already claimed addeda

panditdhamdhere · Sep 9, 2024 · 7c8e48d · 7c8e48d
1 parent a98bccb
commit 7c8e48d
Showing 1 changed file with 14 additions and 1 deletion.
diff --git a/src/MerkleAirdrop.sol b/src/MerkleAirdrop.sol
@@ -14,15 +14,19 @@ contract MerkleAirdrop {
     //////////// //////ERRORS /////////////////////
     ///////////////////////////////////////////////
     error MerkleAirdrop__InvalidProof();
+    error MerkleAirdrop__AlreadyClaimed();
 
     ///////////////////////////////////////////////
-    ///////////////STORAGE VARIABLES //////////////
+    ///////////////STATE VARIABLES //////////////
     ///////////////////////////////////////////////
 
     address[] claimers;
     bytes32 private immutable i_merkleRoot;
     IERC20 private immutable i_airdropToken;
 
+    // storage variable => mapping
+    mapping(address claimer => bool claimed) private s_hasClaimed;
+
     ///////////////////////////////////////////////
     ///////////////////EVENTS/////////////////////
     ///////////////////////////////////////////////
@@ -33,11 +37,19 @@ contract MerkleAirdrop {
         i_airdropToken = airdropToken;
     }
 
+    ///////////////////////////////////////////////
+    ///////////////////FUNCTIONS///////////////////
+    ///////////////////////////////////////////////
+
     function claim(
         address account,
         uint256 amount,
         bytes32[] calldata merkleProof
     ) external {
+        if (s_hasClaimed[account]) {
+            revert MerkleAirdrop__AlreadyClaimed();
+        }
+
         // calculate using the account and the amount. the hash -> leaf node
         bytes32 leaf = keccak256(
             bytes.concat(keccak256(abi.encode(account, amount)))
@@ -46,6 +58,7 @@ contract MerkleAirdrop {
         if (!MerkleProof.verify(merkleProof, i_merkleRoot, leaf)) {
             revert MerkleAirdrop__InvalidProof();
         }
+        s_hasClaimed[account] = true;
         emit Claim(account, amount);
         i_airdropToken.safeTransfer(account, amount);
     }