module Scrivito
  # Represents a collection of {Scrivito::Attribute} instances. It provides convienient ways to
  # find and add attributes and is returned by {Scrivito::ObjClass#attributes}. It behaves almost
  # exactly as an Array, so methods like `#each`, `#select` etc. are available. It is not necessary
  # to manually create an {Scrivito::AttributeCollection}, because a simple Array with attributes
  # can be used instead.
  #
  # @api public
  class AttributeCollection
    include Enumerable
    extend Forwardable

    # Initializes an attribute collection for an obj class.
    #
    # @param [Scrivito::ObjClass] obj_class
    # @param [Array<Scrivito::Attribute>] attributes
    # @return [Scrivito::AttributeCollection]
    def initialize(obj_class, attributes)
      @obj_class = obj_class
      @attributes = attributes
    end

    # Yields successive attributes of the collection. Implements the {Enumerable} interface.
    # @api public
    def_delegators :@attributes, :each

    # Finds an attribute in this collection by its name.
    #
    # @api public
    #
    # See {Scrivito::ObjClass#attributes} for example of how to find an attribute by name.
    #
    # @param [String] name
    # @return [Scrivito::Attribute]
    # @raise [Scrivito::ResourceNotFound] Raised when no attribute with the given +name+ can be found.
    def [](name)
      attribute = @attributes.detect { |attribute| attribute.name == name.to_s }

      unless attribute
        raise ResourceNotFound, "Could not find #{Attribute} with name '#{name}' for" \
          " obj class '#{@obj_class.name}'."
      end

      attribute
    end

    # Adds an attribute to this collection and updates the obj class.
    #
    # @api public
    #
    # See {Scrivito::ObjClass#attributes} for example of how to add an attribute.
    #
    # @param [Scrivito::Attribute, Hash] attribute The attribute to add. Can be either an attribute
    #   instance or an attribute property hash.
    # @return [Scrivito::AttributeCollection]
    def add(attribute)
      attribute = Attribute.new(attribute) unless attribute.respond_to?(:to_cms_rest_api)
      @attributes << attribute
      @obj_class.update(attributes: @attributes)
      self
    end
    alias_method :<<, :add

    # Deletes all attributes from this collection that are equal to the given attribute.
    def_delegators :@attributes, :delete
  end
end