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package javafx.css;

import java.util.Collections;
import java.util.List;
import javafx.scene.Node;

/**
 * A CssMetaData instance provides information about the CSS style and
 * provides the hooks that allow CSS to set a property value.
 * It encapsulates the CSS property name, the type into which the CSS value
 * is converted, and the default value of the property.
 * <p>
 * CssMetaData is the bridge between a value that can be represented
 * syntactically in a .css file, and a {@link StyleableProperty}. There is
 * a one-to-one correspondence between a CssMetaData and a StyleableProperty.
 * Typically, the CssMetaData of a Node will include the CssMetaData of its ancestors.
 * For example, the CssMetaData of a Rectangle includes the CssMetaData of Shape and also of Node.
 * During CSS processing, the CSS engine iterates over the Node's CssMetaData,
 * looks up the parsed value of each {@link javafx.css.CssMetaData#getProperty() property},
 * converts the parsed value, and sets the value on the StyleableProperty.
 * <p>
 * The method {@link Node#getCssMetaData()} is called to obtain the
 * List&lt;CssMetaData&gt;. This method is called frequently and it is prudent
 * to return a static list rather than creating the list on each call. By
 * convention, node classes that have CssMetaData will implement a
 * static method {@code getClassCssMetaData()} and it is customary to have
 * {@code getCssMetaData()} simply return {@code getClassCssMetaData()}. The
 * purpose of {@code getClassCssMetaData()} is to allow sub-classes to easily
 * include the CssMetaData of some ancestor.
 * <p>The {@link javafx.css.StyleablePropertyFactory StyleablePropertyFactory}
 * greatly simplifies creating a StyleableProperty and its corresponding CssMetaData.</p>
 * <p>
 * This example is a typical implementation.
 * <code><pre>
 * private DoubleProperty gapProperty = new StyleableDoubleProperty(0) {
 *     {@literal @}Override
 *      public CssMetaData{@literal <}MyWidget,Number{@literal >} getCssMetaData() {
 *          return GAP_META_DATA;
 *      }
 *
 *      {@literal @}Override
 *      public Object getBean() {
 *          return MyWidget.this;
 *      }
 *
 *      {@literal @}Override
 *      public String getName() {
 *          return "gap";
 *      }
 * };
 *
 * private static final CssMetaData GAP_META_DATA =
 *     new CssMetaData{@literal <}MyWidget,Number{@literal >}("-my-gap", StyleConverter.getSizeConverter(), 0d) {
 *
 *        {@literal @}Override
 *        public boolean isSettable(MyWidget node) {
 *            return node.gapProperty == null || !node.gapProperty.isBound();
 *        }
 *
 *        {@literal @}Override
 *        public StyleableProperty{@literal <}Number{@literal >} getStyleableProperty(MyWidget node) {
 *            return (StyleableProperty{@literal <}Number{@literal >})node.gapProperty;
 *        }
 * };
 *
 * private static final List{@literal <}CssMetaData{@literal <}? extends Node, ?{@literal >}{@literal >} cssMetaDataList;
 * static {
 *     List{@literal <}CssMetaData{@literal <}? extends Node, ?{@literal >}{@literal >} temp =
 *         new ArrayList{@literal <}CssMetaData{@literal <}? extends Node, ?{@literal >}{@literal >}(Control.getClassCssMetaData());
 *     temp.add(GAP_META_DATA);
 *     cssMetaDataList = Collections.unmodifiableList(temp);
 * }
 *
 * public static List{@literal <}CssMetaData{@literal <}? extends Node, ?{@literal >}{@literal >} getClassCssMetaData() {
 *     return cssMetaDataList;
 * }
 *
 * {@literal @}Override
 * public List{@literal <}CssMetaData{@literal <}? extends Node, ?{@literal >}{@literal >} getCssMetaData() {
 *     return getClassCssMetaData();
 * }
 * </pre><code>
 * @param <S> The type of Styleable
 * @param <V> The type into which the parsed value is converted.
 * @since JavaFX 8.0
 * @see javafx.css.StyleablePropertyFactory
 */
public abstract class CssMetaData<S extends Styleable, V> {

    /**
     * Set the value of the corresponding property on the given Node.
     * @param styleable The Styleable on which the property value is being set
     * @param value The value to which the property is set
     * @deprecated This method is no longer called from CSS code.
     * Use {@link StyleableProperty#applyStyle(javafx.css.StyleOrigin, java.lang.Object)}
     */
    @Deprecated
    public void set(S styleable, V value, StyleOrigin origin) {

        final StyleableProperty<V> styleableProperty = getStyleableProperty(styleable);
        final StyleOrigin currentOrigin = styleableProperty.getStyleOrigin();
        final V currentValue = styleableProperty.getValue();

        // RT-21185: Only apply the style if something has changed.
        if ((currentOrigin != origin)
            || (currentValue != null
                ? currentValue.equals(value) == false
                : value != null)) {

            styleableProperty.applyStyle(origin, value);

        }
    }

    /**
     * Check to see if the corresponding property on the given Node is
     * settable. This method is called before any styles are looked up for the
     * given property. It is abstract so that the code can check if the property
     * is settable without expanding the property. Generally, the property is
     * settable if it is not null or is not bound.
     *
     * @param styleable The Styleable on which the property value is being set
     * @return true if the property can be set.
     */
    public abstract boolean isSettable(S styleable);

