from __future__ import annotations

import secrets
from dataclasses import asdict, dataclass

from django.conf import settings
from django.core.cache import cache
from django.db import connections
from django.db.utils import DatabaseError


@dataclass(frozen=True)
class HealthResult:
    ok: bool
    checks: dict[str, str]

    def to_dict(self) -> dict[str, object]:
        return asdict(self)


def readiness() -> HealthResult:
    checks: dict[str, str] = {}
    ok = True
    try:
        with connections["default"].cursor() as cursor:
            cursor.execute("SELECT 1")
            cursor.fetchone()
        checks["database"] = "ok"
    except DatabaseError as exc:
        ok = False
        checks["database"] = f"error:{exc.__class__.__name__}"

    if getattr(settings, "HEALTHCHECK_REQUIRE_CACHE", False):
        key = f"health:{secrets.token_hex(8)}"
        try:
            cache.set(key, "ok", timeout=10)
            if cache.get(key) != "ok":
                raise RuntimeError("cache roundtrip failed")
            cache.delete(key)
            checks["cache"] = "ok"
        except Exception as exc:  # Health boundary: report category, never payload/details.
            ok = False
            checks["cache"] = f"error:{exc.__class__.__name__}"

    return HealthResult(ok=ok, checks=checks)