// DbApplet.java

import  java.applet.*;
import  java.awt.*;
import  java.util.*;

public abstract
    class   DbApplet
    extends Applet
    {
    private Button          oButtonDelete;
    private Button          oButtonInsert;
    private Button          oButtonSelect;
    private Button          oButtonUpdate;
    private ObjectApplet    oApplet;
    private DbManager       oDbManager;

// ABSTRACT METHODS

    public abstract
        String          dbName
        (
        );

    public abstract
        ObjectWithUI    newObject
        (
        );

    protected abstract
        DbManager       newDbManager
        (
        );

// PUBLIC METHODS

    public
        void            init
        (
        )
        {
        super.init();
        try {
            oDbManager = newDbManager();
            }
            catch (Exception x)
                {
                System.out.println("DbApplet error: "+x.getMessage());
                x.printStackTrace();
                };
        setLayout(new GridLayout(1,5,5,5));
        oButtonDelete   = new Button("Delete");
        oButtonInsert   = new Button("Insert");
        oButtonSelect   = new Button("Select");
        oButtonUpdate   = new Button("Update");
        oApplet         = newObject().getUI();
        add(oButtonDelete);
        add(oButtonInsert);
        add(oButtonSelect);
        add(oButtonUpdate);
        add(oApplet);
        }

    public
        boolean handleEvent
        (
        Event   poEvent
        )
        {
        boolean t = false;
        int i;
        try {
            if (Event.ACTION_EVENT == poEvent.id)
                try {
                    if      (t = poEvent.target == oButtonDelete)
                        {
                        i = oDbManager.dbDelete(dbName(),oApplet.getObject());
                        showStatus("Deleted "+i+" item"+(i > 1 ? "s" : ""));
                        }
                    else if (t = poEvent.target == oButtonInsert)
                        {
                        i = oDbManager.dbInsert(dbName(),oApplet.getObject());
                        showStatus("Inserted "+i+" item"+(i > 1 ? "s" : ""));
                        }
                    else if (t = poEvent.target == oButtonSelect)
                        {
                        ListApplet      oListApplet;
                        Frame           oFrame;
                        ObjectWithUI    oObject;
                        Vector          oVector;
                        oObject     = (ObjectWithUI)oApplet.getObject();
                        oVector     = oDbManager.dbSelect(dbName(),oObject);
                        oListApplet = new ListApplet(oObject.getUI());
                        oListApplet.setVector(oVector);
                        new AppletFrame(oListApplet).resize(300,125);
                        i = oVector.size();
                        showStatus("Selected "+i+" item"+(i > 1 ? "s" : ""));
                        }
                    else if (t = poEvent.target == oButtonUpdate)
                        {
                        new AppletFrame(
                                new UpdateApplet(
                                        oDbManager,
                                        dbName(),
                                        (ObjectWithUI)oApplet.getObject(),
                                        (ObjectWithUI)newObject()))
                                .resize(400,150);
                        showStatus("Updating");
                        }
                    }
                    finally
                        {
                        if (t) oApplet.setObject(newObject());
                        };
            }
            catch (Exception x)
                {
                System.out.println("DbApplet error: "+x.getMessage());
                x.printStackTrace();
                }
        return t ? t : super.handleEvent(poEvent);
        }
    }