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

public class JSApplet extends Applet implements ActionListener {

        Socket socket = null;
        ObjectOutputStream os = null;
        ObjectInputStream is = null;

	Panel      north, center;
	Button     searchButton, clearButton;
	List       searchResults;

	public void init() {

		// build the applet display
		setLayout(new BorderLayout());

		north = new Panel();
		north.setLayout(new FlowLayout());

		searchButton = new Button("Begin Search");
		searchButton.addActionListener(this);
		north.add(searchButton);

		clearButton = new Button("Clear Data");
		clearButton.addActionListener(this);
		north.add(clearButton);
		add("North", north);

		searchResults = new List();
		add("Center", searchResults);

		if (connectToServer()) {
			openDatabase();
		}
		else {
			showStatus("Cannot open socket connection.");
		}
	}

	public boolean connectToServer() {
	        try {
			socket = new Socket(getCodeBase().getHost(), 9000);
			os = new ObjectOutputStream(socket.getOutputStream());
			is = new ObjectInputStream(socket.getInputStream());
	        } catch (Exception ex) {
			showStatus(ex.toString());
			return false;
	        }

		return true;
	}

	public void openDatabase() {
		String ack;
		send("open");
		ack = (String)receive();
		if (ack != null)
			showStatus(ack);
	}

	public void send(Object o) {
		try {
			os.writeObject(o);
			os.flush();
		} catch (Exception ex) {
			showStatus(ex.toString());
		}
	}

	public Object receive() {
		Object o = null;
		try {
			o = is.readObject();
		} catch (Exception ex) {
			showStatus(ex.toString());
		}

		return o;
	}

	public void finalize() {
		try {
			send("close");
			os.close();
			is.close();
			socket.close();
		} catch (Exception ex) {}

		super.destroy();
	}

	public void actionPerformed(ActionEvent e) {
		if (e.getActionCommand().equals("Begin Search")) {
			try {
				performSearch();
			} catch (Exception ex) {
				showStatus(ex.toString() + ": Can't issue search");
			}
		}
		else {
			clearListBox();
		}

		return;
	}

	/** Clear the contents of the list box */
	public void clearListBox() {
		searchResults.removeAll();
	}

	/** Issue a SQL query with a WHERE clause */
	public void performSearch() throws Exception {

		Object result;		// Row retrieved from query

		clearListBox();
		send("srch");
		result = receive();
		if (result.equals("ok")) {
			processResults();
		}
		else {
			showStatus((String)result);
		}
	}

	public void processResults() {
		Object result;
		send("fetch");
		result = receive();
		if (result == null) {
			showStatus("No rows found using specified search criteria.");
			return;
		}

		while (result != null) {
			searchResults.addItem((String)result);
			send("fetch");
			result = receive();
		}
	}
}