package geekblog.filters;


import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import geekblog.*;


/**
 * Filter to track hit counts on page reads.
 */
public class HitCountFilter
  implements Filter
{
  private FilterConfig config;
  private String attributeName;
  private Date refDate;

  private static final SimpleDateFormat datef = new SimpleDateFormat("yyyyMMdd");

  public void init(FilterConfig config)
  {
    this.config = config;

    attributeName = config.getInitParameter("attributeName");
    refDate = new Date();

    config.getServletContext().setAttribute(attributeName, new Integer(0));
  }
  public void destroy()
  {
  }


  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
    throws ServletException, java.io.IOException
  {
    ServletContext context = config.getServletContext();
    
    Date todayDate = new Date();
    if (!datef.format(todayDate).equals(datef.format(refDate)))
    {
      synchronized(this)
      {
        refDate = todayDate;
      }
      synchronized(context)
      {
        context.setAttribute(attributeName, new Integer(1));
      }
    }
    else
    {
      synchronized(context)
      {
        Integer hitCount = (Integer)context.getAttribute(attributeName);
        context.setAttribute(attributeName, new Integer(hitCount.intValue() + 1));
      }
    }

    chain.doFilter(request, response);
  }
}