""" RPCClient object is used to create RPC connection to services
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

__RCSID__ = "3c530efac (2020-12-05 00:59:33 +0100) Chris Burr <christopher.burr@cern.ch>"


from DIRAC.Core.DISET.private.InnerRPCClient import InnerRPCClient


class _MagicMethod(object):
  """ This object allows to bundle together a function calling
      an RPC and the remote function name.
      When this object is called (__call__), the call is performed.
  """

  def __init__(self, doRPCFunc, remoteFuncName):
    """ Constructor

        :param doRPCFunc: the function actually performing the RPC call
        :param remoteFuncName: name of the remote function
    """
    self.__doRPCFunc = doRPCFunc
    self.__remoteFuncName = remoteFuncName

  def __getattr__(self, remoteFuncName):
    """ I really do not understand when this would be called.
        I can only imagine it being called by dir, or things like that.
        In any case, it recursively return a MagicMethod object
        where the new remote function name is the old one to which
        we append the new called attribute.
    """
    return _MagicMethod(self.__doRPCFunc, "%s.%s" % (self.__remoteFuncName, remoteFuncName))

  def __call__(self, *args, **kwargs):
    """ Triggers the call.
        it uses the RPC calling function given by RPCClient,
        and gives as argument the remote function name and whatever
        arguments given.
    """
    return self.__doRPCFunc(self.__remoteFuncName, args, **kwargs)

  def __str__(self):
    return "<RPCClient method %s>" % self.__remoteFuncName


class RPCClient(object):
  """ This class contains the mechanism to convert normal calls to RPC calls.

      When instanciated, it creates a :class:`~DIRAC.Core.DISET.private.InnerRPCClient.InnerRPCClient`
      as an attribute. Any attribute which is accessed is then either redirected to InnerRPCClient if it has it,
      or creates a MagicMethod object otherwise. If the attribute is a function, MagicMethod will
      trigger the RPC call, using the InnerRPCClient.

      The typical workflow looks like this::

        rpc = RPCClient('DataManagement/FileCatalog')

        # Here, func is the ping function, which we call remotely.
        # We go through RPCClient.__getattr__ which returns us a MagicMethod object
        func = rpc.ping

        # Here we call the method __call__ of the MagicMethod
        func()

  """

  def __init__(self, *args, **kwargs):
    """
      Constructor
      The arguments are just passed on to InnerRPCClient.
      In practice:

        * args: has to be the service name or URL
        * kwargs: all the arguments InnerRPCClient and BaseClient accept as configuration
    """
    self.__innerRPCClient = InnerRPCClient(*args, **kwargs)

  def __doRPC(self, sFunctionName, args, **kwargs):
    """
      Execute the RPC action. This is given as an attribute
      to MagicMethod

      :param sFunctionName: name of the remote function
      :param args: arguments to pass to the function
    """
    return self.__innerRPCClient.executeRPC(sFunctionName, args, **kwargs)

  def __getattr__(self, attrName):
    """ Function for emulating the existence of functions.

           In literature this is usually called a "stub function".
         If the attribute exists in InnerRPCClient, return it,
         otherwise we create a _MagicMethod instance

    """
    if attrName in dir(self.__innerRPCClient):
      return getattr(self.__innerRPCClient, attrName)
    return _MagicMethod(self.__doRPC, attrName)


def executeRPCStub(rpcStub):
  """
  Playback a stub
  """
  # Generate a RPCClient with the same parameters
  rpcClient = RPCClient(rpcStub[0][0], **rpcStub[0][1])
  # Get a functor to execute the RPC call
  rpcFunc = getattr(rpcClient, rpcStub[1])
  # Reproduce the call
  return rpcFunc(*rpcStub[2])