frontend/src/api/evalClient.ts

/**
 * Polling client for the evaluation endpoint.
 *
 * Polls GET /api/v1/query/{queryId}/evaluation every 3 seconds.
 * Stops on: scores received, 404, or 90s timeout.
 * The backend returns "pending" while the TruLens background thread is still
 * running, and "complete" once the row has been persisted to evaluation_results.
 */
import api from "./client";
import type { EvalPollResponse } from "../types";

const POLL_INTERVAL_MS = 3000;
const POLL_TIMEOUT_MS = 90000;

export function pollEvaluation(
  queryId: string,
  onResult: (response: EvalPollResponse) => void,
  onError: (err: string) => void,
): () => void {
  const startTime = Date.now();
  let intervalId: ReturnType<typeof setInterval> | null = null;

  function stop() {
    if (intervalId !== null) {
      clearInterval(intervalId);
      intervalId = null;
    }
  }

  intervalId = setInterval(async () => {
    if (Date.now() - startTime > POLL_TIMEOUT_MS) {
      stop();
      onError("Evaluation timed out");
      return;
    }

    try {
      const { data } = await api.get<EvalPollResponse>(
        `/query/${queryId}/evaluation`,
      );

      if (data.status === "complete") {
        stop();
        onResult(data);
      }
      // "pending" → keep polling
    } catch (err: unknown) {
      const status = (err as { response?: { status?: number } })?.response?.status;
      // 404 means the provider is "none" or evaluation was skipped — stop silently
      if (status === 404) {
        stop();
      } else {
        stop();
        onError("Failed to fetch evaluation scores");
      }
    }
  }, POLL_INTERVAL_MS);

  return stop;
}