#! %RUBY%

# Copyright (C) 2005  Network Applied Communication Laboratory Co., Ltd.

require "fileutils"

require "bdb"

OLD_METADATA_VERSION = 1
NEW_METADATA_VERSION = 3
BYTE_ORDER_TO_PACK_STR = {
  0 => "V",
  1 => "N",
  2 => "I",
}

def get_metadata_version(db_name)
  metadata_filename = File.join(db_name, "METADATA")
  File.open(metadata_filename, "r") do |file|
    byte_order_flag = file.getc
    pack_str = BYTE_ORDER_TO_PACK_STR[byte_order_flag]
    return file.read.unpack(pack_str).first
  end
end

def lock_database(db_name)
  lock_filename = File.join(db_name, "lock")
  File.open(lock_filename, "w") do |file|
    file.flock(File::LOCK_EX)
    begin
      yield
    ensure
      file.flock(File::LOCK_UN)
    end
  end
end

def convert_text_db(db_name)
  text_db_filename = File.join(db_name, "text.db")
  text_dirname = File.join(db_name, "text")
  return if !File.exist?(text_dirname)
  BDB::Recno.open(text_db_filename, nil, BDB::CREATE) do |db|
    doc_id = 1
    loop do
      p1, p2 = [doc_id].pack("v").unpack("H2H2")
      path = File.join(text_dirname, p1.upcase, p2.upcase, doc_id)
      if !File.exist?(path)
        break
      end
      db[doc_id] = File.read(path)
      doc_id += 1
    end
  end
  File.rename(text_dirname, File.join(db_name, "OLD-text"))
end

def convert_metadata(db_name)
  metadata_filename = File.join(db_name, "METADATA")
  FileUtils.cp(metadata_filename, File.join(db_name, "OLD-METADATA"),
               {:preserve => true})
  File.open(metadata_filename, "r+") do |file|
    byte_order_flag = file.getc
    pack_str = BYTE_ORDER_TO_PACK_STR[byte_order_flag]
    version_str = [NEW_METADATA_VERSION].pack(pack_str)
    file.write(version_str)
  end
end

if $0 == __FILE__
  ARGV.each do |db_name|
    if get_metadata_version(db_name) > OLD_METADATA_VERSION
      puts("#{db_name} is newer database.  Nothing to do.")
      next
    end

    lock_database(db_name) do
      convert_text_db(db_name)
      convert_metadata(db_name)
    end

    old_filenames = File.join(db_name, "OLD-*")
    puts("#{db_name} is converted.")
    puts("please run: rm -rf #{old_filenames}")
  end
end