def create_iso3166_country_list_file
  countries_regions = {}
  iso3166_content   = Mtx::OnlineFile.download("https://en.wikipedia.org/wiki/List_of_ISO_3166_country_codes")

  parse_html_extract_table_data(iso3166_content, %r{^.*?<table[^>]*>}i).
    drop(2).
    reject { |row| row.length < 8 }.
    each do |row|

    row = row.map do |column|
      column.
        gsub(%r{<style>.*?</style>}, '').
        gsub(%r{<a><img></a>},       ', ').
        gsub(%r{<img>},              '').
        gsub(%r{>_<},                '><').
        gsub(%r{<[^>]+>},            '').
        gsub(%r{ },                  '').
        gsub(%r{^, +},               '').
        gsub(%r{[[:space:]]+},       ' ').
        gsub(%r{^ +| +$},            '')
    end

    # 0 ["Albania",
    # 1  "The Republic of Albania",
    # 2  "UN member state ",
    # 3  "AL",
    # 4  "ALB",
    # 5  "008",
    # 6  "ISO 3166-2:AL",
    # 7  ".al"],

    m49_code = row[5].to_i
    name     = row[0].
      gsub(%r{ *\[.*?\]},       '').
      gsub(%r{ *\(the?\)$}i,    '').
      gsub(%r{(,.+?),([^,]+)$}, '\1 and\2')
    official_name = row[1].
      gsub(%r{ *\[.*?\]},       '').
      gsub(%r{ *\(.*?\)$}i,     '').
      gsub(%r{^The +},          '')

    countries_regions[m49_code] = {
      :number        => m49_code,
      :alpha_2_code  => row[3],
      :alpha_3_code  => row[4],
      :name          => name,
      :official_name => name == official_name ? "" : official_name,
    }
  end

  # pp(countries_regions); exit 42

  m49_content = Mtx::OnlineFile.download("https://unstats.un.org/unsd/methodology/m49/overview/", "m49_list.txt")
  m49_data    = parse_html_extract_table_data(m49_content, %r{^.*?<table[^>]+downloadTableEN[^>]*>}i)
  headers     = Hash[ *
    m49_data.
    shift.
    each_with_index.
    map { |text, idx| [ idx, text.downcase.gsub(%r{[^a-z0-9]+}, '_').gsub(%r{^_|_$}, '') ] }.
    flatten
  ]

  maybe_add = lambda do|row, type|
    code = row["#{type}_code"].to_i
    name = row["#{type}_name"]

    return if name.blank? || countries_regions[code]

    countries_regions[code] = {
      :number        => code,
      :alpha_2_code  => "",
      :alpha_3_code  => "",
      :name          => name,
      :official_name => "",
    }
  end

  m49_data.
    map do |row|
    Hash[ *
      row.
      each_with_index.
      map { |text, idx| [ headers[idx], text ] }.
      flatten
    ]
  end.
    each do |row|

    %w{global region sub_region intermediate_region}.each { |type| maybe_add.call(row, type) }

    code = row["m49_code"].to_i

    countries_regions[code] ||= {
      :number        => code,
      :alpha_2_code  => row["iso_alpha2_code"],
      :alpha_3_code  => row["iso_alpha3_code"],
      :name          => row["country_or_area"],
      :official_name => "",
    }
  end

  user_assigned = [ 'AA', 'ZZ' ] \
    + ('M'..'Z').map { |letter| "Q#{letter}" } \
    + ('A'..'Z').map { |letter| "X#{letter}" }

  entries  = countries_regions.values
  entries +=
    user_assigned.
    map do |code|
    {
      :number        => 0,
      :alpha_2_code  => code,
      :alpha_3_code  => "",
      :name          => "User-assigned",
      :official_name => "",
    }
  end

  rows = entries.
    map do |entry|
    [ entry[:alpha_2_code].upcase.to_cpp_string,
      entry[:alpha_3_code].upcase.to_cpp_string,
      sprintf('%3d', entry[:number]),
      entry[:name].to_u8_cpp_string,
      entry[:official_name].to_u8_cpp_string,
    ]
  end

  header = <<EOT
/*
   mkvmerge -- utility for splicing together matroska files
   from component media subtypes

   Distributed under the GPL v2
   see the file COPYING for details
   or visit https://www.gnu.org/licenses/old-licenses/gpl-2.0.html

   ISO 3166 countries & UN M.49 regions

   Written by Moritz Bunkus <moritz@bunkus.org>.
*/

// ------------------------------------------------------------------------
// NOTE: this file is auto-generated by the "dev:iso3166_list" rake target.
// ------------------------------------------------------------------------

#include "common/common_pch.h"

#include "common/iso3166.h"

namespace mtx::iso3166 {

std::vector<region_t> g_regions;

void
init() {
  g_regions.reserve(#{rows.size});

EOT

  footer = <<EOT
}

} // namespace mtx::iso3166
EOT

  rows          = rows.sort_by { |row| [ row[0], row[1], row[3] ].join('::') }
  content       = header + format_table(rows, :column_suffix => ',', :row_prefix => "  g_regions.emplace_back(", :row_suffix => ");").join("\n") + "\n" + footer
  cpp_file_name = "src/common/iso3166_country_list.cpp"

  runq("write", cpp_file_name) { IO.write("#{$source_dir}/#{cpp_file_name}", content); 0 }
end