/*
 * 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.START_TASK_TO_FRONT;
import static android.app.WindowConfiguration.ACTIVITY_TYPE_HOME;
import static android.app.WindowConfiguration.ACTIVITY_TYPE_RECENTS;
import static android.app.WindowConfiguration.WINDOWING_MODE_UNDEFINED;
import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
import static android.os.Trace.TRACE_TAG_ACTIVITY_MANAGER;
import static android.view.WindowManager.TRANSIT_NONE;
import static com.android.server.am.ActivityStackSupervisor.PRESERVE_WINDOWS;
import static com.android.server.wm.RecentsAnimationController.REORDER_KEEP_IN_PLACE;
import static com.android.server.wm.RecentsAnimationController.REORDER_MOVE_TO_ORIGINAL_POSITION;
import static com.android.server.wm.RecentsAnimationController.REORDER_MOVE_TO_TOP;

import android.app.ActivityOptions;
import android.content.ComponentName;
import android.content.Intent;
import android.os.RemoteException;
import android.os.Trace;
import android.util.Slog;
import android.view.IRecentsAnimationRunner;
import com.android.server.wm.RecentsAnimationController;
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 final ActivityManagerService mService;
    private final ActivityStackSupervisor mStackSupervisor;
    private final ActivityStartController mActivityStartController;
    private final WindowManagerService mWindowManager;
    private final UserController mUserController;
    private final ActivityDisplay mDefaultDisplay;
    private final int mCallingPid;

    private int mTargetActivityType;

    // The stack to restore the target stack behind when the animation is finished
    private ActivityStack mRestoreTargetBehindStack;

    RecentsAnimation(ActivityManagerService am, ActivityStackSupervisor stackSupervisor,
            ActivityStartController activityStartController, WindowManagerService wm,
            UserController userController, int callingPid) {
        mService = am;
        mStackSupervisor = stackSupervisor;
        mDefaultDisplay = stackSupervisor.getDefaultDisplay();
        mActivityStartController = activityStartController;
        mWindowManager = wm;
        mUserController = userController;
        mCallingPid = callingPid;
    }

    void startRecentsActivity(Intent intent, IRecentsAnimationRunner recentsAnimationRunner,
            ComponentName recentsComponent, int recentsUid) {
        Trace.traceBegin(TRACE_TAG_ACTIVITY_MANAGER, "RecentsAnimation#startRecentsActivity");

        if (!mWindowManager.canStartRecentsAnimation()) {
            notifyAnimationCancelBeforeStart(recentsAnimationRunner);
            return;
        }

        // If the activity is associated with the recents stack, then try and get that first
        mTargetActivityType = intent.getComponent() != null
                && recentsComponent.equals(intent.getComponent())
                        ? ACTIVITY_TYPE_RECENTS
                        : ACTIVITY_TYPE_HOME;
        final ActivityStack targetStack = mDefaultDisplay.getStack(WINDOWING_MODE_UNDEFINED,
                mTargetActivityType);
        ActivityRecord targetActivity = targetStack != null
                ? targetStack.getTopActivity()
                : null;
        final boolean hasExistingActivity = targetActivity != null;
        if (hasExistingActivity) {
            final ActivityDisplay display = targetActivity.getDisplay();
            mRestoreTargetBehindStack = display.getStackAbove(targetStack);
            if (mRestoreTargetBehindStack == null) {
                notifyAnimationCancelBeforeStart(recentsAnimationRunner);
                return;
            }
        }

        // Send launch hint if we are actually launching the target. If it's already visible
        // (shouldn't happen in general) we don't need to send it.
        if (targetActivity == null || !targetActivity.visible) {
            mStackSupervisor.sendPowerHintForLaunchStartIfNeeded(true /* forceSend */,
                    targetActivity);
        }

        mStackSupervisor.getActivityMetricsLogger().notifyActivityLaunching();

        mService.setRunningRemoteAnimation(mCallingPid, true);

        mWindowManager.deferSurfaceLayout();
        try {
            final ActivityDisplay display;
            if (hasExistingActivity) {
                // Move the recents activity into place for the animation if it is not top most
                display = targetActivity.getDisplay();
                display.moveStackBehindBottomMostVisibleStack(targetStack);
            } else {
                // No recents activity
                ActivityOptions options = ActivityOptions.makeBasic();
                options.setLaunchActivityType(mTargetActivityType);
                options.setAvoidMoveToFront();
                intent.addFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_NO_ANIMATION);

