/*
 * 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.support.graphics.drawable;

import static android.support.annotation.RestrictTo.Scope.LIBRARY_GROUP;

import static java.lang.Math.min;

import android.animation.Animator;
import android.animation.AnimatorInflater;
import android.animation.AnimatorSet;
import android.animation.Keyframe;
import android.animation.ObjectAnimator;
import android.animation.PropertyValuesHolder;
import android.animation.TypeEvaluator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.content.res.Resources;
import android.content.res.Resources.NotFoundException;
import android.content.res.Resources.Theme;
import android.content.res.TypedArray;
import android.content.res.XmlResourceParser;
import android.graphics.Path;
import android.graphics.PathMeasure;
import android.os.Build;
import android.support.annotation.AnimatorRes;
import android.support.annotation.RestrictTo;
import android.support.v4.content.res.TypedArrayUtils;
import android.support.v4.graphics.PathParser;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.util.Xml;
import android.view.InflateException;
import android.view.animation.Interpolator;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import java.io.IOException;
import java.util.ArrayList;

/**
 * This class is used to instantiate animator XML files into Animator objects.
 * <p>
 * For performance reasons, inflation relies heavily on pre-processing of
 * XML files that is done at build time. Therefore, it is not currently possible
 * to use this inflater with an XmlPullParser over a plain XML file at runtime;
 * it only works with an XmlPullParser returned from a compiled resource (R.
 * <em>something</em> file.)
 * @hide
 */
@RestrictTo(LIBRARY_GROUP)
public class AnimatorInflaterCompat {
    private static final String TAG = "AnimatorInflater";
    /**
     * These flags are used when parsing AnimatorSet objects
     */
    private static final int TOGETHER = 0;
    private static final int MAX_NUM_POINTS = 100;
    /**
     * Enum values used in XML attributes to indicate the value for mValueType
     */
    private static final int VALUE_TYPE_FLOAT = 0;
    private static final int VALUE_TYPE_INT = 1;
    private static final int VALUE_TYPE_PATH = 2;
    private static final int VALUE_TYPE_COLOR = 3;
    private static final int VALUE_TYPE_UNDEFINED = 4;

    private static final boolean DBG_ANIMATOR_INFLATER = false;

    /**
     * Loads an {@link Animator} object from a context
     *
     * @param context Application context used to access resources
     * @param id      The resource id of the animation to load
     * @return The animator object reference by the specified id
     * @throws NotFoundException when the animation cannot be loaded
     */
    public static Animator loadAnimator(Context context, @AnimatorRes int id)
            throws NotFoundException {
        Animator objectAnimator;
        // Since AVDC will fall back onto AVD when API is >= 24, therefore, PathParser will need
        // to match the accordingly to be able to call into the right setter/ getter for animation.
        if (Build.VERSION.SDK_INT >= 24) {
            objectAnimator = AnimatorInflater.loadAnimator(context, id);
        } else {
            objectAnimator = loadAnimator(context, context.getResources(), context.getTheme(), id);
        }
        return objectAnimator;
    }

    /**
     * Loads an {@link Animator} object from a resource, context is for loading interpolator.
     *
     * @param resources The resources
     * @param theme     The theme
     * @param id        The resource id of the animation to load
     * @return The animator object reference by the specified id
     * @throws NotFoundException when the animation cannot be loaded
     */
    public static Animator loadAnimator(Context context, Resources resources, Theme theme,
            @AnimatorRes int id) throws NotFoundException {
        return loadAnimator(context, resources, theme, id, 1);
    }

    /**
     * Loads an {@link Animator} object from a resource, context is for loading interpolator.
     */
    public static Animator loadAnimator(Context context, Resources resources, Theme theme,
            @AnimatorRes int id, float pathErrorScale) throws NotFoundException {
        Animator animator;

        XmlResourceParser parser = null;
        try {
            parser = resources.getAnimation(id);
            animator = createAnimatorFromXml(context, resources, theme, parser, pathErrorScale);
            return animator;
        } catch (XmlPullParserException ex) {
            Resources.NotFoundException rnf =
                    new Resources.NotFoundException("Can't load animation resource ID #0x"
                            + Integer.toHexString(id));
            rnf.initCause(ex);
            throw rnf;
        } catch (IOException ex) {
            Resources.NotFoundException rnf =
                    new Resources.NotFoundException("Can't load animation resource ID #0x"
                            + Integer.toHexString(id));
            rnf.initCause(ex);
            throw rnf;
        } finally {
            if (parser != null) parser.close();
        }
    }

