feat: Instant rewards smart contract

packages/zevm-app-contracts/contracts/instant-rewards/InstantRewards.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.7;
+
+import "@openzeppelin/contracts/security/Pausable.sol";
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
+import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
+
+contract InstantRewards is Ownable, Pausable, ReentrancyGuard {
+    /* An ECDSA signature. */
+    struct Signature {
+        uint8 v;
+        bytes32 r;
+        bytes32 s;
+    }
+
+    struct ClaimData {
+        address to;
+        Signature signature;
+        uint256 sigExpiration;
+        bytes32 taskId;
+        uint256 amount;
+    }
+
+    mapping(address => mapping(bytes32 => bool)) public taskCompletedByUser;
+
+    address public signerAddress;
+
+    event Claimed(address indexed to, bytes32 indexed taskId, uint256 amount);
+    event Withdrawn(address indexed wallet, uint256 amount);
+
+    error InvalidSigner();
+    error SignatureExpired();
+    error InvalidAddress();
+    error TaskAlreadyClaimed();
+    error TransferFailed();
+
+    constructor(address signerAddress_, address owner) Ownable() {
+        if (signerAddress_ == address(0)) revert InvalidAddress();
+        transferOwnership(owner);
+        signerAddress = signerAddress_;
+    }
+
+    function _verify(ClaimData memory claimData) private view {
+        bytes32 payloadHash = _calculateHash(claimData);
+
+        bytes32 messageHash = ECDSA.toEthSignedMessageHash(payloadHash);
+
+        address messageSigner = ECDSA.recover(
+            messageHash,
+            claimData.signature.v,
+            claimData.signature.r,
+            claimData.signature.s
+        );
+
+        if (signerAddress != messageSigner) revert InvalidSigner();
+        if (block.timestamp > claimData.sigExpiration) revert SignatureExpired();
+    }
+
+    // Function to compute the hash of the data and tasks for a token
+    function _calculateHash(ClaimData memory claimData) private pure returns (bytes32) {
+        bytes memory encodedData = abi.encode(
+            claimData.to,
+            claimData.sigExpiration,
+            claimData.taskId,
+            claimData.amount
+        );
+
+        return keccak256(encodedData);
+    }
+
+    function claim(ClaimData memory claimData) external whenNotPaused nonReentrant {
+        claimData.to = msg.sender;
+        _verify(claimData);
+
+        if (taskCompletedByUser[claimData.to][claimData.taskId]) revert TaskAlreadyClaimed();
+
+        taskCompletedByUser[claimData.to][claimData.taskId] = true;
+
+        (bool success, ) = claimData.to.call{value: claimData.amount}("");
+        if (!success) revert TransferFailed();
+
+        emit Claimed(claimData.to, claimData.taskId, claimData.amount);
+    }
+
+    function setSignerAddress(address signerAddress_) external onlyOwner {
+        if (signerAddress_ == address(0)) revert InvalidAddress();
+        signerAddress = signerAddress_;
+    }
+
+    function withdraw(address wallet, uint256 amount) external onlyOwner {
+        if (wallet == address(0)) revert InvalidAddress();
+        if (amount > address(this).balance) revert TransferFailed();
+        payable(wallet).transfer(amount);
+        emit Withdrawn(wallet, amount);
+    }
+
+    function pause() external onlyOwner {
+        _pause();
+    }
+
+    function unpause() external onlyOwner {
+        _unpause();
+    }
+
+    receive() external payable {}
+}

