//**************************************************************************
// GetURLInfo.java:     Applet
//
//**************************************************************************

/* <applet code="GetURLInfo.class" name="GetURLInfo" width="500" height="300">
   <param name="Address" value="http://www.eng.uab.edu">
   </applet>
 */

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import java.util.*;

//==========================================================================
// Main Class for applet GetURLInfo
//
//==========================================================================
public class GetURLInfo extends Applet implements Runnable, ActionListener
{
    private Thread   m_GetURLInfo = null;

    // PARAMETER SUPPORT:
    // Parameters allow an HTML author to pass information to the applet;
    // the HTML author specifies them using the <PARAM> tag within the <APPLET>
    // tag.  The following variables are used to store the values of the
    // parameters.
    //----------------------------------------------------------------------

    // Members for applet parameters
    // <type>       <MemberVar>    = <Default Value>
    //----------------------------------------------------------------------
    private String m_Address = "http://www-ece.eng.uab.edu";

    // Parameter names.  To change a name of a parameter, you need only make
    // a single change.  Simply modify the value of the parameter string below.
    //----------------------------------------------------------------------
    private final String PARAM_Address = "Address";

    // UI Controls
    private Button get_button;
    private TextField url_text;
    private TextArea  url_info;
    
    private boolean threadflag = false;

    // GetURLInfo Class Constructor
    //----------------------------------------------------------------------
    public GetURLInfo()
    {
        // TODO: Add constructor code here
    }

    // APPLET INFO SUPPORT:
    // The getAppletInfo() method returns a string describing the applet's
    // author, copyright date, or miscellaneous information.
    //----------------------------------------------------------------------
    public String getAppletInfo()
    {
        return "Name: GetURLInfo\r\n" +
            "Author: David Green\r\n" +
            "Created with Microsoft Visual J++ Version 1.1";
    }

    // PARAMETER SUPPORT
    // The getParameterInfo() method returns an array of strings describing
    // the parameters understood by this applet.
    //
    // GetURLInfo Parameter Information:
    //  { "Name", "Type", "Description" },
    //--------------------------------------------------------------------------
    public String[][] getParameterInfo()
    {
        String[][] info =
        {
            { PARAM_Address, "String", "URL of where to get data" },
        };
        return info;            
    }

    // The init() method is called by the AWT when an applet is first loaded or
    // reloaded.  Override this method to perform whatever initialization your
    // applet needs, such as initializing data structures, loading images or
    // fonts, creating frame windows, setting the layout manager, or adding UI
    // components.
    //----------------------------------------------------------------------
    public void init()
    {
        // PARAMETER SUPPORT
        // The following code retrieves the value of each parameter
        // specified with the <PARAM> tag and stores it in a member
        // variable.
        //------------------------------------------------------------------
        String param;
        
        // Address: URL of where to get data
        //------------------------------------------------------------------
        param = getParameter(PARAM_Address);
        if (param != null)
            m_Address = param;

        resize(500, 300);

        // build UI
        this.add( new Label("URL to get:"));
        
        url_text = new TextField( m_Address, 40 );
        url_text.setBackground(Color.white);
        url_text.setForeground(Color.black);
        this.add( url_text );
        
        get_button = new Button("Get");
        get_button.setForeground(Color.black);
        get_button.setBackground(Color.lightGray);
        
        get_button.addActionListener(this); 
        this.add(get_button);
        
        url_info = new TextArea( "", 18,60, TextArea.SCROLLBARS_BOTH );
        url_info.setBackground(Color.white);
        url_info.setForeground(Color.black);
        this.add( url_info);
    }

    // The start() method is called when the page containing the applet
    // first appears on the screen. The AppletWizard's initial implementation
    // of this method starts execution of the applet's thread.
    //----------------------------------------------------------------------
    public void start()
    {
        if (m_GetURLInfo == null)
        {
            m_GetURLInfo = new Thread(this);
            threadflag = true;
            m_GetURLInfo.start();
        }
        // TODO: Place additional applet start code here
        }
    
    // The stop() method is called when the page containing the applet is
    // no longer on the screen. The AppletWizard's initial implementation of
    // this method stops execution of the applet's thread.
    //----------------------------------------------------------------------
    public void stop()
    {
        if (m_GetURLInfo != null)
        {
            threadflag = false;
            m_GetURLInfo = null;
        }
        
        // TODO: Place additional applet stop code here
    }

    // THREAD SUPPORT
    // The run() method is called when the applet's thread is
    // started. If your applet performs any ongoing activities without
    // waiting for user input, the code for implementing that behavior
    // typically goes here. For example, for an applet that performs
    // animation, the run() method controls the display of images.
    //----------------------------------------------------------------------
    public void run()
    {
        while (threadflag)
        {
            try
            {
                repaint();
                // TODO:  Add additional thread-specific code here
                Thread.sleep(50);
            }
            catch (InterruptedException e)
            {
                // TODO: Place exception-handling code here in case an
                //       InterruptedException is thrown by Thread.sleep(),
                //       meaning that another thread has interrupted this one
                stop();
            }
        }
    }

    // Event handler for button clicking
    public void actionPerformed(ActionEvent event)
    {
        // If the Get button was clicked, handle it
        if (event.getSource() == get_button)
        {
            url_info.setText(read_url_info());
        }
    }
		
    private String read_url_info()
    {
        String result;
        try {
            
            URL url = new URL( (String) url_text.getText() );
            URLConnection conn = url.openConnection();
            
            result = conn.getURL().toExternalForm() + ":\n" ;
            result += "  Content Type: " + conn.getContentType() + "\n";
            result += "  Content Length: " + conn.getContentLength() + "\n";
            result += "  Last Modified: " + new Date(conn.getLastModified()) + "\n";
            result += "  Expiration: " + conn.getExpiration() + "\n";
            result += "  Content Encoding: " + conn.getContentEncoding() +"\n";
            
            // Read and print out the first five lines of the URL.
            result += "First five lines:\n";
            
            InputStreamReader in = new InputStreamReader(conn.getInputStream());
            BufferedReader br = new BufferedReader(in);
            
            for(int i = 0; i < 5; i++) {
                String line = br.readLine();
                if (line == null) break;
                result += "  " + line + "\n";
            }
        }
        catch ( Exception e )
        {
            result = e.toString() + "\n";
        }
                
        return result;
    }
}