module ArabicStemmer

# File lib/arabic_stemmer.rb, line 52
def self.is_word_short(word)
  return word.size <= 4
end

# File lib/arabic_stemmer.rb, line 39
def self.remove_prefix(word)
  # Remove ال وال كال سي ست, al, wal, kal, saya, sata
  # check if the word is >= 5
  prefix_2 = ["ال", "سي", "ست", "لل"]
  letters = word[0..1]
  return word[2..-1] if prefix_2.include? letters

  prefix_3 = ["وال", "كال", "بال"]
  letters = word[0..2]
  return word[3..-1] if prefix_3.include? letters
  return word
end

# File lib/arabic_stemmer.rb, line 31
def self.remove_suffix(word)
  # Remove ات ان ون كم ين هم هن
  suffixes = ["هم", "ين", "ون", "ان", "كم", "ات", "هن"]
  letters = word[-2, 2]
  word.slice!(letters) if suffixes.include? letters
  return word
end

# File lib/arabic_stemmer.rb, line 4
def self.to_arabic_stem(word)
  key_words = ["الله"]

  # 1. Remove non alpha numeric characters.
  word = word.strip.gsub(/[._,،\"\':;&?؟()]/, '')

  # 2. Remove diacratical marks ً َ ُ ٌ ٍ ِ ْ ّ
   word = word.gsub(/[\u064b\u064c\u064d\u064e\u064f\u0650\u0651\u0652]/, '')
  # word = word.gsub(/[\uFE77]/, '')

  # 3. Convert أآإ to ا
  word = word.gsub(/[\u0622\u0623\u0625]/, 'ا')

  # 4. check against some words that should not be stemmed
  return word if key_words.include? word or is_word_short(word)

  # 5. remove prefixes
  word = remove_prefix(word)

  return word if is_word_short(word)
  
  # 6. remove suffixes
  word = remove_suffix(word)
  
  return word
end