class DidYouMean::SpellChecker

# File did_you_mean/spell_checker.rb, line 8
def initialize(dictionary:)
  @dictionary = dictionary
end

# File did_you_mean/spell_checker.rb, line 12
def correct(input)
  normalized_input = normalize(input)
  threshold = normalized_input.length > 3 ? 0.834 : 0.77

  words = @dictionary.select { |word| JaroWinkler.distance(normalize(word), normalized_input) >= threshold }
  words.reject! { |word| input.to_s == word.to_s }
  words.sort_by! { |word| JaroWinkler.distance(word.to_s, normalized_input) }
  words.reverse!

  # Correct mistypes
  threshold   = (normalized_input.length * 0.25).ceil
  corrections = words.select { |c| Levenshtein.distance(normalize(c), normalized_input) <= threshold }

  # Correct misspells
  if corrections.empty?
    corrections = words.select do |word|
      word   = normalize(word)
      length = normalized_input.length < word.length ? normalized_input.length : word.length

      Levenshtein.distance(word, normalized_input) < length
    end.first(1)
  end

  corrections
end