Improve farming code readability [SC-929]

README.md

@@ -113,22 +113,28 @@ contract AMMPoolToken is ERC20Plugins {
 
 Storage access:
 
-- [1 storage slot](https://github.com/1inch/farming/blob/master/contracts/accounting/FarmAccounting.sol#L14-L16) for farming params, updated only on farming restarting:
+- [1 storage slot](https://github.com/1inch/farming/blob/master/contracts/accounting/Farming.sol#L9-L11) for farming params, updated when farming is restarted or stopped:
 
     ```solidity
     uint40 public finished;
     uint32 public duration;
     uint184 public reward;
     ```
+
+- [1 storage slot](https://github.com/1inch/farming/blob/master/contracts/accounting/Farming.sol#L9-L12) for total amount of rewards that haven't been claimed yet, updated when farming is restarted, stopped or when the user claims rewards:
+
+    ```solidity
+    uint256 balance;
+    ```
 
-- [1 storage slot](https://github.com/1inch/farming/blob/master/contracts/accounting/UserAccounting.sol#L7-L8) for farming state, updated only on changing number of farming tokens:
+- [1 storage slot](https://github.com/1inch/farming/blob/master/contracts/accounting/Rewards.sol#L9-L10) for farming state, updated only on changing number of farming tokens:
 
     ```solidity
     uint40 public checkpoint;
     uint216 public farmedPerTokenStored;
     ```
 
-- [1 storage slot](https://github.com/1inch/farming/blob/master/contracts/accounting/UserAccounting.sol#L9) per each farmer, updated on deposits/withdrawals (kudos to [@snjax](https://github.com/snjax)):
+- [1 storage slot](https://github.com/1inch/farming/blob/master/contracts/accounting/Rewards.sol#L11) per each farmer, updated on deposits/withdrawals (kudos to [@snjax](https://github.com/snjax)):
 
     ```solidity
     mapping(address => int256) public corrections;

contracts/Distributor.sol

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import { Ownable } from "@openzeppelin/contracts/access/Ownable.sol";
+
+import { IDistributor } from "./interfaces/IDistributor.sol";
+
+abstract contract Distributor is IDistributor, Ownable {
+    address internal _distributor;
+
+    event DistributorChanged(address oldDistributor, address newDistributor);
+
+    error NotDistributor();
+    error SameDistributor();
+    error ZeroDistributorAddress();
+
+    modifier onlyDistributor {
+        if (msg.sender != _distributor) revert NotDistributor();
+        _;
+    }
+
+    function setDistributor(address distributor_) public virtual onlyOwner {
+        if (distributor_ == address(0)) revert ZeroDistributorAddress();
+        address oldDistributor = _distributor;
+        if (distributor_ == oldDistributor) revert SameDistributor();
+        emit DistributorChanged(oldDistributor, distributor_);
+        _distributor = distributor_;
+    }
+
+    function distributor() public view virtual returns (address) {
+        return _distributor;
+    }
+}

contracts/FarmingLib.sol

@@ -2,20 +2,20 @@
 
 pragma solidity ^0.8.0;
 
-import { FarmAccounting } from "./accounting/FarmAccounting.sol";
-import { UserAccounting } from "./accounting/UserAccounting.sol";
+import { Farming } from "./accounting/Farming.sol";
+import { Rewards } from "./accounting/Rewards.sol";
 
 /// @title FarmingLib
-/// @dev A library for farming logic, using FarmAccounting and UserAccounting.
+/// @dev A library for farming logic, using Farming and Rewards.
 library FarmingLib {
-    using FarmAccounting for FarmAccounting.Info;
-    using UserAccounting for UserAccounting.Info;
+    using Farming for Farming.Info;
+    using Rewards for Rewards.Info;
     using FarmingLib for FarmingLib.Info;
 
-    /// @dev Struct containing farm and user detailed info for farming operations. See {FarmAccounting.Info} and {UserAccounting.Info} for.
+    /// @dev Struct containing farming and rewards detailed info for farming operations. See {Farming.Info} and {Rewards.Info}.
     struct Data {
-        FarmAccounting.Info farmInfo;
-        UserAccounting.Info userInfo;
+        Farming.Info farmingInfo;
+        Rewards.Info rewardsInfo;
     }
 
     /// @dev Struct containing the total supply function and a data slot for EVM storage.
@@ -25,7 +25,7 @@ library FarmingLib {
     }
 
     /**
-     * @notice Creates a new Info struct.
+     * @notice Creates a new FarmingLib.Info struct.
      * @param getTotalSupply The function to get the total supply.
      * @param data The data struct for storage.
      * @return info The created Info struct.
@@ -40,8 +40,8 @@ library FarmingLib {
     }
 
     /**
-     * @notice Retrieves the Data struct from an Info struct.
-     * @param self The Info struct.
+     * @notice Retrieves the FarmingLib.Data struct from an FarmingLib.Info struct.
+     * @param self The Info struct to retrieve data from storage.
      * @return data The retrieved Data struct.
      */
     function getData(Info memory self) internal pure returns(Data storage data) {
@@ -52,84 +52,73 @@ library FarmingLib {
     }
 
