use strict;
use warnings;

use Locale::Currency;
use File::Basename;
use Cache::FileCache;
use Finance::Quote;

die "usage: $0 amount currency_from currency_to\n"
    unless @ARGV == 3;

my $amount = shift @ARGV;

my ($currency_from, $currency_to) = map { uc } @ARGV;

for my $code ($currency_from, $currency_to) {
    die "sorry, currency $code not in ISO 4217\n"
        unless defined code2currency($code);
}

my ($filename) = fileparse($0, '.pl');

my $cache = Cache::FileCache->new({
    cache_root         => "$ENV{HOME}/.$filename",
    default_expires_in => '1 day',
});

my $quote = Finance::Quote->new();

my $ratio = $cache->get("$currency_from:$currency_to");

$ratio = $quote->currency($currency_from, $currency_to)
    unless defined $ratio;

die "sorry, cannot convert from $currency_from to $currency_to\n"
    unless defined $ratio;

$cache->set("$currency_from:$currency_to", $ratio);
print "$amount $currency_from = ", $amount * $ratio, " $currency_to\n";