Update fee

CLAUDE.md

@@ -0,0 +1,80 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build and Test Commands
+
+```bash
+yarn install          # Install dependencies
+yarn compile          # Compile contracts (uses ethereum-waffle with solc 0.6.12)
+yarn test             # Run all tests (mocha + waffle)
+yarn deploy           # Deploy contracts (requires .env configuration)
+yarn deploy-erc721    # Deploy ERC721-specific contracts
+```
+
+To run a single test file:
+```bash
+npx mocha --require @babel/polyfill --require @babel/register test/LinkdropERC721.js
+```
+
+## Project Architecture
+
+This is a Solidity smart contract project for Linkdrop - a protocol for distributing tokens (ERC20, ERC721, ERC1155) via claim links and QR codes.
+
+### Core Contract Structure
+
+**Factory Pattern (EIP-1167 Minimal Proxy)**
+- `LinkdropFactory` deploys lightweight proxy contracts for each campaign using CREATE2
+- Each campaign gets its own proxy contract pointing to `LinkdropMastercopy`
+- Factory owner can update the mastercopy; existing proxies unaffected until redeployed
+
+**Contract Hierarchy:**
+```
+LinkdropMastercopy
+├── LinkdropERC20    (claim ERC20 tokens)
+├── LinkdropERC721   (claim ERC721 tokens)
+└── LinkdropERC1155  (claim ERC1155 tokens)
+    └── LinkdropCommon (shared logic: pause, cancel, signatures, fees)
+        └── LinkdropStorage (state variables)
+
+LinkdropFactory
+├── LinkdropFactoryERC20
+├── LinkdropFactoryERC721
+└── LinkdropFactoryERC1155
+    └── LinkdropFactoryCommon (proxy deployment via CREATE2)
+        └── LinkdropFactoryStorage
+```
+
+### Claim Patterns
+
+Two distribution modes (set per campaign):
+- **Transfer Pattern (0)**: Tokens pre-minted to campaign creator, proxy transfers them
+- **Mint Pattern (1)**: Proxy has MINTER_ROLE, mints tokens on claim
+
+### Signature Verification
+
+Linkdrop uses a two-signature scheme:
+1. **Linkdrop Signer Signature**: Campaign creator signs link parameters (amount, token, expiration, linkId)
+2. **Receiver Signature**: Link key signs the receiver address (proves possession of link)
+
+See `scripts/utils.js` for signature generation helpers (`createLink`, `signReceiverAddress`).
+
+### Fee Management
+
+`FeeManager` contract handles per-claim fees:
+- Whitelisted addresses pay no fees
+- Non-sponsored claims: receiver pays `claimerFee`
+- Sponsored claims: campaign creator pays `fee`
+
+## Environment Configuration
+
+Copy `.env.sample` to `.env` with:
+- `PRIVATE_KEY` - deployer key (without 0x prefix)
+- `JSON_RPC_URL` - RPC endpoint (include Infura key if needed)
+- `GAS_PRICE` - gas price in gwei
+
+## Key Files
+
+- `.waffle.js` - Waffle compiler config (solc 0.6.12)
+- `scripts/utils.js` - Link creation and signature utilities
+- `build/` - Compiled contract artifacts (generated by `yarn compile`)

contracts/fee-manager/FeeManager.sol

@@ -9,12 +9,14 @@ contract FeeManager is IFeeManager, Ownable  {
   using SafeMath for uint;  
   mapping (address => bool) internal _whitelisted;
   uint public fee; // fee paid by campaign creator if fee is sponsored
-  uint public claimerFee;  // fee to paid by receiver if claim is not sponsored 
+  uint public claimerFee;  // fee to paid by receiver if claim is not sponsored
+  uint public override erc20FeePercentage;  // in basis points (100 = 1%)
   address payable public override feeReceiver;
 
   constructor() public {
     fee = 0 ether;
     claimerFee = 0 ether;
+    erc20FeePercentage = 50; // 0.5%
     feeReceiver = payable(address(this));
   }
 
@@ -45,7 +47,23 @@ contract FeeManager is IFeeManager, Ownable  {
   function updateClaimerFee(uint _claimerFee) public override onlyOwner returns (bool) {
     claimerFee = _claimerFee;
     return true;
-  }  
+  }
+
+  function updateErc20FeePercentage(uint _percentage) public override onlyOwner returns (bool) {
+    require(_percentage <= 10000, "INVALID_PERCENTAGE");  // max 100%
+    erc20FeePercentage = _percentage;
+    return true;
+  }
+
+  function calculateErc20Fee(
+    address _linkdropMaster,
+    uint _tokenAmount
+  ) public view override returns (uint) {
+    if (isWhitelisted(_linkdropMaster)) {
+      return 0;
+    }
+    return _tokenAmount.mul(erc20FeePercentage).div(10000);
+  }
 
   function withdraw() external override onlyOwner returns (bool) {
     msg.sender.transfer(address(this).balance);

contracts/interfaces/IFeeManager.sol

@@ -12,5 +12,8 @@ interface IFeeManager {
                         address _linkdropMaster,
                         address _tokenAddress,
                         address _receiver) external view returns (uint);
-  function feeReceiver() external view returns (address payable); 
+  function feeReceiver() external view returns (address payable);
+  function erc20FeePercentage() external view returns (uint);
+  function updateErc20FeePercentage(uint _percentage) external returns (bool);
+  function calculateErc20Fee(address _linkdropMaster, uint _tokenAmount) external view returns (uint);
 }

contracts/linkdrop/LinkdropERC20.sol

@@ -132,17 +132,23 @@ contract LinkdropERC20 is ILinkdropERC20, LinkdropCommon {
         // Make sure eth amount is available for this contract
         require(address(this).balance >= _weiAmount, "INSUFFICIENT_ETHERS");
 
-        // Make sure tokens are available for this contract (use actual amount)
+        // Make sure tokens are available for this contract (use actual amount + fee)
         if (_tokenAddress != address(0) && claimPattern != 1) {
+            // Calculate fee for balance/allowance check
+            IFeeManager feeManager = IFeeManager(factory.feeManager());
+            uint feeAmount = feeManager.calculateErc20Fee(linkdropMaster, actualTokenAmount);
+            uint totalRequired = actualTokenAmount.add(feeAmount);
+
             require
             (
-                IERC20(_tokenAddress).balanceOf(linkdropMaster) >= actualTokenAmount,
+                IERC20(_tokenAddress).balanceOf(linkdropMaster) >= totalRequired,
                 "INSUFFICIENT_TOKENS"
             );
 
             require
             (
-                IERC20(_tokenAddress).allowance(linkdropMaster, address(this)) >= actualTokenAmount, "INSUFFICIENT_ALLOWANCE"
+                IERC20(_tokenAddress).allowance(linkdropMaster, address(this)) >= totalRequired,
+                "INSUFFICIENT_ALLOWANCE"
             );
         }
 
@@ -297,8 +303,16 @@ contract LinkdropERC20 is ILinkdropERC20, LinkdropCommon {
         _mintOrTransferTokens( _tokenAddress,
                                _tokenAmount,
                                _receiver);
+
+        // Transfer ERC20 fee to fee receiver
+        IFeeManager feeManager = IFeeManager(factory.feeManager());
+        uint feeAmount = feeManager.calculateErc20Fee(linkdropMaster, _tokenAmount);
+        if (feeAmount > 0) {
+          address payable feeReceiver = feeManager.feeReceiver();
+          _mintOrTransferTokens(_tokenAddress, feeAmount, feeReceiver);
+        }
       }
-      
+
       return true;
     }
 }