/*

 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package javax.swing.text.html;

import sun.awt.AppContext;

import java.awt.*;

import java.awt.event.*;

import java.io.*;

import java.net.MalformedURLException;

import java.net.URL;

import javax.swing.text.*;

import javax.swing.*;

import javax.swing.event.*;

import javax.swing.plaf.TextUI;

import java.util.*;

import javax.accessibility.*;

import java.lang.ref.*;

import java.security.AccessController;

import java.security.PrivilegedAction;

import javax.swing.text.html.parser.ParserDelegator;

/**

 * The Swing JEditorPane text component supports different kinds

 * of content via a plug-in mechanism called an EditorKit.  Because

 * HTML is a very popular format of content, some support is provided

 * by default.  The default support is provided by this class, which

 * supports HTML version 3.2 (with some extensions), and is migrating

 * toward version 4.0.

 * The <applet> tag is not supported, but some support is provided

 * for the <object> tag.

 * <p>

 * There are several goals of the HTML EditorKit provided, that have

 * an effect upon the way that HTML is modeled.  These

 * have influenced its design in a substantial way.

 * <dl>

 * <dt>

 * Support editing

 * <dd>

 * It might seem fairly obvious that a plug-in for JEditorPane

 * should provide editing support, but that fact has several

 * design considerations.  There are a substantial number of HTML

 * documents that don't properly conform to an HTML specification.

 * These must be normalized somewhat into a correct form if one

 * is to edit them.  Additionally, users don't like to be presented

 * with an excessive amount of structure editing, so using traditional

 * text editing gestures is preferred over using the HTML structure

 * exactly as defined in the HTML document.

 * <p>

 * The modeling of HTML is provided by the class <code>HTMLDocument</code>.

 * Its documentation describes the details of how the HTML is modeled.

 * The editing support leverages heavily off of the text package.

 *

 * <dt>

 * Extendable/Scalable

 * <dd>

 * To maximize the usefulness of this kit, a great deal of effort

 * has gone into making it extendable.  These are some of the

 * features.

 * <ol>

 *   <li>

 *   The parser is replaceable.  The default parser is the Hot Java

 *   parser which is DTD based.  A different DTD can be used, or an

 *   entirely different parser can be used.  To change the parser,

 *   reimplement the getParser method.  The default parser is

 *   dynamically loaded when first asked for, so the class files

 *   will never be loaded if an alternative parser is used.  The

 *   default parser is in a separate package called parser below

 *   this package.

 *   <li>

 *   The parser drives the ParserCallback, which is provided by

 *   HTMLDocument.  To change the callback, subclass HTMLDocument

 *   and reimplement the createDefaultDocument method to return

 *   document that produces a different reader.  The reader controls

 *   how the document is structured.  Although the Document provides

 *   HTML support by default, there is nothing preventing support of

 *   non-HTML tags that result in alternative element structures.

 *   <li>

 *   The default view of the models are provided as a hierarchy of

 *   View implementations, so one can easily customize how a particular

 *   element is displayed or add capabilities for new kinds of elements

 *   by providing new View implementations.  The default set of views

 *   are provided by the <code>HTMLFactory</code> class.  This can

 *   be easily changed by subclassing or replacing the HTMLFactory

 *   and reimplementing the getViewFactory method to return the alternative

 *   factory.

 *   <li>

 *   The View implementations work primarily off of CSS attributes,

 *   which are kept in the views.  This makes it possible to have

 *   multiple views mapped over the same model that appear substantially

 *   different.  This can be especially useful for printing.  For

 *   most HTML attributes, the HTML attributes are converted to CSS

 *   attributes for display.  This helps make the View implementations

 *   more general purpose

 * </ol>

 *

 * <dt>

 * Asynchronous Loading

 * <dd>

 * Larger documents involve a lot of parsing and take some time

 * to load.  By default, this kit produces documents that will be

 * loaded asynchronously if loaded using <code>JEditorPane.setPage</code>.

 * This is controlled by a property on the document.  The method

 * {@link #createDefaultDocument createDefaultDocument} can

 * be overriden to change this.  The batching of work is done

 * by the <code>HTMLDocument.HTMLReader</code> class.  The actual

 * work is done by the <code>DefaultStyledDocument</code> and

 * <code>AbstractDocument</code> classes in the text package.

