JUMBO refactor, still work in progress

packages/backend/src/api.ts

@@ -0,0 +1,106 @@
+import * as Api from "common/Api";
+import * as Cbor from "common/Cbor";
+import * as Client from "common/Client";
+import { Cause, Effect, Either, HashMap, Inspectable, Option, pipe } from "effect";
+
+/* NOTE We shouldn't need to extract this to a separate type, but if we don't do
+ * it the TypeScript parser in VS Code sort of blows up and the syntax colors
+ * turn wrong.
+ */
+type Return<Impl extends Api.ApiBundleImpl<any>> = Effect.Effect<Response, never, Effect.Effect.Context<ReturnType<Impl[keyof Impl]>>>;
+
+const catchToResponse = Effect.catchAll((error: unknown) => pipe(
+	error,
+	Inspectable.toJSON,
+	Cbor.encode,
+	Effect.map(Client.cborBody),
+	Effect.matchEffect({
+		onSuccess: ({ body, headers }) => Effect.fail(new Response(body, { status: 500, headers })),
+		onFailure: () => Effect.fail(new Response(null, { status: 500 })),
+	}),
+));
+
+export const implement = <
+	const Record extends { readonly [_: string]: Api.ApiAny },
+	const Impl extends Api.ApiBundleImpl<Record>,
+>(
+	bundle: Api.ApiBundle<Record>,
+	impl: Impl,
+): (key: string, request: Request) => Return<Impl> => {
+	return (key, requestObject) => {
+		/* Force both return types to be `Response`. We can use the error route
+		 * for it's short-circuit capabilities.
+		 */
+		const effect: Effect.Effect<Response, Response, any> = Effect.gen(function* () {
+			const maybeApi = HashMap.get(bundle.map, key);
+			if (Option.isNone(maybeApi)) {
+				return RESPONSE_API_NOT_FOUND;
+			}
+			const { value: api } = maybeApi;
+
+			const fn = impl[key];
+			if (fn === undefined) {
+				return RESPONSE_API_NOT_IMPLEMENTED;
+			}
+
+			const request = yield* pipe(
+				requestObject,
+				Client.decodeBody(api.request),
+				catchToResponse,
+			);
+
+			const result = yield* pipe(
+				request,
+				fn,
+				Effect.sandbox,
+				Effect.either,
+			);
+
+			const { status, response } = pipe(
+				result,
+				Either.match({
+					onLeft: (cause) => pipe(
+						cause,
+						Cause.failureOrCause,
+						Either.match({
+							onLeft: (error) => ({
+								status: 400,
+								response: pipe(
+									error,
+									Client.encodeBody(api.error),
+									catchToResponse,
+								),
+							}),
+							onRight: (die) => ({
+								status: 500,
+								response: pipe(
+									die,
+									Inspectable.toJSON,
+									Cbor.encode,
+									Effect.map(Client.cborBody),
+									catchToResponse,
+								),
+							}),
+						}),
+					),
+					onRight: (response) => ({
+						status: 200,
+						response: pipe(
+							response,
+							Client.encodeBody(api.response),
+							catchToResponse,
+						),
+					}),
+				}),
+			);
+
+			const { body, headers } = yield* response;
+			return new Response(body, { status, headers });
+		});
+
+		return Effect.catchAll(effect, Effect.succeed);
+	};
+};
+
+const RESPONSE_API_NOT_FOUND = new Response(null, { status: 404 });
+const RESPONSE_API_NOT_IMPLEMENTED = new Response(null, { status: 501 });