#!/usr/bin/perl

use strict;
use warnings;
use Text::CSV_XS;
use Data::Dumper;

my $loc = "location.csv";
my $trans = "transaction.csv";
my $csv = Text::CSV_XS->new();
my %locations;

# error margin
my $delta = 10;

sub lookup_name {
    my ($href, $lat, $long) = @_;

    for my $k (keys %$href) {
        my ($lat2, $long2) = @{$href->{$k}};

        return $k if ((abs($lat - $lat2) < $delta) && (abs($long - $long2) < $delta));
    }

    return "Unknown";
}

open my $fh, "<", $loc or die "Can't open $loc: $!\n";

# skip header line
<$fh>;

while (my $rec = $csv->getline($fh)) {
    my ($lat, $long, $name) = (@$rec)[1, 2, 5];
    push @{$locations{$name}}, $lat, $long;
}
print Dumper( %locations );

$csv = Text::CSV_XS->new();
close($fh);
open $fh, "<", $trans or die "Can't open $trans: $!\n";

# skip header line
<$fh>;

while (my $rec = $csv->getline($fh)) {
    my @fields = @$rec;

    my ($lat, $long) = @fields[20, 21];
    my $name = lookup_name(\%locations, $lat, $long, $delta);

    {
        local $" = ", ";
        print "$name -> @fields\n";
    }
}