import java.awt.*;
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import objectdraw.*;

/*
 * Search and Replace example
 */
//@width 800
//@height 550
public class SearchReplace extends Controller implements ActionListener {

    private JButton loadButton, srButton;
    private JTextArea text;

    private JTextField search;
    private JTextField replace;    
    
    
    public void begin() {
        
        this.resize(800,600);
        
        JPanel p = new JPanel();
        loadButton = new JButton("Load File");
        p.add(loadButton);

        srButton = new JButton("Search and Replace");
        p.add(srButton);

        p.add(new JLabel("Search: "));
        search = new JTextField(12);
        p.add(search);
        p.add(new JLabel("Replace: "));
        replace = new JTextField(12);
        p.add(replace);

        text = new JTextArea();
        text.setFont(new Font("Courier", Font.PLAIN, 16));
        getContentPane().add(new JScrollPane(text), BorderLayout.CENTER);
        getContentPane().add(p, BorderLayout.NORTH);

        loadButton.addActionListener(this);
        srButton.addActionListener(this);

        validate();
    }

    /**
     * Replace all occurrences of 'search' with 'replace' in text.  
     * 
     * Note:  This version finds an occurrence, replaces it, and then starts 
     * over from the beginning.
     */
    private String searchAndReplace(String search, String replace, String text) {
        // find first occurence of search string
        int pos = text.indexOf(search);

        while (pos > -1) {

            text = text.substring(0, pos) 
                + replace 
                + text.substring(pos + search.length());

            // start from end of replacement (in case replacement contains
            // the search string...
            pos = text.indexOf(search, pos + replace.length());

        }

        return text;
    }
    
    
    // Listener for button clicks that loads the
    // specified web pages and puts it in the
    // browser component.
    public void actionPerformed(ActionEvent event) {
        if (event.getSource() == loadButton) {
            loadFile();
        } else {
            text.setText(searchAndReplace(search.getText(), 
                                          replace.getText(), 
                                          text.getText()));
        } 
    }
    

    private void loadFile() {
        text.setText("");  // clear window

        JFileChooser chooser = new JFileChooser();
        if (chooser.showOpenDialog(this) == 
              JFileChooser.APPROVE_OPTION) {
            File file = chooser.getSelectedFile();
            try {
                // read in the file, appending each line
                // to the text window
                BufferedReader input = new BufferedReader(new 
                      FileReader(file));

                String line = input.readLine();
                while (line != null) {
                    text.append(line + "\n");
                    line = input.readLine();
                }

                input.close();
            } catch (IOException e) {
                JOptionPane.showMessageDialog(this, "Error: " + e);
            }
        }
    }
}