/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
 *    project contributors may be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact visigoths@visigoths.org.
 *
 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
 *    without prior written permission of the Visigoth Software Society.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package freemarker.template.utility;

import java.io.IOException;
import java.io.Writer;
import java.util.Map;

import freemarker.template.TemplateTransformModel;

/**
 * Performs an HTML escape of a given template fragment. Specifically,
 * &lt; &gt; &quot; and &amp; are all turned into entities.
 *
 * <p>Usage:<br />
 * From java:</p>
 * <pre>
 * SimpleHash root = new SimpleHash();
 *
 * root.put( "htmlEscape", new freemarker.template.utility.HtmlEscape() );
 *
 * ...
 * </pre>
 *
 * <p>From your FreeMarker template:</p>
 * <pre>
 *
 * The following is HTML-escaped:
 * &lt;transform htmlEscape&gt;
 *   &lt;p&gt;This paragraph has all HTML special characters escaped.&lt;/p&gt;
 * &lt;/transform&gt;
 *
 * ...
 * </pre>
 *
 * @version $Id: HtmlEscape.java,v 1.29 2003/02/25 00:28:16 revusky Exp $
 * @see freemarker.template.utility.XmlEscape
 */
public class HtmlEscape implements TemplateTransformModel {

    private static final char[] LT = "&lt;".toCharArray();
    private static final char[] GT = "&gt;".toCharArray();
    private static final char[] AMP = "&amp;".toCharArray();
    private static final char[] QUOT = "&quot;".toCharArray();

    public Writer getWriter(final Writer out, Map args)
    {
        return new Writer()
        {
            public void write(int c)
            throws
                IOException
            {
                switch(c)
                {
                    case '<': out.write(LT, 0, 4); break;
                    case '>': out.write(GT, 0, 4); break;
                    case '&': out.write(AMP, 0, 5); break;
                    case '"': out.write(QUOT, 0, 6); break;
                    default: out.write(c);
                }
            }

            public void write(char cbuf[], int off, int len)
            throws
                IOException
            {
                int lastoff = off;
                int lastpos = off + len;
                for (int i = off; i < lastpos; i++)
                {
                    switch (cbuf[i])
                    {
                        case '<': out.write(cbuf, lastoff, i - lastoff); out.write(LT, 0, 4); lastoff = i + 1; break;
                        case '>': out.write(cbuf, lastoff, i - lastoff); out.write(GT, 0, 4); lastoff = i + 1; break;
                        case '&': out.write(cbuf, lastoff, i - lastoff); out.write(AMP, 0, 5); lastoff = i + 1; break;
                        case '"': out.write(cbuf, lastoff, i - lastoff); out.write(QUOT, 0, 6); lastoff = i + 1; break;
                    }
                }
                int remaining = lastpos - lastoff;
                if(remaining > 0)
                {
                    out.write(cbuf, lastoff, remaining);
                }
            }
            public void flush() throws IOException {
                out.flush();
            }

            public void close() {
            }
        };
    }
}
