class GraphQL::Analysis::QueryDepth

def call(memo, visit_type, irep_node)
  if irep_node.ast_node.is_a?(GraphQL::Language::Nodes::Field)
    # Don't validate introspection fields or skipped nodes
    not_validated_node = GraphQL::Schema::DYNAMIC_FIELDS.include?(irep_node.definition_name)
    if visit_type == :enter
      if not_validated_node
        memo[:skip_depth] += 1
      elsif memo[:skip_depth] > 0
        # we're inside an introspection query or skipped node
      else
        memo[:current_depth] += 1
      end
    else
      if not_validated_node
        memo[:skip_depth] -= 1
      else
        if memo[:max_depth] < memo[:current_depth]
          memo[:max_depth] = memo[:current_depth]
        end
        memo[:current_depth] -= 1
      end
    end
  end
  memo
end

def final_value(memo)
  @depth_handler.call(memo[:query], memo[:max_depth])
end

def initial_value(query)
  {
    max_depth: 0,
    current_depth: 0,
    skip_depth: 0,
    query: query,
  }
end

def initialize(&block)
  @depth_handler = block
end