/*
 * Copyright (C) 2021 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;

import android.annotation.IntDef;
import android.app.AppOpsManager;
import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.IPackageManager;
import android.content.pm.PackageManager;
import android.content.pm.ParceledListSlice;
import android.content.pm.UserInfo;
import android.os.UserHandle;
import android.os.UserManager;
import android.util.ArraySet;
import android.util.Log;

import androidx.annotation.VisibleForTesting;

import com.android.settings.R;
import com.android.settings.fuelgauge.BatteryOptimizeHistoricalLogEntry.Action;
import com.android.settings.fuelgauge.batteryusage.AppOptModeSharedPreferencesUtils;
import com.android.settingslib.datastore.DataChangeReason;
import com.android.settingslib.fuelgauge.PowerAllowlistBackend;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Arrays;
import java.util.List;

/** A utility class for application usage operation. */
public class BatteryOptimizeUtils {
    private static final String TAG = "BatteryOptimizeUtils";
    private static final String UNKNOWN_PACKAGE = "unknown";

    // Avoid reload the data again since it is predefined in the resource/config.
    private static List<String> sBatteryOptimizeModeList = null;
    private static List<String> sBatteryUnrestrictModeList = null;

    @VisibleForTesting AppOpsManager mAppOpsManager;
    @VisibleForTesting BatteryUtils mBatteryUtils;
    @VisibleForTesting PowerAllowlistBackend mPowerAllowListBackend;
    @VisibleForTesting int mMode;
    @VisibleForTesting boolean mAllowListed;

    private final String mPackageName;
    private final Context mContext;
    private final int mUid;

    // If current user is admin, match apps from all users. Otherwise, only match the currect user.
    private static final int RETRIEVE_FLAG_ADMIN =
            PackageManager.MATCH_ANY_USER
                    | PackageManager.MATCH_DISABLED_COMPONENTS
                    | PackageManager.MATCH_DISABLED_UNTIL_USED_COMPONENTS;
    private static final int RETRIEVE_FLAG =
            PackageManager.MATCH_DISABLED_COMPONENTS
                    | PackageManager.MATCH_DISABLED_UNTIL_USED_COMPONENTS;

    // Optimization modes.
    public static final int MODE_UNKNOWN = 0;
    public static final int MODE_RESTRICTED = 1;
    public static final int MODE_UNRESTRICTED = 2;
    public static final int MODE_OPTIMIZED = 3;

    @IntDef(
            prefix = {"MODE_"},
            value = {
                MODE_UNKNOWN,
                MODE_RESTRICTED,
                MODE_UNRESTRICTED,
                MODE_OPTIMIZED,
            })
    @Retention(RetentionPolicy.SOURCE)
    static @interface OptimizationMode {}

    public BatteryOptimizeUtils(Context context, int uid, String packageName) {
        mUid = uid;
        mContext = context;
        mPackageName = packageName;
        mAppOpsManager = context.getSystemService(AppOpsManager.class);
        mBatteryUtils = BatteryUtils.getInstance(context);
        mPowerAllowListBackend = PowerAllowlistBackend.getInstance(context);
        mMode = getMode(mAppOpsManager, mUid, mPackageName);
        mAllowListed = mPowerAllowListBackend.isAllowlisted(mPackageName, mUid);
    }

    /** Gets the {@link OptimizationMode} based on mode and allowed list. */
    @OptimizationMode
    public static int getAppOptimizationMode(
            int mode, boolean isAllowListed, boolean ignoreUnknownMode) {
        if (!isAllowListed && mode == AppOpsManager.MODE_IGNORED) {
            return MODE_RESTRICTED;
        } else if (isAllowListed && mode == AppOpsManager.MODE_ALLOWED) {
            return MODE_UNRESTRICTED;
        } else if (!isAllowListed && mode == AppOpsManager.MODE_ALLOWED) {
            return MODE_OPTIMIZED;
        } else {
            // MODE_UNKNOWN = isAllowListed + AppOpsManager.MODE_IGNORED
            // Return Unrestricted mode for Unknown mode since it is in allowlist.
            return ignoreUnknownMode ? MODE_UNRESTRICTED : MODE_UNKNOWN;
        }
    }

    /** Gets the {@link OptimizationMode} for associated app. */
    @OptimizationMode
    public int getAppOptimizationMode(boolean refreshList, boolean ignoreUnknownMode) {
        if (refreshList) {
            mPowerAllowListBackend.refreshList();
        }
        mAllowListed = mPowerAllowListBackend.isAllowlisted(mPackageName, mUid);
        mMode =
                mAppOpsManager.checkOpNoThrow(
                        AppOpsManager.OP_RUN_ANY_IN_BACKGROUND, mUid, mPackageName);
        Log.d(
                TAG,
                String.format(
                        "refresh %s state, allowlisted = %s, mode = %d",
                        mPackageName, mAllowListed, mMode));
        return getAppOptimizationMode(mMode, mAllowListed, ignoreUnknownMode);
    }

