♻️ Create backend package (#643)

packages/backend/trpc/context.ts

@@ -0,0 +1,34 @@
+import { createProxySSGHelpers } from "@trpc/react-query/ssg";
+import * as trpc from "@trpc/server";
+import * as trpcNext from "@trpc/server/adapters/next";
+import { GetServerSidePropsContext } from "next";
+import superjson from "superjson";
+
+import { randomid } from "../utils/nanoid";
+import { appRouter } from "./routers";
+
+export async function createContext(
+  opts: trpcNext.CreateNextContextOptions | GetServerSidePropsContext,
+) {
+  let user = opts.req.session.user;
+  if (!user) {
+    user = {
+      id: `user-${randomid()}`,
+      isGuest: true,
+    };
+    opts.req.session.user = user;
+    await opts.req.session.save();
+  }
+  return { user, session: opts.req.session };
+}
+
+export type Context = trpc.inferAsyncReturnType<typeof createContext>;
+
+export const createSSGHelperFromContext = async (
+  ctx: GetServerSidePropsContext,
+) =>
+  createProxySSGHelpers({
+    router: appRouter,
+    ctx: await createContext(ctx),
+    transformer: superjson,
+  });