/*
 * Copyright (C) 2014 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.systemui.recents;

import android.app.Activity;
import android.app.ActivityManager;
import android.app.ActivityOptions;
import android.app.ITaskStackListener;
import android.appwidget.AppWidgetHost;
import android.appwidget.AppWidgetProviderInfo;
import android.content.ActivityNotFoundException;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.os.Handler;
import android.os.SystemClock;
import android.os.UserHandle;
import android.util.Pair;
import android.view.LayoutInflater;
import android.view.View;

import com.android.systemui.R;
import com.android.systemui.RecentsComponent;
import com.android.systemui.recents.misc.Console;
import com.android.systemui.recents.misc.SystemServicesProxy;
import com.android.systemui.recents.model.RecentsTaskLoadPlan;
import com.android.systemui.recents.model.RecentsTaskLoader;
import com.android.systemui.recents.model.Task;
import com.android.systemui.recents.model.TaskGrouping;
import com.android.systemui.recents.model.TaskStack;
import com.android.systemui.recents.views.TaskStackView;
import com.android.systemui.recents.views.TaskStackViewLayoutAlgorithm;
import com.android.systemui.recents.views.TaskViewHeader;
import com.android.systemui.recents.views.TaskViewTransform;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;


/** A proxy implementation for the recents component */
public class AlternateRecentsComponent implements ActivityOptions.OnAnimationStartedListener {

    final public static String EXTRA_FROM_HOME = "recents.triggeredOverHome";
    final public static String EXTRA_FROM_SEARCH_HOME = "recents.triggeredOverSearchHome";
    final public static String EXTRA_FROM_APP_THUMBNAIL = "recents.animatingWithThumbnail";
    final public static String EXTRA_FROM_TASK_ID = "recents.activeTaskId";
    final public static String EXTRA_TRIGGERED_FROM_ALT_TAB = "recents.triggeredFromAltTab";
    final public static String EXTRA_TRIGGERED_FROM_HOME_KEY = "recents.triggeredFromHomeKey";
    final public static String EXTRA_REUSE_TASK_STACK_VIEWS = "recents.reuseTaskStackViews";
    final public static String EXTRA_NUM_VISIBLE_TASKS = "recents.numVisibleTasks";
    final public static String EXTRA_NUM_VISIBLE_THUMBNAILS = "recents.numVisibleThumbnails";

    final public static String ACTION_START_ENTER_ANIMATION = "action_start_enter_animation";
    final public static String ACTION_TOGGLE_RECENTS_ACTIVITY = "action_toggle_recents_activity";
    final public static String ACTION_HIDE_RECENTS_ACTIVITY = "action_hide_recents_activity";

    final static int sMinToggleDelay = 350;

    final static String sToggleRecentsAction = "com.android.systemui.recents.SHOW_RECENTS";
    final static String sRecentsPackage = "com.android.systemui";
    final static String sRecentsActivity = "com.android.systemui.recents.RecentsActivity";

    /**
     * An implementation of ITaskStackListener, that allows us to listen for changes to the system
     * task stacks and update recents accordingly.
     */
    class TaskStackListenerImpl extends ITaskStackListener.Stub {
        @Override
        public void onTaskStackChanged() {
            RecentsConfiguration config = RecentsConfiguration.getInstance();
            if (config.svelteLevel == RecentsConfiguration.SVELTE_NONE) {
                // Load the next task only if we aren't svelte
                RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
                RecentsTaskLoadPlan plan = loader.createLoadPlan(mContext);
                loader.preloadTasks(plan, true /* isTopTaskHome */);
                RecentsTaskLoadPlan.Options launchOpts = new RecentsTaskLoadPlan.Options();
                launchOpts.numVisibleTasks = 1;
                launchOpts.numVisibleTaskThumbnails = 1;
                launchOpts.onlyLoadForCache = true;
                loader.loadTasks(mContext, plan, launchOpts);
            }
        }
    }

    static RecentsComponent.Callbacks sRecentsComponentCallbacks;
    static RecentsTaskLoadPlan sInstanceLoadPlan;