    /**
     * PathDataEvaluator is used to interpolate between two paths which are
     * represented in the same format but different control points' values.
     * The path is represented as an array of PathDataNode here, which is
     * fundamentally an array of floating point numbers.
     */
    private static class PathDataEvaluator implements
            TypeEvaluator<PathParser.PathDataNode[]> {
        private PathParser.PathDataNode[] mNodeArray;

        /**
         * Create a PathParser.PathDataNode[] that does not reuse the animated value.
         * Care must be taken when using this option because on every evaluation
         * a new <code>PathParser.PathDataNode[]</code> will be allocated.
         */
        private PathDataEvaluator() {
        }

        /**
         * Create a PathDataEvaluator that reuses <code>nodeArray</code> for every evaluate() call.
         * Caution must be taken to ensure that the value returned from
         * {@link android.animation.ValueAnimator#getAnimatedValue()} is not cached, modified, or
         * used across threads. The value will be modified on each <code>evaluate()</code> call.
         *
         * @param nodeArray The array to modify and return from <code>evaluate</code>.
         */
        PathDataEvaluator(PathParser.PathDataNode[] nodeArray) {
            mNodeArray = nodeArray;
        }

        @Override
        public PathParser.PathDataNode[] evaluate(float fraction,
                PathParser.PathDataNode[] startPathData,
                PathParser.PathDataNode[] endPathData) {
            if (!PathParser.canMorph(startPathData, endPathData)) {
                throw new IllegalArgumentException("Can't interpolate between"
                        + " two incompatible pathData");
            }

            if (mNodeArray == null || !PathParser.canMorph(mNodeArray, startPathData)) {
                mNodeArray = PathParser.deepCopyNodes(startPathData);
            }

            for (int i = 0; i < startPathData.length; i++) {
                mNodeArray[i].interpolatePathDataNode(startPathData[i],
                        endPathData[i], fraction);
            }

            return mNodeArray;
        }
    }


    private static PropertyValuesHolder getPVH(TypedArray styledAttributes, int valueType,
            int valueFromId, int valueToId, String propertyName) {

        TypedValue tvFrom = styledAttributes.peekValue(valueFromId);
        boolean hasFrom = (tvFrom != null);
        int fromType = hasFrom ? tvFrom.type : 0;
        TypedValue tvTo = styledAttributes.peekValue(valueToId);
        boolean hasTo = (tvTo != null);
        int toType = hasTo ? tvTo.type : 0;

        if (valueType == VALUE_TYPE_UNDEFINED) {
            // Check whether it's color type. If not, fall back to default type (i.e. float type)
            if ((hasFrom && isColorType(fromType)) || (hasTo && isColorType(toType))) {
                valueType = VALUE_TYPE_COLOR;
            } else {
                valueType = VALUE_TYPE_FLOAT;
            }
        }

        boolean getFloats = (valueType == VALUE_TYPE_FLOAT);

        PropertyValuesHolder returnValue = null;

        if (valueType == VALUE_TYPE_PATH) {
            String fromString = styledAttributes.getString(valueFromId);
            String toString = styledAttributes.getString(valueToId);