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

                targetActivity = mDefaultDisplay.getStack(WINDOWING_MODE_UNDEFINED,
                        mTargetActivityType).getTopActivity();
                display = targetActivity.getDisplay();

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

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

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

            // 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);

            mStackSupervisor.getActivityMetricsLogger().notifyActivityLaunched(START_TASK_TO_FRONT,
                    targetActivity);
        } finally {
            mWindowManager.continueSurfaceLayout();
            Trace.traceEnd(TRACE_TAG_ACTIVITY_MANAGER);
        }
    }

    @Override
    public void onAnimationFinished(@RecentsAnimationController.ReorderMode int reorderMode) {
        synchronized (mService) {
            if (mWindowManager.getRecentsAnimationController() == null) return;

            // Just to be sure end the launch hint in case the target activity was never launched.
            // However, if we're keeping the activity and making it visible, we can leave it on.
            if (reorderMode != REORDER_KEEP_IN_PLACE) {
                mStackSupervisor.sendPowerHintForLaunchEndIfNeeded();
            }

            mService.setRunningRemoteAnimation(mCallingPid, false);

            mWindowManager.inSurfaceTransaction(() -> {
                Trace.traceBegin(TRACE_TAG_ACTIVITY_MANAGER,
                        "RecentsAnimation#onAnimationFinished_inSurfaceTransaction");
                mWindowManager.deferSurfaceLayout();
                try {
                    mWindowManager.cleanupRecentsAnimation(reorderMode);

                    final ActivityStack targetStack = mDefaultDisplay.getStack(
                            WINDOWING_MODE_UNDEFINED, mTargetActivityType);
                    final ActivityRecord targetActivity = targetStack.getTopActivity();
                    if (targetActivity == null) {
                        return;
                    }

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

                    if (reorderMode == REORDER_MOVE_TO_TOP) {
                        // Bring the target stack to the front
                        mStackSupervisor.mNoAnimActivities.add(targetActivity);
                        targetStack.moveToFront("RecentsAnimation.onAnimationFinished()");
                    } else if (reorderMode == REORDER_MOVE_TO_ORIGINAL_POSITION){
                        // Restore the target stack to its previous position
                        final ActivityDisplay display = targetActivity.getDisplay();
                        display.moveStackBehindStack(targetStack, mRestoreTargetBehindStack);
                    } else {
                        // Keep target stack in place, nothing changes, so ignore the transition
                        // logic below
                        return;
                    }

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

                    // No reason to wait for the pausing activity in this case, as the hiding of
                    // surfaces needs to be done immediately.
                    mWindowManager.executeAppTransition();

                    // After reordering the stacks, reset the minimized state. At this point, either
                    // the target activity is now top-most and we will stay minimized (if in
                    // split-screen), or we will have returned to the app, and the minimized state
                    // should be reset
                    mWindowManager.checkSplitScreenMinimizedChanged(true /* animate */);
                } finally {
                    mWindowManager.continueSurfaceLayout();
                    Trace.traceEnd(TRACE_TAG_ACTIVITY_MANAGER);
                }
            });
        }
    }

    /**
     * Called only when the animation should be canceled prior to starting.
     */
    private void notifyAnimationCancelBeforeStart(IRecentsAnimationRunner recentsAnimationRunner) {
        try {
            recentsAnimationRunner.onAnimationCanceled();
        } catch (RemoteException e) {
            Slog.e(TAG, "Failed to cancel recents animation before start", e);
        }
    }
}