import http from "node:http";

const port = Number(process.env.PORT || 8787);
const modelName = process.env.NO_REPLY_MODEL || "dirigent-no-reply-v1";
const authToken = process.env.AUTH_TOKEN || "";

function sendJson(res, status, payload) {
  res.writeHead(status, { "Content-Type": "application/json; charset=utf-8" });
  res.end(JSON.stringify(payload));
}

function isAuthorized(req) {
  if (!authToken) return true;
  const header = req.headers.authorization || "";
  return header === `Bearer ${authToken}`;
}

function noReplyChatCompletion(reqBody) {
  return {
    id: `chatcmpl_dirigent_${Date.now()}`,
    object: "chat.completion",
    created: Math.floor(Date.now() / 1000),
    model: reqBody?.model || modelName,
    choices: [
      {
        index: 0,
        message: { role: "assistant", content: "NO_REPLY" },
        finish_reason: "stop"
      }
    ],
    usage: { prompt_tokens: 0, completion_tokens: 1, total_tokens: 1 }
  };
}

function noReplyResponses(reqBody) {
  return {
    id: `resp_dirigent_${Date.now()}`,
    object: "response",
    created_at: Math.floor(Date.now() / 1000),
    model: reqBody?.model || modelName,
    output: [
      {
        type: "message",
        role: "assistant",
        content: [{ type: "output_text", text: "NO_REPLY" }]
      }
    ],
    usage: { input_tokens: 0, output_tokens: 1, total_tokens: 1 }
  };
}

function listModels() {
  return {
    object: "list",
    data: [
      {
        id: modelName,
        object: "model",
        created: Math.floor(Date.now() / 1000),
        owned_by: "dirigent"
      }
    ]
  };
}

const server = http.createServer((req, res) => {
  if (req.method === "GET" && req.url === "/health") {
    return sendJson(res, 200, { ok: true, service: "dirigent-no-reply-api", model: modelName });
  }

  if (req.method === "GET" && req.url === "/v1/models") {
    if (!isAuthorized(req)) return sendJson(res, 401, { error: "unauthorized" });
    return sendJson(res, 200, listModels());
  }

  if (req.method !== "POST") {
    return sendJson(res, 404, { error: "not_found" });
  }

  if (!isAuthorized(req)) {
    return sendJson(res, 401, { error: "unauthorized" });
  }

  let body = "";
  req.on("data", (chunk) => {
    body += chunk;
    if (body.length > 1_000_000) req.destroy();
  });

  req.on("end", () => {
    let parsed = {};
    try {
      parsed = body ? JSON.parse(body) : {};
    } catch {
      return sendJson(res, 400, { error: "invalid_json" });
    }

    if (req.url === "/v1/chat/completions") {
      return sendJson(res, 200, noReplyChatCompletion(parsed));
    }

    if (req.url === "/v1/responses") {
      return sendJson(res, 200, noReplyResponses(parsed));
    }

    return sendJson(res, 404, { error: "not_found" });
  });
});

server.listen(port, () => {
  console.log(`[dirigent-no-reply-api] listening on :${port}`);
});