""" ModelAccessor

    A class for abstracting access to models. Used to get any djangoisms out
    of the synchronizer code base.

    This module will import all models into this module's global scope, so doing
    a "from modelaccessor import *" from a calling module ought to import all
    models into the calling module's scope.
"""

import functools
import os
from xos.config import Config
from diag import update_diag

class ModelAccessor(object):
    def __init__(self):
        self.all_model_classes = self.get_all_model_classes()

    def get_all_model_classes(self):
        """ Build a dictionary of all model class names """
        raise Exception("Not Implemented")

    def get_model_class(self, name):
        """ Given a class name, return that model class """
        return self.all_model_classes[name]

    def has_model_class(self, name):
        """ Given a class name, return that model class """
        return name in self.all_model_classes

    def fetch_pending(self, name, deletion=False):
        """ Execute the default fetch_pending query """
        raise Exception("Not Implemented")

    def reset_queries(self):
        """ Reset any state between passes of synchronizer. For django, to
            limit memory consumption of cached queries.
        """
        pass

    def connection_close(self):
        """ Close any active database connection. For django, to limit memory
            consumption.
        """
        pass

    def check_db_connection_okay(self):
        """ Checks to make sure the db connection is okay """
        pass

    def obj_exists(self, o):
        """ Return True if the object exists in the data model """
        raise Exception("Not Implemented")

    def obj_in_list(self, o, olist):
        """ Return True if o is the same as one of the objects in olist """
        raise Exception("Not Implemented")

    def now(self):
        """ Return the current time for timestamping purposes """
        raise Exception("Not Implemented")

    def update_diag(self, loop_end=None, loop_start=None, syncrecord_start=None, sync_start=None, backend_status=None):
        if self.has_model_class("Diag"):
            return update_diag(self.get_model_class("Diag"), loop_end, loop_start, syncrecord_start, sync_start, backend_status)

    def is_type(self, obj, name):
        """ returns True is obj is of model type "name" """
        raise Exception("Not Implemented")

    def is_instance(self, obj, name):
        """ returns True if obj is of model type "name" or is a descendant """
        raise Exception("Not Implemented")

    def journal_object(self, o, operation, msg=None, timestamp=None):
        pass

def import_models_to_globals():
    # add all models to globals
    for (k, v) in model_accessor.all_model_classes.items():
        globals()[k] = v

    # plcorebase doesn't exist from the synchronizer's perspective, so fake out
    # ModelLink.
    if "ModelLink" not in globals():
        class ModelLink:
            def __init__(self,dest,via,into=None):
                self.dest=dest
                self.via=via
                self.into=into
        globals()["ModelLink"] = ModelLink

def grpcapi_reconnect(client, reactor):
    global model_accessor

    # this will prevent updated timestamps from being automatically updated
    client.xos_orm.caller_kind = "synchronizer"

    from apiaccessor import CoreApiModelAccessor
    model_accessor = CoreApiModelAccessor(orm = client.xos_orm)
    import_models_to_globals()

    # Synchronizer framework isn't ready to embrace reactor yet...
    reactor.stop()

def config_accessor():
    global model_accessor

    accessor_kind = getattr(Config(), "observer_accessor_kind", "django")

    if (accessor_kind == "django"):
       from djangoaccessor import DjangoModelAccessor
       model_accessor = DjangoModelAccessor()
       import_models_to_globals()
    else:
       grpcapi_endpoint = getattr(Config(), "observer_accessor_endpoint", "xos-core.cord.lab:50051")
       grpcapi_username = getattr(Config(), "observer_accessor_username", "xosadmin@opencord.org")
       grpcapi_password = getattr(Config(), "observer_accessor_password")

       # if password starts with "@", then retreive the password from a file
       if grpcapi_password.startswith("@"):
           fn = grpcapi_password[1:]
           if not os.path.exists(fn):
               raise Exception("%s does not exist" % fn)
           grpcapi_password = open(fn).readline().strip()

       from xosapi.xos_grpc_client import SecureClient
       from twisted.internet import reactor

       grpcapi_client = SecureClient(endpoint = grpcapi_endpoint, username = grpcapi_username, password=grpcapi_password)
       grpcapi_client.set_reconnect_callback(functools.partial(grpcapi_reconnect, grpcapi_client, reactor))
       grpcapi_client.start()

       # Start reactor. This will cause the client to connect and then execute
       # grpcapi_callback().

       reactor.run()

config_accessor()