/*
 * Copyright (C) 2017 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.widget;

import static java.lang.annotation.RetentionPolicy.SOURCE;

import android.animation.Animator;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.annotation.ColorInt;
import android.annotation.FloatRange;
import android.annotation.IntDef;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PointF;
import android.graphics.RectF;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.Shape;
import android.text.Layout;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;

import com.android.internal.util.Preconditions;

import java.lang.annotation.Retention;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

A utility class for creating and animating the Smart Select animation.
/**
 * A utility class for creating and animating the Smart Select animation.
 */
final class SmartSelectSprite {

    private static final int EXPAND_DURATION = 300;
    private static final int CORNER_DURATION = 50;

    private final Interpolator mExpandInterpolator;
    private final Interpolator mCornerInterpolator;

    private Animator mActiveAnimator = null;
    private final Runnable mInvalidator;
    @ColorInt
    private final int mFillColor;

    static final Comparator<RectF> RECTANGLE_COMPARATOR = Comparator
            .<RectF>comparingDouble(e -> e.bottom)
            .thenComparingDouble(e -> e.left);

    private Drawable mExistingDrawable = null;
    private RectangleList mExistingRectangleList = null;

    static final class RectangleWithTextSelectionLayout {
        private final RectF mRectangle;
        @Layout.TextSelectionLayout
        private final int mTextSelectionLayout;

        RectangleWithTextSelectionLayout(RectF rectangle, int textSelectionLayout) {
            mRectangle = Preconditions.checkNotNull(rectangle);
            mTextSelectionLayout = textSelectionLayout;
        }

        public RectF getRectangle() {
            return mRectangle;
        }

        @Layout.TextSelectionLayout
        public int getTextSelectionLayout() {
            return mTextSelectionLayout;
        }
    }

    
A rounded rectangle with a configurable corner radius and the ability to expand outside of
its bounding rectangle and clip against it.
/**
     * A rounded rectangle with a configurable corner radius and the ability to expand outside of
     * its bounding rectangle and clip against it.
     */
    private static final class RoundedRectangleShape extends Shape {

        private static final String PROPERTY_ROUND_RATIO = "roundRatio";

        
The direction in which the rectangle will perform its expansion. A rectangle can expand
from its left edge, its right edge or from the center (or, more precisely, the user's
touch point). For example, in left-to-right text, a selection spanning two lines with the
user's action being on the first line will have the top rectangle and expansion direction
of CENTER, while the bottom one will have an expansion direction of RIGHT.
/**
         * The direction in which the rectangle will perform its expansion. A rectangle can expand
         * from its left edge, its right edge or from the center (or, more precisely, the user's
         * touch point). For example, in left-to-right text, a selection spanning two lines with the
         * user's action being on the first line will have the top rectangle and expansion direction
         * of CENTER, while the bottom one will have an expansion direction of RIGHT.
         */
        @Retention(SOURCE)
        @IntDef({ExpansionDirection.LEFT, ExpansionDirection.CENTER, ExpansionDirection.RIGHT})
        private @interface ExpansionDirection {
            int LEFT = -1;
            int CENTER = 0;
            int RIGHT = 1;
        }

        private static @ExpansionDirection int invert(@ExpansionDirection int expansionDirection) {
            return expansionDirection * -1;
        }

        private final RectF mBoundingRectangle;
        private float mRoundRatio = 1.0f;
        private final @ExpansionDirection int mExpansionDirection;

        private final RectF mDrawRect = new RectF();
        private final Path mClipPath = new Path();

        
How offset the left edge of the rectangle is from the left side of the bounding box. /** How offset the left edge of the rectangle is from the left side of the bounding box. */
        private float mLeftBoundary = 0;
        
How offset the right edge of the rectangle is from the left side of the bounding box. /** How offset the right edge of the rectangle is from the left side of the bounding box. */
        private float mRightBoundary = 0;