    Context mContext;
    LayoutInflater mInflater;
    SystemServicesProxy mSystemServicesProxy;
    Handler mHandler;
    TaskStackListenerImpl mTaskStackListener;
    boolean mBootCompleted;
    boolean mStartAnimationTriggered;
    boolean mCanReuseTaskStackViews = true;

    // Task launching
    RecentsConfiguration mConfig;
    Rect mWindowRect = new Rect();
    Rect mTaskStackBounds = new Rect();
    Rect mSystemInsets = new Rect();
    TaskViewTransform mTmpTransform = new TaskViewTransform();
    int mStatusBarHeight;
    int mNavBarHeight;
    int mNavBarWidth;

    // Header (for transition)
    TaskViewHeader mHeaderBar;
    TaskStackView mDummyStackView;

    // Variables to keep track of if we need to start recents after binding
    View mStatusBarView;
    boolean mTriggeredFromAltTab;
    long mLastToggleTime;

    public AlternateRecentsComponent(Context context) {
        RecentsTaskLoader.initialize(context);
        mInflater = LayoutInflater.from(context);
        mContext = context;
        mSystemServicesProxy = new SystemServicesProxy(context);
        mHandler = new Handler();
        mTaskStackBounds = new Rect();

        // Register the task stack listener
        mTaskStackListener = new TaskStackListenerImpl();
        mSystemServicesProxy.registerTaskStackListener(mTaskStackListener);
    }

    public void onStart() {
        // Initialize some static datastructures
        TaskStackViewLayoutAlgorithm.initializeCurve();
        // Load the header bar layout
        reloadHeaderBarLayout();
        // Try and pre-emptively bind the search widget on startup to ensure that we
        // have the right thumbnail bounds to animate to.
        if (Constants.DebugFlags.App.EnableSearchLayout) {
            // If there is no id, then bind a new search app widget
            if (mConfig.searchBarAppWidgetId < 0) {
                AppWidgetHost host = new RecentsAppWidgetHost(mContext,
                        Constants.Values.App.AppWidgetHostId);
                Pair<Integer, AppWidgetProviderInfo> widgetInfo =
                        mSystemServicesProxy.bindSearchAppWidget(host);
                if (widgetInfo != null) {
                    // Save the app widget id into the settings
                    mConfig.updateSearchBarAppWidgetId(mContext, widgetInfo.first);
                }
            }
        }

        // When we start, preload the data associated with the previous recent tasks.
        // We can use a new plan since the caches will be the same.
        RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
        RecentsTaskLoadPlan plan = loader.createLoadPlan(mContext);
        loader.preloadTasks(plan, true /* isTopTaskHome */);
        RecentsTaskLoadPlan.Options launchOpts = new RecentsTaskLoadPlan.Options();
        launchOpts.numVisibleTasks = loader.getApplicationIconCacheSize();
        launchOpts.numVisibleTaskThumbnails = loader.getThumbnailCacheSize();
        launchOpts.onlyLoadForCache = true;
        loader.loadTasks(mContext, plan, launchOpts);
    }

    public void onBootCompleted() {
        mBootCompleted = true;
    }

    /** Shows the recents */
    public void onShowRecents(boolean triggeredFromAltTab, View statusBarView) {
        mStatusBarView = statusBarView;
        mTriggeredFromAltTab = triggeredFromAltTab;

        try {
            startRecentsActivity();
        } catch (ActivityNotFoundException e) {
            Console.logRawError("Failed to launch RecentAppsIntent", e);
        }
    }

    /** Hides the recents */
    public void onHideRecents(boolean triggeredFromAltTab, boolean triggeredFromHomeKey) {
        if (mBootCompleted) {
            ActivityManager.RunningTaskInfo topTask = getTopMostTask();
            if (topTask != null && isRecentsTopMost(topTask, null)) {
                // Notify recents to hide itself
                Intent intent = new Intent(ACTION_HIDE_RECENTS_ACTIVITY);
                intent.setPackage(mContext.getPackageName());
                intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT |
                        Intent.FLAG_RECEIVER_FOREGROUND);
                intent.putExtra(EXTRA_TRIGGERED_FROM_ALT_TAB, triggeredFromAltTab);
                intent.putExtra(EXTRA_TRIGGERED_FROM_HOME_KEY, triggeredFromHomeKey);
                mContext.sendBroadcastAsUser(intent, UserHandle.CURRENT);
            }
        }
    }

