from __future__ import annotations

import json
from enum import Enum
from pathlib import Path
from typing import Generator

from fastapi import Depends
from jose.constants import ALGORITHMS
from passlib.context import CryptContext
from pydantic import BaseModel, Field, PrivateAttr
from sqlalchemy import create_engine
from sqlalchemy.orm import Session, sessionmaker

from .db.models import ORMBaseModel

PRODUCTION_MODE = False

# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "2f7875b0d2be8a76eba8077ab4d9f8b1c749e02647e9ac9e0f909c3acbfc9856"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

CRYPT_CONTEXT = CryptContext(schemes=["bcrypt"], deprecated="auto")

SESSION_LOCAL = None


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


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


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


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


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

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

    __session_local: sessionmaker = PrivateAttr()

    async def connect_db(self) -> None:
        engine = create_engine(
            "sqlite:///./tmp/vpn.db",
            connect_args={"check_same_thread": False},
        )
        self.__session_local = sessionmaker(
            autocommit=False, autoflush=False, bind=engine,
        )
        ORMBaseModel.metadata.create_all(bind=engine)

    @property
    def database(self) -> Session | None:
        if self.__session_local is not None:
            return self.__session_local()


CONFIG_FILE = "tmp/config.json"


async def has_config() -> bool:
    return Path(CONFIG_FILE).is_file()


async def load_config() -> BaseConfig:
    try:
        with open(CONFIG_FILE, "r") as kv:
            return BaseConfig.parse_obj(json.load(kv))

    except FileNotFoundError:
        return BaseConfig()


async def get_db(
    config: BaseConfig = Depends(load_config)
) -> Generator[Session | None, None, None]:
    if db := config.database is None:
        yield None

    else:
        try:
            yield db
        finally:
            db.close()