            PathParser.PathDataNode[] nodesFrom =
                    PathParser.createNodesFromPathData(fromString);
            PathParser.PathDataNode[] nodesTo =
                    PathParser.createNodesFromPathData(toString);
            if (nodesFrom != null || nodesTo != null) {
                if (nodesFrom != null) {
                    TypeEvaluator evaluator = new PathDataEvaluator();
                    if (nodesTo != null) {
                        if (!PathParser.canMorph(nodesFrom, nodesTo)) {
                            throw new InflateException(" Can't morph from " + fromString + " to "
                                    + toString);
                        }
                        returnValue = PropertyValuesHolder.ofObject(propertyName, evaluator,
                                nodesFrom, nodesTo);
                    } else {
                        returnValue = PropertyValuesHolder.ofObject(propertyName, evaluator,
                                (Object) nodesFrom);
                    }
                } else if (nodesTo != null) {
                    TypeEvaluator evaluator = new PathDataEvaluator();
                    returnValue = PropertyValuesHolder.ofObject(propertyName, evaluator,
                            (Object) nodesTo);
                }
            }
        } else {
            TypeEvaluator evaluator = null;
            // Integer and float value types are handled here.
            if (valueType == VALUE_TYPE_COLOR) {
                // special case for colors: ignore valueType and get ints
                evaluator = ArgbEvaluator.getInstance();
            }
            if (getFloats) {
                float valueFrom;
                float valueTo;
                if (hasFrom) {
                    if (fromType == TypedValue.TYPE_DIMENSION) {
                        valueFrom = styledAttributes.getDimension(valueFromId, 0f);
                    } else {
                        valueFrom = styledAttributes.getFloat(valueFromId, 0f);
                    }
                    if (hasTo) {
                        if (toType == TypedValue.TYPE_DIMENSION) {
                            valueTo = styledAttributes.getDimension(valueToId, 0f);
                        } else {
                            valueTo = styledAttributes.getFloat(valueToId, 0f);
                        }
                        returnValue = PropertyValuesHolder.ofFloat(propertyName,
                                valueFrom, valueTo);
                    } else {
                        returnValue = PropertyValuesHolder.ofFloat(propertyName, valueFrom);
                    }
                } else {
                    if (toType == TypedValue.TYPE_DIMENSION) {
                        valueTo = styledAttributes.getDimension(valueToId, 0f);
                    } else {
                        valueTo = styledAttributes.getFloat(valueToId, 0f);
                    }
                    returnValue = PropertyValuesHolder.ofFloat(propertyName, valueTo);
                }
            } else {
                int valueFrom;
                int valueTo;
                if (hasFrom) {
                    if (fromType == TypedValue.TYPE_DIMENSION) {
                        valueFrom = (int) styledAttributes.getDimension(valueFromId, 0f);
                    } else if (isColorType(fromType)) {
                        valueFrom = styledAttributes.getColor(valueFromId, 0);
                    } else {
                        valueFrom = styledAttributes.getInt(valueFromId, 0);
                    }
                    if (hasTo) {
                        if (toType == TypedValue.TYPE_DIMENSION) {
                            valueTo = (int) styledAttributes.getDimension(valueToId, 0f);
                        } else if (isColorType(toType)) {
                            valueTo = styledAttributes.getColor(valueToId, 0);
                        } else {
                            valueTo = styledAttributes.getInt(valueToId, 0);
                        }
                        returnValue = PropertyValuesHolder.ofInt(propertyName, valueFrom, valueTo);
                    } else {
                        returnValue = PropertyValuesHolder.ofInt(propertyName, valueFrom);
                    }
                } else {
                    if (hasTo) {
                        if (toType == TypedValue.TYPE_DIMENSION) {
                            valueTo = (int) styledAttributes.getDimension(valueToId, 0f);
                        } else if (isColorType(toType)) {
                            valueTo = styledAttributes.getColor(valueToId, 0);
                        } else {
                            valueTo = styledAttributes.getInt(valueToId, 0);
                        }
                        returnValue = PropertyValuesHolder.ofInt(propertyName, valueTo);
                    }
                }
            }
            if (returnValue != null && evaluator != null) {
                returnValue.setEvaluator(evaluator);
            }
        }

        return returnValue;
    }

    /**
     * @param anim                The animator, must not be null
     * @param arrayAnimator       Incoming typed array for Animator's attributes.
     * @param arrayObjectAnimator Incoming typed array for Object Animator's
     *                            attributes.
     * @param pixelSize           The relative pixel size, used to calculate the
     *                            maximum error for path animations.
     */
    private static void parseAnimatorFromTypeArray(ValueAnimator anim,
            TypedArray arrayAnimator, TypedArray arrayObjectAnimator, float pixelSize,
            XmlPullParser parser) {
        long duration = TypedArrayUtils.getNamedInt(arrayAnimator, parser, "duration",
                AndroidResources.STYLEABLE_ANIMATOR_DURATION, 300);
        long startDelay = TypedArrayUtils.getNamedInt(arrayAnimator, parser, "startOffset",
                AndroidResources.STYLEABLE_ANIMATOR_START_OFFSET, 0);
        int valueType = TypedArrayUtils.getNamedInt(arrayAnimator, parser, "valueType",
                AndroidResources.STYLEABLE_ANIMATOR_VALUE_TYPE, VALUE_TYPE_UNDEFINED);

        // Change to requiring both value from and to, otherwise, throw exception for now.
        if (TypedArrayUtils.hasAttribute(parser, "valueFrom")
                && TypedArrayUtils.hasAttribute(parser, "valueTo")) {
            if (valueType == VALUE_TYPE_UNDEFINED) {
                valueType = inferValueTypeFromValues(arrayAnimator,
                        AndroidResources.STYLEABLE_ANIMATOR_VALUE_FROM,
                        AndroidResources.STYLEABLE_ANIMATOR_VALUE_TO);
            }
            PropertyValuesHolder pvh = getPVH(arrayAnimator, valueType,
                    AndroidResources.STYLEABLE_ANIMATOR_VALUE_FROM,
                    AndroidResources.STYLEABLE_ANIMATOR_VALUE_TO, "");
            if (pvh != null) {
                anim.setValues(pvh);
            }
        }
        anim.setDuration(duration);
        anim.setStartDelay(startDelay);

