Add helper functions for target USDP repayment

Signed-off-by: 34x4p08 <[email protected]>

contracts/vault-managers/CDPManager01.sol

@@ -211,16 +211,42 @@ contract CDPManager01 is ReentrancyGuard {
     }
 
     /**
-      * @notice Exists with ETH
+      * @notice Repayment is the sum of the principal and interest
+      * @dev Withdraws collateral and repays specified amount of debt
+      * @param asset The address of the collateral
+      * @param assetAmount The amount of the collateral to withdraw
+      * @param repayment The target repayment amount
+      **/
+    function exit_targetRepayment(address asset, uint assetAmount, uint repayment) external returns (uint) {
+
+        uint usdpAmount = _calcPrincipal(asset, msg.sender, repayment);
+
+        return exit(asset, assetAmount, usdpAmount);
+    }
+
+    /**
+      * @notice Withdraws WETH and converts to ETH
       * @param ethAmount ETH amount to withdraw
       * @param usdpAmount The amount of USDP token to repay
       **/
-    function exit_Eth(uint ethAmount, uint usdpAmount) external {
-        exit(WETH, ethAmount, usdpAmount);
+    function exit_Eth(uint ethAmount, uint usdpAmount) external returns (uint) {
+        usdpAmount = exit(WETH, ethAmount, usdpAmount);
         IWETH(WETH).transferFrom(msg.sender, address(this), ethAmount);
         IWETH(WETH).withdraw(ethAmount);
         (bool success, ) = msg.sender.call{value:ethAmount}("");
         require(success, "Unit Protocol: ETH_TRANSFER_FAILED");
+        return usdpAmount;
+    }
+
+    /**
+      * @notice Repayment is the sum of the principal and interest
+      * @notice Withdraws WETH and converts to ETH
+      * @param ethAmount ETH amount to withdraw
+      * @param repayment The target repayment amount
+      **/
+    function exit_Eth_targetRepayment(uint ethAmount, uint repayment) external returns (uint) {
+        uint usdpAmount = _calcPrincipal(WETH, msg.sender, repayment);
+        return exit_Eth(ethAmount, usdpAmount);
     }
 
     // decreases debt
@@ -447,11 +473,16 @@ contract CDPManager01 is ReentrancyGuard {
         }
     }
 
-    function isCurveLP(address asset) public view returns(bool) {
+    function isCurveLP(address asset) public view returns (bool) {
         address underlying = IWrappedToUnderlyingOracle(oracleRegistry.oracleByType(WRAPPED_TO_UNDERLYING_ORACLE_TYPE)).assetToUnderlying(asset);
 
         if (underlying == address(0)) { return false; }
 
         return ICurveRegistry(curveProvider.get_registry()).get_pool_from_lp_token(underlying) != address(0);
     }
+
+    function _calcPrincipal(address asset, address owner, uint repayment) public view returns (uint) {
+        uint fee = vault.stabilityFee(asset, owner) * (block.timestamp - vault.lastUpdate(asset, owner)) / 365 days;
+        return repayment * DENOMINATOR_1E5 / (DENOMINATOR_1E5 + fee);
+    }
 }

test/CDPManager_Keep3r_Chainlink.test.js

@@ -6,6 +6,7 @@ const balance = require('./helpers/balances');
 const BN = web3.utils.BN;
 const { expect } = require('chai');
 const utils = require('./helpers/utils');
+const increaseTime = require('./helpers/timeTravel');
 
 [
 	'chainlinkMainAsset',
@@ -101,22 +102,53 @@ const utils = require('./helpers/utils');
 					await this.utils.join(this.mainCollateral, mainAmount, usdpAmount);
 
 					const mainToWithdraw = ether('50');
-					const usdpToWithdraw = ether('2.5');
+					const usdpToRepay = ether('2.5');
 
-					const { logs } = await this.utils.exit(this.mainCollateral, mainToWithdraw, usdpToWithdraw);
+					const { logs } = await this.utils.exit(this.mainCollateral, mainToWithdraw, usdpToRepay);
 
 					expectEvent.inLogs(logs, 'Exit', {
 						asset: this.mainCollateral.address,
 						user: deployer,
 						main: mainToWithdraw,
-						usdp: usdpToWithdraw,
+						usdp: usdpToRepay,
 					});
 
 					const mainAmountInPosition = await this.vault.collaterals(this.mainCollateral.address, deployer);
 					const usdpInPosition = await this.vault.debts(this.mainCollateral.address, deployer);
 
