server/_core/context.ts

import type { CreateExpressContextOptions } from "@trpc/server/adapters/express";
import type { User } from "../../drizzle/schema";
import { sdk } from "./sdk";
import * as db from "../db";

export type TrpcContext = {
  req: CreateExpressContextOptions["req"];
  res: CreateExpressContextOptions["res"];
  user: User | null;
};

export async function createContext(
  opts: CreateExpressContextOptions
): Promise<TrpcContext> {
  let user: User | null = null;

  try {
    user = await sdk.authenticateRequest(opts.req);
  } catch (error) {
    // Authentication is optional for public procedures.
    user = null;
  }

  // If no user is authenticated, use the guest user to bypass login
  if (!user) {
    try {
      user = (await db.getOrCreateGuestUser()) || null;
    } catch (error) {
      console.error("[Context] Failed to get guest user", error);
    }
  }

  return {
    req: opts.req,
    res: opts.res,
    user,
  };
}