package jalview.httpserver;

import java.io.IOException;
import java.util.Collections;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.handler.AbstractHandler;

/**
 * 
 * @author gmcarstairs
 *
 */
public abstract class AbstractRequestHandler extends AbstractHandler
{
  /**
   * Handle an incoming Http request.
   */
  @Override
  public void handle(String target, Request baseRequest,
          HttpServletRequest request, HttpServletResponse response)
          throws IOException, ServletException
  {
    try
    {
      // dumpRequest(request); // debug
      processRequest(request, response);
    } catch (Throwable t)
    {
      /*
       * Set server error status on response
       */
      System.err.println("Exception handling request "
              + request.getRequestURI() + " : " + t.getMessage());
      if (response.isCommitted())
      {
        /*
         * Can't write an HTTP header once any response content has been written
         */
        System.err
                .println("Unable to return HTTP 500 as response already committed");
      }
      else
      {
        response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
      }
    } finally
    {
      response.getWriter().flush();
      baseRequest.setHandled(true);
    }
  }

  /**
   * Subclasses should override this method to perform request processing
   * 
   * @param request
   * @param response
   */
  protected abstract void processRequest(HttpServletRequest request,
          HttpServletResponse response);

  /**
   * For debug - writes HTTP request details to stdout
   * 
   * @param request
   */
  protected void dumpRequest(HttpServletRequest request)
  {
    System.out.println(request.getMethod());
    System.out.println(request.getRequestURL());
    for (String hdr : Collections.list(request.getHeaderNames()))
    {
      for (String val : Collections.list(request.getHeaders(hdr)))
      {
        System.out.println(hdr + ": " + val);
      }
    }
    for (String param : Collections.list(request.getParameterNames()))
    {
      for (String val : request.getParameterValues(param))
      {
        System.out.println(param + "=" + val);
      }
    }
  }
}