        anim.setRepeatCount(TypedArrayUtils.getNamedInt(arrayAnimator, parser, "repeatCount",
                AndroidResources.STYLEABLE_ANIMATOR_REPEAT_COUNT, 0));
        anim.setRepeatMode(TypedArrayUtils.getNamedInt(arrayAnimator, parser, "repeatMode",
                AndroidResources.STYLEABLE_ANIMATOR_REPEAT_MODE, ValueAnimator.RESTART));

        if (arrayObjectAnimator != null) {
            setupObjectAnimator(anim, arrayObjectAnimator, valueType, pixelSize, parser);
        }
    }


    /**
     * Setup ObjectAnimator's property or values from pathData.
     *
     * @param anim                The target Animator which will be updated.
     * @param arrayObjectAnimator TypedArray for the ObjectAnimator.
     * @param pixelSize           The relative pixel size, used to calculate the
     */
    private static void setupObjectAnimator(ValueAnimator anim, TypedArray arrayObjectAnimator,
            int valueType, float pixelSize, XmlPullParser parser) {
        ObjectAnimator oa = (ObjectAnimator) anim;
        String pathData = TypedArrayUtils.getNamedString(arrayObjectAnimator, parser, "pathData",
                AndroidResources.STYLEABLE_PROPERTY_ANIMATOR_PATH_DATA);

        // Path can be involved in an ObjectAnimator in the following 3 ways:
        // 1) Path morphing: the property to be animated is pathData, and valueFrom and valueTo
        //    are both of pathType. valueType = pathType needs to be explicitly defined.
        // 2) A property in X or Y dimension can be animated along a path: the property needs to be
        //    defined in propertyXName or propertyYName attribute, the path will be defined in the
        //    pathData attribute. valueFrom and valueTo will not be necessary for this animation.
        // 3) PathInterpolator can also define a path (in pathData) for its interpolation curve.
        // Here we are dealing with case 2:
        if (pathData != null) {
            String propertyXName = TypedArrayUtils.getNamedString(arrayObjectAnimator, parser,
                    "propertyXName", AndroidResources.STYLEABLE_PROPERTY_ANIMATOR_PROPERTY_X_NAME);
            String propertyYName = TypedArrayUtils.getNamedString(arrayObjectAnimator, parser,
                    "propertyYName", AndroidResources.STYLEABLE_PROPERTY_ANIMATOR_PROPERTY_Y_NAME);


            if (valueType == VALUE_TYPE_PATH || valueType == VALUE_TYPE_UNDEFINED) {
                // When pathData is defined, we are in case #2 mentioned above. ValueType can only
                // be float type, or int type. Otherwise we fallback to default type.
                valueType = VALUE_TYPE_FLOAT;
            }
            if (propertyXName == null && propertyYName == null) {
                throw new InflateException(arrayObjectAnimator.getPositionDescription()
                        + " propertyXName or propertyYName is needed for PathData");
            } else {
                Path path = PathParser.createPathFromPathData(pathData);
                setupPathMotion(path, oa,  0.5f * pixelSize, propertyXName, propertyYName);
            }
        } else {
            String propertyName =
                    TypedArrayUtils.getNamedString(arrayObjectAnimator, parser, "propertyName",
                            AndroidResources.STYLEABLE_PROPERTY_ANIMATOR_PROPERTY_NAME);
            oa.setPropertyName(propertyName);
        }


        return;

    }

    private static void setupPathMotion(Path path, ObjectAnimator oa, float precision,
            String propertyXName, String propertyYName) {
        // Measure the total length the whole path.
        final PathMeasure measureForTotalLength = new PathMeasure(path, false);
        float totalLength = 0;
        // The sum of the previous contour plus the current one. Using the sum here b/c we want to
        // directly substract from it later.
        ArrayList<Float> contourLengths = new ArrayList<>();
        contourLengths.add(0f);
        do {
            final float pathLength = measureForTotalLength.getLength();
            totalLength += pathLength;
            contourLengths.add(totalLength);

        } while (measureForTotalLength.nextContour());

        // Now determine how many sample points we need, and the step for next sample.
        final PathMeasure pathMeasure = new PathMeasure(path, false);

        final int numPoints = min(MAX_NUM_POINTS, (int) (totalLength / precision) + 1);

        float[] mX = new float[numPoints];
        float[] mY = new float[numPoints];
        final float[] position = new float[2];

        int contourIndex = 0;
        float step = totalLength / (numPoints - 1);
        float currentDistance = 0;

