import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class WriteRandomFile {  
	private RandomAccessFile output;
   
	private static final int NUMBER_RECORDS = 100;

	// enable user to choose file to open
	public void openFile() {
		try { // open file
			output = new RandomAccessFile( "clients.dat", "rw" );
		} 
		catch ( IOException ioException ) {
			System.err.println( "File does not exist." );
		} 
	} 

	// close file and terminate application
	public void closeFile()  {
		try { // close file and exit
			if ( output != null )
				output.close();
      	} 
		catch ( IOException ioException ) {
			System.err.println( "Error closing file." );
			System.exit( 1 );
		} 
	} 

	// add records to file
	public void addRecords() {
		// object to be written to file
		AccountRecord record = new AccountRecord();

		int accountNumber = 0; // account number for AccountRecord object
		String firstName; // first name for AccountRecord object
      	String lastName; // last name for AccountRecord object
      	double balance; // balance for AccountRecord object

      	Scanner input = new Scanner( System.in );

      	System.out.printf( "%s\n%s\n%s\n%s\n\n",
         "To terminate input, type the end-of-file indicator ",
         "when you are prompted to enter input.",
         "On UNIX/Linux/Mac OS X type <ctrl> d then press Enter",
         "On Windows type <ctrl> z then press Enter" );

      	System.out.printf( "%s %s\n%s", "Enter account number (1-100),",
         "first name, last name and balance.", "? " );

      	while (input.hasNext()) { // loop until end-of-file indicator
      		try { // output values to file
      			accountNumber = input.nextInt(); // read account number
      			firstName = input.next(); // read first name
      			lastName = input.next(); // read last name
      			balance = input.nextDouble(); // read balance

      			if ( accountNumber > 0 && accountNumber <= NUMBER_RECORDS ) {
      				record.setAccount( accountNumber );
      				record.setFirstName( firstName );
      				record.setLastName( lastName );
      				record.setBalance( balance );

      				output.seek( ( accountNumber - 1 ) * // position to proper
      						AccountRecord.SIZE ); // location for file
      				record.write( output );
            	} 
      			else
      				System.out.println( "Account must be between 0 and 100." );
      		} 
      		catch ( IOException ioException ) {
      			System.err.println( "Error writing to file." );
      			return;
      		}
         	catch ( NoSuchElementException elementException ) {
         		System.err.println( "Invalid input. Please try again." );
         		input.nextLine(); // discard input so user can try again
         	} 

         	System.out.printf( "%s %s\n%s", "Enter account number (1-100),",
         			"first name, last name and balance.", "? " );
      	} 
	} 
}