user " + userId);
                        packageManager.setApplicationEnabledSetting(
                                packageName,
                                PackageManager.COMPONENT_ENABLED_STATE_DISABLED_UNTIL_USED,
                                0,
                                userId,
                                callingPackage);
                    }

                    // Also disable any associated apps for this carrier app if this is the first
                    // run. We avoid doing this a second time because it is brittle to rely on the
                    // distinction between "default" and "enabled".
                    if (!hasRunOnce) {
                        List<ApplicationInfo> associatedAppList = associatedApps.get(packageName);
                        if (associatedAppList != null) {
                            for (ApplicationInfo associatedApp : associatedAppList) {
                                if (associatedApp.enabledSetting
                                        == PackageManager.COMPONENT_ENABLED_STATE_DEFAULT) {
                                    Slog.i(TAG,
                                            "Update associated state(" + associatedApp.packageName
                                                    + "): DISABLED_UNTIL_USED for user " + userId);
                                    packageManager.setApplicationEnabledSetting(
                                            associatedApp.packageName,
                                            PackageManager
                                                    .COMPONENT_ENABLED_STATE_DISABLED_UNTIL_USED,
                                            0,
                                            userId,
                                            callingPackage);
                                }
                            }
                        }
                    }
                }
            }

            // Mark the execution so we do not disable apps again.
            if (!hasRunOnce) {
                Settings.Secure.putIntForUser(
                        contentResolver, Settings.Secure.CARRIER_APPS_HANDLED, 1, userId);
            }

            if (!enabledCarrierPackages.isEmpty()) {
                // Since we enabled at least one app, ensure we grant default permissions to those
                // apps.
                String[] packageNames = new String[enabledCarrierPackages.size()];
                enabledCarrierPackages.toArray(packageNames);
                packageManager.grantDefaultPermissionsToEnabledCarrierApps(packageNames, userId);
            }
        } catch (RemoteException e) {
            Slog.w(TAG, "Could not reach PackageManager", e);
        }
    }

    /**
     * Returns the list of "default" carrier apps.
     *
     * This is the subset of apps returned by
     * {@link #getDefaultCarrierAppCandidates(IPackageManager, int)} which currently have carrier
     * privileges per the SIM(s) inserted in the device.
     */
    public static List<ApplicationInfo> getDefaultCarrierApps(IPackageManager packageManager,
            TelephonyManager telephonyManager, int userId) {
        // Get all system apps from the default list.
        List<ApplicationInfo> candidates = getDefaultCarrierAppCandidates(packageManager, userId);
        if (candidates == null || candidates.isEmpty()) {
            return null;
        }

        // Filter out apps without carrier privileges.
        // Iterate from the end to avoid creating an Iterator object and because we will be removing
        // elements from the list as we pass through it.
        for (int i = candidates.size() - 1; i >= 0; i--) {
            ApplicationInfo ai = candidates.get(i);
            String packageName = ai.packageName;
            boolean hasPrivileges =
                    telephonyManager.checkCarrierPrivilegesForPackageAnyPhone(packageName) ==
                            TelephonyManager.CARRIER_PRIVILEGE_STATUS_HAS_ACCESS;
            if (!hasPrivileges) {
                candidates.remove(i);
            }
        }

        return candidates;
    }

    /**
     * Returns the list of "default" carrier app candidates.
     *
     * These are the apps subject to the hiding/showing logic in
     * {@link CarrierAppUtils#disableCarrierAppsUntilPrivileged(String, IPackageManager,
     * TelephonyManager, ContentResolver, int)}, as well as the apps which should have default
     * permissions granted, when a matching SIM is inserted.
     *
     * Whether or not the app is actually considered a default app depends on whether the app has
     * carrier privileges as determined by the SIMs in the device.
     */
    public static List<ApplicationInfo> getDefaultCarrierAppCandidates(
            IPackageManager packageManager, int userId) {
        String[] systemCarrierAppsDisabledUntilUsed = Resources.getSystem().getStringArray(
                com.android.internal.R.array.config_disabledUntilUsedPreinstalledCarrierApps);
        return getDefaultCarrierAppCandidatesHelper(packageManager, userId,
                systemCarrierAppsDisabledUntilUsed);
    }

    private static List<ApplicationInfo> getDefaultCarrierAppCandidatesHelper(
            IPackageManager packageManager,
            int userId,
            String[] systemCarrierAppsDisabledUntilUsed) {
        if (systemCarrierAppsDisabledUntilUsed == null
                || systemCarrierAppsDisabledUntilUsed.length == 0) {
            return null;
        }
        List<ApplicationInfo> apps = new ArrayList<>(systemCarrierAppsDisabledUntilUsed.length);
        for (int i = 0; i < systemCarrierAppsDisabledUntilUsed.length; i++) {
            String packageName = systemCarrierAppsDisabledUntilUsed[i];
            ApplicationInfo ai =
                    getApplicationInfoIfSystemApp(packageManager, userId, packageName);
            if (ai != null) {
                apps.add(ai);
            }
        }
        return apps;
    }

    private static Map<String, List<ApplicationInfo>> getDefaultCarrierAssociatedAppsHelper(
            IPackageManager packageManager,
            int userId,
            ArrayMap<String, List<String>> systemCarrierAssociatedAppsDisabledUntilUsed) {
        int size = systemCarrierAssociatedAppsDisabledUntilUsed.size();
        Map<String, List<ApplicationInfo>> associatedApps = new ArrayMap<>(size);
        for (int i = 0; i < size; i++) {
            String carrierAppPackage = systemCarrierAssociatedAppsDisabledUntilUsed.keyAt(i);
            List<String> associatedAppPackages =
                    systemCarrierAssociatedAppsDisabledUntilUsed.valueAt(i);
            for (int j = 0; j < associatedAppPackages.size(); j++) {
                ApplicationInfo ai =
                        getApplicationInfoIfSystemApp(
                                packageManager, userId, associatedAppPackages.get(j));
                // Only update enabled state for the app on /system. Once it has been updated we
                // shouldn't touch it.
                if (ai != null && !ai.isUpdatedSystemApp()) {
                    List<ApplicationInfo> appList = associatedApps.get(carrierAppPackage);
                    if (appList == null) {
                        appList = new ArrayList<>();
                        associatedApps.put(carrierAppPackage, appList);
                    }
                    appList.add(ai);
                }
            }
        }
        return associatedApps;
    }

    @Nullable
    private static ApplicationInfo getApplicationInfoIfSystemApp(
            IPackageManager packageManager,
            int userId,
            String packageName) {
        try {
            ApplicationInfo ai = packageManager.getApplicationInfo(packageName,
                    PackageManager.MATCH_DISABLED_UNTIL_USED_COMPONENTS, userId);
            if (ai != null && ai.isSystemApp()) {
                return ai;
            }
        } catch (RemoteException e) {
            Slog.w(TAG, "Could not reach PackageManager", e);
        }
        return null;
    }
}