    /**
     * Return the corresponding {@link StyleableProperty} for the given Node.
     * Note that calling this method will cause the property to be expanded.
     * @param styleable The Styleable for which the property is returned
     * @return The StyleableProperty corresponding to this CssMetaData for the
     * given Styleable
     */
    public abstract StyleableProperty<V> getStyleableProperty(S styleable);

    private final String property;
    /**
     * @return the CSS property name
     */
    public final String getProperty() {
        return property;
    }

    private final StyleConverter<?,V> converter;
    /**
     * @return The CSS converter that handles conversion from a CSS value to a Java Object
     */
    public final StyleConverter<?,V> getConverter() {
        return converter;
    }

    private final V initialValue;
    /**
     * The initial value of a CssMetaData corresponds to the default
     * value of the StyleableProperty in code.
     * For example, the default value of Shape.fill is Color.BLACK and the
     * initialValue of Shape.StyleableProperties.FILL is also Color.BLACK.
     * <p>
     * There may be exceptions to this, however. The initialValue may depend
     * on the state of the Node. A ScrollBar has a default orientation of
     * horizontal. If the ScrollBar is vertical, however, this method should
     * return Orientation.VERTICAL. Otherwise, a vertical ScrollBar would be
     * incorrectly set to a horizontal ScrollBar when the initial value is
     * applied.
     * @return The initial value of the property, possibly null
     */
    public V getInitialValue(S styleable) {
        return initialValue;
    }

    private final List<CssMetaData<? extends Styleable, ?>> subProperties;
    /**
     * The sub-properties refers to the constituent properties of this property,
     * if any. For example, "-fx-font-weight" is sub-property of "-fx-font".
     */
    public final List<CssMetaData<? extends Styleable, ?>> getSubProperties() {
        return subProperties;
    }

    private final boolean inherits;
    /**
     * If true, the value of this property is the same as
     * the parent's computed value of this property.
     * @default false
     * @see <a href="http://www.w3.org/TR/css3-cascade/#inheritance">CSS Inheritance</a>
     */
    public final boolean isInherits() {
        return inherits;
    }

    /**
     * Construct a CssMetaData with the given parameters and no sub-properties.
     * @param property the CSS property
     * @param converter the StyleConverter used to convert the CSS parsed value to a Java object.
     * @param initialValue The initial or default value of the corresponding StyleableProperty
     * @param inherits true if this property uses CSS inheritance
     * @param subProperties the sub-properties of this property. For example,
     * the -fx-font property has the sub-properties -fx-font-family,
     * -fx-font-size, -fx-font-weight, and -fx-font-style.
     */
    protected CssMetaData(
            final String property,
            final StyleConverter<?,V> converter,
            final V initialValue,
            boolean inherits,
            final List<CssMetaData<? extends Styleable, ?>> subProperties) {

        this.property = property;
        this.converter = converter;
        this.initialValue = initialValue;
        this.inherits = inherits;
        this.subProperties = subProperties != null ? Collections.unmodifiableList(subProperties) : null;

        if (this.property == null || this.converter == null) {
            throw new IllegalArgumentException("neither property nor converter can be null");
        }
    }

    /**
     * Construct a CssMetaData with the given parameters and no sub-properties.
     * @param property the CSS property
     * @param converter the StyleConverter used to convert the CSS parsed value to a Java object.
     * @param initialValue The initial or default value of the corresponding StyleableProperty
     * @param inherits true if this property uses CSS inheritance
     */
    protected CssMetaData(
            final String property,
            final StyleConverter<?,V> converter,
            final V initialValue,
            boolean inherits) {
        this(property, converter, initialValue, inherits, null);
    }

    /**
     * Construct a CssMetaData with the given parameters, inherit set to
     * false and no sub-properties.
     * @param property the CSS property
     * @param converter the StyleConverter used to convert the CSS parsed value to a Java object.
     * @param initialValue The initial or default value of the corresponding StyleableProperty
     */
    protected CssMetaData(
            final String property,
            final StyleConverter<?,V> converter,
            final V initialValue) {
        this(property, converter, initialValue, false, null);
    }

    /**
     * Construct a CssMetaData with the given parameters, initialValue is
     * null, inherit is set to false, and no sub-properties.
     * @param property the CSS property
     * @param converter the StyleConverter used to convert the CSS parsed value to a Java object.
     */
    protected CssMetaData(
            final String property,
            final StyleConverter<?,V> converter) {
        this(property, converter, null, false, null);
    }

    /**
     * Two CssMetaData objects are considered to be equal if their {@link #getProperty() property} values are equal.
     */
    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final CssMetaData<? extends Styleable, ?> other = (CssMetaData<? extends Styleable, ?>) obj;
        if ((this.property == null) ? (other.property != null) : !this.property.equals(other.property)) {
            return false;
        }
        return true;
    }

    @Override
    public int hashCode() {
        int hash = 3;
        hash = 19 * hash + (this.property != null ? this.property.hashCode() : 0);
        return hash;
    }


    @Override public String toString() {
        return  new StringBuilder("CSSProperty {")
            .append("property: ").append(property)
            .append(", converter: ").append(converter.toString())
            .append(", initalValue: ").append(String.valueOf(initialValue))
            .append(", inherits: ").append(inherits)
            .append(", subProperties: ").append(
                (subProperties != null) ? subProperties.toString() : "[]")
            .append("}").toString();
    }


}
