feat: implement simple lending protocol smart contract

broadcast/SimpleLendingProtocol.s.sol/4202/run-1728039577.json

@@ -0,0 +1,52 @@
+{
+  "transactions": [
+    {
+      "hash": "0x0dc452f6a0443be91c8167b6080c424cfc19c6b0c4e2fa544997dc30d11716ad",
+      "transactionType": "CREATE",
+      "contractName": "SimpleLendingProtocol",
+      "contractAddress": "0xf669aeb8401ed77ed8834f95194252e01ff62023",
+      "function": null,
+      "arguments": null,
+      "transaction": {
+        "from": "0xdab8892c07fb4c362dd99d9a2fbff8b555d39cb5",
+        "gas": "0xe64fe",
+        "value": "0x0",
+        "input": 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+        "nonce": "0x19",
+        "chainId": "0x106a"
+      },
+      "additionalContracts": [],
+      "isFixedGasLimit": false
+    }
+  ],
+  "receipts": [
+    {
+      "status": "0x1",
+      "cumulativeGasUsed": "0xbbe8f",
+      "logs": [],
+      "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
+      "type": "0x2",
+      "transactionHash": "0x0dc452f6a0443be91c8167b6080c424cfc19c6b0c4e2fa544997dc30d11716ad",
+      "transactionIndex": "0x1",
+      "blockHash": "0xf2fb624d8f889b823d55a6995548a065652e3959a53f91236521ca5f7403c6f9",
+      "blockNumber": "0xad63da",
+      "gasUsed": "0xb1350",
+      "effectiveGasPrice": "0xf433d",
+      "from": "0xdab8892c07fb4c362dd99d9a2fbff8b555d39cb5",
+      "to": null,
+      "contractAddress": "0xf669aeb8401ed77ed8834f95194252e01ff62023",
+      "l1BaseFeeScalar": "0x2af8",
+      "l1BlobBaseFee": "0x1",
+      "l1BlobBaseFeeScalar": "0x109618",
+      "l1Fee": "0x5be7b440dc98",
+      "l1GasPrice": "0x4e0739f173",
+      "l1GasUsed": "0x6b13"
+    }
+  ],
+  "libraries": [],
+  "pending": [],
+  "returns": {},
+  "timestamp": 1728039577,
+  "chain": 4202,
+  "commit": "56079c6"
+}

broadcast/SimpleLendingProtocol.s.sol/4202/run-latest.json

@@ -0,0 +1,52 @@
+{
+  "transactions": [
+    {
+      "hash": "0x0dc452f6a0443be91c8167b6080c424cfc19c6b0c4e2fa544997dc30d11716ad",
+      "transactionType": "CREATE",
+      "contractName": "SimpleLendingProtocol",
+      "contractAddress": "0xf669aeb8401ed77ed8834f95194252e01ff62023",
+      "function": null,
+      "arguments": null,
+      "transaction": {
+        "from": "0xdab8892c07fb4c362dd99d9a2fbff8b555d39cb5",
+        "gas": "0xe64fe",
+        "value": "0x0",
+        "input": 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+        "nonce": "0x19",
+        "chainId": "0x106a"
+      },
+      "additionalContracts": [],
+      "isFixedGasLimit": false
+    }
+  ],
+  "receipts": [
+    {
+      "status": "0x1",
+      "cumulativeGasUsed": "0xbbe8f",
+      "logs": [],
+      "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
+      "type": "0x2",
+      "transactionHash": "0x0dc452f6a0443be91c8167b6080c424cfc19c6b0c4e2fa544997dc30d11716ad",
+      "transactionIndex": "0x1",
+      "blockHash": "0xf2fb624d8f889b823d55a6995548a065652e3959a53f91236521ca5f7403c6f9",
+      "blockNumber": "0xad63da",
+      "gasUsed": "0xb1350",
+      "effectiveGasPrice": "0xf433d",
+      "from": "0xdab8892c07fb4c362dd99d9a2fbff8b555d39cb5",
+      "to": null,
+      "contractAddress": "0xf669aeb8401ed77ed8834f95194252e01ff62023",
+      "l1BaseFeeScalar": "0x2af8",
+      "l1BlobBaseFee": "0x1",
+      "l1BlobBaseFeeScalar": "0x109618",
+      "l1Fee": "0x5be7b440dc98",
+      "l1GasPrice": "0x4e0739f173",
+      "l1GasUsed": "0x6b13"
+    }
+  ],
+  "libraries": [],
+  "pending": [],
+  "returns": {},
+  "timestamp": 1728039577,
+  "chain": 4202,
+  "commit": "56079c6"
+}

