/*
 * 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 com.android.server.am;

import static android.app.ActivityManager.StackId.INVALID_STACK_ID;
import static android.app.WindowConfiguration.ACTIVITY_TYPE_HOME;
import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
import static android.view.WindowManager.TRANSIT_NONE;
import static com.android.server.am.ActivityStackSupervisor.PRESERVE_WINDOWS;

import android.app.ActivityOptions;
import android.content.ComponentName;
import android.content.Intent;
import android.os.Handler;
import android.view.IRecentsAnimationRunner;
import com.android.server.wm.RecentsAnimationController.RecentsAnimationCallbacks;
import com.android.server.wm.WindowManagerService;

/**
 * Manages the recents animation, including the reordering of the stacks for the transition and
 * cleanup. See {@link com.android.server.wm.RecentsAnimationController}.
 */
class RecentsAnimation implements RecentsAnimationCallbacks {
    private static final String TAG = RecentsAnimation.class.getSimpleName();

    private static final int RECENTS_ANIMATION_TIMEOUT = 10 * 1000;

    private final ActivityManagerService mService;
    private final ActivityStackSupervisor mStackSupervisor;
    private final ActivityStartController mActivityStartController;
    private final WindowManagerService mWindowManager;
    private final UserController mUserController;
    private final Handler mHandler;

    private final Runnable mCancelAnimationRunnable;

    // The stack to restore the home stack behind when the animation is finished
    private ActivityStack mRestoreHomeBehindStack;

    RecentsAnimation(ActivityManagerService am, ActivityStackSupervisor stackSupervisor,
            ActivityStartController activityStartController, WindowManagerService wm,
            UserController userController) {
        mService = am;
        mStackSupervisor = stackSupervisor;
        mActivityStartController = activityStartController;
        mHandler = new Handler(mStackSupervisor.mLooper);
        mWindowManager = wm;
        mUserController = userController;
        mCancelAnimationRunnable = () -> {
            // The caller has not finished the animation in a predefined amount of time, so
            // force-cancel the animation
            mWindowManager.cancelRecentsAnimation();
        };
    }

    void startRecentsActivity(Intent intent, IRecentsAnimationRunner recentsAnimationRunner,
            ComponentName recentsComponent, int recentsUid) {

        // Cancel the previous recents animation if necessary
        mWindowManager.cancelRecentsAnimation();

        final boolean hasExistingHomeActivity = mStackSupervisor.getHomeActivity() != null;
        if (!hasExistingHomeActivity) {
            // No home activity
            final ActivityOptions opts = ActivityOptions.makeBasic();
            opts.setLaunchActivityType(ACTIVITY_TYPE_HOME);
            opts.setAvoidMoveToFront();
            intent.addFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_NO_ANIMATION);

            mActivityStartController.obtainStarter(intent, "startRecentsActivity_noHomeActivity")
                    .setCallingUid(recentsUid)
                    .setCallingPackage(recentsComponent.getPackageName())
                    .setActivityOptions(SafeActivityOptions.fromBundle(opts.toBundle()))
                    .setMayWait(mUserController.getCurrentUserId())
                    .execute();
            mWindowManager.prepareAppTransition(TRANSIT_NONE, false);

            // TODO: Maybe wait for app to draw in this particular case?
        }

        final ActivityRecord homeActivity = mStackSupervisor.getHomeActivity();
        final ActivityDisplay display = homeActivity.getDisplay();

        // Save the initial position of the home activity stack to be restored to after the
        // animation completes
        mRestoreHomeBehindStack = hasExistingHomeActivity
                ? display.getStackAboveHome()
                : null;

        // Move the home activity into place for the animation
        display.moveHomeStackBehindBottomMostVisibleStack();

        // Mark the home activity as launch-behind to bump its visibility for the
        // duration of the gesture that is driven by the recents component
        homeActivity.mLaunchTaskBehind = true;

        // Fetch all the surface controls and pass them to the client to get the animation
        // started
        mWindowManager.initializeRecentsAnimation(recentsAnimationRunner, this, display.mDisplayId);

        // If we updated the launch-behind state, update the visibility of the activities after we
        // fetch the visible tasks to be controlled by the animation
        mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, PRESERVE_WINDOWS);

        // Post a timeout for the animation
        mHandler.postDelayed(mCancelAnimationRunnable, RECENTS_ANIMATION_TIMEOUT);
    }

    @Override
    public void onAnimationFinished(boolean moveHomeToTop) {
        mHandler.removeCallbacks(mCancelAnimationRunnable);
        synchronized (mService) {
            if (mWindowManager.getRecentsAnimationController() == null) return;

            mWindowManager.inSurfaceTransaction(() -> {
                mWindowManager.cleanupRecentsAnimation();

                // Move the home stack to the front
                final ActivityRecord homeActivity = mStackSupervisor.getHomeActivity();
                if (homeActivity == null) {
                    return;
                }

                // Restore the launched-behind state
                homeActivity.mLaunchTaskBehind = false;

                if (moveHomeToTop) {
                    // Bring the home stack to the front
                    final ActivityStack homeStack = homeActivity.getStack();
                    homeStack.mNoAnimActivities.add(homeActivity);
                    homeStack.moveToFront("RecentsAnimation.onAnimationFinished()");
                } else {
                    // Restore the home stack to its previous position
                    final ActivityDisplay display = homeActivity.getDisplay();
                    display.moveHomeStackBehindStack(mRestoreHomeBehindStack);
                }

                mWindowManager.prepareAppTransition(TRANSIT_NONE, false);
                mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, false);
                mStackSupervisor.resumeFocusedStackTopActivityLocked();
            });
        }
    }
}