import { useCallback, useEffect, useRef, useState } from 'react';
import { AssessorApiClient } from '../../api/assessor-api-client';
import type { AssessmentProject } from '../../domain/canonical-model';
import type { DatahubReferenceReadiness } from './datahub-processing-readiness';

const api = new AssessorApiClient();

/** Load only status summaries, with bounded concurrency and no background polling. */
export function useReferenceRecognitionStatus(projects: AssessmentProject[], connected: boolean, refreshKey: number) {
  const [states, setStates] = useState<Record<string, DatahubReferenceReadiness>>({});
  const pending = useRef(new Map<string, symbol>());
  const reportStatus = useCallback((projectId: string, state: DatahubReferenceReadiness) => {
    // A panel result must win over an older overview request for the same client.
    pending.current.delete(projectId);
    setStates(current => ({ ...current, [projectId]: state }));
  }, []);

  useEffect(() => {
    let cancelled = false;
    let next = 0;
    pending.current.clear();
    const queue = connected ? projects.map(project => ({ ...project, token: Symbol() })) : [];
    for (const project of queue) pending.current.set(project.id, project.token);
    setStates(Object.fromEntries(queue.map(project => [project.id, { state: 'checking' }])));
    const loadNext = async () => {
      while (!cancelled && next < queue.length) {
        const { id: projectId, token } = queue[next++];
        if (pending.current.get(projectId) !== token) continue;
        let state: DatahubReferenceReadiness;
        try { state = { state: 'ready', status: await api.getReferenceRecognitionStatus(projectId) }; }
        catch { state = { state: 'unavailable' }; }
        if (!cancelled && pending.current.get(projectId) === token) {
          pending.current.delete(projectId);
          setStates(current => ({ ...current, [projectId]: state }));
        }
      }
    };
    for (let worker = 0; worker < Math.min(3, queue.length); worker++) void loadNext();
    return () => { cancelled = true; };
  }, [projects, connected, refreshKey]);

  return { states, reportStatus };
}