require "set"

module GraphQL
  module InternalRepresentation
    class Node
      def initialize(parent:, ast_node: nil, return_type: nil, name: nil, definition_name: nil, definitions: {}, children: {}, spreads: [], directives: Set.new)
        # Make sure these are kept in sync with #dup
        @ast_node = ast_node
        @return_type = return_type
        @name = name
        @definition_name = definition_name
        @parent = parent
        @definitions = definitions
        @children = children
        @spreads = spreads
        @directives = directives
      end

      # Note: by the time this gets out of the Rewrite phase, this will be empty -- it's emptied out when fragments are merged back in
      # @return [Array<GraphQL::InternalRepresentation::Node>] Fragment names that were spread in this node
      attr_reader :spreads

      # These are the compiled directives from fragment spreads, inline fragments, and the field itself
      # @return [Set<GraphQL::Language::Nodes::Directive>]
      attr_reader :directives

      # @return [String] the name for this node's definition ({#name} may be a field's alias, this is always the name)
      attr_reader :definition_name

      # A cache of type-field pairs for executing & analyzing this node
      #
      # @example On-type from previous return value
      # {
      #   person(id: 1) {
      #     firstName # => defined type is person
      #   }
      # }
      # @example On-type from explicit type condition
      # {
      #   node(id: $nodeId) {
      #     ... on Nameable {
      #       firstName # => defined type is Nameable
      #     }
      #   }
      # }
      # @return [Hash<GraphQL::BaseType => GraphQL::Field>] definitions to use for each possible type
      attr_reader :definitions

      # @return [String] the name to use for the result in the response hash
      attr_reader :name

      # @return [GraphQL::Language::Nodes::AbstractNode] The AST node (or one of the nodes) where this was derived from
      attr_reader :ast_node

      # @return [GraphQL::BaseType]
      attr_reader :return_type

      # @return [Array<GraphQL::Query::Node>]
      attr_reader :children

      # @return [GraphQL::InternalRepresentation::Node] The node which this node is a child of
      attr_reader :parent

      # @return [GraphQL::InternalRepresentation::Node] The root node which this node is a (perhaps-distant) child of, or `self` if this is a root node
      def owner
        @owner ||= begin
          if parent.nil?
            self
          else
            parent.owner
          end
        end
      end

      def inspect(indent = 0)
        own_indent = " " * indent
        self_inspect = "#{own_indent}<Node #{name} (#{definition_name}: {#{definitions.keys.join("|")}} -> #{return_type})>"
        if children.any?
          self_inspect << " {\n#{children.values.map { |n| n.inspect(indent + 2)}.join("\n")}\n#{own_indent}}"
        end
        self_inspect
      end
    end
  end
end