module RuboCop::Rails::SchemaLoader

def db_schema_path
  path = Pathname.pwd
  until path.root?
    schema_path = path.join('db/schema.rb')
    return schema_path if schema_path.exist?
    path = path.join('../').cleanpath
  end
  nil
end

def load(target_ruby_version)
  return @load if defined?(@load)
  @load = load!(target_ruby_version)
end

def load!(target_ruby_version)
  path = db_schema_path
  return unless path
  ast = parse(path, target_ruby_version)
  Schema.new(ast)
end

def parse(path, target_ruby_version)
  klass_name = :"Ruby#{target_ruby_version.to_s.sub('.', '')}"
  klass = ::Parser.const_get(klass_name)
  parser = klass.new(RuboCop::AST::Builder.new)
  buffer = Parser::Source::Buffer.new(path, 1)
  buffer.source = path.read
  parser.parse(buffer)
end

def reset!
  return unless instance_variable_defined?(:@load)
  remove_instance_variable(:@load)
end