        // For each sample point, determine whether we need to move on to next contour.
        // After we find the right contour, then sample it using the current distance value minus
        // the previously sampled contours' total length.
        for (int i = 0; i < numPoints; ++i) {
            pathMeasure.getPosTan(currentDistance, position, null);
            pathMeasure.getPosTan(currentDistance, position, null);

            mX[i] = position[0];
            mY[i] = position[1];
            currentDistance += step;
            if ((contourIndex + 1) < contourLengths.size()
                    && currentDistance > contourLengths.get(contourIndex + 1)) {
                currentDistance -= contourLengths.get(contourIndex + 1);
                contourIndex++;
                pathMeasure.nextContour();
            }
        }

        // Given the x and y value of the sample points, setup the ObjectAnimator properly.
        PropertyValuesHolder x = null;
        PropertyValuesHolder y = null;
        if (propertyXName != null) {
            x = PropertyValuesHolder.ofFloat(propertyXName, mX);
        }
        if (propertyYName != null) {
            y = PropertyValuesHolder.ofFloat(propertyYName, mY);
        }
        if (x == null) {
            oa.setValues(y);
        } else if (y == null) {
            oa.setValues(x);
        } else {
            oa.setValues(x, y);
        }
    }

    private static Animator createAnimatorFromXml(Context context, Resources res, Theme theme,
            XmlPullParser parser,
            float pixelSize)
            throws XmlPullParserException, IOException {
        return createAnimatorFromXml(context, res, theme, parser, Xml.asAttributeSet(parser), null,
                0, pixelSize);
    }

    private static Animator createAnimatorFromXml(Context context, Resources res, Theme theme,
            XmlPullParser parser,
            AttributeSet attrs, AnimatorSet parent, int sequenceOrdering, float pixelSize)
            throws XmlPullParserException, IOException {
        Animator anim = null;
        ArrayList<Animator> childAnims = null;

        // Make sure we are on a start tag.
        int type;
        int depth = parser.getDepth();

        while (((type = parser.next()) != XmlPullParser.END_TAG || parser.getDepth() > depth)
                && type != XmlPullParser.END_DOCUMENT) {

            if (type != XmlPullParser.START_TAG) {
                continue;
            }

            String name = parser.getName();
            boolean gotValues = false;

            if (name.equals("objectAnimator")) {
                anim = loadObjectAnimator(context, res, theme, attrs, pixelSize, parser);
            } else if (name.equals("animator")) {
                anim = loadAnimator(context, res, theme, attrs, null, pixelSize, parser);
            } else if (name.equals("set")) {
                anim = new AnimatorSet();
                TypedArray a = TypedArrayUtils.obtainAttributes(res, theme, attrs,
                        AndroidResources.STYLEABLE_ANIMATOR_SET);

                int ordering = TypedArrayUtils.getNamedInt(a, parser, "ordering",
                        AndroidResources.STYLEABLE_ANIMATOR_SET_ORDERING, TOGETHER);

                createAnimatorFromXml(context, res, theme, parser, attrs, (AnimatorSet) anim,
                        ordering, pixelSize);
                a.recycle();
            } else if (name.equals("propertyValuesHolder")) {
                PropertyValuesHolder[] values = loadValues(context, res, theme, parser,
                        Xml.asAttributeSet(parser));
                if (values != null && anim != null && (anim instanceof ValueAnimator)) {
                    ((ValueAnimator) anim).setValues(values);
                }
                gotValues = true;
            } else {
                throw new RuntimeException("Unknown animator name: " + parser.getName());
            }

            if (parent != null && !gotValues) {
                if (childAnims == null) {
                    childAnims = new ArrayList<Animator>();
                }
                childAnims.add(anim);
            }
        }
        if (parent != null && childAnims != null) {
            Animator[] animsArray = new Animator[childAnims.size()];
            int index = 0;
            for (Animator a : childAnims) {
                animsArray[index++] = a;
            }
            if (sequenceOrdering == TOGETHER) {
                parent.playTogether(animsArray);
            } else {
                parent.playSequentially(animsArray);
            }
        }
        return anim;
    }

    private static PropertyValuesHolder[] loadValues(Context context, Resources res, Theme theme,
            XmlPullParser parser, AttributeSet attrs) throws XmlPullParserException, IOException {
        ArrayList<PropertyValuesHolder> values = null;

        int type;
        while ((type = parser.getEventType()) != XmlPullParser.END_TAG
                && type != XmlPullParser.END_DOCUMENT) {

            if (type != XmlPullParser.START_TAG) {
                parser.next();
                continue;
            }