        
Whether the horizontal bounds are inverted (for RTL scenarios). /** Whether the horizontal bounds are inverted (for RTL scenarios). */
        private final boolean mInverted;

        private final float mBoundingWidth;

        private RoundedRectangleShape(
                final RectF boundingRectangle,
                final @ExpansionDirection int expansionDirection,
                final boolean inverted) {
            mBoundingRectangle = new RectF(boundingRectangle);
            mBoundingWidth = boundingRectangle.width();
            mInverted = inverted && expansionDirection != ExpansionDirection.CENTER;

            if (inverted) {
                mExpansionDirection = invert(expansionDirection);
            } else {
                mExpansionDirection = expansionDirection;
            }

            if (boundingRectangle.height() > boundingRectangle.width()) {
                setRoundRatio(0.0f);
            } else {
                setRoundRatio(1.0f);
            }
        }

        /*
         * In order to achieve the "rounded rectangle hits the wall" effect, we draw an expanding
         * rounded rectangle that is clipped by the bounding box of the selected text.
         */
        @Override
        public void draw(Canvas canvas, Paint paint) {
            if (mLeftBoundary == mRightBoundary) {
                return;
            }

            final float cornerRadius = getCornerRadius();
            final float adjustedCornerRadius = getAdjustedCornerRadius();

            mDrawRect.set(mBoundingRectangle);
            mDrawRect.left = mBoundingRectangle.left + mLeftBoundary - cornerRadius / 2;
            mDrawRect.right = mBoundingRectangle.left + mRightBoundary + cornerRadius / 2;

            canvas.save();
            mClipPath.reset();
            mClipPath.addRoundRect(
                    mDrawRect,
                    adjustedCornerRadius,
                    adjustedCornerRadius,
                    Path.Direction.CW);
            canvas.clipPath(mClipPath);
            canvas.drawRect(mBoundingRectangle, paint);
            canvas.restore();
        }

        void setRoundRatio(@FloatRange(from = 0.0, to = 1.0) final float roundRatio) {
            mRoundRatio = roundRatio;
        }

        float getRoundRatio() {
            return mRoundRatio;
        }

        private void setStartBoundary(final float startBoundary) {
            if (mInverted) {
                mRightBoundary = mBoundingWidth - startBoundary;
            } else {
                mLeftBoundary = startBoundary;
            }
        }

        private void setEndBoundary(final float endBoundary) {
            if (mInverted) {
                mLeftBoundary = mBoundingWidth - endBoundary;
            } else {
                mRightBoundary = endBoundary;
            }
        }

        private float getCornerRadius() {
            return Math.min(mBoundingRectangle.width(), mBoundingRectangle.height());
        }

        private float getAdjustedCornerRadius() {
            return (getCornerRadius() * mRoundRatio);
        }

        private float getBoundingWidth() {
            return (int) (mBoundingRectangle.width() + getCornerRadius());
        }

    }

    
A collection of RoundedRectangleShapes that abstracts them to a single shape whose collective left and right boundary can be manipulated. /**
     * A collection of {@link RoundedRectangleShape}s that abstracts them to a single shape whose
     * collective left and right boundary can be manipulated.
     */
    private static final class RectangleList extends Shape {

        @Retention(SOURCE)
        @IntDef({DisplayType.RECTANGLES, DisplayType.POLYGON})
        private @interface DisplayType {
            int RECTANGLES = 0;
            int POLYGON = 1;
        }

        private static final String PROPERTY_RIGHT_BOUNDARY = "rightBoundary";
        private static final String PROPERTY_LEFT_BOUNDARY = "leftBoundary";

        private final List<RoundedRectangleShape> mRectangles;
        private final List<RoundedRectangleShape> mReversedRectangles;

        private final Path mOutlinePolygonPath;
        private @DisplayType int mDisplayType = DisplayType.RECTANGLES;

        private RectangleList(final List<RoundedRectangleShape> rectangles) {
            mRectangles = new ArrayList<>(rectangles);
            mReversedRectangles = new ArrayList<>(rectangles);
            Collections.reverse(mReversedRectangles);
            mOutlinePolygonPath = generateOutlinePolygonPath(rectangles);
        }

        private void setLeftBoundary(final float leftBoundary) {
            float boundarySoFar = getTotalWidth();
            for (RoundedRectangleShape rectangle : mReversedRectangles) {
                final float rectangleLeftBoundary = boundarySoFar - rectangle.getBoundingWidth();
                if (leftBoundary < rectangleLeftBoundary) {
                    rectangle.setStartBoundary(0);
                } else if (leftBoundary > boundarySoFar) {
                    rectangle.setStartBoundary(rectangle.getBoundingWidth());
                } else {
                    rectangle.setStartBoundary(
                            rectangle.getBoundingWidth() - boundarySoFar + leftBoundary);
                }

