/**
 * Pings the local llama.cpp server to ensure it's up, running, and has a model loaded.
 * If the server is offline or still loading, it terminates the pipeline gracefully.
 */
export async function checkLlmServer(
  url = "http://127.0.0.1:8080/health",
): Promise<void> {
  try {
    const response = await fetch(url);

    // llama.cpp returns a 503 status if the server is up but the model weights are still loading
    if (response.status === 503) {
      console.error(
        "\n ⏳ Local AI engine is starting up, but the model is still loading into memory.",
      );
      console.error(
        "👉 Please wait a minute for the weights to load, then run the pipeline again.\n",
      );
      process.exit(1);
    }

    // Parse the JSON health response (expected: { status: "ok" })
    const data = (await response.json()) as { status?: string };

    if (response.ok && data.status === "ok") {
      console.log("🟢 Local AI engine is connected and ready for inference!");
      return;
    }

    // Catch-all for unexpected active server responses
    console.error(
      `\n ❌ Unknown response from local AI engine health check (Status: ${response.status}).`,
    );
    process.exit(1);
  } catch (_error: unknown) {
    console.error("\n ❌ Could not connect to the local AI engine.");
    console.error(`🔗 Attempted endpoint: ${url}`);
    console.error(
      "👉 Make sure your './llama-server' command is actively running in another terminal tab!\n",
    );
    process.exit(1);
  }
}