全俳句データベース https://horicun.moo.jp/contents/haiku/ in Ruby

get_haiku.rb

#!/usr/bin/env ruby

def get_haiku n
  len = 17

  # Ver 1:
  # https://horicun.moo.jp/contents/haiku/random.html?number_search=1
  hiragana = "あいうえおかきくけこさしすせそたちつてとなにぬねのはひふへほまみむめもやゆよらりるれろわをがぎぐげござじずぜぞだぢづでどばびぶべぼぱぴぷぺぽぁぃぅぇぉゃゅょゎっゐゑーゔん"

  # Ver 2:
  # https://horicun.moo.jp/contents/haiku2/random.html?number_search=1
  # hiragana = [
  # "あ", "い", "う", "え", "お", "か", "き", "く", "け", "こ",
  # "さ", "し", "す", "せ", "そ", "た", "ち", "つ", "て", "と",
  # "な", "に", "ぬ", "ね", "の", "は", "ひ", "ふ", "へ", "ほ",
  # "ま", "み", "む", "め", "も", "や", "ゆ", "よ",
  # "ら", "り", "る", "れ", "ろ", "わ", "を",
  # "が", "ぎ", "ぐ", "げ", "ご", "ざ", "じ", "ず", "ぜ", "ぞ",
  # "だ", "ぢ", "づ", "で", "ど", "ば", "び", "ぶ", "べ", "ぼ",
  # "ぱ", "ぴ", "ぷ", "ぺ", "ぽ", "っ", "ゐ", "ゑ", "ー", "ゔ",
  # "うぃ","うぇ","うぉ","くゎ","ぐゎ",
  # "しぇ","ちぇ","てぃ","とぅ",
  # "じぇ","ぢぇ","でぃ","でゅ","どぅ",
  # "ふぁ","ふぃ","ふぇ","ふぉ",
  # "ゔぁ","ゔぃ","ゔぇ","ゔぉ",
  # "きゃ","きゅ","きょ","しゃ","しゅ","しょ",
  # "ちゃ","ちゅ","ちょ","にゃ","にゅ","にょ",
  # "みゃ","みゅ","みょ","ひゃ","ひゅ","ひょ",
  # "りゃ","りゅ","りょ","ぎゃ","ぎゅ","ぎょ",
  # "じゃ","じゅ","じょ","ぢゃ","ぢゅ","ぢょ",
  # "びゃ","びゅ","びょ","ぴゃ","ぴゅ","ぴょ", "ん"
  # ]

  valid_range = 0 ... hiragana.size ** len
  raise ArgumentError.new n unless valid_range.include? n-=1

  len.times.map do
    next ?あ if n.zero?
    n, mod = n.divmod hiragana.size
    hiragana[mod]
  end.reverse.join
end

if __FILE__ == $PROGRAM_NAME
  if ARGV.size.positive?
    ARGV.map(&:to_i).each { puts "#{_1}: #{get_haiku _1}" }
    return
  end

  puts "=== Example ==="
  # [0, 85**17+1]
  [1, 85, 86, 8121862514056854736084710984000, 85**17].each do
    puts "#{_1}: #{get_haiku _1}"
  end
end

$ ./get_haiku.rb
=== Example ===
1: あああああああああああああああああ
85: ああああああああああああああああん
86: あああああああああああああああいあ
8121862514056854736084710984000: いくーーーーーーーーーーーーーーっ
631134233006543551770782470703125: んんんんんんんんんんんんんんんんん

$ ./get_haiku.rb 1 1145141919810 77016092317948049706681803472219
1: あああああああああああああああああ
1145141919810: ああああああああああええくふみがこ
77016092317948049706681803472219: さみだれをあつめてはやしもがみがわ