#! /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.

require "time"
require "fileutils"

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

class NullWriter
  def write(s)
    # nop
  end
end

def convert_next_mail(mbx, output)
  match_data = nil
  loop do
    l = mbx.gets
    break if l.nil?
    match_data = SEPARATOR.match(l)
    break if match_data
    output.write(l)
  end
  return match_data ? [Time.parse(match_data[1]), match_data[2].to_i] : nil
end

def skip_mbx_header(mbx)
  return convert_next_mail(mbx, NullWriter.new)
end

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

FileUtils.mkdir_p(mh_dirname)

count = 0
open(mbx_filename) do |mbx|
  mail_time, length = *skip_mbx_header(mbx)

  while mail_time
    output_filename = File.join(mh_dirname, count.to_s)
    next_mail_time = nil
    open(output_filename, "w") do |mh|
      next_mail_time, length = *convert_next_mail(mbx, mh)
    end
    File.utime(Time.now, mail_time, output_filename)
    mail_time = next_mail_time
    count += 1
    puts("wrote #{count} mails.") if (count % 100).zero?
  end

  puts("wrote #{count} mails.")
end