import java.applet.*;       // contains class Applet
import java.net.*;          // contains URL
import java.awt.*;          // contains TextArea, Button, FlowLayout
import java.awt.event.*;    // contains WindowListener, ActionEvent
import java.io.*;           // contains InputStream, OutputStream

public class TA extends Applet
 { // The following two functions convert a TextArea into an InputStream and
   // an OutputStream respectively.  They can be used to produce such streams
   // for a (suitably parameterised) command-line application that requires
   // an InputStream (System.in, stdin) & a PrintStream (System.out, stdout)
   // (and System.err, stderr) when the application is being run as an Applet.

   public InputStream textArea2InputStream(final TextArea ta)
    { return new InputStream()
       { String s = ta.getText();  int inPtr=0;
         public int read()  //minimum implementation of an InputStream
          { if( inPtr >= s.length() ) return -1;
            else { inPtr++; return s.charAt(inPtr-1); }
          }//read
       };//InputStream
    }//textArea2InputStream

   public OutputStream textArea2OutputStream(final TextArea t)
    { return new OutputStream()
       { TextArea ta = t;
         public void write(int b) //minimum implementation of an OutputStream
          { byte[] bs = new byte[1]; bs[0] = (byte) b;
            ta.append(new String(bs));
          }//write
       };//OutputStream
    }//textArea2OutputStream
   //
   // NB. There is a constructor PrintStream(OutputStream).
   //
   // OutputStream
   //  |-FilterOutputStream
   //     |-PrintStream


   public URL relativeURL(URL base, String relPath)
   throws MalformedURLException
   // Basically base/filename, but may chop a last filename off base first,
   // e.g., see class Applet, getDocumentBase() etc.
    {  String db = base.toString();
       int pathEnd = db.lastIndexOf(File.separatorChar);  // i.e. \ or /
       return new URL( db.substring(0, 1+pathEnd) + relPath );
    }//relativeURL(,)

   public String urlContents(URL url) throws IOException
   // Read a file at a URL and return its contents as a String
    { InputStream ins = url.openStream();
      StringBuffer sb = new StringBuffer();  int ch;
      while( (ch = ins.read()) >= 0 ) sb.append( (char)ch );
      return sb.toString();
    }//urlContents

// ----------------------------------------------------------------------------

   // Following is a rudimentary test that TextArea can be made into
   // InputStream and OutputStream

   public void init()                                   // Applet requires init
    { this.setLayout(new FlowLayout(FlowLayout.LEFT));

      final TextArea    tIp  = new TextArea("initial input\n", 5, 20);

      final TextArea    tOp  = new TextArea(5, 20);
      final PrintStream opSt = new PrintStream(textArea2OutputStream(tOp)); // *

      Button b1 = new Button("ip->op");              // appends input to output
      b1.addActionListener(
         new ActionListener()
          { public void actionPerformed(ActionEvent e)
             { int ch;
               InputStream ipSt = textArea2InputStream( tIp );             // *
               try{ // in the spec., read(), write() could throw IOException
                  while( (ch = ipSt.read()) > 0 )                       // read
                     opSt.print( (char)ch );                           // print
               }catch(Exception _) { }
          }  } );

      final Button b2 = new Button("clear");          // clears the output area
      b2.addActionListener( new ActionListener()
          { public void actionPerformed(ActionEvent e) { tOp.setText(""); } }
        );

      this.add("ip", tIp);  this.add("b1", b1);
      this.add("op", tOp);  this.add("b2", b2);

      final String inFileName = getParameter("INPUT");   //maybe a file to load
      if( inFileName != null )                        //into the input TextArea
      try{ tIp.setText(urlContents(relativeURL(getDocumentBase(), inFileName)));
         }
      catch(Exception e)
        { opSt.print( "Error in loading [" + inFileName + "]\n"
                    + e.toString() ); }
// ----------------------------------------------------------------------------

      try{ final Button home = new Button("home");
           final URL homeURL = new URL("http://www.allisons.org/ll/");
           home.addActionListener(
              new ActionListener()
               { public void actionPerformed(ActionEvent _)
                  { getAppletContext().showDocument( homeURL, "_top" ); }
               } );
           this.add("home", home);
      } catch(MalformedURLException _) { }

    }//init of the Applet

 }//TA class


// Lloyd Allison, 19/9/2007, licence of this applet is GNU GPL "copyleft".