     /**
-     * @notice Begins farming for a specified period.
-     * @param self The Info struct.
-     * @param amount The amount to farm.
-     * @param period The farming period.
-     * @return reward The farming reward.
+     * @notice Updates farming info with new amount and specified period.
+     * @param self The FarmingLib.Info struct to retrieve data from storage.
+     * @param amount A new amount to farm.
+     * @param period A new farming period.
+     * @return reward Updated farming reward.
      */
-    function startFarming(Info memory self, uint256 amount, uint256 period) internal returns(uint256 reward) {
+    function updateFarmData(Info memory self, uint256 amount, uint256 period) internal returns(uint256 reward) {
         Data storage data = self.getData();
-        data.userInfo.updateFarmedPerToken(_farmedPerToken(self));
-        reward = data.farmInfo.startFarming(amount, period);
+        data.rewardsInfo.updateFarmedPerToken(_farmedPerToken(self));
+        reward = data.farmingInfo.update(amount, period);
     }
 
     /**
      * @notice Stops farming immediately.
      * @param self The FarmingLib.Info struct to retrieve data from storage.
      * @return leftover Amount of reward tokens remaining after farming.
      */
-    function stopFarming(Info memory self) internal returns(uint256 leftover) {
+    function cancelFarming(Info memory self) internal returns(uint256 leftover) {
         Data storage data = self.getData();
-        data.userInfo.updateFarmedPerToken(_farmedPerToken(self));
-        leftover = data.farmInfo.stopFarming();
-    }
-
-    /**
-     * @notice Gets the farmed amount for an account.
-     * @param self The Info struct.
-     * @param account The account to check.
-     * @param balance The account balance.
-     * @return result The farmed amount.
-     */
-    function farmed(Info memory self, address account, uint256 balance) internal view returns(uint256) {
-        return self.getData().userInfo.farmed(account, balance, _farmedPerToken(self));
+        data.rewardsInfo.updateFarmedPerToken(_farmedPerToken(self));
+        leftover = data.farmingInfo.cancel();
     }
 
     /**
-     * @notice Claims the farmed amount for an account.
-     * @param self The Info struct.
-     * @param account The account to claim for.
-     * @param balance The account balance.
-     * @return amount The claimed amount.
+     * @notice Claims the farmed reward tokens for an account.
+     * @param self The FarmingLib.Info struct to retrieve data from storage.
+     * @param account The address of the account to claim for.
+     * @param balance The account balance of farmable tokens.
+     * @return amount The claimed amount of reward tokens.
      */
     function claim(Info memory self, address account, uint256 balance) internal returns(uint256 amount) {
         Data storage data = self.getData();
         uint256 fpt = _farmedPerToken(self);
-        amount = data.userInfo.farmed(account, balance, fpt);
+        amount = data.rewardsInfo.farmed(account, balance, fpt);
         if (amount > 0) {
-            data.userInfo.eraseFarmed(account, balance, fpt);
-            data.farmInfo.claim(amount);
+            data.rewardsInfo.eraseFarmed(account, balance, fpt);
+            data.farmingInfo.claim(amount);
         }
     }
 
     /**
-     * @notice Updates the balances of two accounts.
-     * @param self The Info struct.
-     * @param from The account to transfer from.
-     * @param to The account to transfer to.
+     * @notice Updates the farmable token balances of two accounts.
+     * @param self The FarmingLib.Info struct to retrieve data from storage.
+     * @param from The address of the account to transfer from.
+     * @param to The address of the account to transfer to.
      * @param amount The amount to transfer.
      */
     function updateBalances(Info memory self, address from, address to, uint256 amount) internal {
-        self.getData().userInfo.updateBalances(from, to, amount, _farmedPerToken(self));
+        self.getData().rewardsInfo.updateBalances(from, to, amount, _farmedPerToken(self));
     }
 
-    function _farmedPerToken(Info memory self) private view returns (uint256) {
-        return self.getData().userInfo.farmedPerToken(_infoToContext(self), _lazyGetSupply, _lazyGetFarmed);
-    }
-
-    // UserAccounting bindings
-
-    function _lazyGetSupply(bytes32 context) private view returns(uint256) {
-        Info memory self = _contextToInfo(context);
-        return self.getTotalSupply();
+    /**
+     * @notice Gets the amount of farmed reward tokens for an account.
+     * @param self The FarmingLib.Info struct to retrieve data from storage.
+     * @param account The address of the account to check.
+     * @param balance The farmable token balance of the account.
+     * @return result The number of tokens farmed.
+     */
+    function farmed(Info memory self, address account, uint256 balance) internal view returns(uint256) {
+        return self.getData().rewardsInfo.farmed(account, balance, _farmedPerToken(self));
     }
 
-    function _lazyGetFarmed(bytes32 context, uint256 checkpoint) private view returns(uint256) {
-        Info memory self = _contextToInfo(context);
-        return self.getData().farmInfo.farmedSinceCheckpointScaled(checkpoint);
+    function _farmedPerToken(Info memory self) private view returns (uint256) {
+        return self.getData().rewardsInfo.farmedPerToken(_infoToContext(self), _lazyGetSupply, _lazyGetFarmed);
     }
 
+    // --- Rewards bindings section start ---
     function _contextToInfo(bytes32 context) private pure returns(Info memory self) {
         assembly ("memory-safe") {  // solhint-disable-line no-inline-assembly
             self := context
@@ -141,4 +130,15 @@ library FarmingLib {
             context := self
         }
     }
+
+    function _lazyGetSupply(bytes32 context) private view returns(uint256) {
+        Info memory self = _contextToInfo(context);
+        return self.getTotalSupply();
+    }
+
+    function _lazyGetFarmed(bytes32 context, uint256 checkpoint) private view returns(uint256) {
+        Info memory self = _contextToInfo(context);
+        return self.getData().farmingInfo.farmedSinceCheckpointScaled(checkpoint);
+    }
+    // --- Rewards bindings section end ---
 }