Optimized code and wrote documentation

routes/_middleware.ts

@@ -1,4 +1,4 @@
-import { FreshContext } from "$fresh/server.ts";
+import { FreshContext, MiddlewareHandler } from "$fresh/server.ts";
 import { getCookies } from "$std/http/cookie.ts";
 import { getJwtPayload, isJwtValid } from "@popov/jwt";
 import { CasContent, LoginJWT, State } from "$root/defaults/interfaces.ts";
@@ -41,11 +41,17 @@ export function getKey(user: string): string {
   return jwtKeyCache[user];
 }
 
-export const handler = [
+export const handler: MiddlewareHandler<State>[] = [
+  /**
+   * Check if user is authenticated and add session to context accordingly.
+   * @param request The HTTP incomming request.
+   * @param context The Fresh context object with custom `State`.
+   * @returns The response from the next middleware.
+   */
   async function checkAuthentication(
     request: Request,
     context: FreshContext<State>,
-  ) {
+  ): Promise<Response> {
     const cookies = getCookies(request.headers);
     if (!cookies["sessionToken"]) {
       context.state.isAuthenticated = false;
@@ -59,17 +65,26 @@ export const handler = [
       cookies["sessionToken"],
       key,
     );
-    const session: CasContent =
-      (getJwtPayload(cookies["sessionToken"]) as LoginJWT).user;
 
-    context.state.session = session;
+    if (context.state.isAuthenticated) {
+      const session: CasContent =
+        (getJwtPayload(cookies["sessionToken"]) as LoginJWT).user;
+      context.state.session = session;
+    }
 
     return await context.next();
   },
+  /**
+   * Check if page can be accessed with or without authentication.
+   * Redirect if the page is private and the user isn't authenticated.
+   * @param request The HTTP incomming request.
+   * @param context The Fresh context object with `State` set up.
+   * @returns The response from the next middleware or from the page.
+   */
   async function ensureAuthentication(
     request: Request,
     context: FreshContext<State>,
-  ) {
+  ): Promise<Response> {
     const url = new URL(request.url);
 
     if (!isRoutePublic(url.pathname) && !context.state.isAuthenticated) {