create RLN service, add utils

examples/rln-js/package.json

@@ -9,6 +9,8 @@
     "lint": "next lint"
   },
   "dependencies": {
+    "@waku/rln": "^0.1.1-fa49e29",
+    "ethers": "^5.7.2",
     "next": "13.5.6",
     "protobufjs": "^7.2.5",
     "react": "^18",

examples/rln-js/src/services/rln.ts

@@ -0,0 +1,96 @@
+import { ethers } from "ethers";
+import {
+  create,
+  Keystore,
+  RLNDecoder,
+  RLNEncoder,
+  RLNContract,
+  SEPOLIA_CONTRACT,
+  RLNInstance,
+} from "@waku/rln";
+import { isBrowserProviderValid } from "@/utils/ethereum";
+
+enum RLNEventsNames {
+  Status = "status",
+}
+
+enum StatusEventPayload {
+  WASM_LOADING = "WASM Blob download in progress...",
+  WASM_FAILED = "Failed to download WASM, check console",
+  CONTRACT_LOADING = "Connecting to RLN contract",
+  CONTRACT_FAILED = "Failed to connect to RLN contract",
+}
+
+type EmitterProps = Pick<EventTarget, "addEventListener"> &
+  Pick<EventTarget, "removeEventListener">;
+type IRLN = EmitterProps & {};
+
+export class RLN implements IRLN {
+  private readonly emitter = new EventTarget();
+  private readonly ethProvider: ethers.providers.Web3Provider;
+
+  private rlnInstance: undefined | RLNInstance;
+  private rlnContract: undefined | RLNContract;
+
+  private initialized = false;
+
+  public constructor() {
+    const ethereum = (<any>window)
+      .ethereum as ethers.providers.ExternalProvider;
+    if (!isBrowserProviderValid(ethereum)) {
+      throw Error(
+        "Invalid Ethereum provider present on the page. Check if MetaMask is connected."
+      );
+    }
+    this.ethProvider = new ethers.providers.Web3Provider(ethereum, "any");
+  }
+
+  public async init(): Promise<void> {
+    if (this.initialized) {
+      console.info("RLN is initialized.");
+      return;
+    }
+
+    this.emitStatusEvent(StatusEventPayload.WASM_LOADING);
+    try {
+      this.rlnInstance = await create();
+    } catch (error) {
+      console.error(
+        "Failed at fetching WASM and creating RLN instance: ",
+        error
+      );
+      this.emitStatusEvent(StatusEventPayload.WASM_FAILED);
+      throw error;
+    }
+
+    this.emitStatusEvent(StatusEventPayload.CONTRACT_LOADING);
+    try {
+      this.rlnContract = await RLNContract.init(this.rlnInstance, {
+        registryAddress: SEPOLIA_CONTRACT.address,
+        provider: this.ethProvider.getSigner(),
+      });
+    } catch (error) {
+      console.error("Failed to connect to RLN contract: ", error);
+      this.emitStatusEvent(StatusEventPayload.CONTRACT_FAILED);
+      throw error;
+    }
+  }
+
+  public addEventListener(
+    name: RLNEventsNames,
+    fn: EventListenerOrEventListenerObject
+  ) {
+    return this.emitter.addEventListener(name, fn);
+  }
+
+  public removeEventListener(
+    name: RLNEventsNames,
+    fn: EventListenerOrEventListenerObject
+  ) {
+    return this.emitter.removeEventListener(name, fn);
+  }
+
+  private emitStatusEvent(payload: StatusEventPayload) {
+    this.emitter.dispatchEvent(new Event(payload));
+  }
+}

examples/rln-js/src/utils/ethereum.ts

@@ -0,0 +1,6 @@
+export const isBrowserProviderValid = (obj: any) => {
+  if (obj && typeof obj.request === "function") {
+    return true;
+  }
+  return true;
+};