// Fig. 17.10: CreditInquiry.java
// This program reads a file sequentially and displays the contents in a 
// text area based on the type of account the user requests 
// (credit balance, debit balance or zero balance).
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.text.DecimalFormat;
import javax.swing.*;

import com.deitel.jhtp5.ch17.AccountRecord;

public class CreditInquiry extends JFrame {  
   private JTextArea recordDisplayArea;
   private JButton openButton, creditButton, debitButton, zeroButton;
   private JPanel buttonPanel; 
        
   private ObjectInputStream input;
   private FileInputStream fileInput;
   private File fileName;
   private String accountType;
   
   static private DecimalFormat twoDigits = new DecimalFormat( "0.00" );

   // set up GUI
   public CreditInquiry()
   {
      super( "Credit Inquiry Program" );

      Container container = getContentPane();

      buttonPanel = new JPanel(); // set up panel for buttons
      
      // create and configure button to open file
      openButton = new JButton( "Open File" );
      buttonPanel.add( openButton );

      // register openButton listener
      openButton.addActionListener(

         // anonymous inner class to handle openButton event
         new ActionListener() {

            // open file for processing
            public void actionPerformed( ActionEvent event )
            {
               openFile();
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // create and configure button to get accounts with credit balances
      creditButton = new JButton( "Credit balances" );
      buttonPanel.add( creditButton );
      creditButton.addActionListener( new ButtonHandler() );

      // create and configure button to get accounts with debit balances
      debitButton = new JButton( "Debit balances" );
      buttonPanel.add( debitButton );
      debitButton.addActionListener( new ButtonHandler() );

      // create and configure button to get accounts with zero balances
      zeroButton = new JButton( "Zero balances" );
      buttonPanel.add( zeroButton );
      zeroButton.addActionListener( new ButtonHandler() );

      // set up display area
      recordDisplayArea = new JTextArea();
      JScrollPane scroller = new JScrollPane( recordDisplayArea );

      // attach components to content pane
      container.add( scroller, BorderLayout.CENTER );
      container.add( buttonPanel, BorderLayout.SOUTH );

      creditButton.setEnabled( false ); // disable creditButton
      debitButton.setEnabled( false );  // disable debitButton
      zeroButton.setEnabled( false );   // disable zeroButton

      // register window listener
      addWindowListener(

         // anonymous inner class for windowClosing event
         new WindowAdapter() {

            // close file and terminate program
            public void windowClosing( WindowEvent event )
            {
               closeFile();
               System.exit( 0 );
            }

         } // end anonymous inner class

      ); // end call to addWindowListener

      pack(); // pack components and display window
      setSize( 600, 250 );
      setVisible( true );

   } // end CreditInquiry constructor

   // enable user to choose file to open
   private void openFile()
   {
      // display dialog, so user can choose file
      JFileChooser fileChooser = new JFileChooser();
      fileChooser.setFileSelectionMode( JFileChooser.FILES_ONLY );

      int result = fileChooser.showOpenDialog( this );

      // if user clicked Cancel button on dialog, return
      if ( result == JFileChooser.CANCEL_OPTION )
         return;

      fileName = fileChooser.getSelectedFile(); // obtain selected file

      // display error if file name invalid
      if ( fileName == null || fileName.getName().equals( "" ) )
         JOptionPane.showMessageDialog( this, "Invalid File Name", 
            "Invalid File Name", JOptionPane.ERROR_MESSAGE );

      // open file
      try {

         // close file from previous operation
         if ( input != null )  
            input.close();   

         fileInput = new FileInputStream( fileName );
         input = new ObjectInputStream( fileInput );
         openButton.setEnabled( false );
         creditButton.setEnabled( true );
         debitButton.setEnabled( true );
         zeroButton.setEnabled( true );
      }

      // catch problems manipulating file
      catch ( IOException ioException ) {
         JOptionPane.showMessageDialog( this, "File does not exist", 
            "Invalid File Name", JOptionPane.ERROR_MESSAGE );
      }

   } // end method openFile
  
   // close file before application terminates
   private void closeFile()
   {
      // close file
      try {
          if ( input != null )
             input.close();
      }

      // process exception from closing file
      catch ( IOException ioException ) {
         JOptionPane.showMessageDialog( this, "Error closing file",
            "Error", JOptionPane.ERROR_MESSAGE );

         System.exit( 1 );
      }

   } // end method closeFile

   // read records from file and display only records of appropriate type
   private void readRecords()
   {      
      AccountRecord record;
      
      // read records
      try {
          
          if ( input != null )
             input.close();
      
         fileInput = new FileInputStream( fileName );
         input = new ObjectInputStream( fileInput );

         recordDisplayArea.setText( "The accounts are:\n" );

         // input the values from the file
         while ( true ) {

            // read one AccountRecord
            record = ( AccountRecord ) input.readObject();

            // if proper acount type, display record
            if ( shouldDisplay( record.getBalance() ) )
               recordDisplayArea.append( record.getAccount() + "\t" + 
                  record.getFirstName() + "\t" + record.getLastName() + 
                  "\t" + twoDigits.format( record.getBalance() ) + "\n" );
         }  
         
      } // end try

      // close file when end-of-file reached
      catch ( EOFException eofException ) {
         closeFile();
      }

      // display error if cannot read object because class not found
      catch ( ClassNotFoundException classNotFound ) {
         JOptionPane.showMessageDialog( this, "Unable to create object",
            "Class Not Found", JOptionPane.ERROR_MESSAGE );
      }

      // display error if cannot read because problem with file
      catch ( IOException ioException ) {
         JOptionPane.showMessageDialog( this, "Error reading from file",
            "Error", JOptionPane.ERROR_MESSAGE );
      }

   } // end method readRecords

   // use record type to determine if record should be displayed
   private boolean shouldDisplay( double balance )
   {
      if ( accountType.equals( "Credit balances" ) && balance < 0 )
         return true;

      else if ( accountType.equals( "Debit balances" ) && balance > 0 )
         return true;

      else if ( accountType.equals( "Zero balances" ) && balance == 0 )
         return true;

      return false;
   }
   
   public static void main( String args[] )
   {
      new CreditInquiry();
   }
 
   // class for creditButton, debitButton and zeroButton event handling
   private class ButtonHandler implements ActionListener {

      // read records from file
      public void actionPerformed( ActionEvent event )
      {
         accountType = event.getActionCommand();
         readRecords();
      }

   } // end class ButtonHandler

} // end class CreditInquiry

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