/**
 * useJobStatus — tracks a BullMQ job via WebSocket `job:update` events.
 *
 * Usage:
 *   const { status, result, error } = useJobStatus(jobId);
 *
 * The hook listens for `job:update` events emitted by the backend workers.
 * When the jobId changes, the previous listener is removed and a fresh one
 * is registered for the new job.
 */
import { useEffect, useState } from "react";
import { socket } from "@/lib/socket";

export type JobStatus = "queued" | "active" | "completed" | "failed" | null;

export interface JobUpdatePayload {
  jobId: string;
  jobType: string;
  status: JobStatus;
  message?: string;
  result?: any;
  error?: string;
}

export interface UseJobStatusReturn {
  status: JobStatus;
  message: string;
  result: any;
  error: string | null;
  socketId: string | null;
}

export function useJobStatus(jobId: string | null): UseJobStatusReturn {
  const [status, setStatus] = useState<JobStatus>(jobId ? "queued" : null);
  const [message, setMessage] = useState("");
  const [result, setResult] = useState<any>(null);
  const [error, setError] = useState<string | null>(null);
  const [socketId, setSocketId] = useState<string | null>(
    socket.id ?? null
  );

  // Keep socketId in sync with the socket connection
  useEffect(() => {
    const onConnect = () => setSocketId(socket.id ?? null);
    socket.on("connect", onConnect);
    if (socket.connected) setSocketId(socket.id ?? null);
    return () => { socket.off("connect", onConnect); };
  }, []);

  // Reset state when the jobId changes
  useEffect(() => {
    if (!jobId) {
      setStatus(null);
      setMessage("");
      setResult(null);
      setError(null);
      return;
    }

    setStatus("queued");
    setMessage("");
    setResult(null);
    setError(null);

    const handler = (payload: JobUpdatePayload) => {
      if (payload.jobId !== jobId) return;
      setStatus(payload.status);
      if (payload.message) setMessage(payload.message);
      if (payload.result !== undefined) setResult(payload.result);
      if (payload.error) setError(payload.error);
    };

    socket.on("job:update", handler);
    return () => { socket.off("job:update", handler); };
  }, [jobId]);

  return { status, message, result, error, socketId };
}