CT-205 Added transaction_id decorator

import sys

import os

import tango

from .cspcommons import CmdExecState

from ska.base.control_model import AdminMode,ObsState

import functools

import json

from ska.log_transactions import transaction

from ska.base.control_model import AdminMode,ObsState

from .cspcommons import CmdExecState

def transaction_id(func):

    """

    This decorator add a transaction id to the input of the decorated method. 

    The input of the decorated method is a json string.

    """

    @functools.wraps(func)

    def wrap(*args, **kwargs):

        # Argument of the decorated method can be either positional or named. 

        # Following code manage both cases.

        # A named argument occurs when applied to "do" method of SKA Base Command Classes.

        # argument must be single.

        # note that args[0] is the "self" object of the class of the decorated method.

        if kwargs:

            keys=list(kwargs.keys())

            argin = kwargs[keys[0]]    

        elif len(args)>1:

            argin = args[1]

        else:

            raise Exception('No argument are passed to the transaction ID decorator')

        parameters =json.loads(argin)

        obj = args[0]

        #note: obj.name is the Command Class Name.

        with transaction(obj.name, parameters,logger=obj.logger) as transaction_id:    

            parameters['transaction_id'] = transaction_id

        argin = json.dumps(parameters)

        return func(obj,argin)

    return wrap

class AdminModeCheck(object):

    """

            return f(*args, **kwargs)

        return admin_mode_check

VALID_OBS_STATE = {'reset': [ObsState.ABORTED],

                   'configscan': [ObsState.IDLE, ObsState.READY],

                   'scan': [ObsState.READY],

                   'endscan': [ObsState.SCANNING],

                   'gotoidle': [ObsState.READY, ObsState.IDLE],

                   'addresources': [ObsState.IDLE],

                   'removeresources': [ObsState.IDLE]

                   }

class ObsStateCheck(object):

    """

    Class designed to be a decorator for the CspMaster methods.

    It checks the obsMode attribute value

    """

    def __init__(self, args=False, kwargs=False):

        self._args = args

        self._kwargs = kwargs

    def __call__(self, f):

        @functools.wraps(f)

        def obs_state_check(*args, **kwargs):

            # get the  device instance

            dev_instance = args[0]

            cmd_type = self._args

            dev_instance.logger.info("device obs_state: {}".format(dev_instance._obs_state))

            # Check the obsState attribute value: valid values for the command to

            # execute are defined by VALID_OBS_STATE dictionary

            if dev_instance._obs_state not in VALID_OBS_STATE[cmd_type]:

                msg_args = (f.__name__, ObsState(dev_instance._obs_state).name)

                err_msg = ("{} command can't be issued when the"

                           " obsState is {} ".format(*msg_args))

                tango.Except.throw_exception("Command not executable",

                                             err_msg,

                                             "ObsStateCheck decorator",

                                             tango.ErrSeverity.ERR)

            return f(*args, **kwargs)

        return obs_state_check

class CmdInputArgsCheck(object):

    """

    Class designed to be a decorator for the CspMaster methods.