                boundarySoFar = rectangleLeftBoundary;
            }
        }

        private void setRightBoundary(final float rightBoundary) {
            float boundarySoFar = 0;
            for (RoundedRectangleShape rectangle : mRectangles) {
                final float rectangleRightBoundary = rectangle.getBoundingWidth() + boundarySoFar;
                if (rectangleRightBoundary < rightBoundary) {
                    rectangle.setEndBoundary(rectangle.getBoundingWidth());
                } else if (boundarySoFar > rightBoundary) {
                    rectangle.setEndBoundary(0);
                } else {
                    rectangle.setEndBoundary(rightBoundary - boundarySoFar);
                }

                boundarySoFar = rectangleRightBoundary;
            }
        }

        void setDisplayType(@DisplayType int displayType) {
            mDisplayType = displayType;
        }

        private int getTotalWidth() {
            int sum = 0;
            for (RoundedRectangleShape rectangle : mRectangles) {
                sum += rectangle.getBoundingWidth();
            }
            return sum;
        }

        @Override
        public void draw(Canvas canvas, Paint paint) {
            if (mDisplayType == DisplayType.POLYGON) {
                drawPolygon(canvas, paint);
            } else {
                drawRectangles(canvas, paint);
            }
        }

        private void drawRectangles(final Canvas canvas, final Paint paint) {
            for (RoundedRectangleShape rectangle : mRectangles) {
                rectangle.draw(canvas, paint);
            }
        }

        private void drawPolygon(final Canvas canvas, final Paint paint) {
            canvas.drawPath(mOutlinePolygonPath, paint);
        }

        private static Path generateOutlinePolygonPath(
                final List<RoundedRectangleShape> rectangles) {
            final Path path = new Path();
            for (final RoundedRectangleShape shape : rectangles) {
                final Path rectanglePath = new Path();
                rectanglePath.addRect(shape.mBoundingRectangle, Path.Direction.CW);
                path.op(rectanglePath, Path.Op.UNION);
            }
            return path;
        }

    }

    
Params:
context – the Context in which the animation will run
highlightColor – the highlight color of the underlying TextView
invalidator – a Runnable which will be called every time the animation updates, indicating that the view drawing the animation should invalidate itself/**
     * @param context the {@link Context} in which the animation will run
     * @param highlightColor the highlight color of the underlying {@link TextView}
     * @param invalidator a {@link Runnable} which will be called every time the animation updates,
     *                    indicating that the view drawing the animation should invalidate itself
     */
    SmartSelectSprite(final Context context, @ColorInt int highlightColor,
            final Runnable invalidator) {
        mExpandInterpolator = AnimationUtils.loadInterpolator(
                context,
                android.R.interpolator.fast_out_slow_in);
        mCornerInterpolator = AnimationUtils.loadInterpolator(
                context,
                android.R.interpolator.fast_out_linear_in);
        mFillColor = highlightColor;
        mInvalidator = Preconditions.checkNotNull(invalidator);
    }

    
Performs the Smart Select animation on the view bound to this SmartSelectSprite.
Params:
start –                 The point from which the animation will start. Must be inside
                             destinationRectangles.
destinationRectangles – The rectangles which the animation will fill out by its "selection" and finally join them into a single polygon. In order to get the correct visual behavior, these rectangles should be sorted according to RECTANGLE_COMPARATOR.
onAnimationEnd –        the callback which will be invoked once the whole animation
                             completes
Throws:
IllegalArgumentException – if the given start point is not in any of the
                                 destinationRectangles
See Also:
cancelAnimation()/**
     * Performs the Smart Select animation on the view bound to this SmartSelectSprite.
     *
     * @param start                 The point from which the animation will start. Must be inside
     *                              destinationRectangles.
     * @param destinationRectangles The rectangles which the animation will fill out by its
     *                              "selection" and finally join them into a single polygon. In
     *                              order to get the correct visual behavior, these rectangles
     *                              should be sorted according to {@link #RECTANGLE_COMPARATOR}.
     * @param onAnimationEnd        the callback which will be invoked once the whole animation
     *                              completes
     * @throws IllegalArgumentException if the given start point is not in any of the
     *                                  destinationRectangles
     * @see #cancelAnimation()
     */
    // TODO nullability checks on parameters
    public void startAnimation(
            final PointF start,
            final List<RectangleWithTextSelectionLayout> destinationRectangles,
            final Runnable onAnimationEnd) {
        cancelAnimation();

