//SimpleDB
//Basic client-side read only database
//Andy Harris, 06/00

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

public class SimpleDB extends Applet {

  //Components
  Label[] lbl;
  TextField[] txt;
  Label lblRecNum = new Label("1");
  Button btnNext = new Button("Next");
  Button btnPrev = new Button("Prev");
  Button btnSearch = new Button("Search");
  Button btnAdd = new Button("Add");
  Button btnCopy = new Button("Copy");
  Panel pnlData = new Panel();
  Panel pnlLabels = new Panel();
  Panel pnlControl = new Panel();

  //Data Manipulation Variables
  String[] records = new String[100];
  int numFields = 0;
  int recNum = 0;
  int recordCount = 0;
  String dataFile = "pets.dat";

  //Custom classes
  EventHandler evt = new EventHandler();
  Prompt p;
  CopyFrame cf;
  
  public void init(){
    
    //make a prompt for input and warnings
    p = new Prompt((Frame)this.getParent());

    //get the datafile parameter from HTML
    dataFile = getParameter("DataFile");
    if (dataFile == null){
      p.say("Couldn't find file!!");
      dataFile = "pets.dat";
    } // end if

    //Basic Layout
    String myData = new String();
    setLayout(new BorderLayout());
    add(pnlData, BorderLayout.CENTER);
    add(pnlControl, BorderLayout.SOUTH);
    add(pnlLabels, BorderLayout.WEST);
    pnlData.setLayout(new GridLayout(0,1));
    pnlLabels.setLayout(new GridLayout(0,1));
    
    try {
      //grab the data
      URL dataURL = new URL(getDocumentBase(), dataFile);
      
      //create a reader to get data
      InputStream is = dataURL.openStream();
      InputStreamReader isr = new InputStreamReader(is);
      BufferedReader in = new BufferedReader(isr);
      
      String currentLine = in.readLine();
      //First line contains field names
      StringTokenizer st = new StringTokenizer(currentLine, "\t");

      //Figure out number of fields in database
      numFields = st.countTokens();

      //create arrays
      lbl = new Label[numFields];
      txt = new TextField[numFields];

      //Add the correct number of components
      for(int counter = 0; counter < numFields; counter++){
        lbl[counter] = new Label(st.nextToken());
        txt[counter] = new TextField();
	//txt[counter].setEditable(false);
	pnlLabels.add(lbl[counter]);
	pnlData.add(txt[counter]);
      } // end for loop

      //fill up the records array
      while ( currentLine != null){
        records[recNum] = currentLine;
        currentLine = in.readLine();
	recNum++;
      } // end loop
      
      //close up all the streams
      is.close();
      isr.close();
      in.close();

      //handle any exceptions that might have occurred  
    } catch (MalformedURLException exc){
      p.say("Error with URL");
    } catch (IOException exc) {
      p.say("Error getting data");
      dataFile = "pets.dat";
    } // end try
    
    //add the control pad
    pnlControl.setLayout(new GridLayout(1,0));
    pnlControl.add(new Label("Record #"));
    pnlControl.add(lblRecNum);
    pnlControl.add(btnPrev);
    pnlControl.add(btnCopy);
    pnlControl.add(btnSearch);
    pnlControl.add(btnAdd);
    pnlControl.add(btnNext);

    //register listeners
    btnPrev.addActionListener(evt);
    btnNext.addActionListener(evt);
    btnCopy.addActionListener(evt);
    btnAdd.addActionListener(evt);
    btnSearch.addActionListener(evt);
      
    //show first record
    recordCount = recNum - 1;
    recNum = 1;
    displayRec();

  } // end init

  private void storeRec(){
    //store the current record to the records[] array
    String currentLine = "";
    for(int counter = 0; counter < numFields; counter++){
      currentLine += txt[counter].getText();
      //don't put a tab after the last field
      if(counter < numFields -1){
        currentLine += "\t";
      } // end if
    } // end for loop
    records[recNum] = currentLine;
  } // end storeRec

  private void displayRec(){
    //Display the current record on the form
    String currentLine = records[recNum];
    StringTokenizer st = new StringTokenizer(currentLine, "\t");
    for(int counter = 0; counter < numFields; counter++){
      txt[counter].setText(st.nextToken());
    } // end for loop
    lblRecNum.setText(String.valueOf(recNum));
  } //end displayRec

  private void search(){
    //search for a record
    String currentLine = "";
    p.ask("Search for: ");
    String searchVal = p.getResponse();
    for (int i = 1; i < recordCount; i++){
      currentLine = records[i];
      if (currentLine.indexOf(searchVal) != -1){
	recNum = i;
	displayRec();
	p.say("Record found");
      } // end if
    } // end for
  } // end search

  private void copy(){
    //Display all records in a form suitable for copying
    //Use CopyFrame to do all the work
    cf = new CopyFrame();
  } // end copy
  
  private class EventHandler extends WindowAdapter implements ActionListener{
    //Handle most of the events for the database
    
    public void actionPerformed(ActionEvent e){
      if (e.getActionCommand().equals("Prev")){
        storeRec();
	recNum --;
	//trap for first record
        if (recNum < 1){
	  recNum = recordCount - 1;
	} // end if
        displayRec();
      } else if (e.getActionCommand().equals("Next")){
        storeRec();
        recNum++;
	//trap for last record
	if (recNum >= recordCount){
	  recNum = 1;
	} // end if
        displayRec();

      } else if (e.getActionCommand().equals("Search")){
        search();
      } else if (e.getActionCommand().equals("Copy")){
        copy();
      } else if (e.getActionCommand().equals("Add")){
        recordCount++;
        recNum = recordCount - 1;
        for(int counter = 0; counter < numFields; counter++){
          txt[counter].setText("");
        } // end for loop
        lblRecNum.setText(String.valueOf(recNum));
      } // end if
      
    } // end actionPerformed

    public void windowClosing(WindowEvent e){
      Window theWindow = (Window)e.getSource();
      theWindow.setVisible(false);
      theWindow.dispose();
    } // end windowClosing
    
  } // end EventHandler class

  private class CopyFrame extends Frame implements ActionListener{
    //class designed to encapsualte displaying data
    
    Label instructions = new Label("Use mouse to select and copy data");
    TextArea txtData = new TextArea();
    Panel pnlSouth = new Panel();
    Button btnClose = new Button("Close");
    
    public CopyFrame(){
      super("Copy Data");
      setLayout(new BorderLayout());

      add(instructions, BorderLayout.NORTH);
      add(txtData, BorderLayout.CENTER);
      pnlSouth.add(btnClose);
      add(pnlSouth, BorderLayout.SOUTH);

      for (int i = 0; i < recordCount; i++){
	txtData.append(records[i]);
	txtData.append("\n");
      } // end for loop

      setSize(300,200);
      setVisible(true);
      
      btnClose.addActionListener(this);
      addWindowListener(evt);
    } // end constructor

    //handle button here
    public void actionPerformed(ActionEvent e){
      setVisible(false);
      dispose();
    } // end actionPerformed
    
  } // end copyFrame classDef
    
} // end main class def