Merge pull request #148 from CirclesUBI/20240503-events-discountcost

(circles): introduce event DiscountCost

src/circles/Circles.sol

@@ -157,7 +157,7 @@ contract Circles is ERC1155, ICirclesErrors {
             _calculateDiscountedBalance(totalSupplyBalance.balance, today - totalSupplyBalance.lastUpdatedDay) + _value;
         if (newTotalSupply > MAX_VALUE) {
             // DiscountedBalances: balance exceeds maximum value
-            revert CirclesERC1155AmountExceedsMaxUint190(_account, _id, newTotalSupply, 2);
+            revert CirclesDemurrageAmountExceedsMaxUint190(_account, _id, newTotalSupply, 2);
         }
         totalSupplyBalance.balance = uint192(newTotalSupply);
         totalSupplyBalance.lastUpdatedDay = today;

src/circles/Demurrage.sol

@@ -4,7 +4,7 @@ pragma solidity >=0.8.24;
 import "../errors/Errors.sol";
 import "../lib/Math64x64.sol";
 
-contract Demurrage is ICirclesERC1155Errors {
+contract Demurrage is ICirclesDemurrageErrors {
     // Type declarations
 
     /**
@@ -142,6 +142,10 @@ contract Demurrage is ICirclesERC1155Errors {
      */
     int128[15] internal R;
 
+    // Events
+
+    event DiscountCost(address indexed account, uint256 indexed id, uint256 discountCost);
+
     // Constructor
 
     constructor() {

src/circles/DiscountedBalances.sol

@@ -35,10 +35,30 @@ contract DiscountedBalances is Demurrage {
      * @param _account Address of the account to calculate the balance of
      * @param _id Circles identifier for which to calculate the balance
      * @param _day Day since inflation_day_zero to calculate the balance for
+     * @return balanceOnDay_ The discounted balance of the account for the Circles identifier on specified day
+     * @return discountCost_ The discount cost of the demurrage of the balance since the last update
      */
-    function balanceOfOnDay(address _account, uint256 _id, uint64 _day) public view returns (uint256) {
+    function balanceOfOnDay(address _account, uint256 _id, uint64 _day)
+        public
+        view
+        returns (uint256 balanceOnDay_, uint256 discountCost_)
+    {
         DiscountedBalance memory discountedBalance = discountedBalances[_id][_account];
-        return _calculateDiscountedBalance(discountedBalance.balance, _day - discountedBalance.lastUpdatedDay);
+        if (_day < discountedBalance.lastUpdatedDay) {
+            // DiscountedBalances: day is before last updated day
+            revert CirclesDemurrageDayBeforeLastUpdatedDay(_account, _id, _day, discountedBalance.lastUpdatedDay, 0);
+        }
+        uint256 dayDifference;
+        unchecked {
+            dayDifference = _day - discountedBalance.lastUpdatedDay;
+        }
+        // Calculate the discounted balance
+        balanceOnDay_ = _calculateDiscountedBalance(discountedBalance.balance, dayDifference);
+        // Calculate the discount cost; this can be unchecked as cost is strict positive
+        unchecked {
+            discountCost_ = discountedBalance.balance - balanceOnDay_;
+        }
+        return (balanceOnDay_, discountCost_);
     }
 
     /**
@@ -63,7 +83,7 @@ contract DiscountedBalances is Demurrage {
     function _updateBalance(address _account, uint256 _id, uint256 _balance, uint64 _day) internal {
         if (_balance > MAX_VALUE) {
             // DiscountedBalances: balance exceeds maximum value
-            revert CirclesERC1155AmountExceedsMaxUint190(_account, _id, _balance, 0);
+            revert CirclesDemurrageAmountExceedsMaxUint190(_account, _id, _balance, 0);
         }
         DiscountedBalance storage discountedBalance = discountedBalances[_id][_account];
         discountedBalance.balance = uint192(_balance);
@@ -79,14 +99,28 @@ contract DiscountedBalances is Demurrage {
      */
     function _discountAndAddToBalance(address _account, uint256 _id, uint256 _value, uint64 _day) internal {
         DiscountedBalance storage discountedBalance = discountedBalances[_id][_account];
-        uint256 discountedBalanceValue =
-            _calculateDiscountedBalance(discountedBalance.balance, _day - discountedBalance.lastUpdatedDay);
-        uint256 newBalance = discountedBalanceValue + _value;
-        if (newBalance > MAX_VALUE) {
+        if (_day < discountedBalance.lastUpdatedDay) {
+            // DiscountedBalances: day is before last updated day
+            revert CirclesDemurrageDayBeforeLastUpdatedDay(_account, _id, _day, discountedBalance.lastUpdatedDay, 1);
+        }
+        uint256 dayDifference;
+        unchecked {
+            dayDifference = _day - discountedBalance.lastUpdatedDay;
+        }
+        uint256 discountedBalanceOnDay = _calculateDiscountedBalance(discountedBalance.balance, dayDifference);
+        // Calculate the discount cost; this can be unchecked as cost is strict positive
+        unchecked {
+            uint256 discountCost = discountedBalance.balance - discountedBalanceOnDay;
+            if (discountCost > 0) {
+                emit DiscountCost(_account, _id, discountCost);
+            }
+        }
+        uint256 updatedBalance = discountedBalanceOnDay + _value;
+        if (updatedBalance > MAX_VALUE) {
             // DiscountedBalances: balance exceeds maximum value
-            revert CirclesERC1155AmountExceedsMaxUint190(_account, _id, newBalance, 1);
+            revert CirclesDemurrageAmountExceedsMaxUint190(_account, _id, updatedBalance, 1);
         }
-        discountedBalance.balance = uint192(newBalance);
+        discountedBalance.balance = uint192(updatedBalance);
         discountedBalance.lastUpdatedDay = _day;
     }
 }