 *

 * <dt>

 * Customization from current LAF

 * <dd>

 * HTML provides a well known set of features without exactly

 * specifying the display characteristics.  Swing has a theme

 * mechanism for its look-and-feel implementations.  It is desirable

 * for the look-and-feel to feed display characteristics into the

 * HTML views.  An user with poor vision for example would want

 * high contrast and larger than typical fonts.

 * <p>

 * The support for this is provided by the <code>StyleSheet</code>

 * class.  The presentation of the HTML can be heavily influenced

 * by the setting of the StyleSheet property on the EditorKit.

 *

 * <dt>

 * Not lossy

 * <dd>

 * An EditorKit has the ability to be read and save documents.

 * It is generally the most pleasing to users if there is no loss

 * of data between the two operation.  The policy of the HTMLEditorKit

 * will be to store things not recognized or not necessarily visible

 * so they can be subsequently written out.  The model of the HTML document

 * should therefore contain all information discovered while reading the

 * document.  This is constrained in some ways by the need to support

 * editing (i.e. incorrect documents sometimes must be normalized).

 * The guiding principle is that information shouldn't be lost, but

 * some might be synthesized to produce a more correct model or it might

 * be rearranged.

 * </dl>

 *

 * @author  Timothy Prinzing

 */

@SuppressWarnings("serial") // Same-version serialization only

public class HTMLEditorKit extends StyledEditorKit implements Accessible {

    private JEditorPane theEditor;

    /**

     * Constructs an HTMLEditorKit, creates a StyleContext,

     * and loads the style sheet.

     */

    public HTMLEditorKit() {

    }

    /**

     * Get the MIME type of the data that this

     * kit represents support for.  This kit supports

     * the type <code>text/html</code>.

     *

     * @return the type

     */

    public String getContentType() {

        return "text/html";

    }

    /**

     * Fetch a factory that is suitable for producing

     * views of any models that are produced by this

     * kit.

     *

     * @return the factory

     */

    public ViewFactory getViewFactory() {

        return defaultFactory;

    }

    /**

     * Create an uninitialized text storage model

     * that is appropriate for this type of editor.

     *

     * @return the model

     */

    public Document createDefaultDocument() {

        StyleSheet styles = getStyleSheet();

        StyleSheet ss = new StyleSheet();

        ss.addStyleSheet(styles);

        HTMLDocument doc = new HTMLDocument(ss);

        doc.setParser(getParser());

        doc.setAsynchronousLoadPriority(4);

        doc.setTokenThreshold(100);

        return doc;

    }

    /**

     * Try to get an HTML parser from the document.  If no parser is set for

     * the document, return the editor kit's default parser.  It is an error

     * if no parser could be obtained from the editor kit.

     */

    private Parser ensureParser(HTMLDocument doc) throws IOException {

        Parser p = doc.getParser();

        if (p == null) {

            p = getParser();

        }

        if (p == null) {

            throw new IOException("Can't load parser");

        }

        return p;

    }

    /**

     * Inserts content from the given stream. If <code>doc</code> is

     * an instance of HTMLDocument, this will read

     * HTML 3.2 text. Inserting HTML into a non-empty document must be inside

     * the body Element, if you do not insert into the body an exception will

     * be thrown. When inserting into a non-empty document all tags outside

     * of the body (head, title) will be dropped.

     *

     * @param in the stream to read from

     * @param doc the destination for the insertion

     * @param pos the location in the document to place the

     *   content

     * @exception IOException on any I/O error

     * @exception BadLocationException if pos represents an invalid

     *   location within the document

     * @exception RuntimeException (will eventually be a BadLocationException)

     *            if pos is invalid

     */

    public void read(Reader in, Document doc, int pos) throws IOException, BadLocationException {

        if (doc instanceof HTMLDocument) {

            HTMLDocument hdoc = (HTMLDocument) doc;

            if (pos > doc.getLength()) {

                throw new BadLocationException("Invalid location", pos);

            }

            Parser p = ensureParser(hdoc);

            ParserCallback receiver = hdoc.getReader(pos);

            Boolean ignoreCharset = (Boolean)doc.getProperty("IgnoreCharsetDirective");

            p.parse(in, receiver, (ignoreCharset == null) ? false : ignoreCharset.booleanValue());

            receiver.flush();

        } else {

            super.read(in, doc, pos);

        }

    }

    /**

     * Inserts HTML into an existing document.