    /** Toggles the alternate recents activity */
    public void onToggleRecents(View statusBarView) {
        mStatusBarView = statusBarView;
        mTriggeredFromAltTab = false;

        try {
            toggleRecentsActivity();
        } catch (ActivityNotFoundException e) {
            Console.logRawError("Failed to launch RecentAppsIntent", e);
        }
    }

    public void onPreloadRecents() {
        // Preload only the raw task list into a new load plan (which will be consumed by the
        // RecentsActivity)
        RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
        sInstanceLoadPlan = loader.createLoadPlan(mContext);
        sInstanceLoadPlan.preloadRawTasks(true);
    }

    public void onCancelPreloadingRecents() {
        // Do nothing
    }

    void showRelativeAffiliatedTask(boolean showNextTask) {
        RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
        RecentsTaskLoadPlan plan = loader.createLoadPlan(mContext);
        loader.preloadTasks(plan, true /* isTopTaskHome */);
        TaskStack stack = plan.getTaskStack();

        // Return early if there are no tasks
        if (stack.getTaskCount() == 0) return;

        ActivityManager.RunningTaskInfo runningTask = getTopMostTask();
        // Return early if there is no running task (can't determine affiliated tasks in this case)
        if (runningTask == null) return;
        // Return early if the running task is in the home stack (optimization)
        if (mSystemServicesProxy.isInHomeStack(runningTask.id)) return;

        // Find the task in the recents list
        ArrayList<Task> tasks = stack.getTasks();
        Task toTask = null;
        ActivityOptions launchOpts = null;
        int taskCount = tasks.size();
        int numAffiliatedTasks = 0;
        for (int i = 0; i < taskCount; i++) {
            Task task = tasks.get(i);
            if (task.key.id == runningTask.id) {
                TaskGrouping group = task.group;
                Task.TaskKey toTaskKey;
                if (showNextTask) {
                    toTaskKey = group.getNextTaskInGroup(task);
                    launchOpts = ActivityOptions.makeCustomAnimation(mContext,
                            R.anim.recents_launch_next_affiliated_task_target,
                            R.anim.recents_launch_next_affiliated_task_source);
                } else {
                    toTaskKey = group.getPrevTaskInGroup(task);
                    launchOpts = ActivityOptions.makeCustomAnimation(mContext,
                            R.anim.recents_launch_prev_affiliated_task_target,
                            R.anim.recents_launch_prev_affiliated_task_source);
                }
                if (toTaskKey != null) {
                    toTask = stack.findTaskWithId(toTaskKey.id);
                }
                numAffiliatedTasks = group.getTaskCount();
                break;
            }
        }

        // Return early if there is no next task
        if (toTask == null) {
            if (numAffiliatedTasks > 1) {
                if (showNextTask) {
                    mSystemServicesProxy.startInPlaceAnimationOnFrontMostApplication(
                            ActivityOptions.makeCustomInPlaceAnimation(mContext,
                                    R.anim.recents_launch_next_affiliated_task_bounce));
                } else {
                    mSystemServicesProxy.startInPlaceAnimationOnFrontMostApplication(
                            ActivityOptions.makeCustomInPlaceAnimation(mContext,
                                    R.anim.recents_launch_prev_affiliated_task_bounce));
                }
            }
            return;
        }

        // Launch the task
        if (toTask.isActive) {
            // Bring an active task to the foreground
            mSystemServicesProxy.moveTaskToFront(toTask.key.id, launchOpts);
        } else {
            mSystemServicesProxy.startActivityFromRecents(mContext, toTask.key.id,
                    toTask.activityLabel, launchOpts);
        }
    }

    public void onShowNextAffiliatedTask() {
        showRelativeAffiliatedTask(true);
    }

    public void onShowPrevAffiliatedTask() {
        showRelativeAffiliatedTask(false);
    }

    public void onConfigurationChanged(Configuration newConfig) {
        // Don't reuse task stack views if the configuration changes
        mCanReuseTaskStackViews = false;
        // Reload the header bar layout
        reloadHeaderBarLayout();
    }

