#!/usr/bin/perl
# Copyright (c) 2003  Malte S. Stretz <spamassassin at msquadrat dot de>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of either the Artistic License or the GNU General
# Public License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.


use strict;
use bytes;

use vars qw {
  $opt_f $opt_h
};

use Getopt::Std;
getopts("f:h");

sub usage {
  die "extract-message-from-mbox [-f=file] offset

  Extracts the message starting at offset from file (or stdin). Very useful in
  combination with mass-check logs and mboxes.
";
}

usage() if($opt_h || !defined($ARGV[0]));
my $offset = $ARGV[0];


if($opt_f) {
  do_file($opt_f, $offset);
} else {
  do_stdin($offset);
}

sub do_file {
  my ($in, $offset) = @_;
  open (STDIN, "<$in") or die "Cannot open '$in': $!";
  do_stdin($offset);
  close STDIN;
}

sub do_stdin {
  my ($offset) = @_;
  my $found = 0;

  while(<STDIN>) {

    unless($found) {
      $offset -= length;
      $found = $offset <= 0;
    }
    else {
      $found++ if(/^From /);
      last if($found == 3);
      print;
    }
  }
}