/*
 * Read a file that contains lines of the form
 * last, first
 * Output those lines into another file, in the
 * form first last
 * Illustrates reference parameters, input files, output files
 * This program is deliberately missing comments.
 */

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

void openInput( string & infile, ifstream & fin );
void openOutput( string infile, string outfile, ofstream & fout );
void copyFiles( istream & fin, ostream & fout );
void getNames( string name, string & first, string & last );

int main( )
{
    string infile;  // Input file name
    string outfile; // Output file name
    ifstream fin;     // Input file stream
    ofstream fout;    // Output file stream

    openInput( infile, fin );
    openOutput( infile, outfile, fout );
    copyFiles( fin, fout );

    return 0;
}


/**
 * Usual stuff; you should copy this.
 */
void openInput( string & infile, ifstream & fin )
{
    for( ; ; )
    {
        cout << "Enter the input file name: ";
        cin >> infile;
        fin.open( infile.c_str( ) );
        if( !fin )
        {
           cout << "Bad file." << endl;
           fin.clear( );
        }
        else
           break;
    }
}


/**
 * Usual stuff. This routine also checks to
 * make sure that outfile is different from infile.
 * To avoid this test, call it with infile equal to "".
 */
void openOutput( string infile, string outfile, ofstream & fout )
{
    for( ; ; )
    {
        cout << "Enter the output file name: ";
        cin >> outfile;
        if( infile == outfile )
        {
            cout << "Input and output files are identical!!" << endl;
            continue;
        }
        fout.open( outfile.c_str( ) );
        if( !fout )
        {
           cout << "Bad file." << endl;
           fout.clear( );
        }
        else
           break;
    }
}


/**
 * Copy from fin to fout.
 * Uses getline to read an entire line of input in as a string.
 * Needed because there are blanks on the line.
 * getline also works with cin.
 */
void copyFiles( istream & fin, ostream & fout )
{
    string name, firstName, lastName;

    while( !getline( fin, name ).eof( ) )
    {
        getNames( name, firstName, lastName );
        fout << firstName << " " << lastName << endl;
    }
}


/**
 * Extract firstName and lastName from name.
 * pre: name is of the form last, first
 * post: lastName and firstName are filled in.
 */
void getNames( string name, string & firstName, string & lastName )
{
    int commaPos = name.find( "," );
    lastName = name.substr( 0, commaPos );
    firstName = name.substr( commaPos + 2, name.length( ) - ( commaPos + 2 ) );
}