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import { posix } from "../deps/path.ts";
import type { Middleware, Site } from "../core.ts";
export type Router = (url: URL) => Promise<string | undefined>;
export interface Options {  router: Router;  site: Site;}
/** Render pages on demand */export default function onDemand(options: Options): Middleware {  const { router, site } = options;
  return async (request, next) => {    const response = await next(request);
    if (response.status !== 404) {      return response;    }
    const url = new URL(request.url);    const file = await router(url);
    if (!file) {      return response;    }
    const page = await site.renderPage(file);
    if (!page) {      return response;    }
    // Redirect /example to /example/    const pageUrl = page.data.url as string;    if (!url.pathname.endsWith("/") && pageUrl.endsWith("/")) {      return new Response(null, {        status: 301,        headers: {          "location": posix.join(url.pathname, "/"),        },      });    }
    return new Response(      page.content,      { status: 200 },    );  };}