feat(middleware): PoC of ANS-101 ar-io#27

src/middleware/ANS-101.ts

@@ -0,0 +1,52 @@
+/**
+ * AR.IO Gateway
+ * Copyright (C) 2022-2023 Permanent Data Solutions, Inc. All Rights Reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+import type {
+  ArweaveG8wayMiddleware,
+  ArweaveG8wayMiddlewareContext,
+} from './types.js';
+
+const capabilities: { name: string }[] = [];
+
+/**
+ * Can be instantiated and then injected to add capabilities
+ */
+export const addCapability: ArweaveG8wayMiddlewareContext['addCapability'] =
+  async (capability) => {
+    const found = capabilities.find((c) => c.name === capability.name);
+
+    if (found)
+      throw new Error(
+        `Multiple middleware implementing the ${capability.name} capability`,
+      );
+
+    capabilities.push(capability);
+  };
+
+/**
+ * An Arweave G8way Middleware that exposes an implementation of ANS-101
+ *
+ * See https://specs.g8way.io/?tx=hLSKTSwd5_3xB71zciyK_WFEpK9wVX2IeGzxk9Yl2xY
+ */
+export const createCapabilitiesMiddleware: () => ArweaveG8wayMiddleware =
+  () =>
+  async ({ addCapability }) => {
+    await addCapability({ name: 'reflexive', version: '1.0.0' });
+
+    return async (app) =>
+      app.get('/info/capabilities', (_req, res) => res.json({ capabilities }));
+  };

src/middleware/types.ts

@@ -0,0 +1,39 @@
+/**
+ * AR.IO Gateway
+ * Copyright (C) 2022-2023 Permanent Data Solutions, Inc. All Rights Reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+import type { Express } from 'express';
+
+type JSONValue =
+  | string
+  | number
+  | boolean
+  | { [x: string]: JSONValue }
+  | Array<JSONValue>;
+
+export type ArweaveG8wayCapability<
+  C extends Record<string, JSONValue> = Record<string, JSONValue>,
+> = C & { name: string; version: string };
+
+export type ArweaveG8wayMiddlewareContext = {
+  addCapability: <C extends ArweaveG8wayCapability>(
+    capability: C,
+  ) => Promise<void>;
+};
+
+export type ArweaveG8wayMiddleware = (
+  context: ArweaveG8wayMiddlewareContext,
+) => Promise<(app: Express) => Express | Promise<Express>>;