class PgSearch::Features::Trigram

def self.valid_options
  super + %i[threshold word_similarity]
end

def conditions
  if options[:threshold]
    Arel::Nodes::Grouping.new(
      similarity.gteq(options[:threshold])
    )
  else
    Arel::Nodes::Grouping.new(
      Arel::Nodes::InfixOperation.new(
        infix_operator,
        normalized_query,
        normalized_document
      )
    )
  end
end

def infix_operator
  if word_similarity?
    '<%'
  else
    '%'
  end
end

def normalized_document
  Arel::Nodes::Grouping.new(Arel.sql(normalize(document)))
end

def normalized_query
  sanitized_query = connection.quote(query)
  Arel.sql(normalize(sanitized_query))
end

def rank
  Arel::Nodes::Grouping.new(similarity)
end

def similarity
  Arel::Nodes::NamedFunction.new(
    similarity_function,
    [
      normalized_query,
      normalized_document
    ]
  )
end

def similarity_function
  if word_similarity?
    'word_similarity'
  else
    'similarity'
  end
end

def word_similarity?
  options[:word_similarity]
end