        final ValueAnimator.AnimatorUpdateListener updateListener =
                valueAnimator -> mInvalidator.run();

        final int rectangleCount = destinationRectangles.size();

        final List<RoundedRectangleShape> shapes = new ArrayList<>(rectangleCount);
        final List<Animator> cornerAnimators = new ArrayList<>(rectangleCount);

        RectangleWithTextSelectionLayout centerRectangle = null;

        int startingOffset = 0;
        for (RectangleWithTextSelectionLayout rectangleWithTextSelectionLayout :
                destinationRectangles) {
            final RectF rectangle = rectangleWithTextSelectionLayout.getRectangle();
            if (contains(rectangle, start)) {
                centerRectangle = rectangleWithTextSelectionLayout;
                break;
            }
            startingOffset += rectangle.width();
        }

        if (centerRectangle == null) {
            throw new IllegalArgumentException("Center point is not inside any of the rectangles!");
        }

        startingOffset += start.x - centerRectangle.getRectangle().left;

        final @RoundedRectangleShape.ExpansionDirection int[] expansionDirections =
                generateDirections(centerRectangle, destinationRectangles);

        for (int index = 0; index < rectangleCount; ++index) {
            final RectangleWithTextSelectionLayout rectangleWithTextSelectionLayout =
                    destinationRectangles.get(index);
            final RectF rectangle = rectangleWithTextSelectionLayout.getRectangle();
            final RoundedRectangleShape shape = new RoundedRectangleShape(
                    rectangle,
                    expansionDirections[index],
                    rectangleWithTextSelectionLayout.getTextSelectionLayout()
                            == Layout.TEXT_SELECTION_LAYOUT_RIGHT_TO_LEFT);
            cornerAnimators.add(createCornerAnimator(shape, updateListener));
            shapes.add(shape);
        }

        final RectangleList rectangleList = new RectangleList(shapes);
        final ShapeDrawable shapeDrawable = new ShapeDrawable(rectangleList);

        final Paint paint = shapeDrawable.getPaint();
        paint.setColor(mFillColor);
        paint.setStyle(Paint.Style.FILL);

        mExistingRectangleList = rectangleList;
        mExistingDrawable = shapeDrawable;

        mActiveAnimator = createAnimator(rectangleList, startingOffset, startingOffset,
                cornerAnimators, updateListener, onAnimationEnd);
        mActiveAnimator.start();
    }

    
Returns whether the sprite is currently animating. /** Returns whether the sprite is currently animating. */
    public boolean isAnimationActive() {
        return mActiveAnimator != null && mActiveAnimator.isRunning();
    }

    private Animator createAnimator(
            final RectangleList rectangleList,
            final float startingOffsetLeft,
            final float startingOffsetRight,
            final List<Animator> cornerAnimators,
            final ValueAnimator.AnimatorUpdateListener updateListener,
            final Runnable onAnimationEnd) {
        final ObjectAnimator rightBoundaryAnimator = ObjectAnimator.ofFloat(
                rectangleList,
                RectangleList.PROPERTY_RIGHT_BOUNDARY,
                startingOffsetRight,
                rectangleList.getTotalWidth());

        final ObjectAnimator leftBoundaryAnimator = ObjectAnimator.ofFloat(
                rectangleList,
                RectangleList.PROPERTY_LEFT_BOUNDARY,
                startingOffsetLeft,
                0);

        rightBoundaryAnimator.setDuration(EXPAND_DURATION);
        leftBoundaryAnimator.setDuration(EXPAND_DURATION);

        rightBoundaryAnimator.addUpdateListener(updateListener);
        leftBoundaryAnimator.addUpdateListener(updateListener);

        rightBoundaryAnimator.setInterpolator(mExpandInterpolator);
        leftBoundaryAnimator.setInterpolator(mExpandInterpolator);

        final AnimatorSet cornerAnimator = new AnimatorSet();
        cornerAnimator.playTogether(cornerAnimators);

        final AnimatorSet boundaryAnimator = new AnimatorSet();
        boundaryAnimator.playTogether(leftBoundaryAnimator, rightBoundaryAnimator);

        final AnimatorSet animatorSet = new AnimatorSet();
        animatorSet.playSequentially(boundaryAnimator, cornerAnimator);

        setUpAnimatorListener(animatorSet, onAnimationEnd);

        return animatorSet;
    }

    private void setUpAnimatorListener(final Animator animator, final Runnable onAnimationEnd) {
        animator.addListener(new Animator.AnimatorListener() {
            @Override
            public void onAnimationStart(Animator animator) {
            }

