Deno Fresh Middleware for setting a session token

_middleware.ts

/* 
Fresh Middleware for setting a random sesssion token that can be picked up by Fresh route handlers.
Adopted from a Discord post by Chris Knight (@cknight): https://discord.com/channels/684898665143206084/991511118524715139/1202394052604215397

Import map set in deno.json:
"imports": {
    "$fresh/": "https://deno.land/x/[email protected]/",
    "$std/": "https://deno.land/[email protected]/"
  },
*/

import { FreshContext } from "$fresh/server.ts";
import { getCookies, setCookie } from "$std/http/cookie.ts";

interface State {
  session: string;
}

export async function handler(req: Request, ctx: FreshContext<State>) {
  if (ctx.destination === "route") {
    const cookies = getCookies(req.headers);
    let session = cookies.session;

    if (session) {
      ctx.state.session = cookies.session;
    } else {
      session = crypto.randomUUID();
      ctx.state.session = session;
    }

    const resp = await ctx.next();

    if (!cookies.session) {
      setCookie(resp.headers, {
        name: "session",
        value: session,
        httpOnly: true,
        secure: true,
      });
    }
    return resp;
  }

  const resp = await ctx.next();

  return resp;
}