package PM::FixedWidthFile;

use strict;
use warnings;
use autodie;

use Exporter qw{import};
our @EXPORT_OK = qw{populate_file};

use Carp;

sub populate_file {
    my ($fh, $record_length, $field_data) = @_;

    for my $fields (@$field_data) {
        my $line = pack 'A' . $record_length;
        my $offset = 0;
        _add_field(\$line, \$offset, @$_) for @$fields;
        print {$fh} $line, "\n";
    }   

    return;
}

sub _add_field {
    my ($line_ref, $offset_ref, $length, $data, $r_align) = @_;

    if ($length < length $data) {
        croak "Data [$data] too large for field of length [$length]";
    } 

    my @dat_pad = ($data, ' ' x ($length - length $data));
    substr($$line_ref, $$offset_ref, $length)
        = join '' => @dat_pad[$r_align ? (1, 0) : (0, 1)];
    $$offset_ref += $length;

    return;
}   

1;

=head1 NAME

PM::FixedWidthFile - TODO (for Jake): module documentation in POD format