Remove flashloan receiver

src/Blue.sol

@@ -5,12 +5,11 @@ import {
     IBlueLiquidateCallback,
     IBlueRepayCallback,
     IBlueSupplyCallback,
-    IBlueSupplyCollateralCallback
+    IBlueSupplyCollateralCallback,
+    IBlueFlashBorrower
 } from "src/interfaces/IBlueCallbacks.sol";
 import {IIrm} from "src/interfaces/IIrm.sol";
 import {IERC20} from "src/interfaces/IERC20.sol";
-import {IFlashLender} from "src/interfaces/IFlashLender.sol";
-import {IFlashBorrower} from "src/interfaces/IFlashBorrower.sol";
 
 import {Errors} from "./libraries/Errors.sol";
 import {SharesMath} from "src/libraries/SharesMath.sol";
@@ -35,7 +34,7 @@ struct Signature {
     bytes32 s;
 }
 
-contract Blue is IFlashLender {
+contract Blue {
     using SharesMath for uint256;
     using FixedPointMathLib for uint256;
     using SafeTransferLib for IERC20;
@@ -288,13 +287,12 @@ contract Blue is IFlashLender {
 
     // Flash Loans.
 
-    /// @inheritdoc IFlashLender
-    function flashLoan(IFlashBorrower receiver, address token, uint256 amount, bytes calldata data) external {
-        IERC20(token).safeTransfer(address(receiver), amount);
+    function flashLoan(address token, uint256 amount, bytes calldata data) external {
+        IERC20(token).safeTransfer(msg.sender, amount);
 
-        receiver.onBlueFlashLoan(msg.sender, token, amount, data);
+        IBlueFlashBorrower(msg.sender).onBlueFlashLoan(token, amount, data);
 
-        IERC20(token).safeTransferFrom(address(receiver), address(this), amount);
+        IERC20(token).safeTransferFrom(msg.sender, address(this), amount);
     }
 
     // Authorizations.

src/interfaces/IBlueCallbacks.sol

@@ -16,3 +16,7 @@ interface IBlueSupplyCallback {
 interface IBlueSupplyCollateralCallback {
     function onBlueSupplyCollateral(uint256 amount, bytes calldata data) external;
 }
+
+interface IBlueFlashBorrower {
+    function onBlueFlashLoan(address token, uint256 amount, bytes calldata data) external;
+}

test/forge/Blue.t.sol

@@ -16,7 +16,6 @@ import {
 import {ERC20Mock as ERC20} from "src/mocks/ERC20Mock.sol";
 import {OracleMock as Oracle} from "src/mocks/OracleMock.sol";
 import {IrmMock as Irm} from "src/mocks/IrmMock.sol";
-import {FlashBorrowerMock} from "src/mocks/FlashBorrowerMock.sol";
 
 contract BlueTest is
     Test,
@@ -41,7 +40,6 @@ contract BlueTest is
     Irm private irm;
     Market public market;
     Id public id;
-    FlashBorrowerMock internal flashBorrower;
 
     function setUp() public {
         // Create Blue.
@@ -52,7 +50,6 @@ contract BlueTest is
         collateralAsset = new ERC20("collateral", "C", 18);
         borrowableOracle = new Oracle();
         collateralOracle = new Oracle();
-        flashBorrower = new FlashBorrowerMock(blue);
 
         irm = new Irm(blue);
 
@@ -741,7 +738,7 @@ contract BlueTest is
         borrowableAsset.setBalance(address(this), amount);
         blue.supply(market, amount, address(this), hex"");
 
-        blue.flashLoan(flashBorrower, address(borrowableAsset), amount, bytes(""));
+        blue.flashLoan(address(borrowableAsset), amount, bytes(""));
 
         assertEq(borrowableAsset.balanceOf(address(blue)), amount, "balanceOf");
     }
@@ -834,6 +831,8 @@ contract BlueTest is
         assertEq(blue.collateral(market.id(), address(this)), 0, "no withdraw collateral");
     }
 
+    // Callback functions.
+
     function onBlueSupply(uint256 amount, bytes memory data) external {
         require(msg.sender == address(blue));
         bytes4 selector;
@@ -877,6 +876,10 @@ contract BlueTest is
             borrowableAsset.approve(address(blue), repaid);
         }
     }
+
+    function onBlueFlashLoan(address token, uint256 amount, bytes calldata) external {
+        ERC20(token).approve(address(blue), amount);
+    }
 }
 
 function neq(Market memory a, Market memory b) pure returns (bool) {