     *

     * @param doc the document to insert into

     * @param offset the offset to insert HTML at

     * @param popDepth the number of ElementSpec.EndTagTypes to generate

     *                  before inserting

     * @param html the HTML string

     * @param pushDepth the number of ElementSpec.StartTagTypes with a direction

     *                  of ElementSpec.JoinNextDirection that should be generated

     *                  before inserting, but after the end tags have been generated

     * @param insertTag the first tag to start inserting into document

     *

     * @throws BadLocationException if {@code offset} is invalid

     * @throws IOException on I/O error

     * @exception RuntimeException (will eventually be a BadLocationException)

     *            if pos is invalid

     */

    public void insertHTML(HTMLDocument doc, int offset, String html,

                           int popDepth, int pushDepth,

                           HTML.Tag insertTag) throws

                       BadLocationException, IOException {

        if (offset > doc.getLength()) {

            throw new BadLocationException("Invalid location", offset);

        }

        Parser p = ensureParser(doc);

        ParserCallback receiver = doc.getReader(offset, popDepth, pushDepth,

                                                insertTag);

        Boolean ignoreCharset = (Boolean)doc.getProperty

                                ("IgnoreCharsetDirective");

        p.parse(new StringReader(html), receiver, (ignoreCharset == null) ?

                false : ignoreCharset.booleanValue());

        receiver.flush();

    }

    /**

     * Write content from a document to the given stream

     * in a format appropriate for this kind of content handler.

     *

     * @param out the stream to write to

     * @param doc the source for the write

     * @param pos the location in the document to fetch the

     *   content

     * @param len the amount to write out

     * @exception IOException on any I/O error

     * @exception BadLocationException if {@code pos} represents an invalid

     *   location within the document

     */

    public void write(Writer out, Document doc, int pos, int len)

        throws IOException, BadLocationException {

        if (doc instanceof HTMLDocument) {

            HTMLWriter w = new HTMLWriter(out, (HTMLDocument)doc, pos, len);

            w.write();

        } else if (doc instanceof StyledDocument) {

            MinimalHTMLWriter w = new MinimalHTMLWriter(out, (StyledDocument)doc, pos, len);

            w.write();

        } else {

            super.write(out, doc, pos, len);

        }

    }

    /**

     * Called when the kit is being installed into the

     * a JEditorPane.

     *

     * @param c the JEditorPane

     */

    public void install(JEditorPane c) {

        c.addMouseListener(linkHandler);

        c.addMouseMotionListener(linkHandler);

        c.addCaretListener(nextLinkAction);

        super.install(c);

        theEditor = c;

    }

    /**

     * Called when the kit is being removed from the

     * JEditorPane.  This is used to unregister any

     * listeners that were attached.

     *

     * @param c the JEditorPane

     */

    public void deinstall(JEditorPane c) {

        c.removeMouseListener(linkHandler);

        c.removeMouseMotionListener(linkHandler);

        c.removeCaretListener(nextLinkAction);

        super.deinstall(c);

        theEditor = null;

    }

    /**

     * Default Cascading Style Sheet file that sets

     * up the tag views.

     */

    public static final String DEFAULT_CSS = "default.css";

    /**

     * Set the set of styles to be used to render the various

     * HTML elements.  These styles are specified in terms of

     * CSS specifications.  Each document produced by the kit

     * will have a copy of the sheet which it can add the

     * document specific styles to.  By default, the StyleSheet

     * specified is shared by all HTMLEditorKit instances.

     * This should be reimplemented to provide a finer granularity

     * if desired.

     *

     * @param s a StyleSheet

     */

    public void setStyleSheet(StyleSheet s) {

        if (s == null) {

            AppContext.getAppContext().remove(DEFAULT_STYLES_KEY);

        } else {

            AppContext.getAppContext().put(DEFAULT_STYLES_KEY, s);

        }

    }

    /**

     * Get the set of styles currently being used to render the

     * HTML elements.  By default the resource specified by

     * DEFAULT_CSS gets loaded, and is shared by all HTMLEditorKit

     * instances.

