// GET /relay/balance — peek at the caller's credit balance + tier WITHOUT
// charging anything. Recap clients call this to populate the
// "N credits remaining · Tier: X" banner.
//
// Two auth surfaces (see identity.js):
//   - cloud:   X-Recap-User-Id + X-Recap-Operator-Key → user:<id> pool,
//              tier is the relay's stored (operator-set) value.
//   - license: X-Recap-Install-Id (+ optional Bearer license) → legacy
//              license/install pool, tier from the license.
//
// Returns the standard envelope (result=null, credit_charged=0). No row
// mutation beyond keeping tier_snapshot synced on the license path.

import express from "express";
import { resolveIdentity, identityTier } from "../identity.js";
import { getOrCreateRow, applyTierPromotion } from "../credits.js";
import { envelope, errorEnvelope } from "./envelope.js";

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

  router.get("/balance", async (req, res) => {
    let identity;
    try {
      identity = await resolveIdentity(req);
    } catch (err) {
      const e = await errorEnvelope({
        error: err?.message || "auth_error",
        statusHint: err?.status || 401,
      });
      return res.status(e.statusHint || 401).json(e.body);
    }
    if (identity.kind === "license" && !identity.installId) {
      const e = await errorEnvelope({
        error: "missing X-Recap-Install-Id header",
        statusHint: 400,
      });
      return res.status(400).json(e.body);
    }

    const row = await getOrCreateRow({
      creditKey: identity.creditKey,
      installId: identity.installId,
      license: identity.license,
    });
    // License path: fire the Core→paid promotion bookkeeping (this is
    // typically the FIRST relay call after a license activation) and keep
    // tier_snapshot synced to the license. Cloud path: the tier is the
    // relay's stored, operator-set value — leave it untouched.
    if (identity.kind === "license") {
      const tier = identity.license.tier;
      const promoted = await applyTierPromotion(row, tier);
      if (!promoted) row.tier_snapshot = tier;
    }

    const tier = identityTier(identity, row);
    const body = await envelope({
      result: null,
      creditKey: identity.creditKey,
      installId: identity.installId,
      license: identity.license,
      tier,
      creditCharged: 0,
    });
    res.json(body);
  });

  return router;
}