Add curve gauge

src/CurveGaugeJoin.sol

@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+// Copyright (C) 2022 Dai Foundation
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero 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 Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+pragma solidity 0.6.12;
+
+import "./CropJoin.sol";
+
+interface LiquidityGaugeLike {
+    function crv_token() external view returns (address);
+    function lp_token() external view returns (address);
+    function minter() external view returns (address);
+    function deposit(uint256) external;
+    function withdraw(uint256) external;
+}
+
+interface LiquidityGaugeMinterLike {
+    function mint_for(address,address) external;
+}
+
+// Join adapter for the Curve gauge contract
+contract CurveGaugeJoinImp is CropJoinImp {
+
+    LiquidityGaugeLike          immutable public pool;
+    LiquidityGaugeMinterLike    immutable public minter;
+
+    /**
+        @param vat_                 MCD_VAT DSS core accounting module
+        @param ilk_                 Collateral type
+        @param gem_                 The collateral LP token address
+        @param bonus_               The rewards token contract address.
+        @param pool_                The staking rewards pool.
+    */
+    constructor(
+        address vat_,
+        bytes32 ilk_,
+        address gem_,
+        address bonus_,
+        address pool_
+    )
+        public
+        CropJoinImp(vat_, ilk_, gem_, bonus_)
+    {
+        // Sanity checks
+        require(LiquidityGaugeLike(pool_).crv_token() == bonus_, "CurveGaugeJoin/bonus-mismatch");
+        require(LiquidityGaugeLike(pool_).lp_token() == gem_, "CurveGaugeJoin/gem-mismatch");
+
+        pool = LiquidityGaugeLike(pool_);
+        minter = LiquidityGaugeMinterLike(LiquidityGaugeLike(pool_).minter());
+    }
+
+    function init() external {
+        gem.approve(address(pool), type(uint256).max);
+    }
+
+    function nav() public override view returns (uint256) {
+        return total;
+    }
+
+    function crop() internal override returns (uint256) {
+        if (live == 1) {
+            minter.mint_for(address(pool), address(this));
+        }
+        return super.crop();
+    }
+
+    function join(address urn, address usr, uint256 val) public override {
+        super.join(urn, usr, val);
+        if (val > 0) pool.deposit(val);
+    }
+
+    function exit(address urn, address usr, uint256 val) public override {
+        if (live == 1) {
+            if (val > 0) pool.withdraw(val);
+        }
+        super.exit(urn, usr, val);
+    }
+
+    function flee(address urn, address usr, uint256 val) public override {
+        if (live == 1) {
+            if (val > 0) pool.withdraw(val);
+        }
+        super.flee(urn, usr, val);
+    }
+    function cage() override public auth {
+        require(live == 1, "CurveGaugeJoin/not-live");
+
+        if (total > 0) pool.withdraw(total);
+        live = 0;
+    }
+    function uncage() external auth {
+        require(live == 0, "CurveGaugeJoin/live");
+
+        if (total > 0) pool.deposit(total);
+        live = 1;
+    }
+}