#
# timezone.rb
# written by Shin'ya Adzumi/ICHIGO-DENPA-CLUB
#

module TimeZone

=begin
  ZONES = {
    'gmt' => 0 , 'ut' => 0 , 'utc' => 0 , 'wet' => 0 ,
    'wat' => -60 ,
    'at' => -120 , 
    'adt' => -180 ,
    'ast' => -240 , 'edt' => -240 ,
    'est' => -300 , 'cdt' => -300 ,
    'cst' => -360 , 'mdt' => -360 ,
    'mst' => -420 , 'pdt' => -420 ,
    'pst' => -480 , 'ydt' => -480 ,
    'yst' => -540 , 'hst' => -540 ,
    'ahst' => -600 , 'cat' => -600 , 'hst' => -600 ,
    'nt' => -660 ,
    'idlw' => -720 ,
    'cet' => 60 , 'fwt' => 60 , 'met' => 60 , 'mewt' => 60 ,
    'swt' => 60 , 'bst' => 60 ,
    'eet' => 120 , 'mest' => 120 , 'mesz' => 120 , 'sst' => 120 ,
    'fst' => 120 ,
    'bt' => 180 ,
    'zp4' => 240 ,
    'zp5' => 300 ,
    'zp6' => 360 , 'wadt' => 360 ,
    'wast' => 420 ,
    'cct' => 480 ,
    'jst' => 540 , 'eadt' => 540 ,
    'east' => 600 , 'gst' => 600 ,
    'nzdt' => 660 ,
    'idle' => 720 , 'nzst' => 720 , 'nzt' => 720 ,
  }

  DST = [
    'bst','adt','edt','cdt','mdt','pdt','ydt','hdt','mest','mesz',
    'sst','fst','wadt','eadt','nzdt',
  ]
=end

  ZONES = {
    'ut' => 0 ,    'gmt'=> 0 ,
    'est'=> -300 , 'edt'=> -240 ,
    'cst'=> -360 , 'cdt'=> -300 ,
    'mst'=> -420 , 'mdt'=> -360 ,
    'pst'=> -480 , 'pdt'=> -420 ,
    'uct' => 0 ,   'utc'=> 0 ,
    'jst' => 540 ,
  }

  DST = [
    'edt','cdt','mdt','pdt',
  ]

  def to_h(str)
    to_m(str).to_f / 60
  end

  def to_m(str)
    s = str.downcase
    if( s =~ /^[a-im-z]$/ ) then
      return ('mlkihgfedcbaznopqrstuvwsy'.index(s)-12)*60
    elsif( s =~ /^([+-])(\d{2}):?(\d{2})?$/ ) then
      h = ($2.to_i*60)
      h = h+$3.to_i unless $3.nil?
      h = -h if $1 == '-'
      return h
    elsif( ZONES.key? s ) then
      return ZONES[s]
    end

    raise ArgumentError, 'invalid timezone'
    return nil  
  end

  def to_s(str)
    to_m(str) * 60
  end

  def is_dst?(str)
    s = str.downcase
    if( DST.include? s ) then
      true
    else
      false
    end
  end

  module_function :to_h,:to_m,:to_s,:is_dst?
end

if __FILE__ == $0 then
  p TimeZone::to_h ARGV[0]
  p TimeZone::to_m ARGV[0]
  p TimeZone::to_s ARGV[0]
  p TimeZone::is_dst? ARGV[0]
end