package glg_demos;

import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.imageio.*;
import java.awt.image.*;
import com.genlogic.*;

public final class GlgProcessServletSimple extends HttpServlet 
   implements GlgErrorHandler
{
   static final long serialVersionUID = 0;

   static GlgObject viewport = null;

   // Drawing path relative to the servlet app's dir.
   static String drawing_name = "/drawings/process2.glg";

   // Global simulated data used by all servlets.
   static GlgProcessDemoData data = new GlgProcessDemoData();

   /////////////////////////////////////////////////////////////////
   // A wrapper around the main method, doGet2(), to properly handle
   // the access synchronization and unlocking on an error.
   /////////////////////////////////////////////////////////////////
   public void doGet( HttpServletRequest request, 
                      HttpServletResponse response ) 
      throws ServletException
   { 
      try
      {
         doGet2( request, response );
      } 
      catch( Exception e ) 
      {
         // Unlock if was interrupted by the exception while locked.
         GlgObject.UnlockThread();

         throw new ServletException( e );  // Re-thow to log an error
      }

      // Unlock just in case the code did not do it due to a programming error.
      GlgObject.UnlockThread();
   }

   /////////////////////////////////////////////////////////////////
   // Main servlet's method: everything is handled here.
   /////////////////////////////////////////////////////////////////
   public void doGet2( HttpServletRequest request, 
                      HttpServletResponse response ) 
   {
      InitGLG();   // Init the Toolkit

      // Load the drawing (if first time) and update with data.

      // Get requested width/height of the image.
      int width = GetIntegerParameter( request, "width", 500 );
      int height = GetIntegerParameter( request, "height", 400 );

      // Limit max. size to avoid running out of heap space creating an image.
      if( width > 1000 ) width = 1000;       
      if( height > 1000 ) height = 1000;       

      // This example reuses the same drawing between all servlets' threads.
      // Therefore lock to synchronize and prevent other servlets from 
      // changing the drawing size, etc., before we are done.
      GlgObject.Lock();

      // Load drawing just once and share it among all servlets and threads.
      // Alternatively, each servlet may load its own drawing.
      if( viewport == null )    // First time: load the drawing.
      {
         viewport = LoadDrawing( drawing_name );
         viewport.SetImageSize( width, height );
         viewport.SetupHierarchy();    // Setup to prepare to receive data
      }
      else   // Already loaded, reuse the drawing.
        viewport.SetImageSize( width, height );
         
      ShowPipes( request );      // Show pipes and flow lines if requested.

      data.UpdateProcessData();  // Get the new data values from any source.

      UpdateDrawingWithData();   // Updates drawing with current data.

      // Setup after data update to prepare to generate image.
      viewport.SetupHierarchy();

      // Create an image of the viewport's graphics.
      BufferedImage image = (BufferedImage) viewport.CreateImage( null );

      GlgObject.Unlock();

      // Write the image
      try
      {
         response.setContentType("image/png");
         OutputStream out_stream = response.getOutputStream();
         ImageIO.write( image, "png", out_stream );
         out_stream.close();
      }
      catch( IOException e )
      {
         // Log( "Aborted writing of image file." );
      }
   }

   /////////////////////////////////////////////////////////////////
   // Helper methods
   /////////////////////////////////////////////////////////////////

   int GetIntegerParameter( HttpServletRequest request, String name, 
                           int default_value )
   {
      String parameter_string = request.getParameter( name );
      if( parameter_string == null || parameter_string.equals( "" ) )
        return default_value;

      try
      {
         return Integer.parseInt( parameter_string );
      }
      catch( NumberFormatException e )
      {
         Log( "Invalid parameter value for: " + name + 
             " = " + parameter_string );
         return default_value;
      }
   }

   /////////////////////////////////////////////////////////////////
   void Log( String msg )
   {
      getServletContext().log( "GlgProcessServletSimple: " + msg );
   }

