// File: Browser3.java
// Tim Balls : Sept 1999
// Adds a scroll area to the display
// Add a text input field to allow user to enter URL
// Needs changes to display - to incorporate input field
//		and additional event handling
// Command line parameter is now optional

// Displays the contents of a URL
// Can follow hyperlinks
// Uses Swing classes : JFrame and JEditorPane
// Adds JScrollPane - a controller for a JViewPort


import javax.swing.*;
import javax.swing.event.*;
import java.net.*;
import java.io.IOException;
import java.awt.event.*;
import java.awt.*;

public class Browser3 extends JFrame implements HyperlinkListener,
																ActionListener
{	public static void main( String[] args )
	{	if( args.length == 0 )
		{	new Browser3( "NoURL" );
		}
		else
		{	new Browser3( args[0] );
		}
	}

	private JEditorPane html = new JEditorPane();
	private URL url;
	private JTextField location;
	public Browser3( String site )
	{	setSize( 350, 450 );
		setTitle( "Scrolling Browser" );
		addWindowListener( new WindowAdapter() {
			public void windowClosing( WindowEvent e )
			{	System.exit( 0 );
			}
		});

		// Build more interesting interface
		location = new JTextField( site, 25 );  // 25 cols
		JPanel topLine = new JPanel();
		topLine.setLayout( new FlowLayout( FlowLayout.LEFT ) );
		topLine.add( new JLabel( "URL:" ) );
		topLine.add( location );
		location.addActionListener( this );
		
		// for the JFrame:
		this.getContentPane().setLayout( new BorderLayout() );
		this.getContentPane().add( topLine, BorderLayout.NORTH );

		if( !site.equals( "NoURL" ) )
		{	loadURL( site );
		}
		
		JScrollPane scroller = new JScrollPane();
		JViewport viewport = scroller.getViewport();
		viewport.add( html );
		
		this.getContentPane().add( scroller, BorderLayout.CENTER );
		html.setEditable( false ); // to allow links to be activated
		html.addHyperlinkListener( this );
		
		setVisible( true );
	}

	// When a hyperlink is "clicked" :-
	public void hyperlinkUpdate( HyperlinkEvent e )
	{	if (e.getEventType() == HyperlinkEvent.EventType.ACTIVATED)
		{	try
			{  html.setPage( e.getURL() );
			}
			catch( IOException ioe )
			{	System.out.println( "Can't load url: " + url );
				System.exit( 0 );
			}
		}
		// update text field
		location.setText( "" + e.getURL() );
	}
	
	// When a new URL is entered (and return pressed)
	public void actionPerformed( ActionEvent e )
	{	String site = location.getText();
		loadURL( site );
		// big assumption - it is legal and works!!
	}

	// Attempt to load the html JEditorPane from the URL at "site"
	private void loadURL( String site )
	{	try
		{	url = new URL( site );
		}
		catch( MalformedURLException e )
		{	System.out.println( "Invalid URL specified" );
			System.exit( 0 );
		}
		try
		{	html.setPage( url ); // load page
		}
		catch( IOException e )
		{	System.out.println( "Can't load url: " + url );
			System.exit( 0 );
		}
	}

}