import { useState, useEffect, useCallback, useRef } from "preact/hooks";
import type { ThreadData } from "./types";

export function useThreads(pollMs = 3000, windowMs = 24 * 60 * 60 * 1000) {
  const [threads, setThreads] = useState<ThreadData[]>([]);
  const prevStatuses = useRef<Record<string, string>>({});

  const refresh = useCallback(async () => {
    try {
      const since = Date.now() - windowMs;
      const r = await fetch(`/code/api/threads?since=${since}&t=${Date.now()}`);
      if (!r.ok) return;
      const data = await r.json();
      const sorted: ThreadData[] = (data.threads || []).sort((a: ThreadData, b: ThreadData) => a.startedAt - b.startedAt);

      const prev = prevStatuses.current;
      const isFirstLoad = Object.keys(prev).length === 0;
      for (const t of sorted) {
        const key = `${t.channel}:${t.threadId}`;
        const wasActive = prev[key] === "processing" || prev[key] === "stalled";
        if (!isFirstLoad && wasActive && t.status === "replied") {
          window.dispatchEvent(new CustomEvent("threadReplied", { detail: { threadId: t.threadId } }));
        }
        prev[key] = t.status;
      }

      setThreads(sorted);
    } catch {}
  }, [windowMs]);

  useEffect(() => {
    refresh();
    const id = setInterval(refresh, pollMs);
    return () => clearInterval(id);
  }, [pollMs, windowMs, refresh]);

  return { threads, refresh };
}