from __future__ import annotations

import functools
import json
from enum import Enum

from jose.constants import ALGORITHMS
from passlib.context import CryptContext
from pydantic import BaseModel, BaseSettings, Field
from sqlalchemy import create_engine
from sqlalchemy.engine import Engine


class Settings(BaseSettings):
    production_mode: bool = False
    config_file: str = "tmp/config.json"
    openapi_url: str = "/openapi.json"
    docs_url: str | None = "/docs"
    redoc_url: str | None = None

    @staticmethod
    @functools.lru_cache
    def get() -> Settings:
        return Settings()


class DBType(Enum):
    sqlite = "sqlite"
    mysql = "mysql"


class DBConfig(BaseModel):
    db_type: DBType = DBType.sqlite

    @property
    def db_engine(self) -> Engine:
        return create_engine(
            "sqlite:///./tmp/vpn.db",
            connect_args={"check_same_thread": False},
        )


class JWTConfig(BaseModel):
    secret: str | None = None
    hash_algorithm: str = ALGORITHMS.HS256
    expiry_minutes: int = 30


class CryptoConfig(BaseModel):
    schemes: list[str] = ["bcrypt"]

    @property
    def crypt_context(self) -> CryptContext:
        return CryptContext(
            schemes=self.schemes,
            deprecated="auto",
        )


class Config(BaseModel):
    db: DBConfig = Field(default_factory=DBConfig)
    jwt: JWTConfig = Field(default_factory=JWTConfig)
    crypto: CryptoConfig = Field(default_factory=CryptoConfig)

    @staticmethod
    async def get() -> Config | None:
        try:
            with open(Settings.get().config_file, "r") as config_file:
                return Config.parse_obj(json.load(config_file))

        except FileNotFoundError:
            return None

    @staticmethod
    def set(config: Config) -> None:
        with open(Settings.get().config_file, "w") as config_file:
            config_file.write(config.json(indent=2))

    @property
    def crypt_context(self) -> CryptContext:
        return self.crypto.crypt_context

    @property
    def db_engine(self) -> Engine:
        return self.db.db_engine