/*
 * 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 android.app;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ObjectAnimator;
import android.app.SharedElementCallback.OnSharedElementsReadyListener;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.RectF;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.os.Build.VERSION_CODES;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.ResultReceiver;
import android.transition.Transition;
import android.transition.TransitionListenerAdapter;
import android.transition.TransitionManager;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;

import com.android.internal.view.OneShotPreDrawListener;

import java.util.ArrayList;

This ActivityTransitionCoordinator is created in ActivityOptions#makeSceneTransitionAnimation
to govern the exit of the Scene and the shared elements when calling an Activity as well as
the reentry of the Scene when coming back from the called Activity.
/**
 * This ActivityTransitionCoordinator is created in ActivityOptions#makeSceneTransitionAnimation
 * to govern the exit of the Scene and the shared elements when calling an Activity as well as
 * the reentry of the Scene when coming back from the called Activity.
 */
class ExitTransitionCoordinator extends ActivityTransitionCoordinator {
    private static final String TAG = "ExitTransitionCoordinator";
    private static final long MAX_WAIT_MS = 1000;

    private Bundle mSharedElementBundle;
    private boolean mExitNotified;
    private boolean mSharedElementNotified;
    private Activity mActivity;
    private boolean mIsBackgroundReady;
    private boolean mIsCanceled;
    private Handler mHandler;
    private ObjectAnimator mBackgroundAnimator;
    private boolean mIsHidden;
    private Bundle mExitSharedElementBundle;
    private boolean mIsExitStarted;
    private boolean mSharedElementsHidden;
    private HideSharedElementsCallback mHideSharedElementsCallback;

    public ExitTransitionCoordinator(Activity activity, Window window,
            SharedElementCallback listener, ArrayList<String> names,
            ArrayList<String> accepted, ArrayList<View> mapped, boolean isReturning) {
        super(window, names, listener, isReturning);
        viewsReady(mapSharedElements(accepted, mapped));
        stripOffscreenViews();
        mIsBackgroundReady = !isReturning;
        mActivity = activity;
    }

    void setHideSharedElementsCallback(HideSharedElementsCallback callback) {
        mHideSharedElementsCallback = callback;
    }

    @Override
    protected void onReceiveResult(int resultCode, Bundle resultData) {
        switch (resultCode) {
            case MSG_SET_REMOTE_RECEIVER:
                stopCancel();
                mResultReceiver = resultData.getParcelable(KEY_REMOTE_RECEIVER);
                if (mIsCanceled) {
                    mResultReceiver.send(MSG_CANCEL, null);
                    mResultReceiver = null;
                } else {
                    notifyComplete();
                }
                break;
            case MSG_HIDE_SHARED_ELEMENTS:
                stopCancel();
                if (!mIsCanceled) {
                    hideSharedElements();
                }
                break;
            case MSG_START_EXIT_TRANSITION:
                mHandler.removeMessages(MSG_CANCEL);
                startExit();
                break;
            case MSG_SHARED_ELEMENT_DESTINATION:
                mExitSharedElementBundle = resultData;
                sharedElementExitBack();
                break;
            case MSG_CANCEL:
                mIsCanceled = true;
                finish();
                break;
        }
    }

    private void stopCancel() {
        if (mHandler != null) {
            mHandler.removeMessages(MSG_CANCEL);
        }
    }

    private void delayCancel() {
        if (mHandler != null) {
            mHandler.sendEmptyMessageDelayed(MSG_CANCEL, MAX_WAIT_MS);
        }
    }

    public void resetViews() {
        ViewGroup decorView = getDecor();
        if (decorView != null) {
            TransitionManager.endTransitions(decorView);
        }
        if (mTransitioningViews != null) {
            showViews(mTransitioningViews, true);
            setTransitioningViewsVisiblity(View.VISIBLE, true);
        }
        showViews(mSharedElements, true);
        mIsHidden = true;
        if (!mIsReturning && decorView != null) {
            decorView.suppressLayout(false);
        }
        moveSharedElementsFromOverlay();
        clearState();
    }

