// GET /relay/balance — peek at the current install's credit balance +
// tier WITHOUT charging anything. Recap clients call this to populate
// the "N credits remaining · Tier: X" banner before the user runs any
// transcribe/analyze, so the display is accurate on first load instead
// of saying "balance unknown — no relay calls yet".
//
// Same auth surface as the metered endpoints:
//   X-Recap-Install-Id  (required)
//   Authorization       (optional Bearer LIC1-... — absent = Core)
//
// Returns the standard envelope shape with result=null and
// credit_charged=0. The license-resolution path is identical to
// /relay/transcribe and /relay/analyze, so the cached online check
// against keysat happens here too — but no row mutation, no job-id
// reservation, no upstream backend call.

import express from "express";
import { resolveLicense } from "../keysat-client.js";
import { getOrCreateRow } from "../credits.js";
import { envelope, errorEnvelope } from "./envelope.js";

export function balanceRouter() {
  const router = express.Router();

  router.get("/balance", async (req, res) => {
    const installId = req.header("X-Recap-Install-Id");
    const auth = req.header("Authorization");
    if (!installId) {
      const e = await errorEnvelope({
        error: "missing X-Recap-Install-Id header",
        statusHint: 400,
      });
      return res.status(400).json(e.body);
    }
    const license = await resolveLicense(auth);
    const tier = license.tier;
    // Touch the row so tier_snapshot reflects the most recently seen
    // license tier — same as the metered endpoints do — but commit
    // nothing.
    const row = await getOrCreateRow(installId);
    row.tier_snapshot = tier;
    const body = await envelope({
      result: null,
      installId,
      tier,
      creditCharged: 0,
    });
    res.json(body);
  });

  return router;
}