import { NextRequest } from "next/server";
import { auth } from "@/lib/auth";
import { probeStatus } from "@/lib/server-status";
import { readChatMessages, logMtime } from "@/lib/chat-log";

export const dynamic = "force-dynamic";
export const runtime = "nodejs";

const STATUS_INTERVAL_MS = 5000;
const LOG_POLL_MS = 1500;
const HEARTBEAT_MS = 15_000;
const MAX_LIFETIME_MS = 10 * 60 * 1000;

export async function GET(req: NextRequest) {
  const session = await auth();
  if (!session) {
    return new Response(JSON.stringify({ error: "Unauthorized" }), {
      status: 403,
      headers: { "Content-Type": "application/json" },
    });
  }

  const encoder = new TextEncoder();

  const stream = new ReadableStream({
    async start(controller) {
      let closed = false;
      const timers: ReturnType<typeof setTimeout>[] = [];
      const safeSend = (data: string) => {
        if (closed) return;
        try {
          controller.enqueue(encoder.encode(data));
        } catch {
          closed = true;
        }
      };
      const send = (event: string, payload: unknown) =>
        safeSend(`event: ${event}\ndata: ${JSON.stringify(payload)}\n\n`);
      const heartbeat = () => safeSend(`: hb ${Date.now()}\n\n`);

      const cleanup = () => {
        if (closed) return;
        closed = true;
        for (const t of timers) clearTimeout(t);
        try {
          controller.close();
        } catch {}
      };
      req.signal.addEventListener("abort", cleanup);

      // Initial payload
      try {
        const status = await probeStatus();
        send("status", status);
        const chat = readChatMessages(50);
        send("chat", chat);
      } catch {}

      let lastLogMtime = logMtime();

      const pollStatus = async () => {
        if (closed) return;
        try {
          const status = await probeStatus();
          send("status", status);
        } catch {}
        if (!closed) timers.push(setTimeout(pollStatus, STATUS_INTERVAL_MS));
      };

      const pollLog = () => {
        if (closed) return;
        try {
          const mt = logMtime();
          if (mt && mt !== lastLogMtime) {
            lastLogMtime = mt;
            const chat = readChatMessages(50);
            send("chat", chat);
          }
        } catch {}
        if (!closed) timers.push(setTimeout(pollLog, LOG_POLL_MS));
      };

      const beat = () => {
        if (closed) return;
        heartbeat();
        if (!closed) timers.push(setTimeout(beat, HEARTBEAT_MS));
      };

      timers.push(setTimeout(pollStatus, STATUS_INTERVAL_MS));
      timers.push(setTimeout(pollLog, LOG_POLL_MS));
      timers.push(setTimeout(beat, HEARTBEAT_MS));

      // Hard cap stream lifetime so auth/session stays fresh on reconnect
      timers.push(setTimeout(cleanup, MAX_LIFETIME_MS));
    },
  });

  return new Response(stream, {
    headers: {
      "Content-Type": "text/event-stream; charset=utf-8",
      "Cache-Control": "no-cache, no-transform",
      Connection: "keep-alive",
      "X-Accel-Buffering": "no",
    },
  });
}