from datetime import datetime, timedelta, timezone
from typing import List, Union

from fastapi import Depends, HTTPException, Security, status
from fastapi.security import OAuth2PasswordBearer, SecurityScopes
from jose import JWTError, jwt
from passlib.context import CryptContext
from pydantic import BaseModel, ValidationError

from modules.database import col_users

with open("secret_key", "r", encoding="utf-8") as f:
    SECRET_KEY = f.read()
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_DAYS = 180


class Token(BaseModel):
    access_token: str
    token_type: str


class TokenData(BaseModel):
    user: Union[str, None] = None
    scopes: List[str] = []


class User(BaseModel):
    user: str
    email: Union[str, None] = None
    disabled: Union[bool, None] = None


class UserInDB(User):
    hash: str


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

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="token",
    scopes={
        "me": "Get current user's data.",
        "albums.list": "List albums.",
        "albums.read": "Read albums data.",
        "albums.write": "Modify albums.",
        "photos.list": "List photos.",
        "photos.read": "View photos.",
        "photos.write": "Modify photos.",
        "videos.list": "List videos.",
        "videos.read": "View videos.",
        "videos.write": "Modify videos.",
    },
)


def verify_password(plain_password, hashed_password) -> bool:
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password) -> str:
    return pwd_context.hash(password)


async def get_user(user: str) -> UserInDB:
    found_user = await col_users.find_one({"user": user})

    if found_user is None:
        raise RuntimeError(f"User {user} does not exist")

    return UserInDB(
        user=found_user["user"],
        email=found_user["email"],
        disabled=found_user["disabled"],
        hash=found_user["hash"],
    )


async def authenticate_user(user_name: str, password: str) -> Union[UserInDB, bool]:
    if user := await get_user(user_name):
        return user if verify_password(password, user.hash) else False
    else:
        return False


def create_access_token(
    data: dict, expires_delta: Union[timedelta, None] = None
) -> str:
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.now(tz=timezone.utc) + expires_delta
    else:
        expire = datetime.now(tz=timezone.utc) + timedelta(
            days=ACCESS_TOKEN_EXPIRE_DAYS
        )
    to_encode["exp"] = expire
    return jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)


async def get_current_user(
    security_scopes: SecurityScopes, token: str = Depends(oauth2_scheme)
) -> UserInDB:
    if security_scopes.scopes:
        authenticate_value = f'Bearer scope="{security_scopes.scope_str}"'
    else:
        authenticate_value = "Bearer"

    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": authenticate_value},
    )

    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        user: str = payload.get("sub")
        if user is None:
            raise credentials_exception
        token_scopes = payload.get("scopes", [])
        token_data = TokenData(scopes=token_scopes, user=user)
    except (JWTError, ValidationError) as exc:
        raise credentials_exception from exc

    user_record = await get_user(user=token_data.user)

    if user_record is None:
        raise credentials_exception

    for scope in security_scopes.scopes:
        if scope not in token_data.scopes:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Not enough permissions",
                headers={"WWW-Authenticate": authenticate_value},
            )
    return user_record


async def get_current_active_user(
    current_user: User = Security(get_current_user, scopes=["me"])
):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user