            String name = parser.getName();

            if (name.equals("propertyValuesHolder")) {
                TypedArray a = TypedArrayUtils.obtainAttributes(res, theme, attrs,
                        AndroidResources.STYLEABLE_PROPERTY_VALUES_HOLDER);

                String propertyName = TypedArrayUtils.getNamedString(a, parser, "propertyName",
                        AndroidResources.STYLEABLE_PROPERTY_VALUES_HOLDER_PROPERTY_NAME);
                int valueType = TypedArrayUtils.getNamedInt(a, parser, "valueType",
                        AndroidResources.STYLEABLE_PROPERTY_VALUES_HOLDER_VALUE_TYPE,
                        VALUE_TYPE_UNDEFINED);

                PropertyValuesHolder pvh = loadPvh(context, res, theme, parser, propertyName,
                        valueType);
                if (pvh == null) {
                    pvh = getPVH(a, valueType,
                            AndroidResources.STYLEABLE_PROPERTY_VALUES_HOLDER_VALUE_FROM,
                            AndroidResources.STYLEABLE_PROPERTY_VALUES_HOLDER_VALUE_TO,
                            propertyName);
                }
                if (pvh != null) {
                    if (values == null) {
                        values = new ArrayList<PropertyValuesHolder>();
                    }
                    values.add(pvh);
                }
                a.recycle();
            }

            parser.next();
        }

        PropertyValuesHolder[] valuesArray = null;
        if (values != null) {
            int count = values.size();
            valuesArray = new PropertyValuesHolder[count];
            for (int i = 0; i < count; ++i) {
                valuesArray[i] = values.get(i);
            }
        }
        return valuesArray;
    }

    // When no value type is provided in keyframe, we need to infer the type from the value. i.e.
    // if value is defined in the style of a color value, then the color type is returned.
    // Otherwise, default float type is returned.
    private static int inferValueTypeOfKeyframe(Resources res, Theme theme, AttributeSet attrs,
            XmlPullParser parser) {
        int valueType;
        TypedArray a = TypedArrayUtils.obtainAttributes(res, theme, attrs,
                AndroidResources.STYLEABLE_KEYFRAME);

        TypedValue keyframeValue = TypedArrayUtils.peekNamedValue(a, parser, "value",
                AndroidResources.STYLEABLE_KEYFRAME_VALUE);
        boolean hasValue = (keyframeValue != null);
        // When no value type is provided, check whether it's a color type first.
        // If not, fall back to default value type (i.e. float type).
        if (hasValue && isColorType(keyframeValue.type)) {
            valueType = VALUE_TYPE_COLOR;
        } else {
            valueType = VALUE_TYPE_FLOAT;
        }
        a.recycle();
        return valueType;
    }

    private static int inferValueTypeFromValues(TypedArray styledAttributes, int valueFromId,
            int valueToId) {
        TypedValue tvFrom = styledAttributes.peekValue(valueFromId);
        boolean hasFrom = (tvFrom != null);
        int fromType = hasFrom ? tvFrom.type : 0;
        TypedValue tvTo = styledAttributes.peekValue(valueToId);
        boolean hasTo = (tvTo != null);
        int toType = hasTo ? tvTo.type : 0;

        int valueType;
        // Check whether it's color type. If not, fall back to default type (i.e. float type)
        if ((hasFrom && isColorType(fromType)) || (hasTo && isColorType(toType))) {
            valueType = VALUE_TYPE_COLOR;
        } else {
            valueType = VALUE_TYPE_FLOAT;
        }
        return valueType;
    }

    private static void dumpKeyframes(Object[] keyframes, String header) {
        if (keyframes == null || keyframes.length == 0) {
            return;
        }
        Log.d(TAG, header);
        int count = keyframes.length;
        for (int i = 0; i < count; ++i) {
            Keyframe keyframe = (Keyframe) keyframes[i];
            Log.d(TAG, "Keyframe " + i + ": fraction "
                    + (keyframe.getFraction() < 0 ? "null" : keyframe.getFraction()) + ", "
                    + ", value : " + ((keyframe.hasValue()) ? keyframe.getValue() : "null"));
        }
    }

    // Load property values holder if there are keyframes defined in it. Otherwise return null.
    private static PropertyValuesHolder loadPvh(Context context, Resources res, Theme theme,
            XmlPullParser parser,
            String propertyName, int valueType)
            throws XmlPullParserException, IOException {

