module SequelMapper
  class DirtyMap
    def initialize(storage)
      @storage = storage
    end

    attr_reader :storage
    private     :storage

    def load(record)
      storage.store(hash_key(record), deep_clone(record))
      record
    end

    def dirty?(record)
      record_as_loaded = storage.fetch(hash_key(record), :not_found)

      record != record_as_loaded
    end

    private

    def hash_key(record)
      deep_clone([record.namespace, record.identity])
    end

    def deep_clone(record)
      Marshal.load(Marshal.dump(record))
    end
  end
end