feat: Add IMigrationHelper interface (#185)

* feat: Add IMigrationHelper interface to AaveV2 & export MIGRATION_HELPER with interface on AaveV2Polygon

* revert changes to autogenerated file

* migrate IMigrationHelper interface from AaveV2.sol to src/common/IMigrationHelper.sol

* fix imports

* another import fix, should be gud now

* add suggested changes

* add IERC20WithPermit

* fix more issues raised in review

---------

Co-authored-by: defijesus.eth <defijesus@buzzedbearhideout.com>

src/common/IMigrationHelper.sol

@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import {IPool as IV3Pool} from '../AaveV3.sol';
+import {ILendingPool as IV2Pool} from '../AaveV2.sol';
+import {ICreditDelegationToken} from 'aave-v3-core/contracts/interfaces/ICreditDelegationToken.sol';
+import {IERC20WithPermit} from 'aave-v3-core/contracts/interfaces/IERC20WithPermit.sol';
+
+interface IMigrationHelper {
+  struct PermitInput {
+    IERC20WithPermit aToken;
+    uint256 value;
+    uint256 deadline;
+    uint8 v;
+    bytes32 r;
+    bytes32 s;
+  }
+
+  struct CreditDelegationInput {
+    ICreditDelegationToken debtToken;
+    uint256 value;
+    uint256 deadline;
+    uint8 v;
+    bytes32 r;
+    bytes32 s;
+  }
+
+  struct RepayInput {
+    address asset;
+    uint256 amount;
+    uint256 rateMode;
+  }
+
+  struct RepaySimpleInput {
+    address asset;
+    uint256 rateMode;
+  }
+
+  struct EmergencyTransferInput {
+    IERC20WithPermit asset;
+    uint256 amount;
+    address to;
+  }
+
+  /**
+   * @notice Method to do migration of any types of positions. Migrating whole amount of specified assets
+   * @param assetsToMigrate - list of assets to migrate
+   * @param positionsToRepay - list of assets to be repayed
+   * @param permits - list of EIP712 permits, can be empty, if approvals provided in advance
+   * @param creditDelegationPermits - list of EIP712 signatures (credit delegations) for v3 variable debt token
+   * @dev check more details about permit at PermitInput and /solidity-utils/contracts/oz-common/interfaces/draft-IERC20Permit.sol
+   **/
+  function migrate(
+    address[] memory assetsToMigrate,
+    RepaySimpleInput[] memory positionsToRepay,
+    PermitInput[] memory permits,
+    CreditDelegationInput[] memory creditDelegationPermits
+  ) external;
+
+  /**
+   * @notice Executes an operation after receiving the flash-borrowed assets
+   * @dev Ensure that the contract can return the debt + premium, e.g., has
+   *      enough funds to repay and has approved the Pool to pull the total amount
+   * @param assets The addresses of the flash-borrowed assets
+   * @param amounts The amounts of the flash-borrowed assets
+   * @param premiums The fee of each flash-borrowed asset
+   * @param initiator The address of the flashloan initiator
+   * @param params The byte-encoded params passed when initiating the flashloan
+   * @return True if the execution of the operation succeeds, false otherwise
+   */
+  function executeOperation(
+    address[] calldata assets,
+    uint256[] calldata amounts,
+    uint256[] calldata premiums,
+    address initiator,
+    bytes calldata params
+  ) external returns (bool);
+
+  /**
+   * @notice Public method to optimize the gas costs, to avoid having getReserveData calls on every execution
+   **/
+  function cacheATokens() external;
+
+  /**
+   * @notice Method to get asset and amount to be supplied to V3
+   * @param asset the v2 pool asset
+   * @param amount origin amount
+   * @return address asset to be supplied to the v3 pool
+   * @return uint256 amount to be supplied to the v3 pool
+   */
+  function getMigrationSupply(
+    address asset,
+    uint256 amount
+  ) external view returns (address, uint256);
+
+  /// @notice The source pool
+  function V2_POOL() external returns (IV2Pool);
+
+  /// @notice The destination pool
+  function V3_POOL() external returns (IV3Pool);
+
+  /**
+   * @notice Public method for rescue funds in case of a wrong transfer
+   * @param emergencyInput - array of parameters to transfer out funds
+   **/
+  function rescueFunds(EmergencyTransferInput[] calldata emergencyInput) external;
+
+  function aTokens(address underlying) external returns (address);
+
+  function vTokens(address underlying) external returns (address);
+
+  function sTokens(address underlying) external returns (address);
+}