SoftBank Mail backup (.mbk) to .eml splitter

mbk2eml.rb

#!/usr/bin/env ruby
#
# mbk2eml.rb - mbk to eml splitter
# 
# The .mbk file is the backup file of SoftBank Mail.
# This script splits .mbk file to .eml file.
# The .mbk files can be found from below directory.
# /storage/emulated/0/private/SBMAIL/MBK/
#
# SoftBank mail
# https://play.google.com/store/apps/details?id=jp.softbank.mb.mail&hl=ja
#

require 'time'

stamp = nil
s = stat = ""
i = 0

open(ARGV[0], "r"){|fp|
  while fp.gets
    stat = :vbodybegin if $_ =~ /^BEGIN:VBODY\r\n$/
    stat = :vbodyend   if $_ =~ /^END:VBODY\r\n$/
    
    case stat
    when :vbodyend
      fn = "#{i}.eml"
      p fn
      open(fn, "w") {|fp|
        fp.write(s)
      }
      File.utime(stamp, stamp, fn) unless stamp.nil?
      stamp = nil
      i += 1
      s = stat = ""
    when :vbodybegin
      stat = :vbody1
    when :vbody1
      if $_ =~ /^Date: /
        stamp = Time.parse $_[6..-1]
        p $_[6..-1]
        p stamp
      end
      s += $_
    when :vbody2
      s += $_
    end
  end
}