    /** Prepares the header bar layout. */
    void reloadHeaderBarLayout() {
        Resources res = mContext.getResources();
        mWindowRect = mSystemServicesProxy.getWindowRect();
        mStatusBarHeight = res.getDimensionPixelSize(com.android.internal.R.dimen.status_bar_height);
        mNavBarHeight = res.getDimensionPixelSize(com.android.internal.R.dimen.navigation_bar_height);
        mNavBarWidth = res.getDimensionPixelSize(com.android.internal.R.dimen.navigation_bar_width);
        mConfig = RecentsConfiguration.reinitialize(mContext, mSystemServicesProxy);
        mConfig.updateOnConfigurationChange();
        mConfig.getTaskStackBounds(mWindowRect.width(), mWindowRect.height(), mStatusBarHeight,
                (mConfig.hasTransposedNavBar ? mNavBarWidth : 0), mTaskStackBounds);
        if (mConfig.isLandscape && mConfig.hasTransposedNavBar) {
            mSystemInsets.set(0, mStatusBarHeight, mNavBarWidth, 0);
        } else {
            mSystemInsets.set(0, mStatusBarHeight, 0, mNavBarHeight);
        }

        // Inflate the header bar layout so that we can rebind and draw it for the transition
        TaskStack stack = new TaskStack();
        mDummyStackView = new TaskStackView(mContext, stack);
        TaskStackViewLayoutAlgorithm algo = mDummyStackView.getStackAlgorithm();
        Rect taskStackBounds = new Rect(mTaskStackBounds);
        taskStackBounds.bottom -= mSystemInsets.bottom;
        algo.computeRects(mWindowRect.width(), mWindowRect.height(), taskStackBounds);
        Rect taskViewSize = algo.getUntransformedTaskViewSize();
        int taskBarHeight = res.getDimensionPixelSize(R.dimen.recents_task_bar_height);
        mHeaderBar = (TaskViewHeader) mInflater.inflate(R.layout.recents_task_view_header, null,
                false);
        mHeaderBar.measure(
                View.MeasureSpec.makeMeasureSpec(taskViewSize.width(), View.MeasureSpec.EXACTLY),
                View.MeasureSpec.makeMeasureSpec(taskBarHeight, View.MeasureSpec.EXACTLY));
        mHeaderBar.layout(0, 0, taskViewSize.width(), taskBarHeight);
    }

    /** Gets the top task. */
    ActivityManager.RunningTaskInfo getTopMostTask() {
        SystemServicesProxy ssp = mSystemServicesProxy;
        List<ActivityManager.RunningTaskInfo> tasks = ssp.getRunningTasks(1);
        if (!tasks.isEmpty()) {
            return tasks.get(0);
        }
        return null;
    }

    /** Returns whether the recents is currently running */
    boolean isRecentsTopMost(ActivityManager.RunningTaskInfo topTask, AtomicBoolean isHomeTopMost) {
        SystemServicesProxy ssp = mSystemServicesProxy;
        if (topTask != null) {
            ComponentName topActivity = topTask.topActivity;

            // Check if the front most activity is recents
            if (topActivity.getPackageName().equals(sRecentsPackage) &&
                    topActivity.getClassName().equals(sRecentsActivity)) {
                if (isHomeTopMost != null) {
                    isHomeTopMost.set(false);
                }
                return true;
            }

            if (isHomeTopMost != null) {
                isHomeTopMost.set(ssp.isInHomeStack(topTask.id));
            }
        }
        return false;
    }

    /** Toggles the recents activity */
    void toggleRecentsActivity() {
        // If the user has toggled it too quickly, then just eat up the event here (it's better than
        // showing a janky screenshot).
        // NOTE: Ideally, the screenshot mechanism would take the window transform into account
        if ((SystemClock.elapsedRealtime() - mLastToggleTime) < sMinToggleDelay) {
            return;
        }

