module Vedeu

  # Interfaces can be associated with one another by being members of the same
  # Group. A Group is a collection of interface names.
  #
  class Group

    include Vedeu::Model
    include Vedeu::Toggleable

    # @!attribute [rw] name
    # @return [String]
    attr_accessor :name

    # Return a new instance of Vedeu::Group.
    #
    # @note
    #   A group being visible or not may not necessarily mean the members are of
    #   the same state.
    #
    # @param attributes [Hash]
    # @option attributes members [Set] A collection of names of interfaces
    #   belonging to this group.
    # @option attributes name [String] The name of the group.
    # @option attributes repository [Vedeu::Repository] The storage for all
    #   Group models.
    # @option attributes visible [Boolean] Whether the group is visible or not.
    # @return [Vedeu::Group]
    def initialize(attributes = {})
      @attributes = defaults.merge!(attributes)

      @attributes.each { |key, value| instance_variable_set("@#{key}", value) }
    end

    # Add a member to the group by name.
    #
    # @param member [String]
    # @return [Vedeu::Group]
    def add(member)
      attrs = attributes.merge!(members: members.add(member))

      Vedeu::Group.new(attrs).store
    end

    # Returns the attributes of the group.
    #
    # @return [Hash<Symbol => void>]
    def attributes
      {
        name:       name,
        members:    members,
        repository: repository,
        visible:    visible,
      }
    end

    # Hide the named group of interfaces, or without a name, the group of the
    # currently focussed interface. Useful for hiding part of that which is
    # currently displaying in the terminal.
    #
    # @note
    #   The action of showing a group will effectively clear the terminal and
    #   show the new group, therefore hiding the group may not be necessary.
    #
    # @example
    #   Vedeu.trigger(:_hide_group_, name)
    #   Vedeu.hide_group(name)
    #
    # @return [Vedeu::Group]
    def hide
      super

      @members.each { |member| Vedeu::Interface.hide_interface(member) }

      self
    end

    # Return the members of the group.
    #
    # @return [Set]
    def members
      @_members ||= Set.new(@members)
    end

    # Remove a member from the group by name.
    #
    # @param member [String]
    # @return [Vedeu::Group]
    def remove(member)
      attrs = attributes.merge!(members: members.delete(member))

      Vedeu::Group.new(attrs).store
    end

    # Remove all members from the group.
    #
    # @return [Vedeu::Group]
    def reset
      attrs = defaults.merge!(name: name)

      Vedeu::Group.new(attrs).store
    end

    # Show the named group of interfaces, or without a name, the group of the
    # currently focussed interface.
    #
    # @example
    #   Vedeu.trigger(:_show_group_, name)
    #   Vedeu.show_group(name)
    #
    # @return [Vedeu::Group]
    def show
      super

      @members.each { |member| Vedeu::Interface.show_interface(member) }

      self
    end

    private

    # Returns the default options/attributes for this class.
    #
    # @return [Hash]
    def defaults
      {
        members:    Set.new,
        name:       '',
        repository: Vedeu.groups,
        visible:    true,
      }
    end

  end # Group

end # Vedeu