    private void sharedElementExitBack() {
        final ViewGroup decorView = getDecor();
        if (decorView != null) {
            decorView.suppressLayout(true);
        }
        if (decorView != null && mExitSharedElementBundle != null &&
                !mExitSharedElementBundle.isEmpty() &&
                !mSharedElements.isEmpty() && getSharedElementTransition() != null) {
            startTransition(new Runnable() {
                public void run() {
                    startSharedElementExit(decorView);
                }
            });
        } else {
            sharedElementTransitionComplete();
        }
    }

    private void startSharedElementExit(final ViewGroup decorView) {
        Transition transition = getSharedElementExitTransition();
        transition.addListener(new TransitionListenerAdapter() {
            @Override
            public void onTransitionEnd(Transition transition) {
                transition.removeListener(this);
                if (isViewsTransitionComplete()) {
                    delayCancel();
                }
            }
        });
        final ArrayList<View> sharedElementSnapshots = createSnapshots(mExitSharedElementBundle,
                mSharedElementNames);
        OneShotPreDrawListener.add(decorView, () -> {
            setSharedElementState(mExitSharedElementBundle, sharedElementSnapshots);
        });
        setGhostVisibility(View.INVISIBLE);
        scheduleGhostVisibilityChange(View.INVISIBLE);
        if (mListener != null) {
            mListener.onSharedElementEnd(mSharedElementNames, mSharedElements,
                    sharedElementSnapshots);
        }
        TransitionManager.beginDelayedTransition(decorView, transition);
        scheduleGhostVisibilityChange(View.VISIBLE);
        setGhostVisibility(View.VISIBLE);
        decorView.invalidate();
    }

    private void hideSharedElements() {
        moveSharedElementsFromOverlay();
        if (mHideSharedElementsCallback != null) {
            mHideSharedElementsCallback.hideSharedElements();
        }
        if (!mIsHidden) {
            hideViews(mSharedElements);
        }
        mSharedElementsHidden = true;
        finishIfNecessary();
    }

    public void startExit() {
        if (!mIsExitStarted) {
            backgroundAnimatorComplete();
            mIsExitStarted = true;
            pauseInput();
            ViewGroup decorView = getDecor();
            if (decorView != null) {
                decorView.suppressLayout(true);
            }
            moveSharedElementsToOverlay();
            startTransition(new Runnable() {
                @Override
                public void run() {
                    if (mActivity != null) {
                        beginTransitions();
                    } else {
                        startExitTransition();
                    }
                }
            });
        }
    }

    public void startExit(int resultCode, Intent data) {
        if (!mIsExitStarted) {
            mIsExitStarted = true;
            pauseInput();
            ViewGroup decorView = getDecor();
            if (decorView != null) {
                decorView.suppressLayout(true);
            }
            mHandler = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    mIsCanceled = true;
                    finish();
                }
            };
            delayCancel();
            moveSharedElementsToOverlay();
            if (decorView != null && decorView.getBackground() == null) {
                getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
            }
            final boolean targetsM = decorView == null || decorView.getContext()
                    .getApplicationInfo().targetSdkVersion >= VERSION_CODES.M;
            ArrayList<String> sharedElementNames = targetsM ? mSharedElementNames :
                    mAllSharedElementNames;
            ActivityOptions options = ActivityOptions.makeSceneTransitionAnimation(mActivity, this,
                    sharedElementNames, resultCode, data);
            mActivity.convertToTranslucent(new Activity.TranslucentConversionListener() {
                @Override
                public void onTranslucentConversionComplete(boolean drawComplete) {
                    if (!mIsCanceled) {
                        fadeOutBackground();
                    }
                }
            }, options);
            startTransition(new Runnable() {
                @Override
                public void run() {
                    startExitTransition();
                }
            });
        }
    }

    public void stop() {
        if (mIsReturning && mActivity != null) {
            // Override the previous ActivityOptions. We don't want the
            // activity to have options since we're essentially canceling the
            // transition and finishing right now.
            mActivity.convertToTranslucent(null, null);
            finish();
        }
    }

