/*

 * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package javax.swing.text;

import java.awt.*;

import java.util.*;

import java.io.*;

import javax.swing.SwingUtilities;

import javax.swing.event.ChangeListener;

import javax.swing.event.EventListenerList;

import javax.swing.event.ChangeEvent;

import java.lang.ref.WeakReference;

import java.util.WeakHashMap;

import sun.font.FontManager;

/**

 * A pool of styles and their associated resources.  This class determines

 * the lifetime of a group of resources by being a container that holds

 * caches for various resources such as font and color that get reused

 * by the various style definitions.  This can be shared by multiple

 * documents if desired to maximize the sharing of related resources.

 * <p>

 * This class also provides efficient support for small sets of attributes

 * and compresses them by sharing across uses and taking advantage of

 * their immutable nature.  Since many styles are replicated, the potential

 * for sharing is significant, and copies can be extremely cheap.

 * Larger sets reduce the possibility of sharing, and therefore revert

 * automatically to a less space-efficient implementation.

 * <p>

 * <strong>Warning:</strong>

 * Serialized objects of this class will not be compatible with

 * future Swing releases. The current serialization support is

 * appropriate for short term storage or RMI between applications running

 * the same version of Swing.  As of 1.4, support for long term storage

 * of all JavaBeans<sup><font size="-2">TM</font></sup>

 * has been added to the <code>java.beans</code> package.

 * Please see {@link java.beans.XMLEncoder}.

 *

 * @author  Timothy Prinzing

 */

public class StyleContext implements Serializable, AbstractDocument.AttributeContext {

    /**

     * Returns default AttributeContext shared by all documents that

     * don't bother to define/supply their own context.

     *

     * @return the context

     */

    public static final StyleContext getDefaultStyleContext() {

        if (defaultContext == null) {

            defaultContext = new StyleContext();

        }

        return defaultContext;

    }

    private static StyleContext defaultContext;

    /**

     * Creates a new StyleContext object.

     */

    public StyleContext() {

        styles = new NamedStyle(null);

        addStyle(DEFAULT_STYLE, null);

    }

    /**

     * Adds a new style into the style hierarchy.  Style attributes

     * resolve from bottom up so an attribute specified in a child

     * will override an attribute specified in the parent.

     *

     * @param nm   the name of the style (must be unique within the

     *   collection of named styles in the document).  The name may

     *   be null if the style is unnamed, but the caller is responsible

     *   for managing the reference returned as an unnamed style can't

     *   be fetched by name.  An unnamed style may be useful for things

     *   like character attribute overrides such as found in a style

     *   run.

     * @param parent the parent style.  This may be null if unspecified

     *   attributes need not be resolved in some other style.

     * @return the created style

     */

    public Style addStyle(String nm, Style parent) {

        Style style = new NamedStyle(nm, parent);

        if (nm != null) {

            // add a named style, a class of attributes

            styles.addAttribute(nm, style);

        }

        return style;

    }

    /**

     * Removes a named style previously added to the document.

     *

     * @param nm  the name of the style to remove

     */

    public void removeStyle(String nm) {

        styles.removeAttribute(nm);

    }

    /**

     * Fetches a named style previously added to the document

     *

     * @param nm  the name of the style

     * @return the style

     */

    public Style getStyle(String nm) {

        return (Style) styles.getAttribute(nm);

    }

    /**

     * Fetches the names of the styles defined.

     *

     * @return the list of names as an enumeration

     */

    public Enumeration<?> getStyleNames() {

        return styles.getAttributeNames();

    }

    /**

     * Adds a listener to track when styles are added

     * or removed.

     *

     * @param l the change listener

     */

    public void addChangeListener(ChangeListener l) {

        styles.addChangeListener(l);

    }

    /**

     * Removes a listener that was tracking styles being

     * added or removed.

     *

     * @param l the change listener

     */

    public void removeChangeListener(ChangeListener l) {

        styles.removeChangeListener(l);

    }

    /**

     * Returns an array of all the <code>ChangeListener</code>s added

     * to this StyleContext with addChangeListener().

     *

     * @return all of the <code>ChangeListener</code>s added or an empty

     *         array if no listeners have been added

     * @since 1.4

     */

    public ChangeListener[] getChangeListeners() {

        return ((NamedStyle)styles).getChangeListeners();

    }

    /**

     * Gets the font from an attribute set.  This is

     * implemented to try and fetch a cached font

     * for the given AttributeSet, and if that fails

     * the font features are resolved and the

     * font is fetched from the low-level font cache.

     *

     * @param attr the attribute set

     * @return the font

     */

    public Font getFont(AttributeSet attr) {

        // PENDING(prinz) add cache behavior

        int style = Font.PLAIN;

        if (StyleConstants.isBold(attr)) {

            style |= Font.BOLD;

        }

        if (StyleConstants.isItalic(attr)) {

            style |= Font.ITALIC;

        }

        String family = StyleConstants.getFontFamily(attr);

        int size = StyleConstants.getFontSize(attr);

        /**

         * if either superscript or subscript is

         * is set, we need to reduce the font size

         * by 2.

