/*

 * Copyright 1998-2003 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.html.parser;

import javax.swing.text.SimpleAttributeSet;

import javax.swing.text.html.HTMLEditorKit;

import javax.swing.text.html.HTML;

import javax.swing.text.ChangedCharSetException;

import java.util.*;

import java.io.*;

import java.net.*;

/**

 * A Parser for HTML Documents (actually, you can specify a DTD, but

 * you should really only use this class with the html dtd in swing).

 * Reads an InputStream of HTML and

 * invokes the appropriate methods in the ParserCallback class. This

 * is the default parser used by HTMLEditorKit to parse HTML url's.

 * <p>This will message the callback for all valid tags, as well as

 * tags that are implied but not explicitly specified. For example, the

 * html string (<p>blah) only has a p tag defined. The callback

 * will see the following methods:

 * <ol><li><i>handleStartTag(html, ...)</i></li>

 *     <li><i>handleStartTag(head, ...)</i></li>

 *     <li><i>handleEndTag(head)</i></li>

 *     <li><i>handleStartTag(body, ...)</i></li>

 *     <li>handleStartTag(p, ...)</i></li>

 *     <li>handleText(...)</li>

 *     <li><i>handleEndTag(p)</i></li>

 *     <li><i>handleEndTag(body)</i></li>

 *     <li><i>handleEndTag(html)</i></li>

 * </ol>

 * The items in <i>italic</i> are implied, that is, although they were not

 * explicitly specified, to be correct html they should have been present

 * (head isn't necessary, but it is still generated). For tags that

 * are implied, the AttributeSet argument will have a value of

 * <code>Boolean.TRUE</code> for the key

 * <code>HTMLEditorKit.ParserCallback.IMPLIED</code>.

 * <p>HTML.Attributes defines a type safe enumeration of html attributes.

 * If an attribute key of a tag is defined in HTML.Attribute, the

 * HTML.Attribute will be used as the key, otherwise a String will be used.

 * For example <p foo=bar class=neat> has two attributes. foo is

 * not defined in HTML.Attribute, where as class is, therefore the

 * AttributeSet will have two values in it, HTML.Attribute.CLASS with

 * a String value of 'neat' and the String key 'foo' with a String value of

 * 'bar'.

 * <p>The position argument will indicate the start of the tag, comment

 * or text. Similiar to arrays, the first character in the stream has a

 * position of 0. For tags that are

 * implied the position will indicate

 * the location of the next encountered tag. In the first example,

 * the implied start body and html tags will have the same position as the

 * p tag, and the implied end p, html and body tags will all have the same

 * position.

 * <p>As html skips whitespace the position for text will be the position

 * of the first valid character, eg in the string '\n\n\nblah'

 * the text 'blah' will have a position of 3, the newlines are skipped.

 * <p>

 * For attributes that do not have a value, eg in the html

 * string <code>&lt;foo blah&gt;</code> the attribute <code>blah</code>

 * does not have a value, there are two possible values that will be

 * placed in the AttributeSet's value:

 * <ul>

 * <li>If the DTD does not contain an definition for the element, or the

 *     definition does not have an explicit value then the value in the

 *     AttributeSet will be <code>HTML.NULL_ATTRIBUTE_VALUE</code>.

 * <li>If the DTD contains an explicit value, as in:

 *     <code>&lt;!ATTLIST OPTION selected (selected) #IMPLIED&gt;</code>

 *     this value from the dtd (in this case selected) will be used.

 * </ul>

 * <p>

 * Once the stream has been parsed, the callback is notified of the most

 * likely end of line string. The end of line string will be one of

 * \n, \r or \r\n, which ever is encountered the most in parsing the

 * stream.

 *

 * @author      Sunita Mani

 */

public class DocumentParser extends javax.swing.text.html.parser.Parser {

    private int inbody;

    private int intitle;

    private int inhead;

    private int instyle;

    private int inscript;

    private boolean seentitle;

    private HTMLEditorKit.ParserCallback callback = null;

    private boolean ignoreCharSet = false;

    private static final boolean debugFlag = false;

    public DocumentParser(DTD dtd) {

        super(dtd);

    }

    public void parse(Reader in,  HTMLEditorKit.ParserCallback callback, boolean ignoreCharSet) throws IOException {

        this.ignoreCharSet = ignoreCharSet;

        this.callback = callback;

        parse(in);

        // end of line

        callback.handleEndOfLineString(getEndOfLineString());

    }

    /**

     * Handle Start Tag.

