/*
 * Copyright (C) 2005-2007 Alfresco Software Limited.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program 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 for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 * As a special exception to the terms and conditions of version 2.0 of 
 * the GPL, you may redistribute this Program in connection with Free/Libre 
 * and Open Source Software ("FLOSS") applications as described in Alfresco's 
 * FLOSS exception.  You should have recieved a copy of the text describing 
 * the FLOSS exception, and it is also available here: 
 * http://www.alfresco.com/legal/licensing"
 */
package org.alfresco.web.scripts;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;
import java.text.SimpleDateFormat;
import java.util.TimeZone;

import javax.servlet.http.HttpServletResponse;

import org.alfresco.util.CachingDateFormat;
import org.alfresco.web.ui.common.Utils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * HTTP Servlet Web Script Response
 * 
 * @author davidc
 */
public class WebScriptServletResponse implements WebScriptResponse
{
    // Logger
    private static final Log logger = LogFactory.getLog(WebScriptServletResponse.class);

    // Servlet Response
    private HttpServletResponse res;

    
    /**
     * Construct
     * 
     * @param res
     */
    WebScriptServletResponse(HttpServletResponse res)
    {
        this.res = res;
    }

    /**
     * Gets the HTTP Servlet Response
     * 
     * @return  HTTP Servlet Response
     */
    public HttpServletResponse getHttpServletResponse()
    {
        return res;
    }
    
    /* (non-Javadoc)
     * @see org.alfresco.web.scripts.WebScriptResponse#setStatus(int)
     */
    public void setStatus(int status)
    {
        res.setStatus(status);
    }

    /* (non-Javadoc)
     * @see org.alfresco.web.scripts.WebScriptResponse#setContentType(java.lang.String)
     */
    public void setContentType(String contentType)
    {
        res.setContentType(contentType);
    }

    /* (non-Javadoc)
     * @see org.alfresco.web.scripts.WebScriptResponse#setCache(org.alfresco.web.scripts.WebScriptCache)
     */
    public void setCache(WebScriptCache cache)
    {
        // set Cache-Control
        String cacheControl = "";
        String pragma = "";
        if (cache.getIsPublic())
        {
            cacheControl += "public";
        }
        if (cache.getNeverCache())
        {
            cacheControl += (cacheControl.length() > 0 ? ", " : "") + "no-cache";
            pragma += (pragma.length() > 0) ? ", " : "" + "no-cache";
        }
        if (cache.getMaxAge() != null && cache.getNeverCache() == false)
        {
            cacheControl += (cacheControl.length() > 0 ? ", " : "") + " max-age=" + cache.getMaxAge();
        }
        if (cache.getMustRevalidate() && cache.getNeverCache() == false)
        {
            cacheControl += (cacheControl.length() > 0 ? ", " : "") + " must-revalidate";
        }
        if (cacheControl.length() > 0)
        {
            res.setHeader("Cache-Control", cacheControl);
            if (logger.isDebugEnabled())
                logger.debug("Cache - set response header Cache-Control: " + cacheControl);
        }
        if (pragma.length() > 0)
        {
            res.setHeader("Pragma", pragma);
            if (logger.isDebugEnabled())
                logger.debug("Cache - set response header Pragma: " + pragma);
        }
        
        // set ETag
        if (cache.getETag() != null)
        {
            String eTag = "\"" + cache.getETag() + "\"";
            res.setHeader("ETag", eTag);
            if (logger.isDebugEnabled())
                logger.debug("Cache - set response header ETag: " + eTag);
        }
        
        // set Last Modified
        if (cache.getLastModified() != null)
        {
            res.setDateHeader("Last-Modified", cache.getLastModified().getTime());
            if (logger.isDebugEnabled())
            {
                SimpleDateFormat formatter = getHTTPDateFormat();
                String lastModified = formatter.format(cache.getLastModified());
                logger.debug("Cache - set response header Last-Modified: " + lastModified);
            }
        }
    }

    /* (non-Javadoc)
     * @see org.alfresco.web.scripts.WebScriptResponse#reset()
     */
    public void reset()
    {
        try
        {
            res.reset();
        }
        catch(IllegalStateException e)
        {
        }
    }
    
    /* (non-Javadoc)
     * @see org.alfresco.web.scripts.WebScriptResponse#getWriter()
     */
    public Writer getWriter() throws IOException
    {
        return res.getWriter();
    }

    /* (non-Javadoc)
     * @see org.alfresco.web.scripts.WebScriptResponse#getOutputStream()
     */
    public OutputStream getOutputStream() throws IOException
    {
        return res.getOutputStream();
    }

    /* (non-Javadoc)
     * @see org.alfresco.web.scripts.WebScriptResponse#encodeScriptUrl(java.lang.String)
     */
    public String encodeScriptUrl(String url)
    {
        return url;
    }

    /* (non-Javadoc)
     * @see org.alfresco.web.scripts.WebScriptResponse#getEncodeScriptUrlFunction(java.lang.String)
     */
    public String getEncodeScriptUrlFunction(String name)
    {
        return Utils.encodeJavascript(ENCODE_FUNCTION.replace("$name$", name));
    }
    
    private static final String ENCODE_FUNCTION = "{ $name$: function(url) { return url; } }";
    
    /**
     * Helper to return a HTTP Date Formatter
     * 
     * @return  HTTP Date Formatter
     */
    private static SimpleDateFormat getHTTPDateFormat()
    {
        if (s_dateFormat.get() != null)
        {
            return s_dateFormat.get();
        }

        SimpleDateFormat formatter = CachingDateFormat.getDateFormat("EEE, dd MMM yyyy kk:mm:ss zzz", false);
        formatter.setTimeZone(TimeZone.getTimeZone("GMT"));
        s_dateFormat.set(formatter);
        return s_dateFormat.get();
    }
    
    private static ThreadLocal<SimpleDateFormat> s_dateFormat = new ThreadLocal<SimpleDateFormat>();

}