from fastapi import status, HTTPException, Depends, Header
from fastapi.security import OAuth2PasswordBearer

# from sqlalchemy.orm import Session
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.future import select
from jose import JWTError, jwt
from typing import Annotated, Union
from datetime import datetime, timezone, timedelta
from passlib.context import CryptContext
import uuid

from ...db import models
from . import schemas
from ...dependencies import get_db
from ...config import jwt_config

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")


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


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


async def get_user_by_id(db: AsyncSession, user_id: uuid.uuid4) -> models.User:
    u = await db.execute(select(models.User).filter(models.User.id == user_id))
    return u.scalar_one_or_none()


async def get_user_by_username(db: AsyncSession, username: int) -> models.User:
    u = await db.execute(select(models.User).filter(models.User.username == username))
    return u.scalar_one_or_none()


async def authenticate_user(db: AsyncSession, username: str, password: str):
    user = await get_user_by_username(db, username)
    if not user:
        return False
    if not verify_password(password, user.hashed_password):
        return False
    return user


def create_access_token(data: dict, expires_delta: Union[timedelta, None] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.now(timezone.utc) + expires_delta
    else:
        expire = datetime.now(timezone.utc) + timedelta(weeks=2)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(
        to_encode, jwt_config.SECRET_KEY, algorithm=jwt_config.ALGORITHM
    )
    return encoded_jwt


async def create_user(
    db: AsyncSession, user_data: schemas.UserRegister
) -> schemas.UserInDB:
    user = models.User(
        username=user_data.username,
        name=user_data.name,
        hashed_password=get_password_hash(user_data.password),
    )
    db.add(user)
    await db.commit()
    return schemas.UserInDB.model_validate(user)


async def get_current_user(
    token: Annotated[str, Depends(oauth2_scheme)],
    db: Annotated[AsyncSession, Depends(get_db)],
) -> schemas.UserInDB:
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(
            token, jwt_config.SECRET_KEY, algorithms=[jwt_config.ALGORITHM]
        )
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = schemas.TokenData(username=username)
    except JWTError:
        raise credentials_exception
    user = await get_user_by_username(db, username=token_data.username)
    if user is None:
        raise credentials_exception
    return user


async def get_current_user_or_none(
    token: Annotated[str, Depends(oauth2_scheme)],
    db: Annotated[AsyncSession, Depends(get_db)],
) -> Union[schemas.UserInDB, None]:
    try:
        payload = jwt.decode(
            token, jwt_config.SECRET_KEY, algorithms=[jwt_config.ALGORITHM]
        )
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = schemas.TokenData(username=username)
    except JWTError:
        return None
    user = await get_user_by_username(db, username=token_data.username)
    return user


async def get_current_active_user(
    current_user: Annotated[schemas.User, Depends(get_current_user)],
):
    if not current_user.is_active:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


async def create_anon_user(
    db: Annotated[AsyncSession, Depends(get_db)]
) -> schemas.AnonUser:
    u = models.AnonymousUser()
    db.add(u)
    await db.commit()
    return schemas.AnonUser.model_validate(u)


async def get_anon_user(
    db: Annotated[AsyncSession, Depends(get_db)],
    device_id: Annotated[Union[str, None], Header()] = None,
) -> schemas.AnonUser:
    if device_id:
        u = await db.execute(
            select(models.AnonymousUser).filter(models.AnonymousUser.id == device_id)
        )
        return schemas.AnonUser.model_validate(u.scalar_one_or_none())
    return await create_anon_user(db)