        // If Recents is the front most activity, then we should just communicate with it directly
        // to launch the first task or dismiss itself
        ActivityManager.RunningTaskInfo topTask = getTopMostTask();
        AtomicBoolean isTopTaskHome = new AtomicBoolean(true);
        if (topTask != null && isRecentsTopMost(topTask, isTopTaskHome)) {
            // Notify recents to toggle itself
            Intent intent = new Intent(ACTION_TOGGLE_RECENTS_ACTIVITY);
            intent.setPackage(mContext.getPackageName());
            intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT |
                    Intent.FLAG_RECEIVER_FOREGROUND);
            mContext.sendBroadcastAsUser(intent, UserHandle.CURRENT);
            mLastToggleTime = SystemClock.elapsedRealtime();
            return;
        } else {
            // Otherwise, start the recents activity
            startRecentsActivity(topTask, isTopTaskHome.get());
        }
    }

    /** Starts the recents activity if it is not already running */
    void startRecentsActivity() {
        // Check if the top task is in the home stack, and start the recents activity
        ActivityManager.RunningTaskInfo topTask = getTopMostTask();
        AtomicBoolean isTopTaskHome = new AtomicBoolean(true);
        if (topTask == null || !isRecentsTopMost(topTask, isTopTaskHome)) {
            startRecentsActivity(topTask, isTopTaskHome.get());
        }
    }

    /**
     * Creates the activity options for a unknown state->recents transition.
     */
    ActivityOptions getUnknownTransitionActivityOptions() {
        mStartAnimationTriggered = false;
        return ActivityOptions.makeCustomAnimation(mContext,
                R.anim.recents_from_unknown_enter,
                R.anim.recents_from_unknown_exit,
                mHandler, this);
    }

    /**
     * Creates the activity options for a home->recents transition.
     */
    ActivityOptions getHomeTransitionActivityOptions(boolean fromSearchHome) {
        mStartAnimationTriggered = false;
        if (fromSearchHome) {
            return ActivityOptions.makeCustomAnimation(mContext,
                    R.anim.recents_from_search_launcher_enter,
                    R.anim.recents_from_search_launcher_exit,
                    mHandler, this);
        }
        return ActivityOptions.makeCustomAnimation(mContext,
                R.anim.recents_from_launcher_enter,
                R.anim.recents_from_launcher_exit,
                mHandler, this);
    }

    /**
     * Creates the activity options for an app->recents transition.
     */
    ActivityOptions getThumbnailTransitionActivityOptions(ActivityManager.RunningTaskInfo topTask,
            TaskStack stack, TaskStackView stackView) {
        // Update the destination rect
        Task toTask = new Task();
        TaskViewTransform toTransform = getThumbnailTransitionTransform(stack, stackView,
                topTask.id, toTask);
        if (toTransform != null && toTask.key != null) {
            Rect toTaskRect = toTransform.rect;
            int toHeaderWidth = (int) (mHeaderBar.getMeasuredWidth() * toTransform.scale);
            int toHeaderHeight = (int) (mHeaderBar.getMeasuredHeight() * toTransform.scale);
            Bitmap thumbnail = Bitmap.createBitmap(toHeaderWidth, toHeaderHeight,
                    Bitmap.Config.ARGB_8888);
            if (Constants.DebugFlags.App.EnableTransitionThumbnailDebugMode) {
                thumbnail.eraseColor(0xFFff0000);
            } else {
                Canvas c = new Canvas(thumbnail);
                c.scale(toTransform.scale, toTransform.scale);
                mHeaderBar.rebindToTask(toTask);
                mHeaderBar.draw(c);
                c.setBitmap(null);
            }

            mStartAnimationTriggered = false;
            return ActivityOptions.makeThumbnailAspectScaleDownAnimation(mStatusBarView,
                    thumbnail, toTaskRect.left, toTaskRect.top, toTaskRect.width(),
                    toTaskRect.height(), this);
        }

        // If both the screenshot and thumbnail fails, then just fall back to the default transition
        return getUnknownTransitionActivityOptions();
    }

