import json
from datetime import datetime
from sqlalchemy.orm import load_only
from . import DAOException
from app import db
from app.models import (Service, User)


def save_model_service(service, update_dict=None):
    users_list = update_dict.get('users', []) if update_dict else getattr(service, 'users', [])
    if not users_list:
        error_msg = {'users': ['Missing data for required attribute']}
        raise DAOException(json.dumps(error_msg))
    if update_dict:
        # Make sure the update_dict doesn't contain conflicting
        update_dict.pop('id', None)
        update_dict.pop('users', None)
        # TODO optimize this algorithm
        new_users = User.query.filter(User.id.in_(users_list)).all()
        for x in service.users:
            if x in new_users:
                new_users.remove(x)
            else:
                service.users.remove(x)
        for x in new_users:
            service.users.append(x)
        Service.query.filter_by(id=service.id).update(update_dict)
    else:
        db.session.add(service)
    db.session.commit()


def delete_model_service(service):
    db.session.delete(service)
    db.session.commit()


def get_model_services(service_id=None, user_id=None):
    # TODO need better mapping from function params to sql query.
    if user_id and service_id:
        return Service.query.filter(
            Service.users.any(id=user_id)).filter_by(id=service_id).one()
    elif service_id:
        return Service.query.filter_by(id=service_id).one()
    elif user_id:
        return Service.query.filter(Service.users.any(id=user_id)).all()
    return Service.query.all()