import java.sql.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
import java.rmi.*;
import java.rmi.registry.*;

public class JRApplet extends Applet implements ActionListener {

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

	int	   connectionId;
	JR         servlet;

	public void init() {

		String	registryName;

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

		north = new Panel();
		north.setLayout(new FlowLayout());
		north.add(new Label("Search Criteria:"));
		searchCriteria = new TextField(40);
		north.add(searchCriteria);

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

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

		searchResults = new List();
		add("Center", searchResults);
		validate();
		setVisible(true);

		try {
			// get the host name where the applet was loaded
			registryName = "//" + getCodeBase().getHost() + "/";

			// append the name of the remote object within the registry
			registryName += "jdbcrmi";

			// obtain a reference to the remote object
	                servlet = (JR)Naming.lookup(registryName);
		} catch (Exception e) {

			showStatus("Cannot connect to RMI registry for jdbcrmi");
			return;
		}

		try {
			connectionId = servlet.openDatabase();

			if (connectionId == -1) {
				searchResults.addItem("Cannot open database connection.");
			}
		} catch (Exception ex) {
			searchResults.addItem("Cannot open database connection.");
		}
	}

	public void finalize() {
		try {
			servlet.closeDatabase(connectionId);
		} catch (Exception ex) {}
		super.destroy();
	}

	/* handle applet's action events */
	public void actionPerformed(ActionEvent e) {
		if (e.getActionCommand().equals("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 {

		String searchString;	// SQL where clause
		String result;		// Row retrieved from query

		clearListBox();
		searchString = searchCriteria.getText();
		servlet.performSearch(connectionId, searchString);
		result = servlet.getNextRow(connectionId);
		if (result == null) {
			showStatus("No rows found using specified search criteria.");
			return;
		}

		while (result != null) {
			searchResults.addItem(result);
			result = servlet.getNextRow(connectionId);
		}
	}
}