         */

        if (StyleConstants.isSuperscript(attr) ||

            StyleConstants.isSubscript(attr)) {

            size -= 2;

        }

        return getFont(family, style, size);

    }

    /**

     * Takes a set of attributes and turn it into a foreground color

     * specification.  This might be used to specify things

     * like brighter, more hue, etc.  By default it simply returns

     * the value specified by the StyleConstants.Foreground attribute.

     *

     * @param attr the set of attributes

     * @return the color

     */

    public Color getForeground(AttributeSet attr) {

        return StyleConstants.getForeground(attr);

    }

    /**

     * Takes a set of attributes and turn it into a background color

     * specification.  This might be used to specify things

     * like brighter, more hue, etc.  By default it simply returns

     * the value specified by the StyleConstants.Background attribute.

     *

     * @param attr the set of attributes

     * @return the color

     */

    public Color getBackground(AttributeSet attr) {

        return StyleConstants.getBackground(attr);

    }

    /**

     * Gets a new font.  This returns a Font from a cache

     * if a cached font exists.  If not, a Font is added to

     * the cache.  This is basically a low-level cache for

     * 1.1 font features.

     *

     * @param family the font family (such as "Monospaced")

     * @param style the style of the font (such as Font.PLAIN)

     * @param size the point size >= 1

     * @return the new font

     */

    public Font getFont(String family, int style, int size) {

        fontSearch.setValue(family, style, size);

        Font f = (Font) fontTable.get(fontSearch);

        if (f == null) {

            // haven't seen this one yet.

            Style defaultStyle =

                getStyle(StyleContext.DEFAULT_STYLE);

            if (defaultStyle != null) {

                final String FONT_ATTRIBUTE_KEY = "FONT_ATTRIBUTE_KEY";

                Font defaultFont =

                    (Font) defaultStyle.getAttribute(FONT_ATTRIBUTE_KEY);

                if (defaultFont != null

                      && defaultFont.getFamily().equalsIgnoreCase(family)) {

                    f = defaultFont.deriveFont(style, size);

                }

            }

            if (f == null) {

                f = new Font(family, style, size);

            }

            if (! FontManager.fontSupportsDefaultEncoding(f)) {

                f = FontManager.getCompositeFontUIResource(f);

            }

            FontKey key = new FontKey(family, style, size);

            fontTable.put(key, f);

        }

        return f;

    }

    /**

     * Returns font metrics for a font.

     *

     * @param f the font

     * @return the metrics

     */

    public FontMetrics getFontMetrics(Font f) {

        // The Toolkit implementations cache, so we just forward

        // to the default toolkit.

        return Toolkit.getDefaultToolkit().getFontMetrics(f);

    }

    // --- AttributeContext methods --------------------

    /**

     * Adds an attribute to the given set, and returns

     * the new representative set.

     * <p>

     * This method is thread safe, although most Swing methods

     * are not. Please see

     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How

     * to Use Threads</A> for more information.

     *

     * @param old the old attribute set

     * @param name the non-null attribute name

     * @param value the attribute value

     * @return the updated attribute set

     * @see MutableAttributeSet#addAttribute

     */

    public synchronized AttributeSet addAttribute(AttributeSet old, Object name, Object value) {

        if ((old.getAttributeCount() + 1) <= getCompressionThreshold()) {

            // build a search key and find/create an immutable and unique

            // set.

            search.removeAttributes(search);

            search.addAttributes(old);

            search.addAttribute(name, value);

            reclaim(old);

            return getImmutableUniqueSet();

        }

        MutableAttributeSet ma = getMutableAttributeSet(old);

        ma.addAttribute(name, value);

        return ma;

    }

    /**

     * Adds a set of attributes to the element.

     * <p>

     * This method is thread safe, although most Swing methods

     * are not. Please see

     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How

     * to Use Threads</A> for more information.

     *

     * @param old the old attribute set

     * @param attr the attributes to add

     * @return the updated attribute set

     * @see MutableAttributeSet#addAttribute

     */

    public synchronized AttributeSet addAttributes(AttributeSet old, AttributeSet attr) {

        if ((old.getAttributeCount() + attr.getAttributeCount()) <= getCompressionThreshold()) {

            // build a search key and find/create an immutable and unique

            // set.

            search.removeAttributes(search);

            search.addAttributes(old);

            search.addAttributes(attr);

            reclaim(old);

            return getImmutableUniqueSet();

        }

        MutableAttributeSet ma = getMutableAttributeSet(old);

        ma.addAttributes(attr);

        return ma;

    }

    /**

     * Removes an attribute from the set.

     * <p>

     * This method is thread safe, although most Swing methods

     * are not. Please see

     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How

     * to Use Threads</A> for more information.

     *

     * @param old the old set of attributes

     * @param name the non-null attribute name

     * @return the updated attribute set

     * @see MutableAttributeSet#removeAttribute

     */

    public synchronized AttributeSet removeAttribute(AttributeSet old, Object name) {

        if ((old.getAttributeCount() - 1) <= getCompressionThreshold()) {

            // build a search key and find/create an immutable and unique

            // set.

            search.removeAttributes(search);

            search.addAttributes(old);

            search.removeAttribute(name);

            reclaim(old);

            return getImmutableUniqueSet();

        }

        MutableAttributeSet ma = getMutableAttributeSet(old);

        ma.removeAttribute(name);

        return ma;

    }

    /**

     * Removes a set of attributes for the element.