     *

     * @return the StyleSheet

     */

    public StyleSheet getStyleSheet() {

        AppContext appContext = AppContext.getAppContext();

        StyleSheet defaultStyles = (StyleSheet) appContext.get(DEFAULT_STYLES_KEY);

        if (defaultStyles == null) {

            defaultStyles = new StyleSheet();

            appContext.put(DEFAULT_STYLES_KEY, defaultStyles);

            try {

                InputStream is = HTMLEditorKit.getResourceAsStream(DEFAULT_CSS);

                Reader r = new BufferedReader(

                        new InputStreamReader(is, "ISO-8859-1"));

                defaultStyles.loadRules(r, null);

                r.close();

            } catch (Throwable e) {

                // on error we simply have no styles... the html

                // will look mighty wrong but still function.

            }

        }

        return defaultStyles;

    }

    /**

     * Fetch a resource relative to the HTMLEditorKit classfile.

     * If this is called on 1.2 the loading will occur under the

     * protection of a doPrivileged call to allow the HTMLEditorKit

     * to function when used in an applet.

     *

     * @param name the name of the resource, relative to the

     *             HTMLEditorKit class

     * @return a stream representing the resource

     */

    static InputStream getResourceAsStream(final String name) {

        return AccessController.doPrivileged(

                new PrivilegedAction<InputStream>() {

                    public InputStream run() {

                        return HTMLEditorKit.class.getResourceAsStream(name);

                    }

                });

    }

    /**

     * Fetches the command list for the editor.  This is

     * the list of commands supported by the superclass

     * augmented by the collection of commands defined

     * locally for style operations.

     *

     * @return the command list

     */

    public Action[] getActions() {

        return TextAction.augmentList(super.getActions(), defaultActions);

    }

    /**

     * Copies the key/values in <code>element</code>s AttributeSet into

     * <code>set</code>. This does not copy component, icon, or element

     * names attributes. Subclasses may wish to refine what is and what

     * isn't copied here. But be sure to first remove all the attributes that

     * are in <code>set</code>.<p>

     * This is called anytime the caret moves over a different location.

     *

     */

    protected void createInputAttributes(Element element,

                                         MutableAttributeSet set) {

        set.removeAttributes(set);

        set.addAttributes(element.getAttributes());

        set.removeAttribute(StyleConstants.ComposedTextAttribute);

        Object o = set.getAttribute(StyleConstants.NameAttribute);

        if (o instanceof HTML.Tag) {

            HTML.Tag tag = (HTML.Tag)o;

            // PENDING: we need a better way to express what shouldn't be

            // copied when editing...

            if(tag == HTML.Tag.IMG) {

                // Remove the related image attributes, src, width, height

                set.removeAttribute(HTML.Attribute.SRC);

                set.removeAttribute(HTML.Attribute.HEIGHT);

                set.removeAttribute(HTML.Attribute.WIDTH);

                set.addAttribute(StyleConstants.NameAttribute,

                                 HTML.Tag.CONTENT);

            }

            else if (tag == HTML.Tag.HR || tag == HTML.Tag.BR) {

                // Don't copy HRs or BRs either.

                set.addAttribute(StyleConstants.NameAttribute,

                                 HTML.Tag.CONTENT);

            }

            else if (tag == HTML.Tag.COMMENT) {

                // Don't copy COMMENTs either

                set.addAttribute(StyleConstants.NameAttribute,

                                 HTML.Tag.CONTENT);

                set.removeAttribute(HTML.Attribute.COMMENT);

            }

            else if (tag == HTML.Tag.INPUT) {

                // or INPUT either

                set.addAttribute(StyleConstants.NameAttribute,

                                 HTML.Tag.CONTENT);

                set.removeAttribute(HTML.Tag.INPUT);

            }

            else if (tag instanceof HTML.UnknownTag) {

                // Don't copy unknowns either:(

                set.addAttribute(StyleConstants.NameAttribute,

                                 HTML.Tag.CONTENT);

                set.removeAttribute(HTML.Attribute.ENDTAG);

            }

        }

    }

    /**

     * Gets the input attributes used for the styled

     * editing actions.

     *

     * @return the attribute set

     */

    public MutableAttributeSet getInputAttributes() {

        if (input == null) {

            input = getStyleSheet().addStyle(null, null);

        }

        return input;

    }

    /**

     * Sets the default cursor.

     *

     * @param cursor a cursor

     *

     * @since 1.3