// $Header: /home/cvs/jakarta-jmeter/src/htmlparser/org/htmlparser/scanners/ImageScanner.java,v 1.5 2004/02/10 13:41:09 woolfel Exp $
/*
 * ====================================================================
 * Copyright 2002-2004 The Apache Software Foundation.
 *
 * 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.
 * 
 */

// The developers of JMeter and Apache are greatful to the developers
// of HTMLParser for giving Apache Software Foundation a non-exclusive
// license. The performance benefits of HTMLParser are clear and the
// users of JMeter will benefit from the hard work the HTMLParser
// team. For detailed information about HTMLParser, the project is
// hosted on sourceforge at http://htmlparser.sourceforge.net/.
//
// HTMLParser was originally created by Somik Raha in 2000. Since then
// a healthy community of users has formed and helped refine the
// design so that it is able to tackle the difficult task of parsing
// dirty HTML. Derrick Oswald is the current lead developer and was kind
// enough to assist JMeter.

package org.htmlparser.scanners;
//////////////////
// Java Imports //
//////////////////
import java.util.Hashtable;

import org.htmlparser.tags.ImageTag;
import org.htmlparser.tags.Tag;
import org.htmlparser.tags.data.TagData;
import org.htmlparser.util.LinkProcessor;
import org.htmlparser.util.ParserException;
import org.htmlparser.util.ParserUtils;
/**
 * Scans for the Image Tag. This is a subclass of TagScanner, and is called using a 
 * variant of the template method. If the evaluate() method returns true, that means the
 * given string contains an image tag. Extraction is done by the scan method thereafter
 * by the user of this class.
 */
public class ImageScanner extends TagScanner
{
    public static final String IMAGE_SCANNER_ID = "IMG";
    private Hashtable table;
    private LinkProcessor processor;
    /**
     * Overriding the default constructor
     */
    public ImageScanner()
    {
        super();
        processor = new LinkProcessor();
    }
    /**
     * Overriding the constructor to accept the filter 
     */
    public ImageScanner(String filter, LinkProcessor processor)
    {
        super(filter);
        this.processor = processor;
    }
    /**
     * Extract the location of the image, given the string to be parsed, and the url
     * of the html page in which this tag exists.
     * @param s String to be parsed
     * @param url URL of web page being parsed
     */
    public String extractImageLocn(Tag tag, String url) throws ParserException
    {
        String relativeLink = null;
        try
        {
            table = tag.getAttributes();
            relativeLink = (String) table.get("SRC");

            if (relativeLink != null)
            {
                relativeLink = ParserUtils.removeChars(relativeLink, '\n');
                relativeLink = ParserUtils.removeChars(relativeLink, '\r');
            }
            if (relativeLink == null || relativeLink.length() == 0)
            {
                // try fix
                String tagText = tag.getText().toUpperCase();
                int indexSrc = tagText.indexOf("SRC");
                if (indexSrc != -1)
                {
                    // There is a missing equals.
                    tag.setText(
                        tag.getText().substring(0, indexSrc + 3)
                            + "="
                            + tag.getText().substring(
                                indexSrc + 3,
                                tag.getText().length()));
                    table = tag.redoParseAttributes();
                    relativeLink = (String) table.get("SRC");

                }
            }
            if (relativeLink == null)
                return "";
            else
                return processor.extract(relativeLink, url);
        }
        catch (Exception e)
        {
            throw new ParserException(
                "HTMLImageScanner.extractImageLocn() : Error in extracting image location, relativeLink = "
                    + relativeLink
                    + ", url = "
                    + url,
                e);
        }
    }

    public String[] getID()
    {
        String[] ids = new String[1];
        ids[0] = IMAGE_SCANNER_ID;
        return ids;
    }

    protected Tag createTag(TagData tagData, Tag tag, String url)
        throws ParserException
    {
        String link = extractImageLocn(tag, url);
        return new ImageTag(tagData, link);
    }

}