"""
SaulGPT — Authentication Layer
===============================
JWT token creation/verification + bcrypt password hashing.
"""

from datetime import datetime, timedelta, timezone
from typing import Optional
from jose import JWTError, jwt
import bcrypt

# Secret key — in production, move to .env
SECRET_KEY = "saulgpt-dev-secret-change-in-production-2024"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_DAYS = 30


def hash_password(password: str) -> str:
    salt = bcrypt.gensalt()
    return bcrypt.hashpw(password.encode("utf-8"), salt).decode("utf-8")


def verify_password(plain: str, hashed: str) -> bool:
    try:
        return bcrypt.checkpw(plain.encode("utf-8"), hashed.encode("utf-8"))
    except Exception:
        return False


def create_token(user_id: int) -> str:
    expire = datetime.now(timezone.utc) + timedelta(days=ACCESS_TOKEN_EXPIRE_DAYS)
    payload = {"sub": str(user_id), "exp": expire}
    return jwt.encode(payload, SECRET_KEY, algorithm=ALGORITHM)


def decode_token(token: str) -> Optional[int]:
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        user_id = payload.get("sub")
        if user_id is None:
            return None
        return int(user_id)
    except JWTError:
        return None