#! /usr/bin/ruby

# Copyright (c) 2007 Yuya.Nishida.
# 
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
# ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
# THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

SEPARATOR =
  /\A(\0*\d{2}-\w{3}-\d{4} \d{2}:\d{2}:\d{2} \+\d{4},)(\d+)(;\d+-\w+\r\n)\z/

MbxMailHeader = Struct.new(:head, :length, :tail)

in_filename = ARGV.shift
out_filename = ARGV.shift
if out_filename.nil?
  STDERR.puts("usage: #{File.basename($0)} in_filename out_filename")
  exit(1)
end

open(in_filename) do |in_file|
  open(out_filename, "w") do |out_file|
    # output mbx header
    out_file.write(in_file.read(2048))
    l = in_file.gets
    match_data = SEPARATOR.match(l)

    # processing mails
    count = 0
    while match_data
      count += 1
      header = MbxMailHeader.new(*match_data.captures)
      match_data = nil

      mail = ""
      while l = in_file.gets
        match_data = SEPARATOR.match(l)
        break if match_data
        mail << l
      end

      if header.length.to_i != mail.length
        puts("miss-matched size mail[#{count}]: header (#{header.length}) != mail size (#{mail.length})")
        header.length = mail.length
      end

      out_file.write(header.values.join)
      out_file.write(mail)

      puts("wrote #{count} mails.") if $DEBUG && (count % 100).zero?
    end
    puts("wrote #{count} mails.")
  end
end