    private void startExitTransition() {
        Transition transition = getExitTransition();
        ViewGroup decorView = getDecor();
        if (transition != null && decorView != null && mTransitioningViews != null) {
            setTransitioningViewsVisiblity(View.VISIBLE, false);
            TransitionManager.beginDelayedTransition(decorView, transition);
            setTransitioningViewsVisiblity(View.INVISIBLE, false);
            decorView.invalidate();
        } else {
            transitionStarted();
        }
    }

    private void fadeOutBackground() {
        if (mBackgroundAnimator == null) {
            ViewGroup decor = getDecor();
            Drawable background;
            if (decor != null && (background = decor.getBackground()) != null) {
                background = background.mutate();
                getWindow().setBackgroundDrawable(background);
                mBackgroundAnimator = ObjectAnimator.ofInt(background, "alpha", 0);
                mBackgroundAnimator.addListener(new AnimatorListenerAdapter() {
                    @Override
                    public void onAnimationEnd(Animator animation) {
                        mBackgroundAnimator = null;
                        if (!mIsCanceled) {
                            mIsBackgroundReady = true;
                            notifyComplete();
                        }
                        backgroundAnimatorComplete();
                    }
                });
                mBackgroundAnimator.setDuration(getFadeDuration());
                mBackgroundAnimator.start();
            } else {
                backgroundAnimatorComplete();
                mIsBackgroundReady = true;
            }
        }
    }

    private Transition getExitTransition() {
        Transition viewsTransition = null;
        if (mTransitioningViews != null && !mTransitioningViews.isEmpty()) {
            viewsTransition = configureTransition(getViewsTransition(), true);
            removeExcludedViews(viewsTransition, mTransitioningViews);
            if (mTransitioningViews.isEmpty()) {
                viewsTransition = null;
            }
        }
        if (viewsTransition == null) {
            viewsTransitionComplete();
        } else {
            final ArrayList<View> transitioningViews = mTransitioningViews;
            viewsTransition.addListener(new ContinueTransitionListener() {
                @Override
                public void onTransitionEnd(Transition transition) {
                    viewsTransitionComplete();
                    if (mIsHidden && transitioningViews != null) {
                        showViews(transitioningViews, true);
                        setTransitioningViewsVisiblity(View.VISIBLE, true);
                    }
                    if (mSharedElementBundle != null) {
                        delayCancel();
                    }
                    super.onTransitionEnd(transition);
                }
            });
        }
        return viewsTransition;
    }

    private Transition getSharedElementExitTransition() {
        Transition sharedElementTransition = null;
        if (!mSharedElements.isEmpty()) {
            sharedElementTransition = configureTransition(getSharedElementTransition(), false);
        }
        if (sharedElementTransition == null) {
            sharedElementTransitionComplete();
        } else {
            sharedElementTransition.addListener(new ContinueTransitionListener() {
                @Override
                public void onTransitionEnd(Transition transition) {
                    sharedElementTransitionComplete();
                    if (mIsHidden) {
                        showViews(mSharedElements, true);
                    }
                    super.onTransitionEnd(transition);
                }
            });
            mSharedElements.get(0).invalidate();
        }
        return sharedElementTransition;
    }

    private void beginTransitions() {
        Transition sharedElementTransition = getSharedElementExitTransition();
        Transition viewsTransition = getExitTransition();

        Transition transition = mergeTransitions(sharedElementTransition, viewsTransition);
        ViewGroup decorView = getDecor();
        if (transition != null && decorView != null) {
            setGhostVisibility(View.INVISIBLE);
            scheduleGhostVisibilityChange(View.INVISIBLE);
            if (viewsTransition != null) {
                setTransitioningViewsVisiblity(View.VISIBLE, false);
            }
            TransitionManager.beginDelayedTransition(decorView, transition);
            scheduleGhostVisibilityChange(View.VISIBLE);
            setGhostVisibility(View.VISIBLE);
            if (viewsTransition != null) {
                setTransitioningViewsVisiblity(View.INVISIBLE, false);
            }
            decorView.invalidate();
        } else {
            transitionStarted();
        }
    }

    protected boolean isReadyToNotify() {
        return mSharedElementBundle != null && mResultReceiver != null && mIsBackgroundReady;
    }

