'''
Tutorial link: https://docs.sqlalchemy.org/en/latest/orm/tutorial.html
Sqlalchemy version: 1.2.15
Python version: 3.7
'''
import os
import datetime
from sqlalchemy import (create_engine, Column, Integer,
                        String, ForeignKey, Time, Date)
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship
import sqlalchemy.orm.session

Base = declarative_base()


class Catena(Base):
    """ catena class """
    __tablename__ = 'CATENE'

    id = Column('CHIAVE', Integer, primary_key=True)
    name = Column('NOME', String)
    observations = relationship('FbObservation')

    def __repr__(self):  # optional
        return f'Catena {self.name}'


class FbObservation(Base):
    """ FbObservation class """
    __tablename__ = 'DATI_ACQUISITI'

    # id = Column(Integer, primary_key=True)  # obligatory
    pitch = Column('PITCH', String)
    roll = Column('ROLL', String)
    ora = Column('ORA', Time, primary_key=True)
    sensore = Column('SENSORE', Integer, primary_key=True)
    data = Column('DATA', Date)
    temperature = Column('TEMPERATURA', String)

    chiave_id = Column('CATENA', Integer, ForeignKey('CATENE.CHIAVE'))
    catena = relationship("Catena", lazy="joined", foreign_keys=[chiave_id])

    def __repr__(self):  # optional
        return f'FbObservation {self.roll}'

    @property
    def result_time(self):
        ''' Create a datetime object '''
        start_datetime = datetime.datetime.combine(self.data, self.ora)
        return start_datetime


def create_session() -> sqlalchemy.orm.session:
    """Return the sum of x and y."""
    # engine = create_engine('sqlite:///:memory:')
    db_user = os.environ.get("FDB_DBUSER")
    db_password = os.environ.get("FDB_DBPASSWORD")
    db_url = os.environ.get("FDB_DBURL")
    engine = create_engine(
         "firebird+fdb://" + db_user + ":" + db_password + "@" + db_url)
    session_maker = sessionmaker(bind=engine)
    session = session_maker()

    Base.metadata.create_all(engine)
    return session