src/circles/ERC1155.sol

@@ -32,10 +32,6 @@ abstract contract ERC1155 is DiscountedBalances, Context, ERC165, IERC1155, IERC
     // Used as the URI for all token types by relying on ID substitution, e.g. https://token-cdn-domain/{id}.json
     string private _uri;
 
-    // Events
-
-    event ConvertInflation(uint256 inflationValue, uint256 demurrageValue, uint64 day);
-
     // Constructor
 
     /**
@@ -73,7 +69,8 @@ abstract contract ERC1155 is DiscountedBalances, Context, ERC165, IERC1155, IERC
      * @dev See {IERC1155-balanceOf}.
      */
     function balanceOf(address _account, uint256 _id) public view returns (uint256) {
-        return balanceOfOnDay(_account, _id, day(block.timestamp));
+        (uint256 balance,) = balanceOfOnDay(_account, _id, day(block.timestamp));
+        return balance;
     }
 
     /**
@@ -93,7 +90,7 @@ abstract contract ERC1155 is DiscountedBalances, Context, ERC165, IERC1155, IERC
         uint256[] memory batchBalances = new uint256[](_accounts.length);
 
         for (uint256 i = 0; i < _accounts.length; ++i) {
-            batchBalances[i] = balanceOfOnDay(_accounts.unsafeMemoryAccess(i), _ids.unsafeMemoryAccess(i), today);
+            (batchBalances[i],) = balanceOfOnDay(_accounts.unsafeMemoryAccess(i), _ids.unsafeMemoryAccess(i), today);
         }
 
         return batchBalances;
@@ -171,10 +168,13 @@ abstract contract ERC1155 is DiscountedBalances, Context, ERC165, IERC1155, IERC
             uint256 value = values.unsafeMemoryAccess(i);
 
             if (from != address(0)) {
-                uint256 fromBalance = balanceOfOnDay(from, id, today);
+                (uint256 fromBalance, uint256 discountCost) = balanceOfOnDay(from, id, today);
                 if (fromBalance < value) {
                     revert ERC1155InsufficientBalance(from, fromBalance, value, id);
                 }
+                if (discountCost > 0) {
+                    emit DiscountCost(from, id, discountCost);
+                }
                 unchecked {
                     // Overflow not possible: value <= fromBalance
                     _updateBalance(from, id, fromBalance - value, today);

src/errors/Errors.sol

@@ -35,10 +35,16 @@ interface IHubErrors {
     error CirclesHubNettedFlowMismatch(uint16 vertexPosition, int256 matrixNettedFlow, int256 streamNettedFlow);
 }
 
-interface ICirclesERC1155Errors {
+interface ICirclesDemurrageErrors {
     error CirclesERC1155MintBlocked(address human, address mintV1Status);
 
-    error CirclesERC1155AmountExceedsMaxUint190(address account, uint256 circlesId, uint256 amount, uint8 code);
+    error CirclesDemurrageAmountExceedsMaxUint190(address account, uint256 circlesId, uint256 amount, uint8 code);
+
+    error CirclesDemurrageDayBeforeLastUpdatedDay(
+        address account, uint256 circlesId, uint64 day, uint64 lastUpdatedDay, uint8 code
+    );
+
+    error CirclesERC1155CannotReceiveBatch(uint8 code);
 }
 
 interface ICirclesErrors {
@@ -54,8 +60,6 @@ interface ICirclesErrors {
 
     error CirclesInvalidParameter(uint256 parameter, uint8 code);
 