        PropertyValuesHolder value = null;
        ArrayList<Keyframe> keyframes = null;

        int type;
        while ((type = parser.next()) != XmlPullParser.END_TAG
                && type != XmlPullParser.END_DOCUMENT) {
            String name = parser.getName();
            if (name.equals("keyframe")) {
                if (valueType == VALUE_TYPE_UNDEFINED) {
                    valueType = inferValueTypeOfKeyframe(res, theme, Xml.asAttributeSet(parser),
                            parser);
                }
                Keyframe keyframe = loadKeyframe(context, res, theme, Xml.asAttributeSet(parser),
                        valueType, parser);
                if (keyframe != null) {
                    if (keyframes == null) {
                        keyframes = new ArrayList<Keyframe>();
                    }
                    keyframes.add(keyframe);
                }
                parser.next();
            }
        }

        int count;
        if (keyframes != null && (count = keyframes.size()) > 0) {
            // make sure we have keyframes at 0 and 1
            // If we have keyframes with set fractions, add keyframes at start/end
            // appropriately. If start/end have no set fractions:
            // if there's only one keyframe, set its fraction to 1 and add one at 0
            // if >1 keyframe, set the last fraction to 1, the first fraction to 0
            Keyframe firstKeyframe = keyframes.get(0);
            Keyframe lastKeyframe = keyframes.get(count - 1);
            float endFraction = lastKeyframe.getFraction();
            if (endFraction < 1) {
                if (endFraction < 0) {
                    lastKeyframe.setFraction(1);
                } else {
                    keyframes.add(keyframes.size(), createNewKeyframe(lastKeyframe, 1));
                    ++count;
                }
            }
            float startFraction = firstKeyframe.getFraction();
            if (startFraction != 0) {
                if (startFraction < 0) {
                    firstKeyframe.setFraction(0);
                } else {
                    keyframes.add(0, createNewKeyframe(firstKeyframe, 0));
                    ++count;
                }
            }
            Keyframe[] keyframeArray = new Keyframe[count];
            keyframes.toArray(keyframeArray);
            for (int i = 0; i < count; ++i) {
                Keyframe keyframe = keyframeArray[i];
                if (keyframe.getFraction() < 0) {
                    if (i == 0) {
                        keyframe.setFraction(0);
                    } else if (i == count - 1) {
                        keyframe.setFraction(1);
                    } else {
                        // figure out the start/end parameters of the current gap
                        // in fractions and distribute the gap among those keyframes
                        int startIndex = i;
                        int endIndex = i;
                        for (int j = startIndex + 1; j < count - 1; ++j) {
                            if (keyframeArray[j].getFraction() >= 0) {
                                break;
                            }
                            endIndex = j;
                        }
                        float gap = keyframeArray[endIndex + 1].getFraction()
                                - keyframeArray[startIndex - 1].getFraction();
                        distributeKeyframes(keyframeArray, gap, startIndex, endIndex);
                    }
                }
            }
            value = PropertyValuesHolder.ofKeyframe(propertyName, keyframeArray);
            if (valueType == VALUE_TYPE_COLOR) {
                value.setEvaluator(ArgbEvaluator.getInstance());
            }
        }

        return value;
    }

    private static Keyframe createNewKeyframe(Keyframe sampleKeyframe, float fraction) {
        return sampleKeyframe.getType() == float.class
                ? Keyframe.ofFloat(fraction) :
                (sampleKeyframe.getType() == int.class)
                        ? Keyframe.ofInt(fraction) :
                        Keyframe.ofObject(fraction);
    }

    /**
     * Utility function to set fractions on keyframes to cover a gap in which the
     * fractions are not currently set. Keyframe fractions will be distributed evenly
     * in this gap. For example, a gap of 1 keyframe in the range 0-1 will be at .5, a gap
     * of .6 spread between two keyframes will be at .2 and .4 beyond the fraction at the
     * keyframe before startIndex.
     * Assumptions:
     * - First and last keyframe fractions (bounding this spread) are already set. So,
     * for example, if no fractions are set, we will already set first and last keyframe
     * fraction values to 0 and 1.
     * - startIndex must be >0 (which follows from first assumption).
     * - endIndex must be >= startIndex.
     *
     * @param keyframes  the array of keyframes
     * @param gap        The total gap we need to distribute
     * @param startIndex The index of the first keyframe whose fraction must be set
     * @param endIndex   The index of the last keyframe whose fraction must be set
     */
    private static void distributeKeyframes(Keyframe[] keyframes, float gap,
            int startIndex, int endIndex) {
        int count = endIndex - startIndex + 2;
        float increment = gap / count;
        for (int i = startIndex; i <= endIndex; ++i) {
            keyframes[i].setFraction(keyframes[i - 1].getFraction() + increment);
        }
    }

    private static Keyframe loadKeyframe(Context context, Resources res, Theme theme,
            AttributeSet attrs,
            int valueType, XmlPullParser parser)
            throws XmlPullParserException, IOException {

