/*
 * Copyright (C) 2022 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.intentresolver;

import android.annotation.Nullable;
import android.app.Activity;
import android.app.ActivityManager;
import android.os.UserHandle;
import android.os.UserManager;

/**
 * Helper class to precompute the (immutable) designations of various user handles in the system
 * that may contribute to the current Sharesheet session.
 */
public final class AnnotatedUserHandles {
    /** The user id of the app that started the share activity. */
    public final int userIdOfCallingApp;

    /**
     * The {@link UserHandle} that launched Sharesheet.
     * TODO: I believe this would always be the handle corresponding to {@code userIdOfCallingApp}
     * except possibly if the caller used {@link Activity#startActivityAsUser()} to launch
     * Sharesheet as a different user than they themselves were running as. Verify and document.
     */
    public final UserHandle userHandleSharesheetLaunchedAs;

    /**
     * The {@link UserHandle} that owns the "personal tab" in a tabbed share UI (or the *only* 'tab'
     * in a non-tabbed UI).
     *
     * This is never a work or clone user, but may either be the root user (0) or a "secondary"
     * multi-user profile (i.e., one that's not root, work, nor clone). This is a "secondary"
     * profile only when that user is the active "foreground" user.
     *
     * In the current implementation, we can assert that this is the root user (0) any time we
     * display a tabbed UI (i.e., any time `workProfileUserHandle` is non-null), or any time that we
     * have a clone profile. This note is only provided for informational purposes; clients should
     * avoid making any reliances on that assumption.
     */
    public final UserHandle personalProfileUserHandle;

    /**
     * The {@link UserHandle} that owns the "work tab" in a tabbed share UI. This is (an arbitrary)
     * one of the "managed" profiles associated with {@link personalProfileUserHandle}.
     */
    @Nullable
    public final UserHandle workProfileUserHandle;

    /**
     * The {@link UserHandle} of the clone profile belonging to {@link personalProfileUserHandle}.
     */
    @Nullable
    public final UserHandle cloneProfileUserHandle;

    /**
     * The "tab owner" user handle (i.e., either {@link personalProfileUserHandle} or
     * {@link workProfileUserHandle}) that either matches or owns the profile of the
     * {@link userHandleSharesheetLaunchedAs}.
     *
     * In the current implementation, we can assert that this is the same as
     * `userHandleSharesheetLaunchedAs` except when the latter is the clone profile; then this is
     * the "personal" profile owning that clone profile (which we currently know must belong to
     * user 0, but clients should avoid making any reliances on that assumption).
     */
    public final UserHandle tabOwnerUserHandleForLaunch;

    public AnnotatedUserHandles(Activity forShareActivity) {
        userIdOfCallingApp = forShareActivity.getLaunchedFromUid();
        if ((userIdOfCallingApp < 0) || UserHandle.isIsolated(userIdOfCallingApp)) {
            throw new SecurityException("Can't start a resolver from uid " + userIdOfCallingApp);
        }

        // TODO: integrate logic for `ResolverActivity.EXTRA_CALLING_USER`.
        userHandleSharesheetLaunchedAs = UserHandle.of(UserHandle.myUserId());

        personalProfileUserHandle = UserHandle.of(ActivityManager.getCurrentUser());

        UserManager userManager = forShareActivity.getSystemService(UserManager.class);
        workProfileUserHandle = getWorkProfileForUser(userManager, personalProfileUserHandle);
        cloneProfileUserHandle = getCloneProfileForUser(userManager, personalProfileUserHandle);

        tabOwnerUserHandleForLaunch = (userHandleSharesheetLaunchedAs == workProfileUserHandle)
                ? workProfileUserHandle : personalProfileUserHandle;
    }

    @Nullable
    private static UserHandle getWorkProfileForUser(
            UserManager userManager, UserHandle profileOwnerUserHandle) {
        return userManager.getProfiles(profileOwnerUserHandle.getIdentifier()).stream()
                .filter(info -> info.isManagedProfile()).findFirst()
                .map(info -> info.getUserHandle()).orElse(null);
    }

    @Nullable
    private static UserHandle getCloneProfileForUser(
            UserManager userManager, UserHandle profileOwnerUserHandle) {
        return null;  // Not yet supported in framework.
    }
}