import base64
import json
from datetime import datetime, timezone


def decode_jwt_payload(token: str) -> dict:
    parts = token.split(".")
    if len(parts) != 3:
        raise ValueError("Invalid JWT format")

    payload_b64 = parts[1]
    padding = "=" * (-len(payload_b64) % 4)
    raw = base64.urlsafe_b64decode(payload_b64 + padding)
    return json.loads(raw.decode("utf-8"))


def unix_to_iso_utc(value: int | None) -> str | None:
    if value is None:
        return None
    return datetime.fromtimestamp(value, tz=timezone.utc).isoformat()


def now_utc_ts() -> int:
    return int(datetime.now(tz=timezone.utc).timestamp())