module ActiveModel::Serializer::Caching::ClassMethods

def _skip_digest?
  _cache_options && _cache_options[:skip_digest]
end

def cache(options = {})
  self._cache =
    options.delete(:cache_store) ||
    ActiveModelSerializers.config.cache_store ||
    ActiveSupport::Cache.lookup_store(:null_store)
  self._cache_key = options.delete(:key)
  self._cache_only = options.delete(:only)
  self._cache_except = options.delete(:except)
  self._cache_options = options.empty? ? nil : options
end

def cache_enabled?
  perform_caching? && cache_store && !_cache_only && !_cache_except
end

def cache_store
  return nil if _cache.nil?
  return _cache if _cache.class != ActiveSupport::Cache::NullStore
  if ActiveModelSerializers.config.cache_store
    self._cache = ActiveModelSerializers.config.cache_store
  else
    nil
  end
end

def digest_caller_file(caller_line)
  serializer_file_path = caller_line[CALLER_FILE]
  serializer_file_contents = IO.read(serializer_file_path)
  Digest::MD5.hexdigest(serializer_file_contents)
rescue TypeError, Errno::ENOENT
  warn <<-EOF.strip_heredoc
    Cannot digest non-existent file: '#{caller_line}'.
    Please set `::_cache_digest` of the serializer
    if you'd like to cache it.
    EOF
  ''.freeze
end

def fragment_cache_enabled?
  perform_caching? && cache_store &&
    (_cache_only && !_cache_except || !_cache_only && _cache_except)
end

def fragmented(serializer)
  self._fragmented = serializer
end

def inherited(base)
  super
  caller_line = caller[1]
  base._cache_digest = digest_caller_file(caller_line)
end

def perform_caching
  return @@perform_caching if defined?(@@perform_caching) && !@@perform_caching.nil?
  @@perform_caching = ActiveModelSerializers.config.perform_caching
end