feat: add gas-sponsorship route with basic validations

apps/api/src/index.ts

@@ -23,6 +23,7 @@ import { withCors } from "./middleware/cors";
 import { withErrorHandler } from "./middleware/error";
 import { withSwagger } from "./middleware/swagger";
 import { authRoutes } from "./routes/auth";
+import { gasSponsorshipRoutes } from "./routes/gas-sponsorship";
 import { harvestersRoutes } from "./routes/harvesters";
 import { magicswapRoutes } from "./routes/magicswap";
 import { projectsRoutes } from "./routes/projects";
@@ -125,6 +126,7 @@ const main = async () => {
   app.register(transactionsRoutes(ctx));
   app.register(harvestersRoutes(ctx));
   app.register(magicswapRoutes(ctx));
+  app.register(gasSponsorshipRoutes(ctx));
 
   app.get("/healthcheck", async (_, reply) => {
     try {

apps/api/src/routes/gas-sponsorship.ts

@@ -0,0 +1,74 @@
+import type { FastifyPluginAsync } from "fastify";
+
+import type { ErrorReply } from "../schema";
+import {
+  type ValidateBody,
+  type ValidateParams,
+  type ValidateReply,
+  validateBodySchema,
+  validateReplySchema,
+} from "../schema/gas-sponsorship";
+import type { TdkApiContext } from "../types";
+
+// TODO: Replace with actual sponsored partner IDs or logic to fetch them from another service like TMC
+const fullySponsoredPatnerIds = new Set(["zeeverse", "smols"]);
+
+export const gasSponsorshipRoutes =
+  ({ db }: TdkApiContext): FastifyPluginAsync =>
+  async (app) => {
+    app.post<{
+      Params: ValidateParams;
+      Body: ValidateBody;
+      Reply: ValidateReply | ErrorReply;
+    }>(
+      "/gas-sponsorship/:partnerId/validate",
+      {
+        schema: {
+          body: validateBodySchema,
+          response: {
+            200: validateReplySchema,
+          },
+        },
+      },
+      async (req, reply) => {
+        const { body, params } = req;
+
+        const yesterday = new Date(Date.now() - 24 * 60 * 60 * 1000);
+
+        const last24hTransactions = await db.transaction.count({
+          where: {
+            fromAddress: body.userOp.sender,
+            blockTimestamp: {
+              gte: yesterday,
+            },
+          },
+        });
+
+        const [isPartnerFullySponsored, hasLessThan10Transactions] = [
+          fullySponsoredPatnerIds.has(params.partnerId),
+          last24hTransactions < 10,
+        ];
+
+        let reason = "does not meet the criteria";
+
+        switch (true) {
+          case isPartnerFullySponsored:
+            reason = "partner is fully sponsored";
+            break;
+          case hasLessThan10Transactions:
+            reason = "less than 10 transactions in the last 24 hours";
+            break;
+
+          default:
+            break;
+        }
+
+        const isAllowed = isPartnerFullySponsored || hasLessThan10Transactions;
+
+        reply.send({
+          isAllowed,
+          reason,
+        });
+      },
+    );
+  };

apps/api/src/schema/gas-sponsorship.ts

@@ -0,0 +1,30 @@
+import { type Static, Type } from "@sinclair/typebox";
+
+export const validateBodySchema = Type.Object({
+  clientId: Type.String(),
+  chainId: Type.Number(),
+  userOp: Type.Object({
+    sender: Type.String(),
+    targets: Type.Array(Type.String()),
+    gasLimit: Type.String(),
+    gasPrice: Type.String(),
+    data: Type.Object({
+      targets: Type.Array(Type.String()),
+      callDatas: Type.Array(Type.String()),
+      values: Type.Array(Type.String()),
+    }),
+  }),
+});
+
+export const validateReplySchema = Type.Object({
+  isAllowed: Type.Boolean(),
+  reason: Type.Optional(Type.String()),
+});
+
+const validateParamsSchema = Type.Object({
+  partnerId: Type.String(),
+});
+
+export type ValidateParams = Static<typeof validateParamsSchema>;
+export type ValidateReply = Static<typeof validateReplySchema>;
+export type ValidateBody = Static<typeof validateBodySchema>;