import rpcconsts, options, json

type
  RpcJsonError* = enum rjeInvalidJson, rjeVersionError, rjeNoMethod, rjeNoId
  RpcJsonErrorContainer* = tuple[err: RpcJsonError, msg: string]

const
  jsonErrorMessages*: array[RpcJsonError, (int, string)] =
    [
      (JSON_PARSE_ERROR, "Invalid JSON"),
      (INVALID_REQUEST, "JSON 2.0 required"),
      (INVALID_REQUEST, "No method requested"),
      (INVALID_REQUEST, "No id specified")
    ]

template jsonValid*(jsonString: string, node: var JsonNode): (bool, string) =
  var
    valid = true
    msg = ""
  try: node = parseJson(line)
  except:
    valid = false
    msg = getCurrentExceptionMsg()
  (valid, msg)

proc checkJsonErrors*(line: string, node: var JsonNode): Option[RpcJsonErrorContainer] =
  ## Tries parsing line into node, if successful checks required fields
  ## Returns: error state or none
  let res = jsonValid(line, node)
  if not res[0]:
    return some((rjeInvalidJson, res[1]))
  if not node.hasKey("jsonrpc"):
    return some((rjeVersionError, ""))
  if not node.hasKey("method"):
    return some((rjeNoMethod, ""))
  if not node.hasKey("id"):
    return some((rjeNoId, ""))
  return none(RpcJsonErrorContainer)