            @Override
            public void onAnimationEnd(Animator animator) {
                mExistingRectangleList.setDisplayType(RectangleList.DisplayType.POLYGON);
                mInvalidator.run();

                onAnimationEnd.run();
            }

            @Override
            public void onAnimationCancel(Animator animator) {
            }

            @Override
            public void onAnimationRepeat(Animator animator) {
            }
        });
    }

    private ObjectAnimator createCornerAnimator(
            final RoundedRectangleShape shape,
            final ValueAnimator.AnimatorUpdateListener listener) {
        final ObjectAnimator animator = ObjectAnimator.ofFloat(
                shape,
                RoundedRectangleShape.PROPERTY_ROUND_RATIO,
                shape.getRoundRatio(), 0.0F);
        animator.setDuration(CORNER_DURATION);
        animator.addUpdateListener(listener);
        animator.setInterpolator(mCornerInterpolator);
        return animator;
    }

    private static @RoundedRectangleShape.ExpansionDirection int[] generateDirections(
            final RectangleWithTextSelectionLayout centerRectangle,
            final List<RectangleWithTextSelectionLayout> rectangles) {
        final @RoundedRectangleShape.ExpansionDirection int[] result = new int[rectangles.size()];

        final int centerRectangleIndex = rectangles.indexOf(centerRectangle);

        for (int i = 0; i < centerRectangleIndex - 1; ++i) {
            result[i] = RoundedRectangleShape.ExpansionDirection.LEFT;
        }

        if (rectangles.size() == 1) {
            result[centerRectangleIndex] = RoundedRectangleShape.ExpansionDirection.CENTER;
        } else if (centerRectangleIndex == 0) {
            result[centerRectangleIndex] = RoundedRectangleShape.ExpansionDirection.LEFT;
        } else if (centerRectangleIndex == rectangles.size() - 1) {
            result[centerRectangleIndex] = RoundedRectangleShape.ExpansionDirection.RIGHT;
        } else {
            result[centerRectangleIndex] = RoundedRectangleShape.ExpansionDirection.CENTER;
        }

        for (int i = centerRectangleIndex + 1; i < result.length; ++i) {
            result[i] = RoundedRectangleShape.ExpansionDirection.RIGHT;
        }

        return result;
    }

    
A variant of RectF.contains(float, float) that also allows the point to reside on the right boundary of the rectangle. 
Params:
rectangle – the rectangle inside which the point should be to be considered "contained"
point –     the point which will be tested
Returns:
whether the point is inside the rectangle (or on it's right boundary)/**
     * A variant of {@link RectF#contains(float, float)} that also allows the point to reside on
     * the right boundary of the rectangle.
     *
     * @param rectangle the rectangle inside which the point should be to be considered "contained"
     * @param point     the point which will be tested
     * @return whether the point is inside the rectangle (or on it's right boundary)
     */
    private static boolean contains(final RectF rectangle, final PointF point) {
        final float x = point.x;
        final float y = point.y;
        return x >= rectangle.left && x <= rectangle.right && y >= rectangle.top
                && y <= rectangle.bottom;
    }

    private void removeExistingDrawables() {
        mExistingDrawable = null;
        mExistingRectangleList = null;
        mInvalidator.run();
    }

    
Cancels any active Smart Select animation that might be in progress.
/**
     * Cancels any active Smart Select animation that might be in progress.
     */
    public void cancelAnimation() {
        if (mActiveAnimator != null) {
            mActiveAnimator.cancel();
            mActiveAnimator = null;
            removeExistingDrawables();
        }
    }

    public void draw(Canvas canvas) {
        if (mExistingDrawable != null) {
            mExistingDrawable.draw(canvas);
        }
    }

}