class PgSearch::Features::Trigram

def self.valid_options
  super + [:threshold]
end

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