    /** Returns the transition rect for the given task id. */
    TaskViewTransform getThumbnailTransitionTransform(TaskStack stack, TaskStackView stackView,
            int runningTaskId, Task runningTaskOut) {
        // Find the running task in the TaskStack
        Task task = null;
        ArrayList<Task> tasks = stack.getTasks();
        if (runningTaskId != -1) {
            // Otherwise, try and find the task with the
            int taskCount = tasks.size();
            for (int i = taskCount - 1; i >= 0; i--) {
                Task t = tasks.get(i);
                if (t.key.id == runningTaskId) {
                    task = t;
                    runningTaskOut.copyFrom(t);
                    break;
                }
            }
        }
        if (task == null) {
            // If no task is specified or we can not find the task just use the front most one
            task = tasks.get(tasks.size() - 1);
        }

        // Get the transform for the running task
        stackView.getScroller().setStackScrollToInitialState();
        mTmpTransform = stackView.getStackAlgorithm().getStackTransform(task,
                stackView.getScroller().getStackScroll(), mTmpTransform, null);
        return mTmpTransform;
    }

    /** Starts the recents activity */
    void startRecentsActivity(ActivityManager.RunningTaskInfo topTask, boolean isTopTaskHome) {
        if (sInstanceLoadPlan == null) {
            // Create a new load plan if onPreloadRecents() was never triggered
            RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
            sInstanceLoadPlan = loader.createLoadPlan(mContext);
        }
        RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
        loader.preloadTasks(sInstanceLoadPlan, isTopTaskHome);
        TaskStack stack = sInstanceLoadPlan.getTaskStack();

        // Prepare the dummy stack for the transition
        mDummyStackView.updateMinMaxScrollForStack(stack, mTriggeredFromAltTab, isTopTaskHome);
        TaskStackViewLayoutAlgorithm.VisibilityReport stackVr =
                mDummyStackView.computeStackVisibilityReport();
        boolean hasRecentTasks = stack.getTaskCount() > 0;
        boolean useThumbnailTransition = (topTask != null) && !isTopTaskHome && hasRecentTasks;

        if (useThumbnailTransition) {
            // Ensure that we load the running task's icon
            RecentsTaskLoadPlan.Options launchOpts = new RecentsTaskLoadPlan.Options();
            launchOpts.runningTaskId = topTask.id;
            launchOpts.loadThumbnails = false;
            launchOpts.onlyLoadForCache = true;
            loader.loadTasks(mContext, sInstanceLoadPlan, launchOpts);

            // Try starting with a thumbnail transition
            ActivityOptions opts = getThumbnailTransitionActivityOptions(topTask, stack,
                    mDummyStackView);
            if (opts != null) {
                startAlternateRecentsActivity(topTask, opts, EXTRA_FROM_APP_THUMBNAIL, stackVr);
            } else {
                // Fall through below to the non-thumbnail transition
                useThumbnailTransition = false;
            }
        }

        if (!useThumbnailTransition) {
            // If there is no thumbnail transition, but is launching from home into recents, then
            // use a quick home transition and do the animation from home
            if (hasRecentTasks) {
                // Get the home activity info
                String homeActivityPackage = mSystemServicesProxy.getHomeActivityPackageName();
                // Get the search widget info
                AppWidgetProviderInfo searchWidget = null;
                String searchWidgetPackage = null;
                if (mConfig.hasSearchBarAppWidget()) {
                    searchWidget = mSystemServicesProxy.getAppWidgetInfo(
                            mConfig.searchBarAppWidgetId);
                } else {
                    searchWidget = mSystemServicesProxy.resolveSearchAppWidget();
                }
                if (searchWidget != null && searchWidget.provider != null) {
                    searchWidgetPackage = searchWidget.provider.getPackageName();
                }
                // Determine whether we are coming from a search owned home activity
                boolean fromSearchHome = false;
                if (homeActivityPackage != null && searchWidgetPackage != null &&
                        homeActivityPackage.equals(searchWidgetPackage)) {
                    fromSearchHome = true;
                }

