import abc

class QueryException(Exception):
    pass

class OrmSubject(object, metaclass=abc.ABCMeta):
    @abc.abstractmethod
    def addObserver(self, ormObserver):
        pass

    @abc.abstractmethod
    def removeObserver(self, ormObserver):
        pass

    @abc.abstractmethod
    def notify(self, subject):
        pass

class Observer(object, metaclass=abc.ABCMeta):
    @abc.abstractmethod
    def update(self, subject):
        pass

class BaseOrm(OrmSubject):

    def __init__(self):
        self.__observers = []
        self.__oldValues = {}

    def addObserver(self, ormObserver):
        print("Added: {0}".format(ormObserver))
        self.__observers.append(ormObserver)

    def removeObserver(self, ormObserver):
        self.__observers.remove(ormObserver)

    def notify(self, object):
        for observer in self.__observers:
            observer.update(object)

    @classmethod
    def query(cls, **kwargs):
        objects = []
        from app import db
        if kwargs:
            if hasattr(cls, '__tablename__'):
                table = cls.__tablename__
            else:
                table = cls.__name__
            o = db.query(table, **kwargs)
            if table.lower() == 'user':
                for user in o:
                    objects.append(cls(user[1], user[2], user[3], user[4], user[0]))
            elif table.lower() == 'portfolio':
                for portfolio in o:
                    user = db.query('user', id = portfolio[2])[0]
                    objects.append(cls(portfolio[1], user, portfolio[3], portfolio[4], portfolio[0]))
        else:
            raise QueryException("{0}: Missing at least one query parameter".format(cls))
        return objects
    
    def commit(self):
        self.notify(self)
        self.__oldValues = {}
        
    def rollback(self):
        for k, v in self.__oldValues.items():
            setattr(self, k, v) 
        self.__oldValues = {}
    
    @property
    def id(self):
        return self.__id

    @id.setter
    def id(self, id):
        try:
            self.__oldValues['id'] = self.id
        except AttributeError:
            pass
        self.__id = id