siftlode/frontend/src/components/moduleRegistry.tsx

import type { ComponentType } from "react";
import { lazyWithPreload, type PreloadableComponent } from "../lib/lazyWithPreload";
import type { Page } from "../lib/urlState";
import type { PanelId, PanelLayout } from "../lib/panelLayout";
import Sidebar from "./Sidebar";
import PlaylistsRail from "./PlaylistsRail";
import { Feed, FeedPage, Messages, MessagesPage } from "./modulePages";

// The RENDER half of the module registry: which component (and side rail) each page renders. The
// metadata half — nav order, label, icon, gate — lives in lib/modules.ts (imported by NavSidebar /
// Header / App's gate check). Together they let App drive the whole shell from `page` alone, with no
// `page === X` chrome conditionals.
//
// Every content entry is a PROP-FREE component: it reads `me` from useMe() and its module-local state
// from the scoped providers, so App renders `<Content />` uniformly. The two that need per-render
// wiring get a thin wrapper in modulePages (FeedPage supplies the GLOBAL feed scope; the channel page
// threads its own isolated scope to <Feed> directly — see the scope note in FeedFiltersProvider).

// Route-level code splitting: each page is its own lazy chunk (admin-only pages never reach
// non-admins; the logged-out landing pulls only the shell). Rendered inside App's <Suspense>. Each
// one is preloadable: App fetches the chunks of every page the account can reach once the first page
// is on screen (preloadPages below), so switching modules never shows the chunk fallback.
const Home = lazyWithPreload(() => import("./Home"));
const Channels = lazyWithPreload(() => import("./Channels"));
const Playlists = lazyWithPreload(() => import("./Playlists"));
const PlexBrowse = lazyWithPreload(() => import("./PlexBrowse"));
const PlexSidebar = lazyWithPreload(() => import("./PlexSidebar"));
const NotificationsPanel = lazyWithPreload(() => import("./NotificationsPanel"));
const DownloadCenter = lazyWithPreload(() => import("./DownloadCenter"));
const Stats = lazyWithPreload(() => import("./Stats"));
const Scheduler = lazyWithPreload(() => import("./Scheduler"));
const ConfigPanel = lazyWithPreload(() => import("./ConfigPanel"));
const AdminUsers = lazyWithPreload(() => import("./AdminUsers"));
const AuditLog = lazyWithPreload(() => import("./AuditLog"));
const AdminLogs = lazyWithPreload(() => import("./AdminLogs"));
const SettingsPanel = lazyWithPreload(() => import("./SettingsPanel"));

export type PageDef = {
  // Prop-free by construction: reads `me` + module state from hooks/providers. Preloadable by type, so
  // a new page cannot silently opt out of preloadPages.
  Component: PreloadableComponent<object>;
  // The content column's max width. The header + toolbar centre on this same width (via --content-mw)
  // so the floating chrome lines up with the centred content instead of spanning the whole column.
  // MUST match the max-w the page's own content wrapper uses. Omit for a full-width page (feed).
  maxWidth?: string;
};

// page id → the component App renders in the content column (+ its shell chrome config).
export const PAGE_CONTENT: Record<Page, PageDef> = {
  home: { Component: Home, maxWidth: "80rem" },
  // The two wrappers preload the lazy chunk they render.
  feed: { Component: Object.assign(FeedPage, { preload: Feed.preload }) },
  channels: { Component: Channels, maxWidth: "96rem" },
  playlists: { Component: Playlists, maxWidth: "64rem" },
  plex: { Component: PlexBrowse, maxWidth: "100rem" },
  notifications: { Component: NotificationsPanel, maxWidth: "48rem" },
  messages: { Component: Object.assign(MessagesPage, { preload: Messages.preload }) },
  downloads: { Component: DownloadCenter, maxWidth: "56rem" },
  stats: { Component: Stats },
  scheduler: { Component: Scheduler },
  config: { Component: ConfigPanel },
  users: { Component: AdminUsers, maxWidth: "48rem" },
  audit: { Component: AuditLog },
  logs: { Component: AdminLogs },
  settings: { Component: SettingsPanel },
};

// The uniform side-rail contract — shell layout/collapse only; the rail reads its module state from
// its provider and `me` from useMe().
type RailProps = {
  layout: PanelLayout;
  setLayout: (l: PanelLayout) => void;
  collapsed: boolean;
  onToggleCollapse: () => void;
};

// Which collapse flag a rail uses (feed + plex share the filter rail's flag; playlists has its own).
type RailCollapseKey = "filter" | "playlists";

export type RailDef = {
  Rail: ComponentType<RailProps>;
  // The persisted panel-layout record this rail edits (App owns the panelLayouts map).
  panelId: PanelId;
  collapse: RailCollapseKey;
};

// page id → its side rail (only the three pages that have one). App renders it in the rail slot.
export const PAGE_RAIL: Partial<Record<Page, RailDef>> = {
  feed: { Rail: Sidebar, panelId: "feed", collapse: "filter" },
  plex: { Rail: PlexSidebar, panelId: "plex", collapse: "filter" },
  playlists: { Rail: PlaylistsRail, panelId: "playlists", collapse: "playlists" },
};

/** Fetch the code of these pages and of their side rails now, ahead of their first visit. Errors are
 *  swallowed: a chunk that fails to preload is simply fetched (and its failure surfaced) on visit. */
export function preloadPages(pages: Page[]): void {
  for (const p of pages) {
    PAGE_CONTENT[p].Component.preload().catch(() => {});
    const rail = PAGE_RAIL[p]?.Rail as Partial<PreloadableComponent<RailProps>> | undefined;
    rail?.preload?.().catch(() => {});
  }
}