# -*- mode: ruby -*-
require 'nokogiri'
require 'open-uri'

doc = Nokogiri::HTML(URI.open('https://www.timeanddate.com/time/zones/'))

h = {}

doc.css('#tz-abb tbody tr').each do |tr|
  tds = tr.css('td')
  abbr = tds[0].text.strip.downcase
  offset = tds[3].text.strip.gsub(/UTC\s*/, '')
  next if offset.include?('/') # skip ambiguous timezones
  next if offset.empty?


  hour, min = offset.split(':', 2)
  offset = (Integer(hour) * 60 + (Integer(min || 0)))*60
  if h.has_key?(abbr)
    h[abbr] = false
  else
    h[abbr] = offset
  end
end

h.delete_if{|_,v| !v}

lines = File.readlines('zonetab.list')
lines.select{|l| l.include?(',')}.
  map{|l| l.split(',', 2)[0]}.
  each{|a| h.delete(a)}

lines.insert(-2, h.sort.map{|k,v| "#{k},#{v}\n"})
lines.flatten!
File.write('zonetab.list', lines.join)