♻️ Create backend package (#643)

packages/backend/trpc/trpc.ts

@@ -0,0 +1,28 @@
+import { initTRPC, TRPCError } from "@trpc/server";
+import superjson from "superjson";
+
+import { Context } from "./context";
+
+const t = initTRPC.context<Context>().create({
+  transformer: superjson,
+  errorFormatter({ shape }) {
+    return shape;
+  },
+});
+
+export const router = t.router;
+
+export const publicProcedure = t.procedure;
+
+export const middleware = t.middleware;
+
+const checkAuthIfRequired = middleware(async ({ ctx, next }) => {
+  if (process.env.AUTH_REQUIRED === "true" && ctx.session) {
+    throw new TRPCError({ code: "UNAUTHORIZED", message: "Login is required" });
+  }
+  return next();
+});
+
+export const possiblyPublicProcedure = t.procedure.use(checkAuthIfRequired);
+
+export const mergeRouters = t.mergeRouters;