// ---------------------------------------------------------------------------
// Tiny API proxy for interactive dashboard features.
// Runs inside the container on localhost; nginx proxies /api/chat here.
// ---------------------------------------------------------------------------

const http = require("http");
const https = require("https");
const { URL } = require("url");

const PORT = process.env.API_PORT || 3001;
const OPENWEBUI_URL = process.env.OPENWEBUI_URL || "http://100.103.83.12:3000";
const OPENWEBUI_TOKEN = process.env.OPENWEBUI_TOKEN || "";
const GPU_STATS_URL = process.env.GPU_STATS_URL || "http://gpu-stats:9101/stats";
const OLLAMA_URL = process.env.OLLAMA_URL || "http://100.103.83.12:11435";

function request(url, options = {}) {
  return new Promise((resolve, reject) => {
    const u = new URL(url);
    const client = u.protocol === "https:" ? https : http;
    const req = client.request(
      u,
      {
        method: options.method || "GET",
        headers: options.headers || {},
        timeout: options.timeout || 120000,
      },
      (res) => {
        let body = "";
        res.setEncoding("utf8");
        res.on("data", (chunk) => (body += chunk));
        res.on("end", () => resolve({ status: res.statusCode, headers: res.headers, body }));
      }
    );
    req.on("error", reject);
    req.on("timeout", () => {
      req.destroy();
      reject(new Error("Timeout"));
    });
    if (options.body) req.write(options.body);
    req.end();
  });
}

function jsonResponse(res, status, data) {
  res.writeHead(status, { "Content-Type": "application/json" });
  res.end(JSON.stringify(data));
}

function readBody(req) {
  return new Promise((resolve, reject) => {
    let body = "";
    req.on("data", (chunk) => (body += chunk));
    req.on("end", () => resolve(body));
    req.on("error", reject);
  });
}

const server = http.createServer(async (req, res) => {
  // Very small CORS allowlist: only dashboard origin, but since this sits behind
  // nginx on the same origin we can keep it strict.
  res.setHeader("Access-Control-Allow-Origin", "*");
  res.setHeader("Access-Control-Allow-Methods", "POST, OPTIONS");
  res.setHeader("Access-Control-Allow-Headers", "Content-Type");

  if (req.method === "OPTIONS") {
    res.writeHead(204);
    res.end();
    return;
  }

  const url = new URL(req.url, `http://127.0.0.1:${PORT}`);

  if (url.pathname === "/health" && req.method === "GET") {
    return jsonResponse(res, 200, { ok: true });
  }

  // Always drain the request body before responding, otherwise leftover bytes
  // corrupt keep-alive connections (e.g. nginx upstream keepalive).
  req.resume();

  if (url.pathname === "/api/gpu-stats" && req.method === "GET") {
    try {
      const upstream = await request(GPU_STATS_URL, { timeout: 8000 });
      res.writeHead(upstream.status, {
        "Content-Type": "application/json",
        "Cache-Control": "no-store",
      });
      res.end(upstream.body);
    } catch (e) {
      return jsonResponse(res, 502, { error: `GPU stats unreachable: ${e.message}` });
    }
  }

  if (url.pathname === "/api/ollama" && req.method === "GET") {
    try {
      const upstream = await request(`${OLLAMA_URL}/api/ps`, { timeout: 8000 });
      res.writeHead(upstream.status, {
        "Content-Type": "application/json",
        "Cache-Control": "no-store",
      });
      res.end(upstream.body);
    } catch (e) {
      return jsonResponse(res, 502, { error: `Ollama unreachable: ${e.message}` });
    }
  }

  if (url.pathname === "/api/chat" && req.method === "POST") {
    if (!OPENWEBUI_TOKEN) {
      return jsonResponse(res, 503, { error: "OPENWEBUI_TOKEN not configured" });
    }

    try {
      const raw = await readBody(req);
      const body = JSON.parse(raw || "{}");
      const { model, prompt } = body;
      if (!model || !prompt) {
        return jsonResponse(res, 400, { error: "model and prompt are required" });
      }

      const payload = JSON.stringify({
        model,
        messages: [{ role: "user", content: prompt }],
        stream: false,
      });

      const upstream = await request(`${OPENWEBUI_URL}/api/chat/completions`, {
        method: "POST",
        headers: {
          "Content-Type": "application/json",
          Authorization: `Bearer ${OPENWEBUI_TOKEN}`,
        },
        body: payload,
      });

      if (upstream.status < 200 || upstream.status >= 300) {
        return jsonResponse(res, upstream.status, { error: `Open WebUI ${upstream.status}`, body: upstream.body });
      }

      const data = JSON.parse(upstream.body);
      const message = data.choices?.[0]?.message?.content || data.response || "(no response)";
      return jsonResponse(res, 200, { message });
    } catch (e) {
      return jsonResponse(res, 500, { error: e.message });
    }
  }

  res.writeHead(404);
  res.end("Not found");
});

// This is a tiny internal proxy: never let a per-request error kill the
// process (that would take down the GPU stats proxy too).
process.on("uncaughtException", (err) => {
  console.error("uncaughtException:", err);
});
process.on("unhandledRejection", (err) => {
  console.error("unhandledRejection:", err);
});

server.listen(PORT, "127.0.0.1", () => {
  console.log(`Dashboard API proxy listening on 127.0.0.1:${PORT}`);
});