package org.ignition.blojsom.servlet;

import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.util.*;

public class PermalinkFilter
implements Filter
{
    public void init(FilterConfig filterConfig)
    {
    }

    public void destroy()
    {
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
    throws IOException, ServletException
    {
        HttpServletRequest hreq = (HttpServletRequest)request;
        String uri = hreq.getRequestURI();
        if (!uri.endsWith("/")) {
            int lastSlash = uri.lastIndexOf('/');
            if (lastSlash >= 0) {
                hreq = new PermalinkRequest(hreq, uri.substring(lastSlash + 1));
            }
        }
        chain.doFilter(hreq, response);
    }

    private class PermalinkRequest
    extends HttpServletRequestWrapper
    {
        private Map params;
        private String uri;
        private String url;
        private String pathInfo;
        
        public PermalinkRequest(HttpServletRequest request, String permalink)
        {
            super(request);
            params = new HashMap(request.getParameterMap());
            params.put("permalink", new String[]{ permalink });
            params = Collections.unmodifiableMap(params);

            uri = chopPermalink(request.getRequestURI(), permalink);
            url = chopPermalink(request.getRequestURL().toString(), permalink);
            pathInfo = chopPermalink(request.getPathInfo(), permalink);
        }

        private String chopPermalink(String str, String permalink)
        {
            return str.substring(0, str.length() - permalink.length());
        }

        public String getRequestURI()
        {
            return uri;
        }

        public StringBuffer getRequestURL()
        {
            return new StringBuffer(url);
        }

        public String getPathInfo()
        {
            return pathInfo;
        }

        public String getParameter(String name)
        {
            String[] values = getParameterValues(name);
            return (values != null) ? values[0] : null;
        }
        
        public Map getParameterMap()
        {
            return params;
        }
        
        public Enumeration getParameterNames()
        {
            return Collections.enumeration(params.keySet());
        }
        
        public String[] getParameterValues(String name)
        {
            return (String[])params.get(name);
        }
    }
}