import { Router } from "express";
import type { Db } from "../lib/db.js";
import type { Cache } from "../lib/redis.js";

export function healthRouter(deps: { db?: Db; cache?: Cache }): Router {
  const router = Router();

  // Liveness: 200 whenever the process is listening.
  router.get("/healthz", (_req, res) => {
    res.type("text/plain").send("ok");
  });

  // Readiness: every configured backend must answer.
  router.get("/readyz", async (_req, res) => {
    const body: Record<string, string> = {};
    let ready = true;
    const check = async (name: string, fn?: () => Promise<void>) => {
      if (!fn) return;
      try {
        await fn();
        body[name] = "ok";
      } catch (err) {
        ready = false;
        body[name] = `unavailable: ${(err as Error).message || "error"}`;
      }
    };
    await check("postgres", deps.db && (() => deps.db!.ping()));
    await check("redis", deps.cache && (() => deps.cache!.ping()));
    res
      .status(ready ? 200 : 503)
      .json({ status: ready ? "ready" : "not-ready", ...body });
  });

  return router;
}