feat: add OpenAPI spec

Author: WipeAir

src/bootstrap.ts

@@ -3,6 +3,7 @@ import { Server } from "hyper-express";
 import { dispatchHandlerController } from "./dispatch-handler/controller";
 import { getConfig } from "./utils/config";
 import { getLogger } from "./utils/logger";
+import { getOpenApiSpec } from "./utils/openapi";
 
 /**
  * Describes the result of the bootstrap function.
@@ -32,6 +33,20 @@ export const bootstrap = (async (): Promise<BootstrapResult> => {
 	// Register the handler controller.
 	server.post("/dispatch", dispatchHandlerController);
 
+	// Serve the OpenAPI specification as a static file.
+	server.get("/openapi.yaml", async (_, res) => {
+		const content = await getOpenApiSpec();
+
+		res
+			.status(200)
+			.header(
+				"cache-control",
+				"public, max-age 172800, stale-while-revalidate 172800"
+			)
+			.header("content-type", "application/yaml")
+			.send(content);
+	});
+
 	// Set up a global not found handler
 	server.set_not_found_handler((_, res) => {
 		res.status(404).json({

src/utils/openapi.ts

@@ -0,0 +1,23 @@
+import fsp from "fs/promises";
+import path from "path";
+
+let _cache: string | null = null;
+
+/**
+ * Provides the OpenAPI specification as a string in YAML format.
+ */
+export async function getOpenApiSpec(): Promise<string> {
+	if (!_cache) {
+		const specPath = path.join(__dirname, "../assets/openapi/openapi.yaml");
+
+		try {
+			_cache = await fsp.readFile(specPath, "utf-8");
+		} catch (err) {
+			console.error("Failed to read OpenAPI spec file", err);
+
+			throw err;
+		}
+	}
+
+	return _cache;
+}