Merge pull request #534 from ava-labs/staking-rewards

Staking rewards

contracts/mocks/ExampleERC20.sol

@@ -13,12 +13,13 @@ import {
     ERC20Burnable,
     ERC20
 } from "@openzeppelin/[email protected]/token/ERC20/extensions/ERC20Burnable.sol";
+import {IERC20Mintable} from "../staking/interfaces/IERC20Mintable.sol";
 
-contract ExampleERC20 is ERC20Burnable {
+contract ExampleERC20 is ERC20Burnable, IERC20Mintable {
     string private constant _TOKEN_NAME = "Mock Token";
     string private constant _TOKEN_SYMBOL = "EXMP";
 
-    uint256 private constant _MAX_MINT = 1e16;
+    uint256 private constant _MAX_MINT = 1e19;
 
     constructor() ERC20(_TOKEN_NAME, _TOKEN_SYMBOL) {
         _mint(msg.sender, 1e28);
@@ -30,4 +31,11 @@ contract ExampleERC20 is ERC20Burnable {
 
         _mint(msg.sender, amount);
     }
+
+    function mint(address account, uint256 amount) external {
+        // Can only mint 10 at a time.
+        require(amount <= _MAX_MINT, "ExampleERC20: max mint exceeded");
+
+        _mint(account, amount);
+    }
 }

contracts/staking/ERC20TokenStakingManager.sol

@@ -8,7 +8,7 @@ pragma solidity 0.8.25;
 import {IERC20TokenStakingManager} from "./interfaces/IERC20TokenStakingManager.sol";
 import {Initializable} from
     "@openzeppelin/[email protected]/proxy/utils/Initializable.sol";
-import {IERC20} from "@openzeppelin/[email protected]/token/ERC20/IERC20.sol";
+import {IERC20Mintable} from "./interfaces/IERC20Mintable.sol";
 import {SafeERC20TransferFrom} from "@utilities/SafeERC20TransferFrom.sol";
 import {SafeERC20} from "@openzeppelin/[email protected]/token/ERC20/utils/SafeERC20.sol";
 import {ICMInitializable} from "../utilities/ICMInitializable.sol";
@@ -21,13 +21,13 @@ contract ERC20TokenStakingManager is
     PoSValidatorManager,
     IERC20TokenStakingManager
 {
-    using SafeERC20 for IERC20;
-    using SafeERC20TransferFrom for IERC20;
+    using SafeERC20 for IERC20Mintable;
+    using SafeERC20TransferFrom for IERC20Mintable;
 
     // solhint-disable private-vars-leading-underscore
     /// @custom:storage-location erc7201:avalanche-icm.storage.ERC20TokenStakingManager
     struct ERC20TokenStakingManagerStorage {
-        IERC20 _token;
+        IERC20Mintable _token;
         uint8 _tokenDecimals;
     }
     // solhint-enable private-vars-leading-underscore
@@ -63,22 +63,25 @@ contract ERC20TokenStakingManager is
      */
     function initialize(
         PoSValidatorManagerSettings calldata settings,
-        IERC20 token
+        IERC20Mintable token
     ) external reinitializer(2) {
         __ERC20TokenStakingManager_init(settings, token);
     }
 
     // solhint-disable func-name-mixedcase
     function __ERC20TokenStakingManager_init(
         PoSValidatorManagerSettings calldata settings,
-        IERC20 token
+        IERC20Mintable token
     ) internal onlyInitializing {
         __POS_Validator_Manager_init(settings);
         __ERC20TokenStakingManager_init_unchained(token);
     }
 
     // solhint-disable func-name-mixedcase
-    function __ERC20TokenStakingManager_init_unchained(IERC20 token) internal onlyInitializing {
+    function __ERC20TokenStakingManager_init_unchained(IERC20Mintable token)
+        internal
+        onlyInitializing
+    {
         ERC20TokenStakingManagerStorage storage $ = _getERC20StakingManagerStorage();
         require(address(token) != address(0), "ERC20TokenStakingManager: zero token address");
         $._token = token;
@@ -116,7 +119,12 @@ contract ERC20TokenStakingManager is
         return _getERC20StakingManagerStorage()._token.safeTransferFrom(value);
     }
 
-    function _unlock(uint256 value, address to) internal virtual override {
+    function _unlock(address to, uint256 value) internal virtual override {
         _getERC20StakingManagerStorage()._token.safeTransfer(to, value);
     }
+
+    function _reward(address account, uint256 amount) internal virtual override {
+        ERC20TokenStakingManagerStorage storage $ = _getERC20StakingManagerStorage();
+        $._token.mint(account, amount);
+    }
 }

contracts/staking/ExampleRewardCalculator.sol

@@ -10,6 +10,8 @@ import {IRewardCalculator} from "./interfaces/IRewardCalculator.sol";
 contract ExampleRewardCalculator is IRewardCalculator {
     uint256 public constant SECONDS_IN_YEAR = 31536000;
 
+    uint8 public constant UPTIME_REWARDS_THRESHOLD_PERCENTAGE = 80;
+
     uint64 public immutable rewardBasisPoints;
 
     constructor(uint64 rewardBasisPoints_) {
@@ -21,11 +23,23 @@ contract ExampleRewardCalculator is IRewardCalculator {
      */
     function calculateReward(
         uint256 stakeAmount,
-        uint64 startTime,
-        uint64 endTime,
+        uint64 validatorStartTime,
+        uint64 stakingStartTime,
+        uint64 stakingEndTime,
+        uint64 uptimeSeconds,
         uint256, // initialSupply
         uint256 // endSupply
     ) external view returns (uint256) {
-        return (stakeAmount * rewardBasisPoints * (endTime - startTime)) / SECONDS_IN_YEAR / 1000;
+        // Equivalent to uptimeSeconds/(validator.endedAt - validator.startedAt) < UPTIME_REWARDS_THRESHOLD_PERCENTAGE/100
+        // Rearranged to prevent integer division truncation.
+        if (
+            uptimeSeconds * 100
+                < (stakingEndTime - validatorStartTime) * UPTIME_REWARDS_THRESHOLD_PERCENTAGE
+        ) {
+            return 0;
+        }
+
+        return (stakeAmount * rewardBasisPoints * (stakingEndTime - stakingStartTime))
+            / SECONDS_IN_YEAR / 10000;
     }
 }

contracts/staking/NativeTokenStakingManager.sol

@@ -6,6 +6,8 @@
 pragma solidity 0.8.25;
 
 import {INativeTokenStakingManager} from "./interfaces/INativeTokenStakingManager.sol";
+import {INativeMinter} from
+    "@avalabs/[email protected]/contracts/interfaces/INativeMinter.sol";
 import {Address} from "@openzeppelin/[email protected]/utils/Address.sol";
 import {Initializable} from
     "@openzeppelin/[email protected]/proxy/utils/Initializable.sol";
@@ -21,6 +23,9 @@ contract NativeTokenStakingManager is
 {
     using Address for address payable;
 
+    INativeMinter public constant NATIVE_MINTER =
+        INativeMinter(0x0200000000000000000000000000000000000001);
+
     constructor(ICMInitializable init) {
         if (init == ICMInitializable.Disallowed) {
             _disableInitializers();
@@ -80,7 +85,11 @@ contract NativeTokenStakingManager is
         return value;
     }
 
-    function _unlock(uint256 value, address to) internal virtual override {
+    function _unlock(address to, uint256 value) internal virtual override {
         payable(to).sendValue(value);
     }
+
+    function _reward(address account, uint256 amount) internal virtual override {
+        NATIVE_MINTER.mintNativeCoin(account, amount);
+    }
 }