import { FreshContext } from "$fresh/server.ts";
import { Route, State } from "$root/defaults/interfaces.ts";
import { ComponentChildren } from "preact";

/**
 * Generates a catch-all [slug] route that dynamically loads partials.
 * This enables direct URL navigation to sub-pages (e.g. /admin/modules).
 * @param basePath The base path of the module, should be `import.meta.dirname!`.
 * @returns A route handler that loads the partial matching the slug.
 */
export default function makeSlug(basePath: string): Route {
  return async function SlugRoute(
    request: Request,
    context: FreshContext<State>,
  ): Promise<ComponentChildren | Response> {
    const slug = context.params.slug;

    // Try partials/<slug>.tsx, then partials/(admin)/<slug>.tsx
    let page: Route | undefined;
    try {
      page = (await import(`${basePath}/partials/${slug}.tsx`)).Page;
    } catch {
      try {
        page = (await import(`${basePath}/partials/(admin)/${slug}.tsx`)).Page;
      } catch {
        // No partial found for this slug
      }
    }

    // For multi-segment slugs (e.g. "overview/12345"), try
    // partials/<dir>/[param].tsx and inject the param into context.params
    if (!page && slug.includes("/")) {
      const idx = slug.indexOf("/");
      const dir = slug.slice(0, idx);
      const param = slug.slice(idx + 1);

      // Discover the dynamic segment name from the file system
      try {
        const entries: string[] = [];
        for await (const entry of Deno.readDir(`${basePath}/partials/${dir}`)) {
          if (entry.isFile) entries.push(entry.name);
        }
        const dynFile = entries.find((n) =>
          n.startsWith("[") && n.endsWith("].tsx")
        );
        if (dynFile) {
          const paramName = dynFile.slice(1, -5); // "[numEtud].tsx" → "numEtud"
          context.params[paramName] = param;
          page = (await import(`${basePath}/partials/${dir}/${dynFile}`)).Page;
        }
      } catch {
        // directory doesn't exist or no dynamic file
      }
    }

    if (!page) {
      return context.renderNotFound();
    }

    return page(request, context);
  };
}