"""Request-level caching for user principals (group_ids + role_id).

Avoids N+1 queries by loading principals once per request in deps.py
and reusing them in visibility.py and permission_resolver.py.
"""

from __future__ import annotations

import uuid
from contextvars import ContextVar
from dataclasses import dataclass


@dataclass
class UserPrincipals:
    """Cached user principals for the current request."""
    user_id: uuid.UUID
    tenant_id: uuid.UUID
    group_ids: list[uuid.UUID]
    role_id: uuid.UUID | None


# ContextVar — async-safe, isolated per request
_principals_ctx: ContextVar[UserPrincipals | None] = ContextVar(
    "user_principals", default=None
)


def set_principals(principals: UserPrincipals) -> None:
    """Set principals for the current request context."""
    _principals_ctx.set(principals)


def get_principals() -> UserPrincipals | None:
    """Get principals for the current request context, or None if not set."""
    return _principals_ctx.get()


def clear_principals() -> None:
    """Clear principals at end of request (optional — ContextVar is
    isolated per task, but explicit cleanup is good practice)."""
    _principals_ctx.set(None)