import uuid
from datetime import datetime, timedelta, timezone

from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from jose import JWTError, jwt
from passlib.context import CryptContext
from sqlalchemy.orm import Session

from .config import settings
from .database import get_db
from .models import User

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/auth/login", auto_error=False)


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


def verify_password(plain: str, hashed: str) -> bool:
    return pwd_context.verify(plain, hashed)


def create_access_token(user_id: uuid.UUID) -> str:
    expire = datetime.now(timezone.utc) + timedelta(minutes=settings.jwt_expire_minutes)
    payload = {"sub": str(user_id), "exp": expire}
    return jwt.encode(payload, settings.jwt_secret, algorithm=settings.jwt_algorithm)


def _decode_user_id(token: str) -> uuid.UUID:
    try:
        payload = jwt.decode(token, settings.jwt_secret, algorithms=[settings.jwt_algorithm])
        return uuid.UUID(payload["sub"])
    except (JWTError, KeyError, ValueError):
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid or expired token")


def get_current_user(
    token: str | None = Depends(oauth2_scheme),
    db: Session = Depends(get_db),
) -> User:
    if not token:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Not authenticated")
    user_id = _decode_user_id(token)
    user = db.get(User, user_id)
    if not user:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="User not found")
    return user


def get_current_user_optional(
    token: str | None = Depends(oauth2_scheme),
    db: Session = Depends(get_db),
) -> User | None:
    if not token:
        return None
    try:
        user_id = _decode_user_id(token)
    except HTTPException:
        return None
    return db.get(User, user_id)