-    error CirclesERC1155CannotReceiveBatch(uint8 code);
-
     error CirclesAmountOverflow(uint256 amount, uint8 code);
 
     error CirclesArraysLengthMismatch(uint256 lengthArray1, uint256 lengthArray2, uint8 code);

src/lift/DemurrageCircles.sol

@@ -17,13 +17,11 @@ contract DemurrageCircles is MasterCopyNonUpgradable, ERC20DiscountedBalances, E
 
     INameRegistry public nameRegistry;
 
-    address public avatar;
-
     // Events
 
-    event Deposit(address indexed account, uint256 amount, uint256 inflationaryAmount);
+    event DepositDemurraged(address indexed account, uint256 amount, uint256 inflationaryAmount);
 
-    event Withdraw(address indexed account, uint256 amount, uint256 inflationaryAmount);
+    event WithdrawDemurraged(address indexed account, uint256 amount, uint256 inflationaryAmount);
 
     // Modifiers
 
@@ -74,7 +72,7 @@ contract DemurrageCircles is MasterCopyNonUpgradable, ERC20DiscountedBalances, E
 
         uint256 inflationaryAmount = _calculateInflationaryBalance(_amount, day(block.timestamp));
 
-        emit Withdraw(msg.sender, _amount, inflationaryAmount);
+        emit WithdrawDemurraged(msg.sender, _amount, inflationaryAmount);
     }
 
     function totalSupply() external view override returns (uint256) {
@@ -107,7 +105,7 @@ contract DemurrageCircles is MasterCopyNonUpgradable, ERC20DiscountedBalances, E
 
         uint256 inflationaryAmount = _calculateInflationaryBalance(_amount, day(block.timestamp));
 
-        emit Deposit(_from, _amount, inflationaryAmount);
+        emit DepositDemurraged(_from, _amount, inflationaryAmount);
 
         return this.onERC1155Received.selector;
     }

src/lift/ERC20DiscountedBalances.sol

@@ -11,6 +11,8 @@ contract ERC20DiscountedBalances is ERC20Permit, Demurrage, IERC20 {
 
     // State variables
 
+    address public avatar;
+
     /**
      * @dev The mapping of addresses to the discounted balances.
      */
@@ -55,7 +57,8 @@ contract ERC20DiscountedBalances is ERC20Permit, Demurrage, IERC20 {
     }
 
     function balanceOf(address _account) external view returns (uint256) {
-        return balanceOfOnDay(_account, day(block.timestamp));
+        (uint256 balance,) = balanceOfOnDay(_account, day(block.timestamp));
+        return balance;
     }
 
     function allowance(address _owner, address _spender) external view returns (uint256) {
@@ -68,9 +71,28 @@ contract ERC20DiscountedBalances is ERC20Permit, Demurrage, IERC20 {
 
     // Public functions
 
-    function balanceOfOnDay(address _account, uint64 _day) public view returns (uint256) {
+    function balanceOfOnDay(address _account, uint64 _day)
+        public
+        view
+        returns (uint256 balanceOnDay_, uint256 discountCost_)
+    {
         DiscountedBalance memory discountedBalance = discountedBalances[_account];
-        return _calculateDiscountedBalance(discountedBalance.balance, _day - discountedBalance.lastUpdatedDay);
+        if (_day < discountedBalance.lastUpdatedDay) {
+            // ERC20 DiscountedBalances: day is before last updated day
+            revert CirclesDemurrageDayBeforeLastUpdatedDay(
+                _account, toTokenId(avatar), _day, discountedBalance.lastUpdatedDay, 0
+            );
+        }
+        uint256 dayDifference;
+        unchecked {
+            dayDifference = _day - discountedBalance.lastUpdatedDay;
+        }
+        balanceOnDay_ = _calculateDiscountedBalance(discountedBalance.balance, _day - discountedBalance.lastUpdatedDay);
+        // Calculate the discount cost; this can be unchecked as cost is strict positive
+        unchecked {
+            discountCost_ = discountedBalance.balance - balanceOnDay_;
+        }
+        return (balanceOnDay_, discountCost_);
     }
 
     // Internal functions
@@ -83,7 +105,7 @@ contract ERC20DiscountedBalances is ERC20Permit, Demurrage, IERC20 {
     function _updateBalance(address _account, uint256 _balance, uint64 _day) internal {
         if (_balance > MAX_VALUE) {
             // Balance exceeds maximum value.
-            revert CirclesERC1155AmountExceedsMaxUint190(_account, 0, _balance, 0);
+            revert CirclesDemurrageAmountExceedsMaxUint190(_account, toTokenId(avatar), _balance, 0);
         }
         DiscountedBalance storage discountedBalance = discountedBalances[_account];
         discountedBalance.balance = uint192(_balance);
@@ -92,23 +114,41 @@ contract ERC20DiscountedBalances is ERC20Permit, Demurrage, IERC20 {
 
