package inputOutput;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.Enumeration;

import java.util.zip.ZipFile;
import java.util.zip.ZipEntry;
import javax.swing.JComboBox;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;

/**
 *   Class to open a ZIP file, and display a list of files
 *   stored within it.
 *   When the user selects a ZIP file, the contents of the
 *   file (assumed to be text) are displayed in the text
 *   area.
 *
 *   @author Bryan J. Higgs, 19 September, 1999
 */
public class ReadZipFile2 extends JFrame
{
  /**
   *   Main entry point.
   */
  public static void main(String[] args)
  {
    try
    {
      // Set the system look and feel
      UIManager.setLookAndFeel( UIManager.getSystemLookAndFeelClassName() );
    } 
    catch (Exception ex)
    {
      // Ignore
    } 
    
    ReadZipFile2 frame = new ReadZipFile2();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
  }
  
  /**
   *   Constructor.
   */
  public ReadZipFile2()
  {
    setTitle("ZIP File Reader 2");
      
    // Set up frame menus
    JMenuBar menuBar = new JMenuBar();
    setJMenuBar(menuBar);
    
    JMenu fileMenu = new JMenu("File");
    menuBar.add(fileMenu);
    
    JMenuItem openItem = new JMenuItem("Open");
    fileMenu.add(openItem);
    openItem.addActionListener( new OpenAction() );
    
    JMenuItem exitItem = new JMenuItem("Exit");
    fileMenu.add(exitItem);
    exitItem.addActionListener( new ActionListener()
      {
        public void actionPerformed(ActionEvent event)
        {
          System.exit(0);
        }
      }
    );
    
    // Set the size of the combo box, and
    // hook it up to its actions
    m_fileList.setEditable(false);
    m_fileList.addItem("Use File->Open to select ZIP file");
    m_fileList.addActionListener( new ActionListener()
    {
      public void actionPerformed(ActionEvent event)
      {
        String item = (String) m_fileList.getSelectedItem();
        if (item != null)
          loadZipFile(item);
      }
    }
    );
    m_fileText.setEditable(false);
    m_fileText.setBackground(Color.WHITE);
    
    add(m_fileList, BorderLayout.SOUTH);
    add(new JScrollPane(m_fileText), BorderLayout.CENTER);
    pack();
  }
  
  /**
   *   Inner class to handle open file events.
   */
  private class OpenAction implements ActionListener
  {
    public void actionPerformed(ActionEvent event)
    {
      JFileChooser chooser = new JFileChooser();
      chooser.setCurrentDirectory( new File(".") );
      TypeFileFilter filter = new TypeFileFilter(".zip");
      filter.setDescription("ZIP files");
      chooser.setFileFilter(filter);
      int ret = chooser.showOpenDialog(ReadZipFile2.this);
      if (ret == JFileChooser.APPROVE_OPTION)
      {
        String zipFileName = chooser.getSelectedFile().getPath();
        scanZipFile(zipFileName);
      }
    }
  }
  
  /**
   * Scans the ZIP file and populates the combo box.
   */
  public void scanZipFile(String zipFileName)
  {
    // Clean out the list, in case it's already in use.
    m_fileList.removeAllItems();
    
    ZipEntry entry = null;
    try
    {
      // Close any previous zip file that
      // might have been open.
      if (m_zipFile != null)
      {
        m_zipFile.close();
        m_zipFile = null;
      }
      // Open the new Zip file
      m_zipFile = new ZipFile(zipFileName);
      // Go through all the entries and
      // populate the fileList combo box.
      Enumeration en = m_zipFile.entries();
      while (en.hasMoreElements())
      {
        entry = (ZipEntry)en.nextElement();
        m_fileList.addItem(entry.getName());
      }
    }
    catch (IOException ioe)
    {
      ioe.printStackTrace();
    }
  }
  
  /**
   *   Displays the files within the ZIP file,
   *   in the List component.
   */
  private void loadZipFile(String name)
  {
    InputStream in = null;
    try
    {
      // Get the Zip entry from the already open ZipFile
      ZipEntry entry = m_zipFile.getEntry(name);
      if (entry != null)
      {
        // Populate the text area with the contents of the entry.
        m_fileText.setText("");
        in = m_zipFile.getInputStream(entry);
        BufferedReader reader = 
                    new BufferedReader(
                            new InputStreamReader(in));
        String line;
        while ( (line = reader.readLine()) != null )
        {
          m_fileText.append(line + "\n");
        }
      }
    }
    catch (IOException ioe)
    {
      ioe.printStackTrace();
    }
    finally
    {
      try
      {
        if (in != null)
          in.close();
      } 
      catch (IOException ex)
      {
        // Ignore
      }
    }
  }
  
  /////// Private data /////////
  
  private JComboBox m_fileList = new JComboBox();
  private JTextArea m_fileText = new JTextArea(30, 80);
  private ZipFile   m_zipFile;
}