// [TSM.ID].[11031972] -- All Rights Reserved. Proprietary & Confidential.
import { NextRequest, NextResponse } from "next/server";
import Redis from "ioredis";

// Klien Redis khusus untuk Subscriber (Mendengarkan event OmniBrain)
// Karena ini adalah endpoint streaming, kita membutuhkan instance Redis tersendiri per koneksi (opsional),
// namun karena SSE bersifat long-lived, kita instansiasi dalam blok handler.
const redisUrl = process.env.REDIS_URL || "redis://localhost:6379";

export async function GET(req: NextRequest) {
  const searchParams = req.nextUrl.searchParams;
  const channel = searchParams.get("channel"); // Misalnya: "room_alpha_events"

  if (!channel) {
    return NextResponse.json({ error: "Missing channel" }, { status: 400 });
  }

  const redis = new Redis(redisUrl);

  const stream = new ReadableStream({
    async start(controller) {
      // 1. Subscribe ke channel spesifik di Redis
      await redis.subscribe(channel, (err) => {
        if (err) {
          console.error("[SSE] Gagal subscribe ke Redis:", err);
          controller.error(err);
        } else {
          console.log(`[SSE] OmniBrain terhubung ke saluran: ${channel}`);
        }
      });

      // 2. Dengarkan pesan yang dipancarkan oleh API /emit
      redis.on("message", (subChannel, message) => {
        if (subChannel === channel) {
          // Format SSE: "data: {JSON}\n\n"
          controller.enqueue(`data: ${message}\n\n`);
        }
      });

      // 3. Keep-Alive (Mencegah koneksi HTTP ditutup oleh Proxy/Nginx)
      const keepAlive = setInterval(() => {
        controller.enqueue(":\n\n"); // Komentar SSE untuk keep-alive
      }, 15000);

      // 4. Deteksi klien putus
      req.signal.addEventListener("abort", () => {
        clearInterval(keepAlive);
        redis.disconnect();
        console.log(`[SSE] Klien terputus dari saluran: ${channel}`);
      });
    },
    cancel() {
      redis.disconnect();
    }
  });

  return new NextResponse(stream, {
    headers: {
      "Content-Type": "text/event-stream",
      "Cache-Control": "no-cache, no-transform",
      "Connection": "keep-alive",
      "Access-Control-Allow-Origin": "*",
    },
  });
}