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import { merge } from "../core/utils/object.ts";import { log } from "../core/utils/log.ts";import onDemand, {  getRouter,  MiddlewareOptions,} from "../middlewares/on_demand.ts";import { posix } from "../deps/path.ts";
import type Site from "../core/site.ts";import type { Page } from "../core/file.ts";
export interface Options {  /** The file path to save the routes */  routesPath?: string;
  /** The file path to save the preloaded modules */  preloadPath?: string;
  /** Extra data to pass to the pages */  extraData?: (request: Request) => Record<string, unknown>;}
// Default optionsexport const defaults: Options = {  routesPath: "/_routes.json",  preloadPath: "/_preload.ts",};
/** A plugin to generate pages on demand in the server side */export default function (userOptions?: Options) {  const options = merge(defaults, userOptions);
  return (site: Site) => {    const collector = new JsonRouterCollector({      root: site.root(),      routesPath: options.routesPath,      preloadPath: options.preloadPath,      src: site.options.src,    });
    // Collect and save the routes automatically    site.addEventListener("beforeSave", async () => {      collector.collectRoutes(site.onDemandPages);      const specifiers: string[] = [];
      for (const [path, entry] of site.fs.entries) {        const ext = posix.extname(path);
        switch (ext) {          case ".ts":          case ".tsx":          case ".js":          case ".jsx":          case ".mjs":            specifiers.push(entry.flags.has("remote") ? entry.src : path);            break;
          default:            break;        }      }      await collector.saveRoutes(specifiers);    });
    // Ignore the routes files by the watcher    site.options.watcher.ignore.push(options.routesPath);    site.options.watcher.ignore.push(options.preloadPath);
    // Add the ondemand middleware    site.options.server.middlewares ||= [];
    site._data.on_demand = {      extraData: options.extraData,      routesFile: site.root(options.routesPath),    } as MiddlewareOptions;
    site.options.server.middlewares.push(onDemand({      site,      router: getRouter(collector.routes),    }));  };}
interface JsonRouterCollectorOptions {  root: string;  routesPath: string;  preloadPath: string;  src: string;}
/** * Class to load and manage static routes in a JSON file *  Used by default if no router is provided */export class JsonRouterCollector {  options: JsonRouterCollectorOptions;
  /** Pages that must be generated on demand */  routes = new Map<string, string>();
  constructor(options: JsonRouterCollectorOptions) {    this.options = options;  }
  /** Collect the routes of all pages with data.ondemand = true */  collectRoutes(pages: Page[]): void {    this.routes.clear();
    pages.forEach((page) => {      this.routes.set(        page.data.url,        page.src.path + (page.src.ext || ""),      );    });  }
  /** Save the routes into the routesFile */  async saveRoutes(specifiers: string[]): Promise<void> {    if (!this.routes.size) {      return;    }
    const routesFile = posix.join(this.options.root, this.options.routesPath);    const preloadFile = posix.join(this.options.root, this.options.preloadPath);    const data: Record<string, string> = {};
    this.routes.forEach((path, url) => {      data[url] = path;    });
    // Write the routes file    await Deno.writeTextFile(routesFile, `${JSON.stringify(data, null, 2)}\n`);
    log.info(      `[on_demand plugin] Routes saved at <gray>${routesFile}</gray>`,    );
    // Write the preload file    if (specifiers.length && Object.keys(data).length) {      const code = [        "/**",        " * Don't execute this function",        " * It's just statically analyzable so dynamic imports work on Deno Deploy",        " * @see https://deno.com/deploy/changelog#statically-analyzable-dynamic-imports",        " */",        "export function toStaticallyAnalyzableDynamicImports() {",        ...specifiers.map((path) =>          `  import("./${posix.join(".", this.options.src, path)}");`        ),        "}",        "",      ].join("\n");
      await Deno.writeTextFile(preloadFile, code);
      log.info(        `[on_demand plugin] Preloader saved at <gray>${preloadFile}</gray>`,      );    }  }}