import os
import jwt
from datetime import datetime, timedelta, timezone
from typing import Optional

SECRET_KEY = os.getenv("JWT_SECRET", "choreus-super-secret-key-2026-family-chores")
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_DAYS = 30

GOOGLE_CLIENT_ID = os.getenv("GOOGLE_CLIENT_ID", "")

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

def decode_access_token(token: str) -> Optional[dict]:
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        return payload
    except jwt.PyJWTError:
        return None

def get_current_week_identifier() -> str:
    now = datetime.now(timezone.utc)
    year, week, _ = now.isocalendar()
    return f"{year}-W{week:02d}"