add: smart-contracts

smart-contracts/on-chain-balances-resolver/Balances.sol

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: MIT
+
+// Adapted from https://github.com/MyCryptoHQ/eth-scan
+
+pragma solidity >= 0.8.0;
+
+contract Balances {
+    struct Result {
+        bool success;
+        uint256 balance;
+    }
+
+    function tokensBalance(address owner, address[] calldata contracts) external view returns (Result[] memory results) {
+        results = new Result[](contracts.length);
+
+        bytes memory data = abi.encodeWithSignature("balanceOf(address)", owner);
+
+        for (uint256 i = 0; i < contracts.length; i++) {
+            results[i] = staticCall(contracts[i], data, 8000000);
+        }
+    }
+
+    function staticCall(
+        address target,
+        bytes memory data,
+        uint256 gas
+    ) private view returns (Result memory) {
+        uint256 size = codeSize(target);
+
+        if (size > 0) {
+            (bool success, bytes memory result) = target.staticcall{ gas: gas }(data);
+            if (success) {
+                uint256 balance = abi.decode(result, (uint256));
+                return Result(success, balance);
+            }
+        }
+
+        return Result(false, 0);
+    }
+
+    function codeSize(address _address) private view returns (uint256 size) {
+        // solhint-disable-next-line no-inline-assembly
+        assembly {
+         size := extcodesize(_address)
+      }
+    }
+}
+

smart-contracts/on-chain-balances-resolver/artifacts/abi.json

@@ -0,0 +1,38 @@
+[
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "owner",
+        "type": "address"
+      },
+      {
+        "internalType": "address[]",
+        "name": "contracts",
+        "type": "address[]"
+      }
+    ],
+    "name": "tokensBalance",
+    "outputs": [
+      {
+        "components": [
+          {
+            "internalType": "bool",
+            "name": "success",
+            "type": "bool"
+          },
+          {
+            "internalType": "uint256",
+            "name": "balance",
+            "type": "uint256"
+          }
+        ],
+        "internalType": "struct Balances.Result[]",
+        "name": "results",
+        "type": "tuple[]"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  }
+]