module ActiveFedora
  module Core
    extend ActiveSupport::Autoload
    extend ActiveSupport::Concern

    autoload :FedoraIdTranslator
    autoload :FedoraUriTranslator

    included do
      ##
      # :singleton-method:
      #
      # Accepts a logger conforming to the interface of Log4r which can be
      # retrieved on both a class and instance level by calling +logger+.
      mattr_accessor :logger, instance_writer: false
    end

    def ldp_source
      @ldp_source
    end

    # Constructor.  You may supply a custom +:id+, or we call the Fedora Rest API for the
    # next available Fedora id, and mark as new object.
    # Also, if +attrs+ does not contain +:id+ but does contain +:namespace+ it will pass the
    # +:namespace+ value to Fedora::Repository.nextid to generate the next id available within
    # the given namespace.
    def initialize(attributes_or_id = nil, &_block)
      init_internals
      attributes = initialize_attributes(attributes_or_id)
      @ldp_source = build_ldp_resource(attributes.delete(:id))
      raise IllegalOperation, "Attempting to recreate existing ldp_source: `#{ldp_source.subject}'" unless ldp_source.new?
      assert_content_model
      load_attached_files
      self.attributes = attributes

      yield self if block_given?
      run_callbacks :initialize
    end

    ##
    # @param [#to_s] uri a full fedora URI or relative ID to set this resource
    #   to.
    # @note This can only be run on an unpersisted resource.
    def uri=(uri)
      if persisted?
        raise AlreadyPersistedError, "You can not set a URI for a persisted ActiveFedora object."
      else
        @ldp_source = build_ldp_resource(self.class.uri_to_id(uri))
      end
    end

    # Reloads the object from Fedora.
    def reload
      check_persistence unless persisted?
      clear_association_cache
      clear_attached_files
      refresh
      load_attached_files
      self
    end

    # Initialize an empty model object and set its +resource+
    # example:
    #
    #   class Post < ActiveFedora::Base
    #   end
    #
    #   post = Post.allocate
    #   post.init_with_resource(Ldp::Resource.new('http://example.com/post/1'))
    #   post.title # => 'hello world'
    def init_with_resource(rdf_resource)
      init_internals
      @ldp_source = rdf_resource
      load_attached_files
      run_callbacks :find
      run_callbacks :initialize
      self
    end

    def ==(other)
      other.equal?(self) ||
        (other.instance_of?(self.class) &&
          other.id == id &&
          !other.new_record?)
    end

    def freeze
      @resource.freeze
      # @attributes = @attributes.clone.freeze
      attached_files.freeze
      self
    end

    delegate :frozen?, to: :attached_files

    # Returns +true+ if the record is read only. Records loaded through joins with piggy-back
    # attributes will be marked as read only since they cannot be saved.
    def readonly?
      @readonly
    end

    # Marks this record as read only.
    def readonly!
      @readonly = true
    end

    protected

      # This can be overriden to assert a different model
      # It's normally called once in the lifecycle, by #create#
      def assert_content_model
        self.has_model = self.class.to_s
      end

      module ClassMethods
        SLASH = '/'.freeze

        def generated_association_methods
          @generated_association_methods ||= begin
            mod = const_set(:GeneratedAssociationMethods, Module.new)
            include mod
            mod
          end
        end

        # Returns a suitable uri object for :has_model
        # Should reverse Model#from_class_uri
        # TODO this is a poorly named method
        def to_class_uri(_attrs = {})
          name
        end

        private

          def relation
            Relation.new(self)
          end
      end

    private

      def init_internals
        @resource          = nil
        @readonly          = false
        @association_cache = {}
      end

      def build_ldp_resource(id = nil)
        ActiveFedora.fedora.ldp_resource_service.build(self.class, id)
      end

      def check_persistence
        if destroyed?
          raise ActiveFedora::ObjectNotFoundError, "Can't reload an object that has been destroyed"
        else
          raise ActiveFedora::ObjectNotFoundError, "Can't reload an object that hasn't been saved"
        end
      end

      def initialize_attributes(attributes_or_id)
        case attributes_or_id
        when String
          attributes = { id: attributes_or_id }.with_indifferent_access
        when Hash
          attributes = attributes_or_id.with_indifferent_access
          # TODO: Remove when we decide using 'pid' is no longer supported.
          if !attributes.key?(:id) && attributes.key?(:pid)
            Deprecation.warn Core, 'Initializing with :pid is deprecated and will be removed in active-fedora 10.0. Use :id instead'
            attributes[:id] = attributes.delete(:pid)
          end

        when NilClass
          attributes = {}.with_indifferent_access
        else
          raise ArgumentError, "#{attributes_or_id.class} is not acceptable"
        end
        attributes
      end
  end
end