class GraphQL::StaticValidation::VariablesAreInputTypes

def get_type_name(ast_type)
  if ast_type.respond_to?(:of_type)
    get_type_name(ast_type.of_type)
  else
    ast_type.name
  end
end

def validate(context)
  context.visitor[GraphQL::Language::Nodes::VariableDefinition] << -> (node, parent) {
    validate_is_input_type(node, context)
  }
end

def validate_is_input_type(node, context)
  type_name = get_type_name(node.type)
  type = context.schema.types[type_name]
  if !type.kind.input?
    context.errors << message("#{type.name} isn't a valid input type (on $#{node.name})", node, context: context)
  end
end