/*
 * Copyright (C) 2016 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.wm;

import static com.android.server.wm.AppTransition.DEFAULT_APP_TRANSITION_DURATION;
import static com.android.server.wm.WindowManagerDebugConfig.DEBUG_ANIM;
import static com.android.server.wm.WindowManagerDebugConfig.TAG_WITH_CLASS_NAME;
import static com.android.server.wm.WindowManagerDebugConfig.TAG_WM;

import android.animation.Animator;
import android.animation.ValueAnimator;
import android.graphics.Rect;
import android.os.Debug;
import android.util.ArrayMap;
import android.util.Slog;
import android.view.animation.LinearInterpolator;

/**
 * Enables animating bounds of objects.
 *
 * In multi-window world bounds of both stack and tasks can change. When we need these bounds to
 * change smoothly and not require the app to relaunch (e.g. because it handles resizes and
 * relaunching it would cause poorer experience), these class provides a way to directly animate
 * the bounds of the resized object.
 *
 * The object that is resized needs to implement {@link AnimateBoundsUser} interface.
 */
public class BoundsAnimationController {
    private static final boolean DEBUG_LOCAL = false;
    private static final boolean DEBUG = DEBUG_LOCAL || DEBUG_ANIM;
    private static final String TAG = TAG_WITH_CLASS_NAME || DEBUG_LOCAL
            ? "BoundsAnimationController" : TAG_WM;
    private static final int DEBUG_ANIMATION_SLOW_DOWN_FACTOR = 1;

    // Only accessed on UI thread.
    private ArrayMap<AnimateBoundsUser, BoundsAnimator> mRunningAnimations = new ArrayMap<>();

    private final class BoundsAnimator extends ValueAnimator
            implements ValueAnimator.AnimatorUpdateListener, ValueAnimator.AnimatorListener {
        private final AnimateBoundsUser mTarget;
        private final Rect mFrom;
        private final Rect mTo;
        private final Rect mTmpRect = new Rect();
        private final Rect mTmpTaskBounds = new Rect();
        private final boolean mMoveToFullScreen;
        // True if this this animation was cancelled and will be replaced the another animation from
        // the same {@link #AnimateBoundsUser} target.
        private boolean mWillReplace;
        // True to true if this animation replaced a previous animation of the same
        // {@link #AnimateBoundsUser} target.
        private final boolean mReplacement;

        // Depending on whether we are animating from
        // a smaller to a larger size
        private final int mFrozenTaskWidth;
        private final int mFrozenTaskHeight;

        BoundsAnimator(AnimateBoundsUser target, Rect from, Rect to,
                boolean moveToFullScreen, boolean replacement) {
            super();
            mTarget = target;
            mFrom = from;
            mTo = to;
            mMoveToFullScreen = moveToFullScreen;
            mReplacement = replacement;
            addUpdateListener(this);
            addListener(this);

            // If we are animating from smaller to larger, we want to change the task bounds
            // to their final size immediately so we can use scaling to make the window
            // larger. Likewise if we are going from bigger to smaller, we want to wait until
            // the end so we don't have to upscale from the smaller finished size.
            if (animatingToLargerSize()) {
                mFrozenTaskWidth = mTo.width();
                mFrozenTaskHeight = mTo.height();
            } else {
                mFrozenTaskWidth = mFrom.width();
                mFrozenTaskHeight = mFrom.height();
            }
        }

        boolean animatingToLargerSize() {
            if (mFrom.width() * mFrom.height() > mTo.width() * mTo.height()) {
                return false;
            }
            return true;
        }

        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            final float value = (Float) animation.getAnimatedValue();
            final float remains = 1 - value;
            mTmpRect.left = (int) (mFrom.left * remains + mTo.left * value + 0.5f);
            mTmpRect.top = (int) (mFrom.top * remains + mTo.top * value + 0.5f);
            mTmpRect.right = (int) (mFrom.right * remains + mTo.right * value + 0.5f);
            mTmpRect.bottom = (int) (mFrom.bottom * remains + mTo.bottom * value + 0.5f);
            if (DEBUG) Slog.d(TAG, "animateUpdate: mTarget=" + mTarget + " mBounds="
                    + mTmpRect + " from=" + mFrom + " mTo=" + mTo + " value=" + value
                    + " remains=" + remains);

            if (remains != 0) {
                mTmpTaskBounds.set(mTmpRect.left, mTmpRect.top,
                        mTmpRect.left + mFrozenTaskWidth, mTmpRect.top + mFrozenTaskHeight);
            }

            if (!mTarget.setPinnedStackSize(mTmpRect, remains != 0 ? mTmpTaskBounds : null)) {
                // Whoops, the target doesn't feel like animating anymore. Let's immediately finish
                // any further animation.
                animation.cancel();
            }
        }


