Tasks: Implement balancer v2 swapper task

packages/tasks/contracts/interfaces/swap/IBalancerV2Swapper.sol

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+// SPDX-License-Identifier: GPL-3.0-or-later
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+pragma solidity >=0.8.0;
+
+import './IBaseSwapTask.sol';
+
+/**
+ * @dev Balancer v2 swapper task interface
+ */
+interface IBalancerV2Swapper is IBaseSwapTask {
+    /**
+     * @dev Execution function
+     */
+    function call(address tokenIn, uint256 amountIn, uint256 slippage) external;
+}

packages/tasks/contracts/swap/BalancerV2Swapper.sol

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+// SPDX-License-Identifier: GPL-3.0-or-later
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+pragma solidity ^0.8.0;
+
+import '@mimic-fi/v3-helpers/contracts/math/FixedPoint.sol';
+import '@mimic-fi/v3-helpers/contracts/utils/BytesHelpers.sol';
+import '@mimic-fi/v3-connectors/contracts/interfaces/balancer/IBalancerV2SwapConnector.sol';
+
+import './BaseSwapTask.sol';
+import '../interfaces/swap/IBalancerV2Swapper.sol';
+import '../interfaces/liquidity/balancer/IBalancerPool.sol';
+
+/**
+ * @title Balancer v2 swapper task
+ * @dev Task that extends the base swap task to use Balancer
+ */
+contract BalancerV2Swapper is IBalancerV2Swapper, BaseSwapTask {
+    using FixedPoint for uint256;
+    using BytesHelpers for bytes;
+
+    // Execution type for relayers
+    bytes32 public constant override EXECUTION_TYPE = keccak256('BALANCER_V2_SWAPPER');
+
+    /**
+     * @dev Balancer v2 swap config. Only used in the initalizer
+     */
+    struct BalancerV2SwapConfig {
+        BaseSwapConfig baseSwapConfig;
+    }
+
+    /**
+     * @dev Initializes the Balancer v2 swapper
+     * @param config Balancer v2 swap config
+     */
+    function initialize(BalancerV2SwapConfig memory config) external initializer {
+        __BalancerV2Swapper_init(config);
+    }
+
+    /**
+     * @dev Initializes the Balancer v2 swapper. It does call upper contracts.
+     * @param config Balancer v2 swap config
+     */
+    function __BalancerV2Swapper_init(BalancerV2SwapConfig memory config) internal onlyInitializing {
+        __BaseSwapTask_init(config.baseSwapConfig);
+        __BalancerV2Swapper_init_unchained(config);
+    }
+
+    /**
+     * @dev Initializes the balancer swapper. It does not call upper contracts
+     * @param config Balancer V2 swap config
+     */
+    function __BalancerV2Swapper_init_unchained(BalancerV2SwapConfig memory config) internal onlyInitializing {
+        // solhint-disable-previous-line no-empty-blocks
+    }
+
+    /**
+     * @dev Executes the Balancer v2 swapper task
+     */
+    function call(address tokenIn, uint256 amountIn, uint256 slippage)
+        external
+        override
+        authP(authParams(tokenIn, amountIn, slippage))
+    {
+        if (amountIn == 0) amountIn = getTaskAmount(tokenIn);
+        _beforeBalancerV2Swapper(tokenIn, amountIn, slippage);
+
+        address tokenOut = getTokenOut(tokenIn);
+        uint256 price = _getPrice(tokenIn, tokenOut);
+        uint256 minAmountOut = amountIn.mulUp(price).mulUp(FixedPoint.ONE - slippage);
+
+        bytes memory connectorData = abi.encodeWithSelector(
+            IBalancerV2SwapConnector.execute.selector,
+            tokenIn,
+            tokenOut,
+            amountIn,
+            minAmountOut,
+            IBalancerPool(tokenIn).getPoolId(),
+            new bytes32[](0),
+            new address[](0)
+        );
+
+        bytes memory result = ISmartVault(smartVault).execute(connector, connectorData);
+        _afterBalancerV2Swapper(tokenIn, amountIn, slippage, tokenOut, result.toUint256());
+    }
+
+    /**
+     * @dev Before Balancer V2 swapper hook
+     */
+    function _beforeBalancerV2Swapper(address token, uint256 amount, uint256 slippage) internal virtual {
+        _beforeBaseSwapTask(token, amount, slippage);
+    }
+
+    /**
+     * @dev After Balancer v2 swapper hook
+     */
+    function _afterBalancerV2Swapper(
+        address tokenIn,
+        uint256 amountIn,
+        uint256 slippage,
+        address tokenOut,
+        uint256 amountOut
+    ) internal virtual {
+        _afterBaseSwapTask(tokenIn, amountIn, slippage, tokenOut, amountOut);
+    }
+}

packages/tasks/test/swap/BalancerV2Swapper.test.ts

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+import { deploy, deployProxy, getSigners, ZERO_ADDRESS } from '@mimic-fi/v3-helpers'
+import { SignerWithAddress } from '@nomiclabs/hardhat-ethers/dist/src/signer-with-address'
+import { Contract } from 'ethers'
+
+import { buildEmptyTaskConfig, deployEnvironment } from '../../src/setup'
+import { itBehavesLikeBaseSwapTask } from './BaseSwapTask.behavior'
+
+describe('BalancerV2Swapper', () => {
+  let task: Contract
+  let smartVault: Contract, authorizer: Contract, connector: Contract, owner: SignerWithAddress
+
+  before('setup', async () => {
+    // eslint-disable-next-line prettier/prettier
+    [, owner] = await getSigners()
+    ;({ authorizer, smartVault } = await deployEnvironment(owner))
+  })
+
+  before('deploy connector', async () => {
+    connector = await deploy('BalancerV2SwapConnectorMock', [ZERO_ADDRESS])
+    const overrideConnectorCheckRole = smartVault.interface.getSighash('overrideConnectorCheck')
+    await authorizer.connect(owner).authorize(owner.address, smartVault.address, overrideConnectorCheckRole, [])
+    await smartVault.connect(owner).overrideConnectorCheck(connector.address, true)
+  })
+
+  beforeEach('deploy task', async () => {
+    task = await deployProxy(
+      'BalancerV2Swapper',
+      [],
+      [
+        {
+          baseSwapConfig: {
+            connector: connector.address,
+            tokenOut: ZERO_ADDRESS,
+            maxSlippage: 0,
+            customTokensOut: [],
+            customMaxSlippages: [],
+            taskConfig: buildEmptyTaskConfig(owner, smartVault),
+          },
+        },
+      ]
+    )
+  })
+
+  describe('swapper', () => {
+    beforeEach('set params', async function () {
+      this.owner = owner
+      this.task = task
+      this.authorizer = authorizer
+    })
+
+    itBehavesLikeBaseSwapTask('BALANCER_V2_SWAPPER')
+  })
+})