"""
City repository with database CRUD operations
SPDX - License - Identifier: LGPL - 3.0 - or -later
Copyright © 2022 Concordia CERC group
Project Coder Peter Yefi peteryefi@gmail.com
"""

import datetime
import pickle
from typing import Union, Dict

from sqlalchemy import select
from sqlalchemy.exc import SQLAlchemyError

from hub.city_model_structure.city import City as CityHub
from hub.hub_logger import logger
from hub.persistence import Repository
from hub.persistence.models import City as Model
from hub.version import __version__


class City(Repository):
  _instance = None

  def __init__(self, db_name: str, dotenv_path: str, app_env: str):
    super().__init__(db_name, dotenv_path, app_env)

  def __new__(cls, db_name, dotenv_path, app_env):
    """
    Implemented for a singleton pattern
    """
    if cls._instance is None:
      cls._instance = super(City, cls).__new__(cls)
    return cls._instance

  def insert(self, city: CityHub, application_id, user_id: int) -> Union[Model, Dict]:
    """
    Insert a city
    :param city: The complete city instance
    :param application_id: Application id owning the instance
    :param user_id: User id owning the instance
    :return: City and Dictionary
    """
    try:
      db_city = Model(
        pickle.dumps(city),
        city.name,
        city.level_of_detail,
        city.climate_file,
        application_id,
        user_id,
        __version__)

      self.session.add(db_city)
      self.session.flush()
      self.session.commit()
      return db_city
    except SQLAlchemyError as err:
      logger.error(f'An error occurred while creating city: {err}')

  def get_by_id(self, city_id: int) -> Model:
    """
    Fetch a City based on the id
    :param city_id: the city id
    :return: a city
    """
    try:
      return self.session.execute(select(Model).where(Model.id == city_id)).first()[0]
    except SQLAlchemyError as err:
      logger.error(f'Error while fetching city: {err}')

  def _get_by_hub_version_and_name(self, hub_release: str, city_name: str) -> Model:
    """
    Fetch a City based on the name and hub project
    :param hub_release: the hub release
    :param city_name: the name of the city
    :return: a city
    """
    try:
      return self.session.execute(select(Model)
                                  .where(Model.hub_release == hub_release, Model.name == city_name)
                                  ).first()
    except SQLAlchemyError as err:
      logger.error(f'Error while fetching city: {err}')

  def get_by_name(self, city_name: str) -> [Model]:
    """
    Fetch city based on the name
    :param city_name: the name of the building
    :return: [ModelCity] with the provided name
    """
    try:
      result_set = self.session.execute(select(Model).where(Model.name == city_name))
      return [building[0] for building in result_set]
    except SQLAlchemyError as err:
      logger.error(f'Error while fetching city by name: {err}')

  def get_by_user(self, user_id: int) -> [Model]:
      """
      Fetch city based on the user who created it
      :param user_id: the id of the user
      :return: [ModelCity] with the provided name
      """
      try:
        result_set = self.session.execute(select(Model).where(Model.user_id == user_id))
        return [building[0] for building in result_set]
      except SQLAlchemyError as err:
        logger.error(f'Error while fetching city by name: {err}')

  def update(self, city_id: int, city: CityHub):
    """
    Updates a city name (other updates makes no sense)
    :param city_id: the id of the city to be updated
    :param city: the city object
    :return:
    """
    try:
      now = datetime.datetime.utcnow()
      self.session.query(Model).filter(Model.id == city_id).update({'name': city.name,'updated': now})
      self.session.commit()
    except SQLAlchemyError as err:
      logger.error(f'Error while updating city: {err}')

  def delete_city(self, city_id: int):
    """
    Deletes a City with the id
    :param city_id: the city id
    :return: a city
    """
    try:
      self.session.query(Model).filter(Model.id == city_id).delete()
      self.session.commit()
    except SQLAlchemyError as err:
      logger.error(f'Error while fetching city: {err}')