     function _discountAndAddToBalance(address _account, uint256 _value, uint64 _day) internal {
         DiscountedBalance storage discountedBalance = discountedBalances[_account];
-        uint256 newBalance = _calculateDiscountedBalanceAndCache(
-            discountedBalance.balance, _day - discountedBalance.lastUpdatedDay
-        ) + _value;
-        if (newBalance > MAX_VALUE) {
+        if (_day < discountedBalance.lastUpdatedDay) {
+            // ERC20 DiscountedBalances: day is before last updated day
+            revert CirclesDemurrageDayBeforeLastUpdatedDay(
+                _account, toTokenId(avatar), _day, discountedBalance.lastUpdatedDay, 1
+            );
+        }
+        uint256 dayDifference;
+        unchecked {
+            dayDifference = _day - discountedBalance.lastUpdatedDay;
+        }
+        uint256 discountedBalanceOnDay = _calculateDiscountedBalanceAndCache(discountedBalance.balance, dayDifference);
+        unchecked {
+            uint256 discountCost = discountedBalance.balance - discountedBalanceOnDay;
+            if (discountCost > 0) {
+                emit DiscountCost(_account, toTokenId(avatar), discountCost);
+            }
+        }
+        uint256 updatedBalance = discountedBalanceOnDay + _value;
+        if (updatedBalance > MAX_VALUE) {
             // Balance exceeds maximum value.
-            revert CirclesERC1155AmountExceedsMaxUint190(_account, 0, newBalance, 1);
+            revert CirclesDemurrageAmountExceedsMaxUint190(_account, toTokenId(avatar), updatedBalance, 1);
         }
-        discountedBalance.balance = uint192(newBalance);
+        discountedBalance.balance = uint192(updatedBalance);
         discountedBalance.lastUpdatedDay = _day;
     }
 
     function _transfer(address _from, address _to, uint256 _amount) internal {
         uint64 day = day(block.timestamp);
-        uint256 fromBalance = balanceOfOnDay(_from, day);
+        (uint256 fromBalance, uint256 discountCost) = balanceOfOnDay(_from, day);
         if (fromBalance < _amount) {
             revert ERC20InsufficientBalance(_from, fromBalance, _amount);
         }
+        if (discountCost > 0) {
+            emit DiscountCost(_from, toTokenId(avatar), discountCost);
+        }
         unchecked {
             _updateBalance(_from, fromBalance - _amount, day);
         }
@@ -124,10 +164,13 @@ contract ERC20DiscountedBalances is ERC20Permit, Demurrage, IERC20 {
 
     function _burn(address _owner, uint256 _amount) internal {
         uint64 day = day(block.timestamp);
-        uint256 ownerBalance = balanceOfOnDay(_owner, day);
+        (uint256 ownerBalance, uint256 discountCost) = balanceOfOnDay(_owner, day);
         if (ownerBalance < _amount) {
             revert ERC20InsufficientBalance(_owner, ownerBalance, _amount);
         }
+        if (discountCost > 0) {
+            emit DiscountCost(_owner, toTokenId(avatar), discountCost);
+        }
         unchecked {
             _updateBalance(_owner, ownerBalance - _amount, day);
         }

src/lift/InflationaryCircles.sol

@@ -21,9 +21,9 @@ contract InflationaryCircles is MasterCopyNonUpgradable, ERC20InflationaryBalanc
 
     // Events
 
-    event Deposit(address indexed account, uint256 amount, uint256 demurragedAmount);
+    event DepositInflationary(address indexed account, uint256 amount, uint256 demurragedAmount);
 
-    event Withdraw(address indexed account, uint256 amount, uint256 demurragedAmount);
+    event WithdrawInflationary(address indexed account, uint256 amount, uint256 demurragedAmount);
 
     // Modifiers
 
@@ -80,7 +80,7 @@ contract InflationaryCircles is MasterCopyNonUpgradable, ERC20InflationaryBalanc
 
         hub.safeTransferFrom(address(this), msg.sender, toTokenId(avatar), demurragedAmount, "");
 
-        emit Withdraw(msg.sender, _amount, demurragedAmount);
+        emit WithdrawInflationary(msg.sender, _amount, demurragedAmount);
     }
 
     function name() external view returns (string memory) {
@@ -108,7 +108,7 @@ contract InflationaryCircles is MasterCopyNonUpgradable, ERC20InflationaryBalanc
         // calculate inflationary amount to mint to sender
         uint256 inflationaryAmount = _mintFromDemurragedAmount(_from, _amount);
 
-        emit Deposit(_from, inflationaryAmount, _amount);
+        emit DepositInflationary(_from, inflationaryAmount, _amount);
 
         return this.onERC1155Received.selector;
     }