add DopexStrategyForSA (#221)

contracts/strategies/arbitrum/dopex/DopexStrategyForSA.sol

@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity 0.8.13;
+
+import "../../BaseStrategy.sol";
+import "./interfaces/IMultiRewards.sol";
+
+contract DopexStrategyForSA is BaseStrategy {
+    IMultiRewards immutable rewarder;
+
+    constructor(
+        address _stakingContract,
+        BaseStrategySettings memory _baseStrategySettings,
+        StrategySettings memory _strategySettings
+    ) BaseStrategy(_baseStrategySettings, _strategySettings) {
+        rewarder = IMultiRewards(_stakingContract);
+    }
+
+    function _depositToStakingContract(uint256 _amount, uint256) internal override {
+        depositToken.approve(address(rewarder), _amount);
+        rewarder.stake(_amount);
+    }
+
+    function _withdrawFromStakingContract(uint256 _amount) internal override returns (uint256 _withdrawAmount) {
+        rewarder.withdraw(_amount);
+        return _amount;
+    }
+
+    function _pendingRewards() internal view override returns (Reward[] memory) {
+        Reward[] memory pendingRewards = new Reward[](supportedRewards.length);
+        for (uint256 i; i < pendingRewards.length; i++) {
+            address reward = supportedRewards[i];
+            uint256 pending = rewarder.earned(address(this), reward);
+            pendingRewards[i] = Reward({reward: reward, amount: pending});
+        }
+        return pendingRewards;
+    }
+
+    function _getRewards() internal override {
+        rewarder.getReward();
+    }
+
+    function totalDeposits() public view override returns (uint256) {
+        return rewarder.balanceOf(address(this));
+    }
+
+    function _emergencyWithdraw() internal override {
+        rewarder.exit();
+        depositToken.approve(address(rewarder), 0);
+    }
+}

contracts/strategies/arbitrum/dopex/interfaces/IMultiRewards.sol

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.13;
+
+interface IMultiRewards {
+    function balanceOf(address account) external view returns (uint256);
+    function rewardTokens(uint256 index) external view returns (address);
+    function earned(address account, address reward) external view returns (uint256);
+    function getReward() external;
+    function stake(uint256 amount) external;
+    function withdraw(uint256 amount) external;
+    function exit() external;
+}