51 lines
1.7 KiB
TypeScript
51 lines
1.7 KiB
TypeScript
export const BEFORE_PAGE_REFRESH = "app:before-page-refresh";
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export const PAGE_DOWNLOAD_ACTIVE_ATTRIBUTE = "data-page-download-active";
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export type PageRefreshRequest = {
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save: (action: () => Promise<void>) => void;
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block: (message: string) => void;
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};
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const downloadListeners = new Set<() => void>();
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let activePageDownloads = 0;
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export function isPageDownloadActive() {
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return activePageDownloads > 0;
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}
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export function subscribeToPageDownloadActivity(listener: () => void) {
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downloadListeners.add(listener);
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return () => { downloadListeners.delete(listener); };
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}
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function publishDownloadActivity() {
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if (typeof document !== "undefined") {
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document.documentElement?.toggleAttribute(PAGE_DOWNLOAD_ACTIVE_ATTRIBUTE, isPageDownloadActive());
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}
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for (const listener of downloadListeners) listener();
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}
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export async function withActivePageDownload<T>(download: () => Promise<T>): Promise<T> {
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if (++activePageDownloads === 1) publishDownloadActivity();
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try {
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return await download();
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} finally {
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if (--activePageDownloads === 0) publishDownloadActivity();
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}
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}
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function assertPageDownloadFinished() {
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if (isPageDownloadActive()) throw new Error("文件正在下载，请等下载完成后再刷新。");
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}
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export async function preparePageRefresh() {
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assertPageDownloadFinished();
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const actions: Array<() => Promise<void>> = [];
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let blocked = "";
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window.dispatchEvent(new CustomEvent<PageRefreshRequest>(BEFORE_PAGE_REFRESH, {
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detail: { save: action => actions.push(action), block: message => { blocked ||= message; } },
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}));
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if (blocked) throw new Error(blocked);
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for (const action of actions) await action();
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assertPageDownloadFinished();
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}
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