                ActivityOptions opts = getHomeTransitionActivityOptions(fromSearchHome);
                startAlternateRecentsActivity(topTask, opts,
                        fromSearchHome ? EXTRA_FROM_SEARCH_HOME : EXTRA_FROM_HOME, stackVr);
            } else {
                // Otherwise we do the normal fade from an unknown source
                ActivityOptions opts = getUnknownTransitionActivityOptions();
                startAlternateRecentsActivity(topTask, opts, EXTRA_FROM_HOME, stackVr);
            }
        }
        mLastToggleTime = SystemClock.elapsedRealtime();
    }

    /** Starts the recents activity */
    void startAlternateRecentsActivity(ActivityManager.RunningTaskInfo topTask,
            ActivityOptions opts, String extraFlag,
            TaskStackViewLayoutAlgorithm.VisibilityReport vr) {
        Intent intent = new Intent(sToggleRecentsAction);
        intent.setClassName(sRecentsPackage, sRecentsActivity);
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
                | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS
                | Intent.FLAG_ACTIVITY_TASK_ON_HOME);
        if (extraFlag != null) {
            intent.putExtra(extraFlag, true);
        }
        intent.putExtra(EXTRA_TRIGGERED_FROM_ALT_TAB, mTriggeredFromAltTab);
        intent.putExtra(EXTRA_FROM_TASK_ID, (topTask != null) ? topTask.id : -1);
        intent.putExtra(EXTRA_REUSE_TASK_STACK_VIEWS, mCanReuseTaskStackViews);
        intent.putExtra(EXTRA_NUM_VISIBLE_TASKS, vr.numVisibleTasks);
        intent.putExtra(EXTRA_NUM_VISIBLE_THUMBNAILS, vr.numVisibleThumbnails);
        if (opts != null) {
            mContext.startActivityAsUser(intent, opts.toBundle(), UserHandle.CURRENT);
        } else {
            mContext.startActivityAsUser(intent, UserHandle.CURRENT);
        }
        mCanReuseTaskStackViews = true;
    }

    /** Sets the RecentsComponent callbacks. */
    public void setRecentsComponentCallback(RecentsComponent.Callbacks cb) {
        sRecentsComponentCallbacks = cb;
    }

    /** Notifies the callbacks that the visibility of Recents has changed. */
    public static void notifyVisibilityChanged(boolean visible) {
        if (sRecentsComponentCallbacks != null) {
            sRecentsComponentCallbacks.onVisibilityChanged(visible);
        }
    }

    /**
     * Returns the preloaded load plan and invalidates it.
     */
    public static RecentsTaskLoadPlan consumeInstanceLoadPlan() {
        RecentsTaskLoadPlan plan = sInstanceLoadPlan;
        sInstanceLoadPlan = null;
        return plan;
    }

    /**** OnAnimationStartedListener Implementation ****/

    @Override
    public void onAnimationStarted() {
        // Notify recents to start the enter animation
        if (!mStartAnimationTriggered) {
            // There can be a race condition between the start animation callback and
            // the start of the new activity (where we register the receiver that listens
            // to this broadcast, so we add our own receiver and if that gets called, then
            // we know the activity has not yet started and we can retry sending the broadcast.
            BroadcastReceiver fallbackReceiver = new BroadcastReceiver() {
                @Override
                public void onReceive(Context context, Intent intent) {
                    if (getResultCode() == Activity.RESULT_OK) {
                        mStartAnimationTriggered = true;
                        return;
                    }

                    // Schedule for the broadcast to be sent again after some time
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            onAnimationStarted();
                        }
                    }, 25);
                }
            };

            // Send the broadcast to notify Recents that the animation has started
            Intent intent = new Intent(ACTION_START_ENTER_ANIMATION);
            intent.setPackage(mContext.getPackageName());
            intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT |
                    Intent.FLAG_RECEIVER_FOREGROUND);
            mContext.sendOrderedBroadcastAsUser(intent, UserHandle.CURRENT, null,
                    fallbackReceiver, null, Activity.RESULT_CANCELED, null, null);
        }
    }
}