feat: add instapoolV4 for Base

contracts/base/connectors/instapool_v4/events.sol

@@ -0,0 +1,10 @@
+pragma solidity >=0.7.0;
+pragma experimental ABIEncoderV2;
+
+contract Events {
+    event LogFlashBorrow(address token, uint256 tokenAmt);
+    event LogFlashPayback(address token, uint256 tokenAmt);
+
+    event LogFlashMultiBorrow(address[] token, uint256[] tokenAmts);
+    event LogFlashMultiPayback(address[] token, uint256[] tokenAmts);
+}

contracts/base/connectors/instapool_v4/interfaces.sol

@@ -0,0 +1,11 @@
+pragma solidity >=0.7.0;
+pragma experimental ABIEncoderV2;
+
+interface InstaFlashV4Interface {
+    function flashLoan(address[] memory tokens, uint256[] memory amts, uint route, bytes memory data, bytes memory extraData) external;
+}
+
+interface AccountInterface {
+    function enable(address) external;
+    function disable(address) external;
+}

contracts/base/connectors/instapool_v4/main.sol

@@ -0,0 +1,136 @@
+pragma solidity ^0.7.0;
+pragma experimental ABIEncoderV2;
+
+/**
+ * @title Instapool.
+ * @dev Inbuilt Flash Loan in DSA
+ */
+
+import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
+import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+import { AccountInterface } from "./interfaces.sol";
+import { Stores } from "../../common/stores.sol";
+import { Variables } from "./variables.sol";
+import { Events } from "./events.sol";
+
+contract LiquidityResolver is Stores, Variables, Events {
+    using SafeERC20 for IERC20;
+
+    /**
+     * @dev Borrow Flashloan and Cast spells.
+     * @notice Borrow Flashloan and Cast spells.
+     * @param token Token Address.
+     * @param amt Token Amount.
+     * @param route Flashloan source route.
+     * @param data targets & data for cast.
+     * @param extraData to be kept bytes(0) in most cases. Can be useful to decide data for some particular routes
+     */
+    function flashBorrowAndCast(
+        address token,
+        uint amt,
+        uint route,
+        bytes memory data,
+        bytes memory extraData
+    ) external payable returns (string memory _eventName, bytes memory _eventParam) {
+        AccountInterface(address(this)).enable(address(instaPool));
+        (string[] memory _targets, bytes[] memory callDatas) = abi.decode(data, (string[], bytes[]));
+
+        bytes memory callData_ = abi.encodeWithSignature("cast(string[],bytes[],address)", _targets, callDatas, address(instaPool));
+
+        address[] memory tokens_ = new address[](1);
+        tokens_[0] = token;
+        uint[] memory amts_ = new uint[](1);
+        amts_[0] = amt;
+        instaPool.flashLoan(tokens_, amts_, route, callData_, extraData);
+
+        AccountInterface(address(this)).disable(address(instaPool));
+
+        _eventName = "LogFlashBorrow(address,uint256)";
+        _eventParam = abi.encode(token, amt);
+    }
+
+    /**
+     * @dev Return token to InstaPool.
+     * @notice Return token to InstaPool.
+     * @param token Token Address.
+     * @param amt Token Amount.
+     * @param getId Get token amount at this ID from `InstaMemory` Contract.
+     * @param setId Set token amount at this ID in `InstaMemory` Contract.
+    */
+    function flashPayback(
+        address token,
+        uint amt,
+        uint getId,
+        uint setId
+    ) external payable returns (string memory _eventName, bytes memory _eventParam) {
+        uint _amt = getUint(getId, amt);
+        
+        IERC20 tokenContract = IERC20(token);
+
+        tokenContract.safeTransfer(address(instaPool), _amt);
+
+        setUint(setId, _amt);
+
+        _eventName = "LogFlashPayback(address,uint256)";
+        _eventParam = abi.encode(token, amt);
+    }
+
+    /**
+     * @dev Borrow multi-tokens Flashloan and Cast spells.
+     * @notice Borrow multi-tokens Flashloan and Cast spells.
+     * @param tokens_ Array of Token Addresses.
+     * @param amts_ Array of Token Amounts.
+     * @param route Flashloan source route.
+     * @param data targets & data for cast.
+     * @param extraData to be kept bytes(0) in most cases. Can be useful to decide data for some particular routes
+     */
+    function flashMultiBorrowAndCast(
+        address[] memory tokens_,
+        uint[] memory amts_,
+        uint route,
+        bytes memory data,
+        bytes memory extraData
+    ) external payable returns (string memory _eventName, bytes memory _eventParam) {
+        AccountInterface(address(this)).enable(address(instaPool));
+        (string[] memory _targets, bytes[] memory callDatas) = abi.decode(data, (string[], bytes[]));
+
+        bytes memory callData_ = abi.encodeWithSignature("cast(string[],bytes[],address)", _targets, callDatas, address(instaPool));
+
+        instaPool.flashLoan(tokens_, amts_, route, callData_, extraData);
+
+        AccountInterface(address(this)).disable(address(instaPool));
+        _eventName = "LogFlashMultiBorrow(address[],uint256[])";
+        _eventParam = abi.encode(tokens_, amts_);
+    }
+
+    /**
+     * @dev Return multi-tokens to InstaPool.
+     * @notice Return multi-tokens to InstaPool.
+     * @param tokens_ Array of Token Addresses.
+     * @param amts_ Array of Token Amounts.
+     * @param getIds Array of getId token amounts.
+     * @param setIds Array of setId token amounts.
+    */
+    function flashMultiPayback(
+        address[] memory tokens_,
+        uint[] memory amts_,
+        uint[] memory getIds,
+        uint[] memory setIds
+    ) external payable returns (string memory _eventName, bytes memory _eventParam) {
+        for (uint i = 0; i < tokens_.length; i++) {
+            amts_[i] = getUint(getIds[i], amts_[i]);
+
+        IERC20(tokens_[i]).safeTransfer(address(instaPool), amts_[i]);
+
+            setUint(setIds[i], amts_[i]);
+        }
+
+        _eventName = "LogFlashMultiPayback(address[],uint256[])";
+        _eventParam = abi.encode(tokens_, amts_);
+    }
+
+}
+
+contract ConnectV2InstaPoolV4 is LiquidityResolver {
+    string public name = "Instapool-v4";
+}

contracts/base/connectors/instapool_v4/variables.sol

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+pragma solidity ^0.7.0;
+pragma experimental ABIEncoderV2;
+
+import { InstaFlashV4Interface } from "./interfaces.sol";
+
+contract Variables {
+
+    /**
+    * @dev Instapool contract proxy
+    */
+    InstaFlashV4Interface public constant instaPool = InstaFlashV4Interface(0xA18519a6bb1282954e933DA0A775924E4CcE6019);
+
+}