// GET /relay/capabilities — operator-aware metadata for Recap clients
// to plan their audio handling. Returns the upper bounds the relay's
// CURRENT routing config can comfortably accept, so Recap can decide
// whether to chunk a long video before sending it.
//
// Today's logic:
//   - When the operator's transcribe_backend_preference routes through
//     Gemini at all (gemini_first / gemini_only), we report Gemini-safe
//     limits (60 min / 30 MB / 2700 s chunks). Even with hardware as
//     overflow, the FIRST attempt is Gemini, which needs the chunk
//     budget.
//   - When the operator's preference is hardware-only (or hardware-
//     first with overflow to Gemini disabled in spirit), we report
//     "unbounded" — the operator's Parakeet wrapper can typically
//     ingest 2+ hour podcasts in a single shot, so chunking just adds
//     extra inference passes and timestamp-stitching overhead.
//
// Recap reads this once on boot + on policy refresh; when its
// transcriptionProvider is "relay", it honors these limits instead of
// its own hardcoded thresholds. For non-relay providers, Recap's
// internal per-provider thresholds apply.

import express from "express";
import { getConfigSnapshot } from "../config.js";

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

  router.get("/capabilities", async (_req, res) => {
    const cfg = await getConfigSnapshot();
    const txPref =
      cfg.relay_transcribe_backend_preference || "gemini_first";
    const hasParakeet = !!cfg.relay_parakeet_base_url;

    // Conservative default: Gemini-safe limits unless the operator has
    // explicitly said "use hardware (only or first) and I've got a
    // Parakeet endpoint wired up". Without the Parakeet endpoint we
    // can't make use of larger inputs — Gemini's the only path —
    // so we'd just be lying to the client.
    const hardwareCapable =
      hasParakeet && (txPref === "hardware_only" || txPref === "hardware_first");

    if (hardwareCapable) {
      res.json({
        // Effective unbounded — Parakeet wrappers commonly handle 2+
        // hour audio in one shot. Set high but finite ceilings so a
        // 24-hour file doesn't OOM the operator's GPU box silently.
        max_audio_mb: 500,
        max_audio_minutes: 240,
        preferred_chunk_seconds: null,
        // Diagnostic — Recap doesn't need this but the dashboard / a
        // curious operator might want to know which limit shape they
        // returned and why.
        reason: "hardware-capable backend preference (" + txPref + ")",
      });
    } else {
      res.json({
        // Gemini File-API + practical reliability limits. Matches
        // Recap's pre-relay defaults so existing chunking behavior
        // is preserved.
        max_audio_mb: 30,
        max_audio_minutes: 60,
        preferred_chunk_seconds: 2700, // 45 min chunks
        reason: "Gemini-backed preference (" + txPref + ")",
      });
    }
  });

  return router;
}