    /** Gets the {@link OptimizationMode} for associated app. */
    @OptimizationMode
    public int getAppOptimizationMode() {
        return getAppOptimizationMode(/* refreshList= */ true, /* ignoreUnknownMode= */ true);
    }

    /** Resets optimization mode for all applications. */
    public static void resetAppOptimizationMode(
            Context context, IPackageManager ipm, AppOpsManager aom) {
        AppOptModeSharedPreferencesUtils.clearAll(context);
        resetAppOptimizationModeInternal(
                context,
                ipm,
                aom,
                PowerAllowlistBackend.getInstance(context),
                BatteryUtils.getInstance(context));
    }

    /** Sets the {@link OptimizationMode} for associated app. */
    public void setAppUsageState(@OptimizationMode int mode, Action action, boolean forceMode) {
        if (!forceMode && getAppOptimizationMode() == mode) {
            Log.w(TAG, "set the same optimization mode for: " + mPackageName);
            return;
        }
        setAppUsageStateInternal(
                mContext, mode, mUid, mPackageName, mBatteryUtils, mPowerAllowListBackend, action);
    }

    /** Sets the {@link OptimizationMode} for associated app. */
    public void setAppUsageState(@OptimizationMode int mode, Action action) {
        setAppUsageState(mode, action, /* forceMode= */ false);
    }

    /** Return {@code true} if it is disabled for default optimized mode only. */
    public boolean isDisabledForOptimizeModeOnly() {
        return getForceBatteryOptimizeModeList(mContext).contains(mPackageName)
                || mBatteryUtils.getPackageUid(mPackageName) == BatteryUtils.UID_NULL;
    }

    /** Return {@code true} if this package is system or default active app. */
    public boolean isSystemOrDefaultApp() {
        mPowerAllowListBackend.refreshList();
        return isSystemOrDefaultApp(mContext, mPowerAllowListBackend, mPackageName, mUid);
    }

    /** Return {@code true} if the optimization mode of this package can be changed */
    public boolean isOptimizeModeMutable() {
        return !isDisabledForOptimizeModeOnly() && !isSystemOrDefaultApp();
    }

    /**
     * Return {@code true} if the optimization mode is mutable and current state is not restricted
     */
    public boolean isSelectorPreferenceEnabled() {
        // Enable the preference if apps are not set into restricted mode, otherwise disable it
        return isOptimizeModeMutable()
                && getAppOptimizationMode() != BatteryOptimizeUtils.MODE_RESTRICTED;
    }

    String getPackageName() {
        return mPackageName == null ? UNKNOWN_PACKAGE : mPackageName;
    }

    int getUid() {
        return mUid;
    }

    /** Gets the list of installed applications. */
    public static ArraySet<ApplicationInfo> getInstalledApplications(
            Context context, IPackageManager ipm) {
        final ArraySet<ApplicationInfo> applications = new ArraySet<>();
        final UserManager um = context.getSystemService(UserManager.class);
        for (UserInfo userInfo : um.getProfiles(UserHandle.myUserId())) {
            try {
                @SuppressWarnings("unchecked")
                final ParceledListSlice<ApplicationInfo> infoList =
                        ipm.getInstalledApplications(
                                userInfo.isAdmin() ? RETRIEVE_FLAG_ADMIN : RETRIEVE_FLAG,
                                userInfo.id);
                if (infoList != null) {
                    applications.addAll(infoList.getList());
                }
            } catch (Exception e) {
                Log.e(TAG, "getInstalledApplications() is failed", e);
                return null;
            }
        }
        // Removes the application which is disabled by the system.
        applications.removeIf(
                info ->
                        info.enabledSetting != PackageManager.COMPONENT_ENABLED_STATE_DISABLED_USER
                                && !info.enabled);
        return applications;
    }

    @VisibleForTesting
    static void resetAppOptimizationModeInternal(
            Context context,
            IPackageManager ipm,
            AppOpsManager aom,
            PowerAllowlistBackend allowlistBackend,
            BatteryUtils batteryUtils) {
        final ArraySet<ApplicationInfo> applications = getInstalledApplications(context, ipm);
        if (applications == null || applications.isEmpty()) {
            Log.w(TAG, "no data found in the getInstalledApplications()");
            return;
        }

        // App preferences are already clear when code reach here, and there may be no
        // setAppUsageStateInternal call to notifyChange. So always trigger notifyChange here.
        BatterySettingsStorage.get(context).notifyChange(DataChangeReason.DELETE);

        allowlistBackend.refreshList();
        // Resets optimization mode for each application.
        for (ApplicationInfo info : applications) {
            final int mode =
                    aom.checkOpNoThrow(
                            AppOpsManager.OP_RUN_ANY_IN_BACKGROUND, info.uid, info.packageName);
            @OptimizationMode
            final int optimizationMode =
                    getAppOptimizationMode(
                            mode,
                            allowlistBackend.isAllowlisted(info.packageName, info.uid),
                            /* ignoreUnknownMode= */ false);
            // Ignores default optimized state or system/default apps.
            if (optimizationMode == MODE_OPTIMIZED
                    || isSystemOrDefaultApp(
                            context, allowlistBackend, info.packageName, info.uid)) {
                continue;
            }