        TypedArray a = TypedArrayUtils.obtainAttributes(res, theme, attrs,
                AndroidResources.STYLEABLE_KEYFRAME);

        Keyframe keyframe = null;

        float fraction = TypedArrayUtils.getNamedFloat(a, parser, "fraction",
                AndroidResources.STYLEABLE_KEYFRAME_FRACTION, -1);

        TypedValue keyframeValue = TypedArrayUtils.peekNamedValue(a, parser, "value",
                AndroidResources.STYLEABLE_KEYFRAME_VALUE);
        boolean hasValue = (keyframeValue != null);
        if (valueType == VALUE_TYPE_UNDEFINED) {
            // When no value type is provided, check whether it's a color type first.
            // If not, fall back to default value type (i.e. float type).
            if (hasValue && isColorType(keyframeValue.type)) {
                valueType = VALUE_TYPE_COLOR;
            } else {
                valueType = VALUE_TYPE_FLOAT;
            }
        }

        if (hasValue) {
            switch (valueType) {
                case VALUE_TYPE_FLOAT:
                    float value = TypedArrayUtils.getNamedFloat(a, parser, "value",
                            AndroidResources.STYLEABLE_KEYFRAME_VALUE, 0);
                    keyframe = Keyframe.ofFloat(fraction, value);
                    break;
                case VALUE_TYPE_COLOR:
                case VALUE_TYPE_INT:
                    int intValue = TypedArrayUtils.getNamedInt(a, parser, "value",
                            AndroidResources.STYLEABLE_KEYFRAME_VALUE, 0);
                    keyframe = Keyframe.ofInt(fraction, intValue);
                    break;
            }
        } else {
            keyframe = (valueType == VALUE_TYPE_FLOAT) ? Keyframe.ofFloat(fraction) :
                    Keyframe.ofInt(fraction);
        }

        final int resID = TypedArrayUtils.getNamedResourceId(a, parser, "interpolator",
                AndroidResources.STYLEABLE_KEYFRAME_INTERPOLATOR, 0);
        if (resID > 0) {
            final Interpolator interpolator = AnimationUtilsCompat.loadInterpolator(context, resID);
            keyframe.setInterpolator(interpolator);
        }
        a.recycle();

        return keyframe;
    }

    private static ObjectAnimator loadObjectAnimator(Context context, Resources res, Theme theme,
            AttributeSet attrs,
            float pathErrorScale, XmlPullParser parser) throws NotFoundException {
        ObjectAnimator anim = new ObjectAnimator();

        loadAnimator(context, res, theme, attrs, anim, pathErrorScale, parser);

        return anim;
    }

    /**
     * Creates a new animation whose parameters come from the specified context
     * and attributes set.
     *
     * @param res   The resources
     * @param attrs The set of attributes holding the animation parameters
     * @param anim  Null if this is a ValueAnimator, otherwise this is an
     */
    private static ValueAnimator loadAnimator(Context context, Resources res, Theme theme,
            AttributeSet attrs, ValueAnimator anim, float pathErrorScale, XmlPullParser parser)
            throws NotFoundException {
        TypedArray arrayAnimator = TypedArrayUtils.obtainAttributes(res, theme, attrs,
                AndroidResources.STYLEABLE_ANIMATOR);
        TypedArray arrayObjectAnimator = TypedArrayUtils.obtainAttributes(res, theme, attrs,
                AndroidResources.STYLEABLE_PROPERTY_ANIMATOR);

        if (anim == null) {
            anim = new ValueAnimator();
        }

        parseAnimatorFromTypeArray(anim, arrayAnimator, arrayObjectAnimator, pathErrorScale,
                parser);

        final int resID = TypedArrayUtils.getNamedResourceId(arrayAnimator, parser, "interpolator",
                AndroidResources.STYLEABLE_ANIMATOR_INTERPOLATOR, 0);
        if (resID > 0) {
            final Interpolator interpolator = AnimationUtilsCompat.loadInterpolator(context, resID);
            anim.setInterpolator(interpolator);
        }

        arrayAnimator.recycle();
        if (arrayObjectAnimator != null) {
            arrayObjectAnimator.recycle();
        }
        return anim;
    }

    private static boolean isColorType(int type) {
        return (type >= TypedValue.TYPE_FIRST_COLOR_INT) && (type
                <= TypedValue.TYPE_LAST_COLOR_INT);
    }
}