'''
Tutorial link: https://docs.sqlalchemy.org/en/latest/orm/tutorial.html
Sqlalchemy version: 1.2.15
Python version: 3.7
'''

import os
from sqlalchemy import (create_engine, Column, Integer,
                        SmallInteger, String, ForeignKey, DateTime, Numeric)
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship
import sqlalchemy.orm.session

Base = declarative_base()


class Platform(Base):
    """ Platform class """
    __tablename__ = 'platform'
    __table_args__ = {"schema": "gba"}

    id = Column('platform_id', Integer, primary_key=True)
    identifier = Column('identifier', String)
    sta_identifier = Column('sta_identifier', String)
    name = Column('name', String)
    # datasets = relationship('Dataset')
    datasets = relationship('Dataset', back_populates="platform", lazy=True)

    def __repr__(self):
        return f'Platform {self.name}'


class Phenomenon(Base):
    """ phenomenon class """
    __tablename__ = 'phenomenon'
    __table_args__ = {"schema": "gba"}

    id = Column('phenomenon_id', Integer, primary_key=True)
    name = Column('name', String)
    sta_identifier = Column('sta_identifier', String)
    # datasets = relationship('Dataset')
    datasets = relationship('Dataset', back_populates="phenomenon", lazy=True)

    def __repr__(self):
        return f'Phenomenon {self.name}'


class Procedure(Base):
    """ procedure class """
    __tablename__ = 'procedure'
    __table_args__ = {"schema": "gba"}

    id = Column('procedure_id', Integer, primary_key=True)
    name = Column('name', String)
    sta_identifier = Column('sta_identifier', String)
    # datasets = relationship('Dataset')
    datasets = relationship('Dataset', back_populates="procedure", lazy=True)

    def __repr__(self):
        return f'Procedure {self.name}'


class Dataset(Base):
    """ dataset class """
    __tablename__ = 'dataset'
    __table_args__ = {"schema": "gba"}

    id = Column('dataset_id', Integer, primary_key=True)
    name = Column('name', String)
    is_published = Column('is_published', SmallInteger)
    is_hidden = Column('is_hidden', SmallInteger)
    dataset_type = Column('dataset_type', String)
    observation_type = Column('observation_type', String)
    value_type = Column('value_type', String)

    last_time = Column('last_time', DateTime)
    last_value = Column('last_value', Numeric(20, 10))
    fk_last_observation_id = Column(
        'fk_last_observation_id',
        Integer
    )
    # last_observation = relationship(
    #     "Observation", foreign_keys=[fk_last_observation_id])

    first_time = Column('first_time', DateTime)
    first_value = Column('first_value', Numeric(20, 10))
    fk_first_observation_id = Column(
        'fk_first_observation_id',
        Integer
    )
    # first_observation = relationship("Observation", foreign_keys=[
    #                                  fk_first_observation_id])

    observations = relationship(
        'Observation', back_populates='dataset', lazy=True)

    fk_procedure_id = Column('fk_procedure_id', Integer, ForeignKey(
        'gba.procedure.procedure_id'), nullable=False)
    # procedure = relationship("Procedure", lazy="joined")
    procedure = relationship(
        "Procedure", back_populates="datasets", lazy="joined")

    fk_phenomenon_id = Column(
        'fk_phenomenon_id', Integer, ForeignKey('gba.phenomenon.phenomenon_id'), nullable=False)
    # phenomenon = relationship("Phenomenon", lazy="joined", foreign_keys=[fk_phenomenon_id])
    phenomenon = relationship(
        "Phenomenon", back_populates="datasets",  lazy="joined")

    # fk_platform_id = Column(
    #     'fk_platform_id', Integer, ForeignKey('gba.platform.platform_id'), nullable=True)
    # # platform = relationship("Platform", lazy="joined", foreign_keys=[fk_platform_id])
    fk_platform_id = Column('fk_platform_id', Integer, ForeignKey(
        'gba.platform.platform_id'), nullable=True)
    platform = relationship(
        "Platform", back_populates="datasets",  lazy="joined")

    def __repr__(self):
        return f'Dataset {self.name}'


class Observation(Base):
    """ observation class """
    __tablename__ = 'observation'
    __table_args__ = {"schema": "gba"}

    id = Column('observation_id', Integer, primary_key=True)
    name = Column('name', String)
    value_type = Column('value_type', String)
    # pitch = Column('PITCH', String)
    # roll = Column('ROLL', String)
    sampling_time_start = Column('sampling_time_start', DateTime)
    sampling_time_end = Column('sampling_time_end', DateTime)
    result_time = Column('result_time', DateTime)
    sta_identifier = Column('sta_identifier', String)
    value_quantity = Column('value_quantity', Numeric(20, 10), nullable=False)

    # fk_dataset_id = Column('fk_dataset_id', Integer,
    #                        ForeignKey('gba.dataset.dataset_id'))
    # dataset = relationship("Dataset", lazy="joined",
    #                        foreign_keys=[fk_dataset_id])
    fk_dataset_id = Column(Integer, ForeignKey(
        'gba.dataset.dataset_id'), nullable=False)
    dataset = relationship("Dataset", back_populates="observations")

    def __repr__(self):
        return f'Observation {self.name}'

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


def create_pg_session() -> sqlalchemy.orm.sessionmaker:
    """ create postgres db session """
    dbschema = ''
    db_user = os.environ.get("POSTGIS_DBUSER")
    db_password = os.environ.get("POSTGIS_DBPASSWORD")
    db_url = os.environ.get("POSTGIS_DBURL")
    engine = create_engine(
        "postgresql+psycopg2://" + db_user + ":" + db_password + "@" + db_url,
        connect_args={'options': '-csearch_path={}'.format(dbschema)},
        isolation_level="READ UNCOMMITTED")
    session_maker = sessionmaker(bind=engine)
    session = session_maker()

    # Base.metadata.create_all(engine)
    return session