        @Override
        public void onAnimationStart(Animator animation) {
            if (DEBUG) Slog.d(TAG, "onAnimationStart: mTarget=" + mTarget
                    + " mReplacement=" + mReplacement);
            if (animatingToLargerSize()) {
                mTarget.setPinnedStackSize(mFrom, mTo);
            }

            if (!mReplacement) {
                mTarget.onAnimationStart();
            }
        }

        @Override
        public void onAnimationEnd(Animator animation) {
            if (DEBUG) Slog.d(TAG, "onAnimationEnd: mTarget=" + mTarget
                    + " mMoveToFullScreen=" + mMoveToFullScreen + " mWillReplace=" + mWillReplace);

            finishAnimation();
            if (mMoveToFullScreen && !mWillReplace) {
                mTarget.moveToFullscreen();
            }
        }

        @Override
        public void onAnimationCancel(Animator animation) {
            finishAnimation();
        }

        @Override
        public void cancel() {
            mWillReplace = true;
            if (DEBUG) Slog.d(TAG, "cancel: willReplace mTarget=" + mTarget);
            super.cancel();
        }

        /** Returns true if the animation target is the same as the input bounds. */
        public boolean isAnimatingTo(Rect bounds) {
            return mTo.equals(bounds);
        }

        private void finishAnimation() {
            if (DEBUG) Slog.d(TAG, "finishAnimation: mTarget=" + mTarget
                    + " callers" + Debug.getCallers(2));
            if (!mWillReplace) {
                mTarget.onAnimationEnd();
            }
            removeListener(this);
            removeUpdateListener(this);
            mRunningAnimations.remove(mTarget);
        }

        @Override
        public void onAnimationRepeat(Animator animation) {

        }
    }

    public interface AnimateBoundsUser {
        /**
         * Asks the target to directly (without any intermediate steps, like scheduling animation)
         * resize its bounds.
         *
         * @return Whether the target still wants to be animated and successfully finished the
         * operation. If it returns false, the animation will immediately be cancelled. The target
         * should return false when something abnormal happened, e.g. it was completely removed
         * from the hierarchy and is not valid anymore.
         */
        boolean setSize(Rect bounds);
        /**
         * Behaves as setSize, but freezes the bounds of any tasks in the target at taskBounds,
         * to allow for more flexibility during resizing. Only
         * works for the pinned stack at the moment.
         */
        boolean setPinnedStackSize(Rect bounds, Rect taskBounds);

        void onAnimationStart();

        /**
         * Callback for the target to inform it that the animation has ended, so it can do some
         * necessary cleanup.
         */
        void onAnimationEnd();

        void moveToFullscreen();

        void getFullScreenBounds(Rect bounds);
    }

    void animateBounds(final AnimateBoundsUser target, Rect from, Rect to) {
        boolean moveToFullscreen = false;
        if (to == null) {
            to = new Rect();
            target.getFullScreenBounds(to);
            moveToFullscreen = true;
        }

        final BoundsAnimator existing = mRunningAnimations.get(target);
        final boolean replacing = existing != null;

        if (DEBUG) Slog.d(TAG, "animateBounds: target=" + target + " from=" + from + " to=" + to
                + " moveToFullscreen=" + moveToFullscreen + " replacing=" + replacing);

        if (replacing) {
            if (existing.isAnimatingTo(to)) {
                // Just les the current animation complete if it has the same destination as the
                // one we are trying to start.
                if (DEBUG) Slog.d(TAG, "animateBounds: same destination as existing=" + existing
                        + " ignoring...");
                return;
            }
            existing.cancel();
        }
        final BoundsAnimator animator =
                new BoundsAnimator(target, from, to, moveToFullscreen, replacing);
        mRunningAnimations.put(target, animator);
        animator.setFloatValues(0f, 1f);
        animator.setDuration(DEFAULT_APP_TRANSITION_DURATION * DEBUG_ANIMATION_SLOW_DOWN_FACTOR);
        animator.setInterpolator(new LinearInterpolator());
        animator.start();
    }
}