     */

    protected void handleStartTag(TagElement tag) {

        Element elem = tag.getElement();

        if (elem == dtd.body) {

            inbody++;

        } else if (elem == dtd.html) {

        } else if (elem == dtd.head) {

            inhead++;

        } else if (elem == dtd.title) {

            intitle++;

        } else if (elem == dtd.style) {

            instyle++;

        } else if (elem == dtd.script) {

            inscript++;

        }

        if (debugFlag) {

            if (tag.fictional()) {

                debug("Start Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());

            } else {

                debug("Start Tag: " + tag.getHTMLTag() + " attributes: " +

                      getAttributes() + " pos: " + getCurrentPos());

            }

        }

        if (tag.fictional()) {

            SimpleAttributeSet attrs = new SimpleAttributeSet();

            attrs.addAttribute(HTMLEditorKit.ParserCallback.IMPLIED,

                               Boolean.TRUE);

            callback.handleStartTag(tag.getHTMLTag(), attrs,

                                    getBlockStartPosition());

        } else {

            callback.handleStartTag(tag.getHTMLTag(), getAttributes(),

                                    getBlockStartPosition());

            flushAttributes();

        }

    }

    protected void handleComment(char text[]) {

        if (debugFlag) {

            debug("comment: ->" + new String(text) + "<-"

                  + " pos: " + getCurrentPos());

        }

        callback.handleComment(text, getBlockStartPosition());

    }

    /**

     * Handle Empty Tag.

     */

    protected void handleEmptyTag(TagElement tag) throws ChangedCharSetException {

        Element elem = tag.getElement();

        if (elem == dtd.meta && !ignoreCharSet) {

            SimpleAttributeSet atts = getAttributes();

            if (atts != null) {

                String content = (String)atts.getAttribute(HTML.Attribute.CONTENT);

                if (content != null) {

                    if ("content-type".equalsIgnoreCase((String)atts.getAttribute(HTML.Attribute.HTTPEQUIV))) {

                        if (!content.equalsIgnoreCase("text/html") &&

                                !content.equalsIgnoreCase("text/plain")) {

                            throw new ChangedCharSetException(content, false);

                        }

                    } else if ("charset" .equalsIgnoreCase((String)atts.getAttribute(HTML.Attribute.HTTPEQUIV))) {

                        throw new ChangedCharSetException(content, true);

                    }

                }

            }

        }

        if (inbody != 0 || elem == dtd.meta || elem == dtd.base || elem == dtd.isindex || elem == dtd.style || elem == dtd.link) {

            if (debugFlag) {

                if (tag.fictional()) {

                    debug("Empty Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());

                } else {

                    debug("Empty Tag: " + tag.getHTMLTag() + " attributes: "

                          + getAttributes() + " pos: " + getCurrentPos());

                }

            }

            if (tag.fictional()) {

                SimpleAttributeSet attrs = new SimpleAttributeSet();

                attrs.addAttribute(HTMLEditorKit.ParserCallback.IMPLIED,

                                   Boolean.TRUE);

                callback.handleSimpleTag(tag.getHTMLTag(), attrs,

                                         getBlockStartPosition());

            } else {

                callback.handleSimpleTag(tag.getHTMLTag(), getAttributes(),

                                         getBlockStartPosition());

                flushAttributes();

            }

        }

    }

    /**

     * Handle End Tag.

     */

    protected void handleEndTag(TagElement tag) {

        Element elem = tag.getElement();

        if (elem == dtd.body) {

            inbody--;

        } else if (elem == dtd.title) {

            intitle--;

            seentitle = true;

        } else if (elem == dtd.head) {

            inhead--;

        } else if (elem == dtd.style) {

            instyle--;

        } else if (elem == dtd.script) {

            inscript--;

        }

        if (debugFlag) {

            debug("End Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());

        }

        callback.handleEndTag(tag.getHTMLTag(), getBlockStartPosition());

    }

    /**

     * Handle Text.

     */

    protected void handleText(char data[]) {

        if (data != null) {

            if (inscript != 0) {

                callback.handleComment(data, getBlockStartPosition());

                return;

            }

            if (inbody != 0 || ((instyle != 0) ||

                                ((intitle != 0) && !seentitle))) {

                if (debugFlag) {

                    debug("text:  ->" + new String(data) + "<-" + " pos: " + getCurrentPos());

                }

                callback.handleText(data, getBlockStartPosition());

            }

        }

    }

    /*

     * Error handling.

     */

    protected void handleError(int ln, String errorMsg) {

        if (debugFlag) {

            debug("Error: ->" + errorMsg + "<-" + " pos: " + getCurrentPos());

        }

        /* PENDING: need to improve the error string. */

        callback.handleError(errorMsg, getCurrentPos());

    }

    /*

     * debug messages

     */

    private void debug(String msg) {

        System.out.println(msg);

    }

}