include_directives.rb

module JSONAPI
  class IncludeDirectives
    # Construct an IncludeDirectives Hash from an array of dot separated include strings.
    # For example ['posts.comments.tags']
    # will transform into =>
    # {
    #   posts: {
    #     comments: {
    #       tags: {}
    #     }
    #   }
    # }

    def initialize(resource_klass, includes_array)
      @resource_klass = resource_klass
      @include_directives_hash = {}
      includes_array.each do |include|
        parse_include(include)
      end
    end

    def include_directives
      @include_directives_hash
    end

    private

    def parse_include(include)
      path = JSONAPI::Path.new(resource_klass: @resource_klass,
                               path_string: include,
                               ensure_default_field: false,
                               parse_fields: false)

      current = @include_directives_hash

      path.segments.each do |segment|
        relationship_name = segment.relationship.name.to_sym

        current[relationship_name] ||= {}
        current = current[relationship_name]
      end

    rescue JSONAPI::Exceptions::InvalidRelationship => _e
      raise JSONAPI::Exceptions::InvalidInclude.new(@resource_klass, include)
    end
  end
end