use strict;
use vars qw(@Claim_Fields %Claim_Table);

@Claim_Fields = (
    [ 'claim_batch_number', 'N', 'A8' ],
    [ 'claim_number', 'N', 'A6' ],
    [ 'claim_type', 'L', 'A2'],
    [ 'payment_direct', 'N', 'A2'],
);
%Claim_Table = get_table();

##</code><code>##


Main:
{
    my $data_file = $ARGV[0];
    my $sort_by = $ARGV[1];
    open(CLAIMS, $data_file) or die "CANNOT OPEN FILE: $!";
    my @claim_records = ();
    while (<CLAIMS>) {
        push(@claim_records, read_record($_));
    }
    close(CLAIMS);

##</code><code>##

    &Sort_File($sort_by, @claim_records);
}

##</code><code>##


sub Sort_File {
    my ($sort_by, @claim_records) = @_;

    my $sort_sub;

    # If the sorting type is numeric
    if ( $Claim_Table{$sort_by} eq 'N' ) {

        # Create sub for numeric sort
        $sort_sub = sub { $a->{$sort_by} <=> $b->{$sort_by} };

    } # End if numeric

    # Otherwise it's lexical
    else {

        # Create sub for lexical sort
        $sort_sub = sub { $a->{$sort_by} cmp $b->{$sort_by} };

    }

    foreach my $record ( sort $sort_sub @claim_records ) {
        print STDOUT $record->{'claim_number'}, "\n";
    }
}

##</code><code>##

sub read_record {
    my ($line) = @_;
    my %claim_record = ();
    @claim_record{ get_fields() } = unpack( get_template(), $line);
    return \%claim_record;
}

##
## Returns all of the field names in @Claim_Fields
##
sub get_fields {
    my @fields = ();
    foreach my $claim_field ( @Claim_Fields ) {
        push(@fields, $claim_field->[0]);
    }
    return @fields;
}

##
## Builds the template from the template fields in @Claim_Fields
##
sub get_template {
    my $template = '';
    foreach my $claim_field ( @Claim_Fields ) {
        $template .= $claim_field->[2];
    }
    return $template;
}

##
## Builds a hash table for lookup from @Claim_Fields
##
sub get_table {
    my %table = ();
    foreach my $claim_field ( @Claim_Fields ) {
        $table{$claim_field->[0]} = $claim_field->[1];
    }
    return %table;
}