require 'yaml'
require 'rake'
require 'rbconfig'
require 'fileutils'

LIMIT_FILESIZE = 1000000000

def os
  @os ||= (
    host_os = RbConfig::CONFIG['host_os']
    case host_os
    when /mswin|msys|mingw|cygwin|bccwin|wince|emc/
      :windows
    when /darwin|mac os/
      :macosx
    when /linux/
      :linux
    when /solaris|bsd/
      :unix
    else
      raise Error::WebDriverError, "unknown os: #{host_os.inspect}"
    end
  )
end

def file_count(file_size)
  return 1 if file_size < LIMIT_FILESIZE

  4.step(Float::INFINITY, 4) do |i|
    next if (file_size / i) > LIMIT_FILESIZE
    return i
  end
end

TABLES = %w[table_names].freeze

config = YAML.load_file('config/database.yml')['production']
conf_file = File.dirname(__FILE__) + '/tmp/my.conf'
outputs_dir = File.dirname(__FILE__) + '/txts/outputs'
splits_dir = File.dirname(__FILE__) + '/txts/splits'
FileUtils.rm(Dir.glob(outputs_dir + '/*'))
FileUtils.rm(Dir.glob(splits_dir + '/*'))

File.open(conf_file, 'w') do |f|
  f.puts "[client]"
  f.puts "user=#{config['username']}"
  f.puts "password=#{config['password']}"
end

TABLES.each do |table|
  sh "mysql --defaults-file=tmp/my.conf -h\"#{config['host']}\" -D \"#{config['database']}\" -e \"select * from #{table}\" -s -N > txts/outputs/#{table}.txt", verbose: false

  file_size = File.size("txts/outputs/#{table}.txt")
  rows = `wc -l txts/outputs/#{table}.txt`.match(/\s*(\d*)/)[1].to_i

  @file_count = file_count(file_size)

  if os == :macosx
    # MAC OSでは、`-d`オプションが利用できない。使いたい場合は、brew install coreutils
    sh "gsplit -d -l #{(rows / @file_count) + 4} txts/outputs/#{table}.txt txts/splits/#{table}.txt. &>/dev/null", verbose: false
  else
    sh "split -d -l #{(rows / @file_count) + 4} txts/outputs/#{table}.txt txts/splits/#{table}.txt. &>/dev/null", verbose: false
  end
end
FileUtils.rm(conf_file)