from __future__ import annotations

import os
from collections.abc import Mapping
from datetime import UTC, datetime
from typing import cast

from django.http import JsonResponse
from django.views.decorators.cache import never_cache

from apps.health.checks import check_backup, check_cache, check_celery, check_db

CRITICAL_CHECKS = {"db", "cache"}


@never_cache
def health_view(request):
    checks: dict[str, Mapping[str, object]] = {
        "db": check_db(),
        "cache": check_cache(),
        "celery": check_celery(),
        "backup": check_backup(),
    }

    if any(cast(str, checks[name]["status"]) == "fail" for name in CRITICAL_CHECKS):
        overall_status = "unhealthy"
    elif any(cast(str, check["status"]) == "fail" for check in checks.values()):
        overall_status = "degraded"
    else:
        overall_status = "ok"

    payload = {
        "status": overall_status,
        "version": {
            "git_sha": os.environ.get("GIT_SHA", "unknown"),
            "build": os.environ.get("BUILD_ID", "unknown"),
        },
        "checks": checks,
        "timestamp": datetime.now(UTC).strftime("%Y-%m-%dT%H:%M:%SZ"),
    }
    response_status = 503 if overall_status == "unhealthy" else 200
    return JsonResponse(payload, status=response_status)