package server;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

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

import com.facebook.thrift.TException;
import com.facebook.thrift.TProcessor;
import com.facebook.thrift.protocol.TBinaryProtocol;
import com.facebook.thrift.protocol.TProtocol;
import com.facebook.thrift.protocol.TProtocolFactory;
import com.facebook.thrift.transport.TIOStreamTransport;
import com.facebook.thrift.transport.TTransport;
import com.facebook.thrift.transport.TTransportException;
import com.facebook.thrift.transport.TTransportFactory;

/**
 * <p>
 * A servlet for exposing Thrift services over HTTP. To use, create a subclass that
 * supplies a {@link TProcessor}. For example,
 * </p>
 * <pre>
 * public class CalculatorTServlet extends TServlet {
 *   public CalculatorTServlet() {
 *     super(new Calculator.Processor(new CalculatorHandler()));
 *   }
 * }
 * </pre>
 * <p>
 * This code is based heavily on {@link com.facebook.thrift.server.TSimpleServer}.
 * </p>
 * @author Tom White
 */
public class TServlet extends HttpServlet {
  protected TProcessor processor_ = null;
  protected TTransportFactory inputTransportFactory_ = new TTransportFactory();
  protected TTransportFactory outputTransportFactory_ = new TTransportFactory();
  protected TProtocolFactory inputProtocolFactory_ = new TBinaryProtocol.Factory();
  protected TProtocolFactory outputProtocolFactory_ = new TBinaryProtocol.Factory();
  
  public TServlet(TProcessor processor) {
    processor_ = processor;
  }

  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
	  
    response.setContentType("application/x-thrift");
    InputStream in = request.getInputStream();
    OutputStream out = response.getOutputStream();
    
    TTransport client = new TIOStreamTransport(in, out);
    TProcessor processor = null;
    TTransport inputTransport = null;
    TTransport outputTransport = null;
    TProtocol inputProtocol = null;
    TProtocol outputProtocol = null;
    try {
      processor = processor_;
      inputTransport = inputTransportFactory_.getTransport(client);
      outputTransport = outputTransportFactory_.getTransport(client);
      inputProtocol = inputProtocolFactory_.getProtocol(inputTransport);
      outputProtocol = outputProtocolFactory_.getProtocol(outputTransport);
      while (processor.process(inputProtocol, outputProtocol)) {}
    } catch (TTransportException ttx) {
      // Client died, just move on
    } catch (TException tx) {
      tx.printStackTrace();
    } catch (Exception x) {
      x.printStackTrace();
    }

    if (inputTransport != null) {
      inputTransport.close();
    }

    if (outputTransport != null) {
      outputTransport.close();
    }
      
  }
}