velxio/frontend/src/hooks/useAutoSaveProject.ts

67 lines
2.4 KiB
TypeScript

/**
* Auto-save hook — skeleton.
*
* The actual save logic (debouncing, dirty detection, owner eligibility,
* PUT to /api/projects/{id}) is supplied by an installed implementation.
* OSS without an overlay registers no implementation, and the hook stays
* idle forever — exactly the behavior we want once project persistence
* moves to the private overlay (Phase 3 of the OSS split).
*
* The skeleton always runs the same useState + useEffect, so registering
* an implementation later cannot change the hook count and break React.
* Implementations are expected to be installed once at module load via
* installAutoSaveImpl() — see ./autoSaveImpl.ts for the default wiring.
*/
import { useEffect, useState } from 'react';
export type AutoSaveStatus = 'idle' | 'dirty' | 'saving' | 'saved' | 'error';
export interface AutoSaveState {
status: AutoSaveStatus;
lastSavedAt: number | null;
errorMessage: string | null;
}
/** Implementation contract: receive a setter, return an unsubscribe. */
export type AutoSaveImpl = (emit: (state: AutoSaveState) => void) => () => void;
const IDLE: AutoSaveState = { status: 'idle', lastSavedAt: null, errorMessage: null };
let installedImpl: AutoSaveImpl | null = null;
/** Hooks that mounted before an impl was installed, waiting to start it. */
const installWaiters = new Set<() => void>();
export function installAutoSaveImpl(impl: AutoSaveImpl | null): void {
installedImpl = impl;
// Overlays load through a dynamic import that races the first React
// commit: a hook whose mount effect ran before the overlay chunk
// evaluated used to see `installedImpl === null` and stay idle for the
// whole life of the tab — no auto-save, no unload flush. Start those
// already-mounted hooks now that the impl exists.
if (impl) installWaiters.forEach((start) => start());
}
export function useAutoSaveProject(): AutoSaveState {
const [state, setState] = useState<AutoSaveState>(IDLE);
useEffect(() => {
let cleanup: (() => void) | null = null;
const start = () => {
if (installedImpl && !cleanup) cleanup = installedImpl(setState);
};
start();
// Late-install support only — swapping a live impl at runtime is still
// unsupported (the first installed impl keeps running until unmount).
installWaiters.add(start);
return () => {
installWaiters.delete(start);
cleanup?.();
cleanup = null;
};
}, []);
return state;
}