 					expect(mainAmountInPosition).to.be.bignumber.equal(mainAmount.sub(mainToWithdraw));
-					expect(usdpInPosition).to.be.bignumber.equal(usdpAmount.sub(usdpToWithdraw));
+					expect(usdpInPosition).to.be.bignumber.equal(usdpAmount.sub(usdpToRepay));
+				})
+
+				it('Should partially repay the debt of a position using `exit_targetRepayment`', async function() {
+					await this.vaultParameters.setStabilityFee(this.mainCollateral.address, 10_001);
+					const mainAmount = ether('100');
+					const usdpAmount = ether('20');
+
+					await this.utils.join(this.mainCollateral, mainAmount, usdpAmount);
+
+					await increaseTime(3600 * 24 * 365);
+
+					await this.utils.updatePrice();
+
+					const mainToWithdraw = ether('1');
+					const repayment = ether('11');
+
+					const receipt = await this.utils.exitTarget(this.mainCollateral, mainToWithdraw, repayment);
+
+					expectEvent(receipt, 'Exit', {
+						asset: this.mainCollateral.address,
+						user: deployer,
+						main: mainToWithdraw,
+					});
+
+					// the principal is about 10 USDP
+					expect(ether('10').sub(receipt.logs[0].args.usdp)).to.be.bignumber.lt(ether('0.001'));
+
+					const usdpInPosition = await this.vault.debts(this.mainCollateral.address, deployer);
+
+					// accumulated debt is about 1 USDP
+					expect(usdpInPosition.sub(ether('11'))).to.be.bignumber.lt(ether('0.001'));
 				})
 
 				it('Should partially repay the debt of a position and withdraw collaterals partially using ETH', async function() {
@@ -126,25 +158,25 @@ const utils = require('./helpers/utils');
 					await this.utils.joinEth(mainAmount, usdpAmount);
 
 					const mainToWithdraw = ether('1');
-					const usdpToWithdraw = ether('0.5');
+					const usdpToRepay = ether('0.5');
 
 					const wethBalanceBefore = await balance.current(this.weth.address);
 
-					const { logs } = await this.utils.exitEth(mainToWithdraw, usdpToWithdraw);
+					const { logs } = await this.utils.exitEth(mainToWithdraw, usdpToRepay);
 
 					expectEvent.inLogs(logs, 'Exit', {
 						asset: this.weth.address,
 						user: deployer,
 						main: mainToWithdraw,
-						usdp: usdpToWithdraw,
+						usdp: usdpToRepay,
 					});
 
 					const mainAmountInPosition = await this.vault.collaterals(this.weth.address, deployer);
 					const usdpInPosition = await this.vault.debts(this.weth.address, deployer);
 					const wethBalanceAfter = await balance.current(this.weth.address);
 
 					expect(mainAmountInPosition).to.be.bignumber.equal(mainAmount.sub(mainToWithdraw));
-					expect(usdpInPosition).to.be.bignumber.equal(usdpAmount.sub(usdpToWithdraw));
+					expect(usdpInPosition).to.be.bignumber.equal(usdpAmount.sub(usdpToRepay));
 					expect(wethBalanceBefore.sub(wethBalanceAfter)).to.be.bignumber.equal(mainToWithdraw);
 				})
 

test/helpers/utils.js

@@ -411,6 +411,7 @@ module.exports = (context, mode) => {
 		buyout,
 		triggerLiquidation: w.triggerLiquidation,
 		exit: w.exit,
+		exitTarget: w.exitTarget,
 		exitEth: w.exitEth,
 		repayAllAndWithdraw,
 		repayAllAndWithdrawEth,

test/helpers/wrappers.js

@@ -23,15 +23,24 @@ module.exports = function(context, mode) {
 		},
 		exit: async (asset, mainAmount, usdpAmount) => {
 			if (+usdpAmount > 0) {
-				const debt = await context.vault.debts(asset.address, context.deployer)
-				await context.usdp.approve(context.vault.address, debt)
+				await context.usdp.approve(context.vault.address, usdpAmount)
 			}
 			return context.vaultManager.exit(
 				asset.address,
 				mainAmount, // main
 				usdpAmount,	// USDP
 			);
 		},
+		exitTarget: async (asset, mainAmount, repayment) => {
+			if (+repayment > 0) {
+				await context.usdp.approve(context.vault.address, repayment)
+			}
+			return context.vaultManager.exit_targetRepayment(
+				asset.address,
+				mainAmount, // main
+				repayment,	// USDP
+			);
+		},
 		exitEth: async (mainAmount, usdpAmount) => {
 			const debt = await context.vault.debts(context.weth.address, context.deployer)
 			await context.usdp.approve(context.vault.address, debt)