#!/usr/bin/env perl

use Email::Simple;
use IO::File;

use strict;
use warnings;

die usage() unless $#ARGV == 0;
my $path = shift;

local $/;
my $email = Email::Simple->new(<>);

my $msgid = $email->header('Message-ID');
$msgid =~ s/<(.*)@.*>/$1/;

my $fh = IO::File->new(">$path/$msgid") ||
  die "Couldn't write to $path/$msgid: $!\n";
print $fh $email->as_string;
$fh->close;

sub usage {
  "Usage: $0 path\n";
}