            // Resets to the default mode: MODE_OPTIMIZED.
            setAppUsageStateInternal(
                    context,
                    MODE_OPTIMIZED,
                    info.uid,
                    info.packageName,
                    batteryUtils,
                    allowlistBackend,
                    Action.RESET);
        }
    }

    static int getMode(AppOpsManager appOpsManager, int uid, String packageName) {
        return appOpsManager.checkOpNoThrow(
                AppOpsManager.OP_RUN_ANY_IN_BACKGROUND, uid, packageName);
    }

    static boolean isSystemOrDefaultApp(
            Context context,
            PowerAllowlistBackend powerAllowlistBackend,
            String packageName,
            int uid) {
        return powerAllowlistBackend.isSysAllowlisted(packageName)
                // Always forced unrestricted apps are one type of system important apps.
                || getForceBatteryUnrestrictModeList(context).contains(packageName)
                || powerAllowlistBackend.isDefaultActiveApp(packageName, uid);
    }

    static List<String> getForceBatteryOptimizeModeList(Context context) {
        if (sBatteryOptimizeModeList == null) {
            sBatteryOptimizeModeList =
                    Arrays.asList(
                            context.getResources()
                                    .getStringArray(
                                            R.array.config_force_battery_optimize_mode_apps));
        }
        return sBatteryOptimizeModeList;
    }

    static List<String> getForceBatteryUnrestrictModeList(Context context) {
        if (sBatteryUnrestrictModeList == null) {
            sBatteryUnrestrictModeList =
                    Arrays.asList(
                            context.getResources()
                                    .getStringArray(
                                            R.array.config_force_battery_unrestrict_mode_apps));
        }
        return sBatteryUnrestrictModeList;
    }

    private static void setAppUsageStateInternal(
            Context context,
            @OptimizationMode int mode,
            int uid,
            String packageName,
            BatteryUtils batteryUtils,
            PowerAllowlistBackend powerAllowlistBackend,
            Action action) {
        if (mode == MODE_UNKNOWN) {
            Log.d(TAG, "set unknown app optimization mode.");
            return;
        }

        // MODE_RESTRICTED = AppOpsManager.MODE_IGNORED + !allowListed
        // MODE_UNRESTRICTED = AppOpsManager.MODE_ALLOWED + allowListed
        // MODE_OPTIMIZED = AppOpsManager.MODE_ALLOWED + !allowListed
        final int appOpsManagerMode =
                mode == MODE_RESTRICTED ? AppOpsManager.MODE_IGNORED : AppOpsManager.MODE_ALLOWED;
        final boolean allowListed = mode == MODE_UNRESTRICTED;

        setAppOptimizationModeInternal(
                context,
                appOpsManagerMode,
                allowListed,
                uid,
                packageName,
                batteryUtils,
                powerAllowlistBackend,
                action);
    }

    private static void setAppOptimizationModeInternal(
            Context context,
            int appStandbyMode,
            boolean allowListed,
            int uid,
            String packageName,
            BatteryUtils batteryUtils,
            PowerAllowlistBackend powerAllowlistBackend,
            Action action) {
        final String packageNameKey =
                BatteryOptimizeLogUtils.getPackageNameWithUserId(
                        packageName, UserHandle.myUserId());
        try {
            batteryUtils.setForceAppStandby(uid, packageName, appStandbyMode);
            if (allowListed) {
                powerAllowlistBackend.addApp(packageName, uid);
            } else {
                powerAllowlistBackend.removeApp(packageName, uid);
            }
        } catch (Exception e) {
            // Error cases, set standby mode as -1 for logging.
            appStandbyMode = -1;
            Log.e(TAG, "set OPTIMIZATION MODE failed for " + packageName, e);
        }
        BatteryOptimizeLogUtils.writeLog(
                context, action, packageNameKey, createLogEvent(appStandbyMode, allowListed));
        if (action != Action.RESET) { // reset has been notified in resetAppOptimizationMode
            BatterySettingsStorage.get(context).notifyChange(toChangeReason(action));
        }
    }

    private static String createLogEvent(int appStandbyMode, boolean allowListed) {
        return appStandbyMode < 0
                ? "Apply optimize setting ERROR"
                : String.format(
                        "\tStandbyMode: %s, allowListed: %s, mode: %s",
                        appStandbyMode,
                        allowListed,
                        getAppOptimizationMode(
                                appStandbyMode, allowListed, /* ignoreUnknownMode= */ false));
    }

    private static @DataChangeReason int toChangeReason(Action action) {
        return action == Action.RESTORE ? DataChangeReason.RESTORE : DataChangeReason.UPDATE;
    }
}