cic-stack/apps/cic-ussd/cic_ussd/session/ussd_session.py
2021-08-06 16:29:01 +00:00

259 lines
8.9 KiB
Python

# standard imports
import logging
from typing import Optional
import json
# external imports
import celery
from redis import Redis
from sqlalchemy.orm.session import Session
# local imports
from cic_ussd.cache import Cache
from cic_ussd.db.models.base import SessionBase
from cic_ussd.db.models.ussd_session import UssdSession as DbUssdSession
logg = logging.getLogger()
class UssdSession:
"""
This class defines the USSD session object that is called whenever a user interacts with the system.
:cvar store: The in-memory redis cache.
:type store: Redis
"""
store: Redis = None
def __init__(self,
external_session_id: str,
msisdn: str,
service_code: str,
state: str,
user_input: str,
data: Optional[dict] = None):
"""
This function is called whenever a USSD session object is created and saves the instance to a JSON DB.
:param external_session_id: The Africa's Talking session ID.
:type external_session_id: str.
:param service_code: The USSD service code from which the user used to gain access to the system.
:type service_code: str.
:param msisdn: The user's phone number.
:type msisdn: str.
:param user_input: The data or choice the user has made while interacting with the system.
:type user_input: str.
:param state: The name of the USSD menu that the user was interacting with.
:type state: str.
:param data: Any additional data that was persisted during the user's interaction with the system.
:type data: dict.
"""
self.data = data
self.external_session_id = external_session_id
self.msisdn = msisdn
self.service_code = service_code
self.state = state
self.user_input = user_input
session = self.store.get(external_session_id)
if session:
session = json.loads(session)
self.version = session.get('version') + 1
else:
self.version = 1
self.session = {
'data': self.data,
'external_session_id': self.external_session_id,
'msisdn': self.msisdn,
'service_code': self.service_code,
'state': self.state,
'user_input': self.user_input,
'version': self.version
}
self.store.set(self.external_session_id, json.dumps(self.session))
self.store.persist(self.external_session_id)
def set_data(self, key: str, value: str) -> None:
"""
This function adds or updates data to the session data.
:param key: The name used to identify the data.
:type key: str.
:param value: The actual data to be stored in the session data.
:type value: str.
"""
if self.data is None:
self.data = {}
self.data[key] = value
self.store.set(self.external_session_id, json.dumps(self.session))
def get_data(self, key: str) -> Optional[str]:
"""
This function attempts to fetch data from the session data using the identifier for the specific data.
:param key: The name used as the identifier for the specific data.
:type key: str.
:return: This function returns the queried data if found, else it doesn't return any value.
:rtype: str.
"""
if self.data is not None:
return self.data.get(key)
else:
return None
def to_json(self):
""" This function serializes the in memory ussd session object to a JSON object
:return: A JSON object of a ussd session in memory
:rtype: dict
"""
return {
"data": self.data,
"external_session_id": self.external_session_id,
"msisdn": self.msisdn,
"user_input": self.user_input,
"service_code": self.service_code,
"state": self.state,
"version": self.version
}
def create_ussd_session(
state: str,
external_session_id: str,
msisdn: str,
service_code: str,
user_input: str,
data: Optional[dict] = None) -> UssdSession:
"""
:param state:
:type state:
:param external_session_id:
:type external_session_id:
:param msisdn:
:type msisdn:
:param service_code:
:type service_code:
:param user_input:
:type user_input:
:param data:
:type data:
:return:
:rtype:
"""
return UssdSession(external_session_id=external_session_id,
msisdn=msisdn,
user_input=user_input,
state=state,
service_code=service_code,
data=data
)
def update_ussd_session(ussd_session: UssdSession,
user_input: str,
state: str,
data: Optional[dict] = None) -> UssdSession:
""""""
if data is None:
data = ussd_session.data
return UssdSession(
external_session_id=ussd_session.external_session_id,
msisdn=ussd_session.msisdn,
user_input=user_input,
state=state,
service_code=ussd_session.service_code,
data=data
)
def create_or_update_session(external_session_id: str,
msisdn: str,
service_code: str,
user_input: str,
state: str,
session,
data: Optional[dict] = None) -> UssdSession:
"""
:param external_session_id:
:type external_session_id:
:param msisdn:
:type msisdn:
:param service_code:
:type service_code:
:param user_input:
:type user_input:
:param state:
:type state:
:param session:
:type session:
:param data:
:type data:
:return:
:rtype:
"""
session = SessionBase.bind_session(session=session)
existing_ussd_session = session.query(DbUssdSession).filter_by(
external_session_id=external_session_id).first()
if existing_ussd_session:
ussd_session = update_ussd_session(ussd_session=existing_ussd_session,
state=state,
user_input=user_input,
data=data
)
else:
ussd_session = create_ussd_session(external_session_id=external_session_id,
msisdn=msisdn,
service_code=service_code,
user_input=user_input,
state=state,
data=data
)
SessionBase.release_session(session=session)
return ussd_session
def persist_ussd_session(external_session_id: str, queue: Optional[str]):
"""This function asynchronously retrieves a cached ussd session object matching an external ussd session id and adds
it to persistent storage.
:param external_session_id: Session id value provided by ussd service provided.
:type external_session_id: str
:param queue: Name of worker queue to submit tasks to.
:type queue: str
"""
s_persist_ussd_session = celery.signature(
'cic_ussd.tasks.ussd_session.persist_session_to_db',
[external_session_id],
queue=queue
)
s_persist_ussd_session.apply_async()
def save_session_data(queue: Optional[str], session: Session, data: dict, ussd_session: dict):
"""This function is stores information to the session data attribute of a cached ussd session object.
:param data: A dictionary containing data for a specific ussd session in redis that needs to be saved
temporarily.
:type data: dict
:param queue: The queue on which the celery task should run.
:type queue: str
:param session: Database session object.
:type session: Session
:param ussd_session: A ussd session passed to the state machine.
:type ussd_session: UssdSession
"""
cache = Cache.store
external_session_id = ussd_session.get('external_session_id')
existing_session_data = ussd_session.get('data')
if existing_session_data:
data = {**existing_session_data, **data}
in_redis_ussd_session = cache.get(external_session_id)
in_redis_ussd_session = json.loads(in_redis_ussd_session)
create_or_update_session(
external_session_id=external_session_id,
msisdn=in_redis_ussd_session.get('msisdn'),
service_code=in_redis_ussd_session.get('service_code'),
user_input=in_redis_ussd_session.get('user_input'),
state=in_redis_ussd_session.get('state'),
session=session,
data=data
)
persist_ussd_session(external_session_id=external_session_id, queue=queue)