packages/zevm-app-contracts/test/instant-rewards/instant-rewards.ts

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+import { SignerWithAddress } from "@nomiclabs/hardhat-ethers/signers";
+import { expect } from "chai";
+import { BigNumber, utils } from "ethers";
+import { ethers } from "hardhat";
+
+import { InstantRewards } from "../../typechain-types";
+import { ClaimData, getSignature } from "./test.helpers";
+
+describe("Instant Rewards Contract test", () => {
+  let instantRewards: InstantRewards,
+    owner: SignerWithAddress,
+    signer: SignerWithAddress,
+    user: SignerWithAddress,
+    addrs: SignerWithAddress[];
+
+  const encodeTaskId = (taskId: string) => utils.keccak256(utils.defaultAbiCoder.encode(["string"], [taskId]));
+
+  const getClaimDataSigned = async (
+    signer: SignerWithAddress,
+    amount: BigNumber,
+    sigExpiration: number,
+    taskId: string,
+    to: string
+  ) => {
+    const claimData: ClaimData = {
+      amount,
+      sigExpiration,
+      taskId,
+      to,
+    };
+
+    const signature = await getSignature(signer, claimData);
+    return {
+      ...claimData,
+      signature,
+    };
+  };
+
+  beforeEach(async () => {
+    [owner, signer, user, ...addrs] = await ethers.getSigners();
+    const instantRewardsFactory = await ethers.getContractFactory("InstantRewards");
+
+    instantRewards = await instantRewardsFactory.deploy(signer.address, owner.address);
+
+    await instantRewards.deployed();
+  });
+
+  it("Should claim", async () => {
+    const currentBlock = await ethers.provider.getBlock("latest");
+    const sigExpiration = currentBlock.timestamp + 1000;
+    const amount = utils.parseEther("1");
+    const taskId = encodeTaskId("WALLET/TASK/EPOC");
+    const to = owner.address;
+
+    // transfer some funds to the contract
+    await owner.sendTransaction({
+      to: instantRewards.address,
+      value: amount,
+    });
+
+    const claimDataSigned = await getClaimDataSigned(signer, amount, sigExpiration, taskId, to);
+
+    const tx = instantRewards.claim(claimDataSigned);
+    await expect(tx).to.emit(instantRewards, "Claimed").withArgs(owner.address, taskId, amount);
+  });
+
+  it("Should claim if pause and unpause", async () => {
+    const currentBlock = await ethers.provider.getBlock("latest");
+    const sigExpiration = currentBlock.timestamp + 1000;
+    const amount = utils.parseEther("1");
+    const taskId = encodeTaskId("WALLET/TASK/EPOC");
+    const to = owner.address;
+
+    await instantRewards.pause();
+    await instantRewards.unpause();
+
+    // transfer some funds to the contract
+    await owner.sendTransaction({
+      to: instantRewards.address,
+      value: amount,
+    });
+
+    const claimDataSigned = await getClaimDataSigned(signer, amount, sigExpiration, taskId, to);
+
+    const tx = instantRewards.claim(claimDataSigned);
+    await expect(tx).to.emit(instantRewards, "Claimed").withArgs(owner.address, taskId, amount);
+  });
+
+  it("Should revert if try to claim on behalf of somebody else", async () => {
+    const currentBlock = await ethers.provider.getBlock("latest");
+    const sigExpiration = currentBlock.timestamp + 1000;
+    const amount = utils.parseEther("1");
+    const taskId = encodeTaskId("WALLET/TASK/EPOC");
+    const to = user.address;
+
+    const claimDataSigned = await getClaimDataSigned(signer, amount, sigExpiration, taskId, to);
+
+    const tx = instantRewards.claim(claimDataSigned);
+    await expect(tx).to.revertedWith("InvalidSigner");
+  });
+
+  it("Should revert if try to claim with an expired signature", async () => {
+    const currentBlock = await ethers.provider.getBlock("latest");
+    const sigExpiration = currentBlock.timestamp - 1000;
+    const amount = utils.parseEther("1");
+    const taskId = encodeTaskId("WALLET/TASK/EPOC");
+    const to = owner.address;
+
+    const claimDataSigned = await getClaimDataSigned(signer, amount, sigExpiration, taskId, to);
+
+    const tx = instantRewards.claim(claimDataSigned);
+    await expect(tx).to.revertedWith("SignatureExpired");
+  });
+
+  it("Should revert if try to claim when contract it's paused", async () => {
+    const currentBlock = await ethers.provider.getBlock("latest");
+    const sigExpiration = currentBlock.timestamp + 1000;
+    const amount = utils.parseEther("1");
+    const taskId = encodeTaskId("WALLET/TASK/EPOC");
+    const to = owner.address;
+
+    await instantRewards.pause();
+
+    const claimDataSigned = await getClaimDataSigned(signer, amount, sigExpiration, taskId, to);
+
+    const tx = instantRewards.claim(claimDataSigned);
+    await expect(tx).to.revertedWith("Pausable: paused");
+  });
+
+  it("Should revert if not owner try to pause", async () => {
+    const tx = instantRewards.connect(user).pause();
+    await expect(tx).to.revertedWith("Ownable: caller is not the owner");
+  });
+
+  it("Should transfer ownership", async () => {
+    {
+      const ownerAddr = await instantRewards.owner();
+      expect(ownerAddr).to.be.eq(owner.address);
+    }
+    await instantRewards.transferOwnership(user.address);
+    {
+      const ownerAddr = await instantRewards.owner();
+      expect(ownerAddr).to.be.eq(user.address);
+    }
+  });
+
+  it("Should withdraw by owner", async () => {
+    const amount = utils.parseEther("2");
+    const amountToWithdraw = utils.parseEther("1");
+    // transfer some funds to the contract
+    await owner.sendTransaction({
+      to: instantRewards.address,
+      value: amount,
+    });
+
+    const userBalanceBefore = await ethers.provider.getBalance(user.address);
+
+    const tx = instantRewards.withdraw(user.address, amountToWithdraw);
+    await expect(tx).to.emit(instantRewards, "Withdrawn").withArgs(user.address, amountToWithdraw);
+
+    const balanceOfContract = await ethers.provider.getBalance(instantRewards.address);
+    expect(balanceOfContract).to.be.eq(amount.sub(amountToWithdraw));
+    const balanceOfUser = await ethers.provider.getBalance(user.address);
+    expect(balanceOfUser).to.be.eq(userBalanceBefore.add(amountToWithdraw));
+  });
+});

packages/zevm-app-contracts/test/instant-rewards/test.helpers.ts

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+import { SignerWithAddress } from "@nomiclabs/hardhat-ethers/signers";
+import { BigNumber } from "ethers";
+import { ethers } from "hardhat";
+
+export interface Signature {
+  r: string;
+  s: string;
+  v: number;
+}
+
+export interface ClaimData {
+  amount: BigNumber;
+  sigExpiration: number;
+  taskId: string;
+  to: string;
+}
+
+export interface ClaimDataSigned extends ClaimData {
+  signature: Signature;
+}
+
+export const getSignature = async (signer: SignerWithAddress, claimData: ClaimData) => {
+  let payload = ethers.utils.defaultAbiCoder.encode(
+    ["address", "uint256", "bytes32", "uint256"],
+    [claimData.to, claimData.sigExpiration, claimData.taskId, claimData.amount]
+  );
+
+  const payloadHash = ethers.utils.keccak256(payload);
+
+  // This adds the message prefix
+  const signature = await signer.signMessage(ethers.utils.arrayify(payloadHash));
+  return ethers.utils.splitSignature(signature);
+};