// Standard response envelope. Every /relay/* response (success and
// error both) goes through this so Recap clients can keep their
// credit-balance display accurate regardless of what happened.
//
// Shape: { result, credits_remaining, tier, credit_charged }

import { getOrCreateRow, computeRemaining } from "../credits.js";
import { getTierQuotas } from "../config.js";

// Build the envelope around a result object.
export async function envelope({
  result = null,
  installId,
  // License is optional but recommended — without it, balance lookups
  // route to the install-keyed row even for paid users, which would
  // briefly underreport their balance after a commitCredit landed on
  // their license-keyed row. Routes pass it through from resolveLicense.
  license = null,
  // Explicit ledger key override (cloud `user:<id>` path). Takes
  // precedence over (installId, license) when present.
  creditKey = null,
  tier,
  creditCharged = 0,
}) {
  const quota = await getTierQuotas();
  const row = await getOrCreateRow({ installId, license, creditKey });
  // tier_snapshot on the row was just updated by commitCredit; if no
  // credit was committed (free reuse via job_id) it still reflects
  // the last-known tier for this install, which is fine.
  const balance = computeRemaining(row, quota);
  return {
    result,
    // `total` = tier allotment + purchased top-up. Recap renders this
    // as the headline number on its credits pill. `remaining` alone
    // wouldn't reflect purchased credits at all — so a buyer who
    // just bought 5 credits and had 0 tier credits left would still
    // see "0 relay credits" until their tier renewed.
    credits_remaining: balance.total, // null = unlimited (Max)
    // Breakdown for clients that want to display it.
    tier_remaining: balance.remaining,
    purchased_balance: balance.purchased,
    tier,
    credit_charged: creditCharged,
  };
}

// Same shape but for error responses. The error reason goes in `error`
// alongside `result: null`. Clients should still update their balance
// display from `credits_remaining` so failed calls (which were
// refunded) reflect the unchanged balance.
export async function errorEnvelope({
  error,
  installId,
  license = null,
  creditKey = null,
  tier = "core",
  statusHint = 500,
}) {
  let creditsRemaining = null;
  let tierRemaining = null;
  let purchased = 0;
  try {
    const quota = await getTierQuotas();
    const row = await getOrCreateRow({
      installId: creditKey ? null : installId || "unknown",
      license,
      creditKey,
    });
    const balance = computeRemaining(row, quota);
    creditsRemaining = balance.total;
    tierRemaining = balance.remaining;
    purchased = balance.purchased;
  } catch {}
  return {
    statusHint,
    body: {
      result: null,
      error: typeof error === "string" ? error : error?.message || "unknown_error",
      credits_remaining: creditsRemaining,
      tier_remaining: tierRemaining,
      purchased_balance: purchased,
      tier,
      credit_charged: 0,
    },
  };
}