/*
 * Copyright (C) 2018 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 android.permission;

import android.Manifest;
import android.annotation.IntRange;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.RequiresPermission;
import android.annotation.SystemApi;
import android.annotation.SystemService;
import android.annotation.TestApi;
import android.content.Context;
import android.content.pm.IPackageManager;
import android.content.pm.permission.SplitPermissionInfoParcelable;
import android.os.RemoteException;
import android.util.Log;

import com.android.internal.annotations.Immutable;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * System level service for accessing the permission capabilities of the platform.
 *
 * @hide
 */
@TestApi
@SystemApi
@SystemService(Context.PERMISSION_SERVICE)
public final class PermissionManager {
    private static final String TAG = PermissionManager.class.getName();

    private final @NonNull Context mContext;

    private final IPackageManager mPackageManager;

    private List<SplitPermissionInfo> mSplitPermissionInfos;

    /**
     * Creates a new instance.
     *
     * @param context The current context in which to operate.
     * @hide
     */
    public PermissionManager(@NonNull Context context, IPackageManager packageManager) {
        mContext = context;
        mPackageManager = packageManager;
    }

    /**
     * Gets the version of the runtime permission database.
     *
     * @return The database version, -1 when this is an upgrade from pre-Q, 0 when this is a fresh
     * install.
     *
     * @hide
     */
    @TestApi
    @SystemApi
    @RequiresPermission(Manifest.permission.ADJUST_RUNTIME_PERMISSIONS_POLICY)
    public @IntRange(from = 0) int getRuntimePermissionsVersion() {
        try {
            return mPackageManager.getRuntimePermissionsVersion(mContext.getUserId());
        } catch (RemoteException e) {
            throw e.rethrowFromSystemServer();
        }
    }

    /**
     * Sets the version of the runtime permission database.
     *
     * @param version The new version.
     *
     * @hide
     */
    @TestApi
    @SystemApi
    @RequiresPermission(Manifest.permission.ADJUST_RUNTIME_PERMISSIONS_POLICY)
    public void setRuntimePermissionsVersion(@IntRange(from = 0) int version) {
        try {
            mPackageManager.setRuntimePermissionsVersion(version, mContext.getUserId());
        } catch (RemoteException e) {
            throw e.rethrowFromSystemServer();
        }
    }

    /**
     * Get set of permissions that have been split into more granular or dependent permissions.
     *
     * <p>E.g. before {@link android.os.Build.VERSION_CODES#Q} an app that was granted
     * {@link Manifest.permission#ACCESS_COARSE_LOCATION} could access he location while it was in
     * foreground and background. On platforms after {@link android.os.Build.VERSION_CODES#Q}
     * the location permission only grants location access while the app is in foreground. This
     * would break apps that target before {@link android.os.Build.VERSION_CODES#Q}. Hence whenever
     * such an old app asks for a location permission (i.e. the
     * {@link SplitPermissionInfo#getSplitPermission()}), then the
     * {@link Manifest.permission#ACCESS_BACKGROUND_LOCATION} permission (inside
     * {@link SplitPermissionInfo#getNewPermissions}) is added.
     *
     * <p>Note: Regular apps do not have to worry about this. The platform and permission controller
     * automatically add the new permissions where needed.
     *
     * @return All permissions that are split.
     */
    public @NonNull List<SplitPermissionInfo> getSplitPermissions() {
        if (mSplitPermissionInfos != null) {
            return mSplitPermissionInfos;
        }

        List<SplitPermissionInfoParcelable> parcelableList;
        try {
            parcelableList = mPackageManager.getSplitPermissions();
        } catch (RemoteException e) {
            Log.w(TAG, "Error getting split permissions", e);
            return Collections.emptyList();
        }

        mSplitPermissionInfos = splitPermissionInfoListToNonParcelableList(parcelableList);

        return mSplitPermissionInfos;
    }

    private List<SplitPermissionInfo> splitPermissionInfoListToNonParcelableList(
            List<SplitPermissionInfoParcelable> parcelableList) {
        final int size = parcelableList.size();
        List<SplitPermissionInfo> list = new ArrayList<>(size);
        for (int i = 0; i < size; i++) {
            list.add(new SplitPermissionInfo(parcelableList.get(i)));
        }
        return list;
    }

    /**
     * Converts a {@link List} of {@link SplitPermissionInfo} into a List of
     * {@link SplitPermissionInfoParcelable} and returns it.
     * @hide
     */
    public static List<SplitPermissionInfoParcelable> splitPermissionInfoListToParcelableList(
            List<SplitPermissionInfo> splitPermissionsList) {
        final int size = splitPermissionsList.size();
        List<SplitPermissionInfoParcelable> outList = new ArrayList<>(size);
        for (int i = 0; i < size; i++) {
            SplitPermissionInfo info = splitPermissionsList.get(i);
            outList.add(new SplitPermissionInfoParcelable(
                    info.getSplitPermission(), info.getNewPermissions(), info.getTargetSdk()));
        }
        return outList;
    }

    /**
     * A permission that was added in a previous API level might have split into several
     * permissions. This object describes one such split.
     */
    @Immutable
    public static final class SplitPermissionInfo {
        private @NonNull final SplitPermissionInfoParcelable mSplitPermissionInfoParcelable;

        @Override
        public boolean equals(@Nullable Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            SplitPermissionInfo that = (SplitPermissionInfo) o;
            return mSplitPermissionInfoParcelable.equals(that.mSplitPermissionInfoParcelable);
        }

        @Override
        public int hashCode() {
            return mSplitPermissionInfoParcelable.hashCode();
        }

        /**
         * Get the permission that is split.
         */
        public @NonNull String getSplitPermission() {
            return mSplitPermissionInfoParcelable.getSplitPermission();
        }

        /**
         * Get the permissions that are added.
         */
        public @NonNull List<String> getNewPermissions() {
            return mSplitPermissionInfoParcelable.getNewPermissions();
        }

        /**
         * Get the target API level when the permission was split.
         */
        public int getTargetSdk() {
            return mSplitPermissionInfoParcelable.getTargetSdk();
        }

        /**
         * Constructs a split permission.
         *
         * @param splitPerm old permission that will be split
         * @param newPerms list of new permissions that {@code rootPerm} will be split into
         * @param targetSdk apps targetting SDK versions below this will have {@code rootPerm}
         * split into {@code newPerms}
         * @hide
         */
        public SplitPermissionInfo(@NonNull String splitPerm, @NonNull List<String> newPerms,
                int targetSdk) {
            this(new SplitPermissionInfoParcelable(splitPerm, newPerms, targetSdk));
        }

        private SplitPermissionInfo(@NonNull SplitPermissionInfoParcelable parcelable) {
            mSplitPermissionInfoParcelable = parcelable;
        }
    }
}