// Fig. 17.22: FileEditor.java
// This class declares methods that manipulate bank account
// records in a random access file.
import java.io.*;

import com.deitel.jhtp5.ch17.RandomAccessAccountRecord;

public class FileEditor {
   
   RandomAccessFile file; // reference to the file
   
   // open the file
   public FileEditor( File fileName ) throws IOException
   {
      file = new RandomAccessFile( fileName, "rw" );
   }
   
   // close the file
   public void closeFile() throws IOException
   {
      if ( file != null )
         file.close();
   }
   
   // get a record from the file
   public RandomAccessAccountRecord getRecord( int accountNumber )
      throws IllegalArgumentException, NumberFormatException, IOException
   {
      RandomAccessAccountRecord record = new RandomAccessAccountRecord();

      if ( accountNumber < 1 || accountNumber > 100 )
         throw new IllegalArgumentException( "Out of range" );

      // seek appropriate record in file
      file.seek( ( accountNumber - 1 ) * RandomAccessAccountRecord.SIZE );
      
      record.read( file );

      return record;

   } // end method getRecord
   
   // update record in file
   public void updateRecord( int accountNumber, String firstName, 
      String lastName, double balance )
      throws IllegalArgumentException, IOException
   {
      RandomAccessAccountRecord record = getRecord( accountNumber );
      if ( accountNumber == 0 )
         throw new IllegalArgumentException( "Account does not exist" );

      // seek appropriate record in file
      file.seek( ( accountNumber - 1 ) * RandomAccessAccountRecord.SIZE );   

      record = new RandomAccessAccountRecord( accountNumber,
         firstName, lastName, balance );
         
      record.write( file ); // write updated record to file
      
   } // end method updateRecord
   
   // add record to file
   public void newRecord( int accountNumber, String firstName, 
      String lastName, double balance )
      throws IllegalArgumentException, IOException
   {
      RandomAccessAccountRecord record = getRecord( accountNumber );
      
      if ( record.getAccount() != 0 )
         throw new IllegalArgumentException( "Account already exists" );

       // seek appropriate record in file
      file.seek( ( accountNumber - 1 ) * RandomAccessAccountRecord.SIZE );   

      record = new RandomAccessAccountRecord( accountNumber, 
         firstName, lastName, balance );
         
      record.write( file ); // write record to file
      
   } // end method newRecord
   
   // delete record from file
   public void deleteRecord( int accountNumber )
      throws IllegalArgumentException, IOException
   {
      RandomAccessAccountRecord record = getRecord( accountNumber );
      
      if ( record.getAccount() == 0 )
         throw new IllegalArgumentException( "Account does not exist" );
      
      // seek appropriate record in file
      file.seek( ( accountNumber - 1 ) * RandomAccessAccountRecord.SIZE );

      // create a blank record to write to the file
      record = new RandomAccessAccountRecord();
      record.write( file );
      
   } // end method deleteRecord
   
} // end class EditFile


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