Use project composition to calculate fees

Instead of calculating fees at the vintage level
we should be calculating fees at the project
level. In order to achieve that, use the newly
implemented pool function `totalPerProjectTCO2Supply`
to determine how many credits of a project are
found in a pool.

src/FeeCalculator.sol

@@ -11,6 +11,7 @@ import {SD59x18, sd, intoUint256} from "@prb/math/src/SD59x18.sol";
 
 import {IFeeCalculator, FeeDistribution} from "./interfaces/IFeeCalculator.sol";
 import "./interfaces/IPool.sol";
+import {VintageData, ITCO2} from "./interfaces/ITCO2.sol";
 
 /// @title FeeCalculator
 /// @author Neutral Labs Inc.
@@ -146,7 +147,7 @@ contract FeeCalculator is IFeeCalculator, Ownable {
     {
         require(depositAmount > 0, "depositAmount must be > 0");
 
-        uint256 feeAmount = getDepositFee(depositAmount, getTokenBalance(pool, tco2), getTotalSupply(pool));
+        uint256 feeAmount = getDepositFee(depositAmount, getProjectSupply(pool, tco2), getTotalSupply(pool));
 
         require(feeAmount <= depositAmount, "Fee must be lower or equal to deposit amount");
         require(feeAmount > 0, "Fee must be greater than 0");
@@ -195,22 +196,13 @@ contract FeeCalculator is IFeeCalculator, Ownable {
 
         require(redemptionAmount > 0, "redemptionAmount must be > 0");
 
-        uint256 feeAmount = getRedemptionFee(redemptionAmount, getTokenBalance(pool, tco2), getTotalSupply(pool));
+        uint256 feeAmount = getRedemptionFee(redemptionAmount, getProjectSupply(pool, tco2), getTotalSupply(pool));
 
         require(feeAmount <= redemptionAmount, "Fee must be lower or equal to redemption amount");
         require(feeAmount > 0, "Fee must be greater than 0");
         feeDistribution = calculateFeeShares(feeAmount);
     }
 
-    /// @notice Gets the balance of the TCO2 token in a given pool.
-    /// @param pool The address of the pool.
-    /// @param tco2 The address of the TCO2 token.
-    /// @return The balance of the TCO2 token in the pool.
-    function getTokenBalance(address pool, address tco2) private view returns (uint256) {
-        uint256 tokenBalance = IERC20(tco2).balanceOf(pool);
-        return tokenBalance;
-    }
-
     /// @notice Gets the total supply of a given pool.
     /// @param pool The address of the pool.
     /// @return The total supply of the pool.
@@ -219,6 +211,15 @@ contract FeeCalculator is IFeeCalculator, Ownable {
         return totalSupply;
     }
 
+    /// @notice Gets the total supply of a project in the pool.
+    /// @param pool The address of the pool.
+    /// @return The total supply of the pool.
+    function getProjectSupply(address pool, address tco2) private view returns (uint256) {
+        VintageData memory vData = ITCO2(tco2).getVintageData();
+        uint256 projectSupply = IPool(pool).totalPerProjectTCO2Supply(vData.projectTokenId);
+        return projectSupply;
+    }
+
     /// @notice Calculates the ratios for deposit fee calculation.
     /// @param amount The amount to be deposited.
     /// @param current The current balance of the pool.

src/interfaces/IPool.sol

@@ -10,7 +10,14 @@ pragma solidity ^0.8.13;
 /// @notice This interface defines methods exposed by the Pool
 interface IPool {
     /// @notice Exposes the total TCO2 supply, tracked as the aggregation of deposit,
-    /// redemmption and bridge actions
+    /// redemption and bridge actions
     /// @return supply Current supply
     function totalTCO2Supply() external view returns (uint256 supply);
+
+    /// @notice Exposes the total TCO2 supply of a project in a pool,
+    /// tracked as the aggregation of deposit, redemmption and bridge actions
+    /// @param projectTokenId The token id of the project as it's tracked
+    /// in the CarbonProjects contract
+    /// @return supply Current supply of a project in the pool
+    function totalPerProjectTCO2Supply(uint256 projectTokenId) external view returns (uint256 supply);
 }

