add MetaMask abstraction, add default start to RLN Instance, expose RLN Contract

src/create.ts

@@ -0,0 +1,9 @@
+import type { RLNInstance } from "./rln.js";
+
+export async function create(): Promise<RLNInstance> {
+  // A dependency graph that contains any wasm must all be imported
+  // asynchronously. This file does the single async import, so
+  // that no one else needs to worry about it again.
+  const rlnModule = await import("./rln.js");
+  return rlnModule.create();
+}

src/index.ts

@@ -4,6 +4,7 @@ import {
   RLN_STORAGE_ABI,
   SEPOLIA_CONTRACT,
 } from "./constants.js";
+import { create } from "./create.js";
 import { Keystore } from "./keystore/index.js";
 import {
   IdentityCredential,
@@ -14,16 +15,8 @@ import {
 import { RLNContract } from "./rln_contract.js";
 import { MerkleRootTracker } from "./root_tracker.js";
 
-// reexport the create function, dynamically imported from rln.ts
-export async function create(): Promise<RLNInstance> {
-  // A dependency graph that contains any wasm must all be imported
-  // asynchronously. This file does the single async import, so
-  // that no one else needs to worry about it again.
-  const rlnModule = await import("./rln.js");
-  return await rlnModule.create();
-}
-
 export {
+  create,
   Keystore,
   RLNInstance,
   IdentityCredential,

src/metamask.ts

@@ -0,0 +1,15 @@
+import { ethers } from "ethers";
+
+export const extractMetaMaskAccount =
+  async (): Promise<ethers.providers.Web3Provider> => {
+    const ethereum = (window as any).ethereum;
+
+    if (!ethereum) {
+      throw Error(
+        "Missing or invalid Ethereum provider. Please install MetaMask."
+      );
+    }
+
+    await ethereum.request({ method: "eth_requestAccounts" });
+    return new ethers.providers.Web3Provider(ethereum, "any");
+  };

src/rln.ts

@@ -1,10 +1,14 @@
 import type { IRateLimitProof } from "@waku/interfaces";
 import init from "@waku/zerokit-rln-wasm";
 import * as zerokitRLN from "@waku/zerokit-rln-wasm";
+import { ethers } from "ethers";
 
 import { buildBigIntFromUint8Array, writeUIntLE } from "./byte_utils.js";
+import { SEPOLIA_CONTRACT } from "./constants.js";
 import { dateToEpoch, epochIntToBytes } from "./epoch.js";
+import { extractMetaMaskAccount } from "./metamask.js";
 import verificationKey from "./resources/verification_key.js";
+import { RLNContract } from "./rln_contract.js";
 import * as wc from "./witness_calculator.js";
 import { WitnessCalculator } from "./witness_calculator.js";
 
@@ -158,12 +162,39 @@ export function sha256(input: Uint8Array): Uint8Array {
   return zerokitRLN.hash(lenPrefixedData);
 }
 
+type StartRLNOptions = {
+  /**
+   * If not set - will extract MetaMask account and get provider from it.
+   */
+  provider?: ethers.providers.Web3Provider;
+  /**
+   * If not set - will use default SEPOLIA_CONTRACT address.
+   */
+  registryAddress?: string;
+};
+
 export class RLNInstance {
+  private _contract: null | RLNContract = null;
+
   constructor(
     private zkRLN: number,
     private witnessCalculator: WitnessCalculator
   ) {}
 
+  public get contract(): null | RLNContract {
+    return this._contract;
+  }
+
+  public async start(options: StartRLNOptions = {}): Promise<void> {
+    const provider = options.provider || (await extractMetaMaskAccount());
+    const registryAddress = options.registryAddress || SEPOLIA_CONTRACT.address;
+
+    this._contract = await RLNContract.init(this, {
+      registryAddress,
+      provider: provider.getSigner(),
+    });
+  }
+
   generateIdentityCredentials(): IdentityCredential {
     const memKeys = zerokitRLN.generateExtendedMembershipKey(this.zkRLN); // TODO: rename this function in zerokit rln-wasm
     return IdentityCredential.fromBytes(memKeys);