     * <p>

     * This method is thread safe, although most Swing methods

     * are not. Please see

     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How

     * to Use Threads</A> for more information.

     *

     * @param old the old attribute set

     * @param names the attribute names

     * @return the updated attribute set

     * @see MutableAttributeSet#removeAttributes

     */

    public synchronized AttributeSet removeAttributes(AttributeSet old, Enumeration<?> names) {

        if (old.getAttributeCount() <= getCompressionThreshold()) {

            // build a search key and find/create an immutable and unique

            // set.

            search.removeAttributes(search);

            search.addAttributes(old);

            search.removeAttributes(names);

            reclaim(old);

            return getImmutableUniqueSet();

        }

        MutableAttributeSet ma = getMutableAttributeSet(old);

        ma.removeAttributes(names);

        return ma;

    }

    /**

     * Removes a set of attributes for the element.

     * <p>

     * This method is thread safe, although most Swing methods

     * are not. Please see

     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How

     * to Use Threads</A> for more information.

     *

     * @param old the old attribute set

     * @param attrs the attributes

     * @return the updated attribute set

     * @see MutableAttributeSet#removeAttributes

     */

    public synchronized AttributeSet removeAttributes(AttributeSet old, AttributeSet attrs) {

        if (old.getAttributeCount() <= getCompressionThreshold()) {

            // build a search key and find/create an immutable and unique

            // set.

            search.removeAttributes(search);

            search.addAttributes(old);

            search.removeAttributes(attrs);

            reclaim(old);

            return getImmutableUniqueSet();

        }

        MutableAttributeSet ma = getMutableAttributeSet(old);

        ma.removeAttributes(attrs);

        return ma;

    }

    /**

     * Fetches an empty AttributeSet.

     *

     * @return the set

     */

    public AttributeSet getEmptySet() {

        return SimpleAttributeSet.EMPTY;

    }

    /**

     * Returns a set no longer needed by the MutableAttributeSet implmentation.

     * This is useful for operation under 1.1 where there are no weak

     * references.  This would typically be called by the finalize method

     * of the MutableAttributeSet implementation.

     * <p>

     * This method is thread safe, although most Swing methods

     * are not. Please see

     * <A HREF="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How

     * to Use Threads</A> for more information.

     *

     * @param a the set to reclaim

     */

    public void reclaim(AttributeSet a) {

        if (SwingUtilities.isEventDispatchThread()) {

            attributesPool.size(); // force WeakHashMap to expunge stale entries

        }

        // if current thread is not event dispatching thread

        // do not bother with expunging stale entries.

    }

    // --- local methods -----------------------------------------------

    /**

     * Returns the maximum number of key/value pairs to try and

     * compress into unique/immutable sets.  Any sets above this

     * limit will use hashtables and be a MutableAttributeSet.

     *

     * @return the threshold

     */

    protected int getCompressionThreshold() {

        return THRESHOLD;

    }

    /**

     * Create a compact set of attributes that might be shared.

     * This is a hook for subclasses that want to alter the

     * behavior of SmallAttributeSet.  This can be reimplemented

     * to return an AttributeSet that provides some sort of

     * attribute conversion.

     *

     * @param a The set of attributes to be represented in the

     *  the compact form.

     */

    protected SmallAttributeSet createSmallAttributeSet(AttributeSet a) {

        return new SmallAttributeSet(a);

    }

    /**

     * Create a large set of attributes that should trade off

     * space for time.  This set will not be shared.  This is

     * a hook for subclasses that want to alter the behavior

     * of the larger attribute storage format (which is

     * SimpleAttributeSet by default).   This can be reimplemented

     * to return a MutableAttributeSet that provides some sort of

     * attribute conversion.

     *

     * @param a The set of attributes to be represented in the

     *  the larger form.

     */

    protected MutableAttributeSet createLargeAttributeSet(AttributeSet a) {

        return new SimpleAttributeSet(a);

    }

    /**

     * Clean the unused immutable sets out of the hashtable.

     */

    synchronized void removeUnusedSets() {

        attributesPool.size(); // force WeakHashMap to expunge stale entries

    }

    /**

     * Search for an existing attribute set using the current search

     * parameters.  If a matching set is found, return it.  If a match

     * is not found, we create a new set and add it to the pool.

     */

    AttributeSet getImmutableUniqueSet() {

        // PENDING(prinz) should consider finding a alternative to

        // generating extra garbage on search key.

        SmallAttributeSet key = createSmallAttributeSet(search);

        WeakReference reference = (WeakReference)attributesPool.get(key);

        SmallAttributeSet a;

        if (reference == null

            || (a = (SmallAttributeSet)reference.get()) == null) {

            a = key;

            attributesPool.put(a, new WeakReference(a));

        }

        return a;

    }