module Vedeu

  # @api private
  module Repository

    # Return the whole repository.
    #
    # @return [Hash]
    def all
      storage
    end

    # Find the entity attributes by name.
    #
    # @param name [String]
    # @return [Hash]
    def find(name)
      storage.fetch(name) { not_found(name) }
    end

    # Find entity by named interface, registers an entity by interface name if
    # not found.
    #
    # @param name [String]
    # @return [Cursor|Offset]
    def find_or_create(name)
      storage.fetch(name) do
        Vedeu.log("Entity (#{entity.to_s}) not found, " \
                  "registering new for: '#{name}'")

        storage.store(name, entity.new({ name: name }))
      end
    end

    # Returns a collection of the names of all the registered entities.
    #
    # @return [Array]
    def registered
      storage.keys
    end

    # Returns a boolean indicating whether the named entity is registered.
    #
    # @param name [String]
    # @return [Boolean]
    def registered?(name)
      storage.key?(name)
    end

    # Reset the repository.
    #
    # @return [Hash]
    def reset
      @_storage = in_memory
    end

    private

    # @param method [Symbol]
    # @return [String]
    def action(method)
      return 'Registering' if method == :add

      'Updating'
    end

    # Access to the storage for this repository.
    #
    # @return [Hash]
    def storage
      @_storage ||= in_memory
    end

    # At present, validates that attributes has a `:name` key that is not nil or
    # empty.
    #
    # @param attributes [Hash]
    # @return [TrueClass|MissingRequired]
    def validate_attributes!(attributes)
      return missing_required unless attributes.key?(:name)
      return missing_required unless defined_value?(attributes[:name])

      true
    end

    # Raises the MissingRequired exception.
    #
    # @param attr [String] A textual representation of the attribute.
    # @raise [MissingRequired] When an attribute, defined by the attr parameter
    #   is missing.
    # @return [MissingRequired]
    def missing_required(attr = 'name')
      fail MissingRequired, "Cannot store data without a #{attr} attribute."
    end

  end # Repository

end # Vedeu