add lastPoolOwnerState abstract contract

contracts/LastPoolOwnerState.sol

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import "./interfaces/IBeforeTransfer.sol";
+import "@openzeppelin/contracts/utils/introspection/IERC165.sol";
+
+/**
+ * @title LastPoolOwnerState
+ * @dev Contract to keep track of the last owner of a Provider pool before a transfer.
+ */
+abstract contract LastPoolOwnerState is IBeforeTransfer, IERC165 {
+    // Mapping to store the last owner of each Provider pool before a transfer
+    mapping(uint256 => address) internal lastPoolOwner;
+
+    /**
+     * @dev Function to be called before a transfer.
+     * @param from Address from which the transfer is initiated.
+     * @param to Address to which the transfer is directed.
+     * @param poolId Identifier of the Provider pool.
+     */
+    function beforeTransfer(address from, address to, uint256 poolId) external virtual override;
+
+    /**
+     * @dev Checks whether a contract supports the specified interface.
+     * @param interfaceId Interface identifier.
+     * @return A boolean indicating whether the contract supports the specified interface.
+     */
+    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
+        return interfaceId == type(IERC165).interfaceId || interfaceId == type(IBeforeTransfer).interfaceId;
+    }
+}

contracts/mocks/MockLastPoolOwner.sol

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import "../LastPoolOwnerState.sol";
+
+/**
+ * @title MockLastPoolOwner
+ * @dev Mock contract to keep track of the last owner of a Provider pool before a transfer.
+ */
+contract MockLastPoolOwner is LastPoolOwnerState {
+    /**
+     * @dev Function to be called before a transfer.
+     * @param from Address from which the transfer is initiated.
+     * @param poolId Identifier of the Provider pool.
+     */
+    function beforeTransfer(address from, address, uint256 poolId) external override {
+        lastPoolOwner[poolId] = from;
+    }
+
+    /**
+     * @dev Function to get the last owner of a Provider pool.
+     * @param poolId Identifier of the Provider pool.
+     * @return Address of the last owner of the Provider pool.
+     */
+    function getLastPoolOwner(uint256 poolId) external view returns (address) {
+        return lastPoolOwner[poolId];
+    }
+}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@poolzfinance/poolz-helper-v2",
-  "version": "3.0.3",
+  "version": "3.0.4",
   "description": "A single source of truth of helper contracts used by Poolz.",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",

test/11_LastPoolOwner.ts

@@ -0,0 +1,29 @@
+import { ethers } from 'hardhat';
+import { deployed } from '../scripts/deploy';
+import { MockLastPoolOwner } from '../typechain-types';
+import { expect } from 'chai';
+
+describe('LastPoolOwner abstract contract', function () {
+  let lastPoolOwner: MockLastPoolOwner;
+  const poolId = ethers.parseUnits('100', 18);
+
+  before(async () => {
+    lastPoolOwner = await deployed('MockLastPoolOwner');
+  });
+
+  it('should support IBeforeTransfer interface', async () => {
+    const IBeforeTransferInterfaceId = '0x1ffb811f';
+    expect(await lastPoolOwner.supportsInterface(IBeforeTransferInterfaceId)).to.equal(true);
+  });
+
+  it('should support IERC165 interface', async () => {
+    const IERC165InterfaceId = '0x01ffc9a7';
+    expect(await lastPoolOwner.supportsInterface(IERC165InterfaceId)).to.equal(true);
+  });
+
+  it('should return lastPoolOwner', async () => {
+    const [addr0] = await ethers.getSigners();
+    await lastPoolOwner.beforeTransfer(addr0.address, addr0.address, poolId);
+    expect(await lastPoolOwner.getLastPoolOwner(poolId)).to.equal(addr0.address);
+  });
+});