import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.net.URL;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JEditorPane;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.event.HyperlinkEvent;
import javax.swing.event.HyperlinkListener;

public class SimpleBrowser {
    private JDialog dialog;
    private JTextField urlField;
    private JEditorPane page;

    public SimpleBrowser(JFrame parent, URL url) {
        try {
            dialog = new JDialog(parent, url.toExternalForm());
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setSize(800, 800);

            // URL を表示するためのテキストフィールド
            JPanel panel = new JPanel();
            urlField = new JTextField(url.toExternalForm());
            urlField.addActionListener(new ActionListener() {
                    public void actionPerformed(ActionEvent event) {
                        go();
                    }
                });

            JButton goButton = new JButton("Go");
            goButton.addActionListener(new ActionListener() {
                    public void actionPerformed(ActionEvent event) {
                        go();
                    }
                });

            panel.setLayout(new BorderLayout());
            panel.add(new JLabel("URL: "), BorderLayout.WEST);
            panel.add(urlField, BorderLayout.CENTER);
            panel.add(goButton, BorderLayout.EAST);
            dialog.getContentPane().add(panel, BorderLayout.NORTH);
            

            // HTML を表示するために JEditorPane を使用する
            // JEditorPane は HTML3.2 までしか解釈できないので、
            // 正しく表示できないページも多い
            page = new JEditorPane(url);
            page.setEditable(false);
            page.setCaretPosition(0);

            // ハイパーリンクの設定
            page.addHyperlinkListener(new HyperlinkListener() {
                    public void hyperlinkUpdate(HyperlinkEvent event) {
                        if (event.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {
                            hyperlinkActivated(event.getURL());
                        }
                    }
                });

            dialog.getContentPane().add(new JScrollPane(page), BorderLayout.CENTER);
            
            JButton closeButton = new JButton("閉じる");
            closeButton.addActionListener(new ActionListener() {
                    public void actionPerformed(ActionEvent event) {
                        dialog.dispose();
                    }
                });

            panel = new JPanel();
            panel.setLayout(new FlowLayout(FlowLayout.RIGHT));
            panel.add(closeButton);

            dialog.getContentPane().add(panel, BorderLayout.SOUTH);
        } catch (IOException ex) {
            showErrorMessage(url.toExternalForm());
        }
    }

    public void show() {
        dialog.setVisible(true);
    }

    // テキストフィールドもしくは「Go」ボタンを押されたときの処理
    private void go() {
        String url = urlField.getText();

        try {
            dialog.setTitle(url);
            page.setPage(url);
            page.setCaretPosition(0);
        } catch (IOException ex) {
            showErrorMessage(url);
        }
    }

    // ハイパーリンクの処理
    // リンク先の HTML を表示する
    private void hyperlinkActivated(URL url) {
        try {
            dialog.setTitle(url.toExternalForm());
            urlField.setText(url.toExternalForm());
            page.setPage(url);
            page.setCaretPosition(0);
        } catch (IOException ex) {
            showErrorMessage(url.toExternalForm());
        }
    }

    private void showErrorMessage(String url) {
        JOptionPane.showMessageDialog(dialog,
                                     url + " の表示ができません",
                                     "Error",
                                     JOptionPane.ERROR_MESSAGE);
    }
}