src/interfaces/ITCO2.sol

@@ -0,0 +1,31 @@
+// SPDX-FileCopyrightText: 2024 Neutral Labs Inc.
+//
+// SPDX-License-Identifier: UNLICENSED
+
+// If you encounter a vulnerability or an issue, please contact <info@neutralx.com>
+pragma solidity ^0.8.13;
+
+struct VintageData {
+    /// @dev A human-readable string which differentiates this from other vintages in
+    /// the same project, and helps build the corresponding TCO2 name and symbol.
+    string name;
+    uint64 startTime; // UNIX timestamp
+    uint64 endTime; // UNIX timestamp
+    uint256 projectTokenId;
+    uint64 totalVintageQuantity;
+    bool isCorsiaCompliant;
+    bool isCCPcompliant;
+    string coBenefits;
+    string correspAdjustment;
+    string additionalCertification;
+    string uri;
+    string registry;
+}
+
+/// @title ITCO2
+/// @notice This interface defines methods exposed by the TCO2
+interface ITCO2 {
+    /// @notice Get the vintage data for the TCO2
+    /// @return vintageData Vintage data of the TCO2
+    function getVintageData() external view returns (VintageData memory vintageData);
+}

test/FeeCalculator.fuzzy.t.sol

@@ -45,7 +45,7 @@ contract FeeCalculatorTestFuzzy is Test {
 
         // Set up mock pool
         mockPool.setTotalSupply(1e12 * 1e18);
-        mockToken.setTokenBalance(address(mockPool), 1e9 * 1e18);
+        mockPool.setProjectSupply(1, 1e9 * 1e18);
 
         vm.expectRevert("Fee must be greater than 0");
         feeCalculator.calculateDepositFees(address(mockPool), address(mockToken), depositAmount);
@@ -65,7 +65,7 @@ contract FeeCalculatorTestFuzzy is Test {
 
         // Set up mock pool
         mockPool.setTotalSupply(total);
-        mockToken.setTokenBalance(address(mockPool), current);
+        mockPool.setProjectSupply(1, current);
 
         // Act
         try feeCalculator.calculateDepositFees(address(mockPool), address(mockToken), depositAmount) {}
@@ -114,7 +114,7 @@ contract FeeCalculatorTestFuzzy is Test {
 
         // Set up mock pool
         mockPool.setTotalSupply(total);
-        mockToken.setTokenBalance(address(mockPool), current);
+        mockPool.setProjectSupply(1, current);
         uint256 oneTimeFee = 0;
         bool oneTimeRedemptionFailed = false;
         uint256 multipleTimesRedemptionFailedCount = 0;
@@ -158,7 +158,7 @@ contract FeeCalculatorTestFuzzy is Test {
                 total -= redemption;
                 current -= redemption;
                 mockPool.setTotalSupply(total);
-                mockToken.setTokenBalance(address(mockPool), current);
+                mockPool.setProjectSupply(1, current);
             } catch Error(string memory reason) {
                 multipleTimesRedemptionFailedCount++;
                 assertTrue(
@@ -204,7 +204,7 @@ contract FeeCalculatorTestFuzzy is Test {
         uint256 multipleTimesDepositFailedCount = 0;
         // Set up mock pool
         mockPool.setTotalSupply(total);
-        mockToken.setTokenBalance(address(mockPool), current);
+        mockPool.setProjectSupply(1, current);
 
         uint256 oneTimeFee = 0;
 
@@ -236,7 +236,7 @@ contract FeeCalculatorTestFuzzy is Test {
                 total += deposit;
                 current += deposit;
                 mockPool.setTotalSupply(total);
-                mockToken.setTokenBalance(address(mockPool), current);
+                mockPool.setProjectSupply(1, current);
             } catch Error(string memory reason) {
                 multipleTimesDepositFailedCount++;
                 assertTrue(
@@ -280,7 +280,7 @@ contract FeeCalculatorTestFuzzy is Test {
         uint256 depositAmount = 100 * 1e18;
         // Set up mock pool
         mockPool.setTotalSupply(200 * 1e18);
-        mockToken.setTokenBalance(address(mockPool), 100 * 1e18);
+        mockPool.setProjectSupply(1, 100 * 1e18);
 
         // Act
         FeeDistribution memory feeDistribution =