feat: Add claimFor method to AcrossMerkleDistributor (#200)

* feat: Update AcrossMerkleDistributor deployment

* Update deployments.json

* feat: Add claimFor method to AcrossMerkleDistributor

Allows a whitelisted account to claim on behalf of a user. Can be used to atomically claim and perform some action for a user, such as claim and stake.

* Update yarn.lock

* Update package.json

* Whitelisted claimer only works for claimFor

* Update MerkleDistributor.ts

Author: nicholaspai

contracts/merkle-distributor/AcrossMerkleDistributor.sol

@@ -2,20 +2,31 @@
 pragma solidity ^0.8.0;
 
 import "@uma/core/contracts/merkle-distributor/implementation/MerkleDistributor.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 
 /**
  * @title  Extended MerkleDistributor contract.
  * @notice Adds additional constraints governing who can claim leaves from merkle windows.
  */
 contract AcrossMerkleDistributor is MerkleDistributor {
-    // Addresses that can claim on user's behalf. Useful to get around the requirement that claim recipient
-    // must also be claimer.
+    using SafeERC20 for IERC20;
+
+    // Addresses that can claim on user's behalf.
     mapping(address => bool) public whitelistedClaimers;
 
     /****************************************
      *                EVENTS
      ****************************************/
     event WhitelistedClaimer(address indexed claimer, bool indexed whitelist);
+    event ClaimFor(
+        address indexed caller,
+        uint256 windowIndex,
+        address indexed account,
+        uint256 accountIndex,
+        uint256 amount,
+        address indexed rewardToken
+    );
 
     /****************************
      *      ADMIN FUNCTIONS
@@ -39,26 +50,47 @@ contract AcrossMerkleDistributor is MerkleDistributor {
     /**
      * @notice Batch claims to reduce gas versus individual submitting all claims. Method will fail
      *         if any individual claims within the batch would fail.
-     * @dev    All claim recipients must be equal to msg.sender or claimer must be whitelisted.
+     * @dev    All claim recipients must be equal to msg.sender.
      * @param claims array of claims to claim.
      */
     function claimMulti(Claim[] memory claims) public override {
-        if (!whitelistedClaimers[msg.sender]) {
-            uint256 claimCount = claims.length;
-            for (uint256 i = 0; i < claimCount; i++) {
-                require(claims[i].account == msg.sender, "invalid claimer");
-            }
+        uint256 claimCount = claims.length;
+        for (uint256 i = 0; i < claimCount; i++) {
+            require(claims[i].account == msg.sender, "invalid claimer");
         }
         super.claimMulti(claims);
     }
 
     /**
      * @notice Claim amount of reward tokens for account, as described by Claim input object.
-     * @dev    Claim recipient must be equal to msg.sender or caller must be whitelisted.
+     * @dev    Claim recipient must be equal to msg.sender.
      * @param _claim claim object describing amount, accountIndex, account, window index, and merkle proof.
      */
     function claim(Claim memory _claim) public override {
-        require(whitelistedClaimers[msg.sender] || _claim.account == msg.sender, "invalid claimer");
+        require(_claim.account == msg.sender, "invalid claimer");
         super.claim(_claim);
     }
+
+    /**
+     * @notice Executes merkle leaf claim on behaf of user. This can only be called by a trusted
+     *         claimer address. This function is designed to be called atomically with other transactions
+     *         that ultimately return the claimed amount to the rightful recipient. For example,
+     *         AcceleratingDistributor could call this function and then stake atomically on behalf of the user.
+     * @dev    Caller must be in whitelistedClaimers struct set to "true".
+     * @param _claim leaf to claim.
+     */
+
+    function claimFor(Claim memory _claim) public {
+        require(whitelistedClaimers[msg.sender], "unwhitelisted claimer");
+        _verifyAndMarkClaimed(_claim);
+        merkleWindows[_claim.windowIndex].rewardToken.safeTransfer(msg.sender, _claim.amount);
+        emit ClaimFor(
+            msg.sender,
+            _claim.windowIndex,
+            _claim.account,
+            _claim.accountIndex,
+            _claim.amount,
+            address(merkleWindows[_claim.windowIndex].rewardToken)
+        );
+    }
 }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@across-protocol/contracts-v2",
-  "version": "1.0.6",
+  "version": "1.0.7",
   "author": "UMA Team",
   "license": "AGPL-3.0",
   "repository": {
@@ -37,7 +37,7 @@
     "@openzeppelin/contracts": "^4.7.3",
     "@uma/common": "^2.28.0",
     "@uma/contracts-node": "^0.3.18",
-    "@uma/core": "^2.40.0",
+    "@uma/core": "^2.41.0",
     "@uma/merkle-distributor": "^1.3.38",
     "arb-bridge-eth": "^0.7.4",
     "arb-bridge-peripherals": "^1.0.5"