import { type NextRequest, NextResponse } from "next/server";

import { RunpodError } from "@/lib/server/runpod/client";
import { rpTranscribe } from "@/lib/server/runpod/endpoints";

import { guard } from "../_guard";

export const runtime = "nodejs";
export const maxDuration = 60; // cold-start STT worker can take a while
export const dynamic = "force-dynamic";

/**
 * Speech-to-text proxy for voice annotations. Accepts base64 WAV (16 kHz mono
 * PCM16, produced in-browser) and returns the transcript. Calls the RunPod
 * voice-to-text endpoint (RUNPOD_STT_URL) — the key stays server-side.
 *
 * POST { audio, language? } -> { transcript, segments? }
 * Auth: session-gated. Rate limit: 20/min.
 */

const MAX_BASE64 = 8_000_000; // ~6 MB decoded WAV — stays under serverless body limits

export async function POST(req: NextRequest) {
  const gate = await guard(req, "transcribe");
  if (!gate.ok) return gate.response;

  let body: { audio?: unknown; language?: unknown };
  try {
    body = await req.json();
  } catch {
    return NextResponse.json({ error: "Invalid JSON body." }, { status: 400 });
  }

  const audio = typeof body.audio === "string" ? body.audio : "";
  const language = typeof body.language === "string" ? body.language : undefined;
  if (!audio) return NextResponse.json({ error: "Missing audio." }, { status: 400 });
  if (audio.length > MAX_BASE64) {
    return NextResponse.json({ error: "Audio too long — keep it under ~30s." }, { status: 413 });
  }

  try {
    const { transcript, segments } = await rpTranscribe(audio, { language, punctuation: true });
    return NextResponse.json({ transcript, segments });
  } catch (e) {
    const msg =
      e instanceof RunpodError ? e.message : e instanceof Error ? e.message : "Transcription failed.";
    return NextResponse.json({ error: msg }, { status: 502 });
  }
}