/**
 * @file gitChanged.ts
 * @description One window event, `agenthub:git-changed` `{laneId, action}`,
 * fired after EVERY git write the dashboard sends for a workspace
 * (`api.lanes.gitAction` fires it, success or failure — a failed shelve or
 * a conflicted restore still moved files). Every view that shows that
 * workspace's git state — the Changes panel of each repo, the header's facts
 * (`useLaneGitFacts`, the rail counts included), the workspace home's branch —
 * listens and reads again, so a switch made in one of them is never left
 * stale in another for a poll interval. The views do not share a callback;
 * this is the bus between them.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useEffect, useRef } from "react";

export const GIT_CHANGED_EVENT = "agenthub:git-changed";

export interface GitChangedDetail {
  laneId: number;
  /** The git action that ran (`switch`, `commit`, `shelve`, …). */
  action: string;
}

/** Tell every view of `laneId` that its git state may have moved. */
export function emitGitChanged(laneId: number, action: string): void {
  if (typeof window === "undefined") return;
  window.dispatchEvent(
    new CustomEvent<GitChangedDetail>(GIT_CHANGED_EVENT, { detail: { laneId, action } })
  );
}

/**
 * Call `fn` after every git write on workspace `laneId`. The latest `fn` is
 * used, so a caller may pass an inline closure without resubscribing.
 */
export function useGitChanged(laneId: number, fn: (action: string) => void): void {
  const latest = useRef(fn);
  latest.current = fn;
  useEffect(() => {
    const on = (e: Event) => {
      const d = (e as CustomEvent<GitChangedDetail>).detail;
      if (d && d.laneId === laneId) latest.current(d.action);
    };
    window.addEventListener(GIT_CHANGED_EVENT, on);
    return () => window.removeEventListener(GIT_CHANGED_EVENT, on);
  }, [laneId]);
}