"""
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
"""

from city_model_structure.city import City
from persistence import BaseRepo
from sqlalchemy.exc import SQLAlchemyError
from sqlalchemy import select
from helpers.city_util import CityUtil
from persistence.models import City as DBCity
import pickle
import requests
from urllib3.exceptions import HTTPError
from typing import Union, Dict


class CityRepo(BaseRepo):
  _instance = None

  def __init__(self, db_name, app_env):
    super().__init__(db_name, app_env)
    self._city_util = CityUtil()

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

  def insert(self, city: City) -> Union[City, Dict]:
    db_city = DBCity()
    db_city.name = city.name
    db_city.climate_reference_city = city.climate_reference_city
    db_city.srs_name = city.srs_name
    db_city.longitude = city.longitude
    db_city.latitude = city.latitude
    db_city.country_code = city.country_code
    db_city.time_zone = city.time_zone
    db_city.lower_corner = city.lower_corner.tolist()
    db_city.upper_corner = city.upper_corner.tolist()
    db_city.city = pickle.dumps(city)

    try:
      # Retrieve hub project latest release
      response = requests.get("https://rs-loy-gitlab.concordia.ca/api/v4/projects/2/repository/branches/master",
                              headers={"PRIVATE-TOKEN": self.config.hub_token})
      recent_commit = response.json()["commit"]["id"]
      exiting_city = self._get_by_hub_version(recent_commit, city.name)

      # Do not persist the same city for the same version of Hub
      if exiting_city is None:
        db_city.hub_release = recent_commit
        cities = self.get_by_name(city.name)
        # update version for the same city but different hub versions

        if len(cities) == 0:
          db_city.city_version = 0
        else:
          db_city.city_version = cities[-1].city_version + 1

        # Persist city
        self.session.add(db_city)
        self.session.flush()
        self.session.commit()
        return db_city
      else:
        return {'message': f'Same version of {city.name} exist'}
    except SQLAlchemyError as err:
      print(f'Error while adding city: {err}')
    except HTTPError as err:
      print(f'Error retrieving Hub latest release: {err}')

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

  def _get_by_hub_version(self, hub_commit: str, city_name: str) -> City:
    """
    Fetch a City based on the name and hub project recent commit
    :param hub_commit: the latest hub commit
    :param city_name: the name of the city
    :return: a city
    """
    try:
      return self.session.execute(select(DBCity)
                                  .where(DBCity.hub_release == hub_commit, DBCity.name == city_name)).first()
    except SQLAlchemyError as err:
      print(f'Error while fetching city: {err}')

  def update(self, city_id: int, city: City):
    """
    Updates a city
    :param city_id: the id of the city to be updated
    :param city: the city object
    :return:
    """
    try:
      self.session.query(DBCity).filter(DBCity.id == city_id) \
        .update({
        'name': city.name, 'srs_name': city.srs_name, 'country_code': city.country_code, 'longitude': city.longitude,
        'latitude': city.latitude, 'time_zone': city.time_zone, 'lower_corner': city.lower_corner.tolist(),
        'upper_corner': city.upper_corner.tolist(), 'climate_reference_city': city.climate_reference_city,
      })

      self.session.commit()
    except SQLAlchemyError as err:
      print(f'Error while updating city: {err}')

  def get_by_name(self, city_name: str) -> [DBCity]:
    """
    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(DBCity).where(DBCity.name == city_name))
      return [building[0] for building in result_set]
    except SQLAlchemyError as err:
      print(f'Error while fetching city by name: {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(DBCity).filter(DBCity.id == city_id).delete()
     self.session.commit()
    except SQLAlchemyError as err:
      print(f'Error while fetching city: {err}')