"""
健康检查端点（无需登录）

- GET /healthz
    用于探活/负载均衡/容器 readinessProbe。
    返回:
        {
            "status": "ok" | "degraded",
            "db_ok":  true | false,
            "env":    "dev" | "production",
            "system": "Pear Admin",
            "timestamp": "2026-09-05T17:00:00+08:00"
        }

    HTTP 状态码：
        200 - 全部正常
        503 - DB 不可达（用于触发 k8s readinessProbe 失败）
"""
from datetime import datetime, timedelta, timezone
import os

from flask import Blueprint, current_app, jsonify
from sqlalchemy import text

from applications.extensions import db

bp = Blueprint("health", __name__)


def _beijing_now() -> str:
    """返回 +08:00 时区 ISO8601 时间字符串。"""
    tz = timezone(timedelta(hours=8))
    return datetime.now(tz).isoformat()


@bp.get("/healthz")
def healthz():
    # 优先按 PEAR_ENV/FLASK_ENV 取环境名；兜底按 DEBUG 反推
    env = (
        os.environ.get("PEAR_ENV")
        or os.environ.get("FLASK_ENV")
        or current_app.config.get("PEAR_ENV")
        or ("dev" if current_app.config.get("DEBUG") else "production")
    )
    system_name = current_app.config.get("SYSTEM_NAME", "Pear Admin")

    # DB 探活：跑一个最轻量的 SELECT 1
    db_ok = True
    db_error = None
    try:
        db.session.execute(text("SELECT 1"))
    except Exception as e:  # noqa: BLE001 - 这里就是要把异常吃掉，转换成 False
        db_ok = False
        db_error = str(e)
    finally:
        try:
            db.session.rollback()
        except Exception:
            pass

    payload = {
        "status": "ok" if db_ok else "degraded",
        "db_ok": db_ok,
        "env": env,
        "system": system_name,
        "timestamp": _beijing_now(),
    }
    if db_error:
        payload["db_error"] = db_error

    return jsonify(payload), (200 if db_ok else 503)