   // GlgErrorHandler interface method for error handling.
   public void Error( String message )
   {
      Log( message );   // Log errors

      Log( GlgObject.GetStackTraceAsString() );   // Print stack
   }

   /////////////////////////////////////////////////////////////////
   void InitGLG()
   {
      // Set an error handler to log errors.
      GlgObject.SetErrorHandler( this );

      GlgObject.Init();    // Init GlgToolkit
   }

   /////////////////////////////////////////////////////////////////
   GlgObject LoadDrawing( String drawing_name )
   {
      // Get drawing URL relative to the servlet's directory.
      URL drawing_url = null; 
      try
      {
         drawing_url = 
            getServletConfig().getServletContext().getResource( drawing_name );
      }
      catch( MalformedURLException e )
      {
         Log( "Malformed URL: " + drawing_name );
         return null;
      }

      if( drawing_url == null )
      {
         Log( "Can't find resource: " + drawing_name );
         return null;
      }

      // Load drawing from the URL
      viewport = 
        GlgObject.LoadWidget( drawing_url.toString(), GlgObject.URL );
      if( viewport == null )
      {
         Log( "Can't load drawing: " + drawing_name );
         return null;
      }

      // Disable viewport border in the image: let html define it if needed.
      viewport.SetDResource( "LineWidth", 0. );

      return viewport;
   }

   //////////////////////////////////////////////////////////////////////////
   // Updates drawing state with data.
   //////////////////////////////////////////////////////////////////////////
   void UpdateDrawingWithData()
   {
      viewport.SetDResource( "SolventValve/Angle", data.SolventValve );
      viewport.SetDResource( "SteamValve/Angle",   data.SteamValve );
      viewport.SetDResource( "CoolingValve/Angle", data.CoolingValve );
      viewport.SetDResource( "WaterValve/Angle",   data.WaterValve );
      
      viewport.SetDResource( "Heater/SteamTemperature", 
                            data.SteamTemperature );
      viewport.SetDResource( "Heater/HeaterTemperature",
                            data.HeaterTemperature );
      viewport.SetDResource( "BeforePreHeaterTemperature",
                            data.BeforePreHeaterTemperature );
      viewport.SetDResource( "PreHeaterTemperature",
                            data.PreHeaterTemperature );
      viewport.SetDResource( "AfterPreHeaterTemperature",
                            data.AfterPreHeaterTemperature );
      viewport.SetDResource( "CoolingTemperature", data.CoolingTemperature );
      
      viewport.SetDResource( "Heater/HeaterLevel",        data.HeaterLevel );
      viewport.SetDResource( "WaterSeparator/WaterLevel", data.WaterLevel );
      
      viewport.SetDResource( "HeaterAlarm", data.HeaterAlarm ? 1. : 0 );
      viewport.SetDResource( "WaterAlarm", data.WaterAlarm ? 1. : 0 );
      
      viewport.SetDResource( "Graph/DataGroup/EntryPoint", 
                            data.HeaterTemperature );
      
      viewport.SetDResource( "PressureGauge/Value", 5. * data.HeaterPressure );
   }

   /////////////////////////////////////////////////////////////////
   // Shows pipes and flow lines if requested.
   // Constraints in the drawing take care of updating associated
   // toggle buttons when the pipe or flow line display state is 
   // changed. The last parameter of SetDResource() is set to true
   // to update the drawing only if the resource value gets changed.
   /////////////////////////////////////////////////////////////////
   void ShowPipes( HttpServletRequest request )
   {
      // Show pipes if requested, default 0.
      int show_pipes = GetIntegerParameter( request, "show_pipes", 0 );
      viewport.SetDResource( "3DPipes/Visibility", (double)show_pipes, true );

      // Show flow if requested, default 1.
      int show_flow = GetIntegerParameter( request, "show_flow", 1 );
      viewport.SetDResource( "FlowGroup/Visibility", (double)show_flow, true );
   }
}