    @Override
    protected void sharedElementTransitionComplete() {
        mSharedElementBundle = mExitSharedElementBundle == null
                ? captureSharedElementState() : captureExitSharedElementsState();
        super.sharedElementTransitionComplete();
    }

    private Bundle captureExitSharedElementsState() {
        Bundle bundle = new Bundle();
        RectF bounds = new RectF();
        Matrix matrix = new Matrix();
        for (int i = 0; i < mSharedElements.size(); i++) {
            String name = mSharedElementNames.get(i);
            Bundle sharedElementState = mExitSharedElementBundle.getBundle(name);
            if (sharedElementState != null) {
                bundle.putBundle(name, sharedElementState);
            } else {
                View view = mSharedElements.get(i);
                captureSharedElementState(view, name, bundle, matrix, bounds);
            }
        }
        return bundle;
    }

    @Override
    protected void onTransitionsComplete() {
        notifyComplete();
    }

    protected void notifyComplete() {
        if (isReadyToNotify()) {
            if (!mSharedElementNotified) {
                mSharedElementNotified = true;
                delayCancel();
                if (mListener == null) {
                    mResultReceiver.send(MSG_TAKE_SHARED_ELEMENTS, mSharedElementBundle);
                    notifyExitComplete();
                } else {
                    final ResultReceiver resultReceiver = mResultReceiver;
                    final Bundle sharedElementBundle = mSharedElementBundle;
                    mListener.onSharedElementsArrived(mSharedElementNames, mSharedElements,
                            new OnSharedElementsReadyListener() {
                                @Override
                                public void onSharedElementsReady() {
                                    resultReceiver.send(MSG_TAKE_SHARED_ELEMENTS,
                                            sharedElementBundle);
                                    notifyExitComplete();
                                }
                            });
                }
            } else {
                notifyExitComplete();
            }
        }
    }

    private void notifyExitComplete() {
        if (!mExitNotified && isViewsTransitionComplete()) {
            mExitNotified = true;
            mResultReceiver.send(MSG_EXIT_TRANSITION_COMPLETE, null);
            mResultReceiver = null; // done talking
            ViewGroup decorView = getDecor();
            if (!mIsReturning && decorView != null) {
                decorView.suppressLayout(false);
            }
            finishIfNecessary();
        }
    }

    private void finishIfNecessary() {
        if (mIsReturning && mExitNotified && mActivity != null && (mSharedElements.isEmpty() ||
                mSharedElementsHidden)) {
            finish();
        }
        if (!mIsReturning && mExitNotified) {
            mActivity = null; // don't need it anymore
        }
    }

    private void finish() {
        stopCancel();
        if (mActivity != null) {
            mActivity.mActivityTransitionState.clear();
            mActivity.finish();
            mActivity.overridePendingTransition(0, 0);
            mActivity = null;
        }
        // Clear the state so that we can't hold any references accidentally and leak memory.
        clearState();
    }

    @Override
    protected void clearState() {
        mHandler = null;
        mSharedElementBundle = null;
        if (mBackgroundAnimator != null) {
            mBackgroundAnimator.cancel();
            mBackgroundAnimator = null;
        }
        mExitSharedElementBundle = null;
        super.clearState();
    }

    @Override
    protected boolean moveSharedElementWithParent() {
        return !mIsReturning;
    }

    @Override
    protected Transition getViewsTransition() {
        if (mIsReturning) {
            return getWindow().getReturnTransition();
        } else {
            return getWindow().getExitTransition();
        }
    }

    protected Transition getSharedElementTransition() {
        if (mIsReturning) {
            return getWindow().getSharedElementReturnTransition();
        } else {
            return getWindow().getSharedElementExitTransition();
        }
    }

    interface HideSharedElementsCallback {
        void hideSharedElements();
    }
}