script/SimpleLendingProtocol.s.sol

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.20;
+
+import {Script, console} from "forge-std/Script.sol";
+import {SimpleLendingProtocol} from "../src/SimpleLendingProtocol.sol";
+
+contract SimpleLendingProtocolScript is Script {
+    SimpleLendingProtocol public protocol;
+
+    function setUp() public {}
+
+    function run() public {
+        vm.startBroadcast();
+
+        protocol = new SimpleLendingProtocol();
+
+        vm.stopBroadcast();
+    }
+}

src/SimpleLendingProtocol.sol

@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+contract SimpleLendingProtocol {
+    struct Loan {
+        address borrower;
+        uint256 amountBorrowed;
+        uint256 collateralAmount;
+        uint256 dueDate;
+        bool isRepaid;
+    }
+
+    mapping(address => uint256) public deposits; // Lender deposits
+    mapping(address => Loan) public loans; // Active loans by borrowers
+
+    uint256 public interestRate = 10; // 10% interest
+    uint256 public loanDuration = 30 days;
+    uint256 public collateralRatio = 150; // Borrower must provide 150% collateral
+
+    event Deposit(address indexed lender, uint256 amount);
+    event Withdraw(address indexed lender, uint256 amount);
+    event LoanTaken(address indexed borrower, uint256 loanAmount, uint256 collateralAmount);
+    event LoanRepaid(address indexed borrower, uint256 repaymentAmount);
+    event CollateralLiquidated(address indexed borrower, uint256 collateralAmount);
+
+    // Deposit funds as a lender
+    function deposit() external payable {
+        require(msg.value > 0, "Deposit amount must be greater than 0");
+        deposits[msg.sender] += msg.value;
+        emit Deposit(msg.sender, msg.value);
+    }
+
+    // Withdraw funds as a lender
+    function withdraw(uint256 amount) external {
+        require(deposits[msg.sender] >= amount, "Insufficient balance");
+        deposits[msg.sender] -= amount;
+        payable(msg.sender).transfer(amount);
+        emit Withdraw(msg.sender, amount);
+    }
+
+    // Take a loan by providing collateral
+    function takeLoan(uint256 loanAmount) external payable {
+        require(msg.value >= (loanAmount * collateralRatio) / 100, "Insufficient collateral");
+        require(loans[msg.sender].amountBorrowed == 0, "Existing loan must be repaid");
+
+        loans[msg.sender] = Loan({
+            borrower: msg.sender,
+            amountBorrowed: loanAmount,
+            collateralAmount: msg.value,
+            dueDate: block.timestamp + loanDuration,
+            isRepaid: false
+        });
+
+        payable(msg.sender).transfer(loanAmount);
+        emit LoanTaken(msg.sender, loanAmount, msg.value);
+    }
+
+    // Repay the loan with interest
+    function repayLoan() external payable {
+        Loan storage loan = loans[msg.sender];
+        require(loan.amountBorrowed > 0, "No active loan");
+        require(block.timestamp <= loan.dueDate, "Loan is overdue");
+
+        uint256 repaymentAmount = loan.amountBorrowed + (loan.amountBorrowed * interestRate) / 100;
+        require(msg.value == repaymentAmount, "Incorrect repayment amount");
+
+        loan.isRepaid = true;
+        deposits[address(this)] += repaymentAmount; // Add interest to pool
+        payable(msg.sender).transfer(loan.collateralAmount); // Return collateral
+        emit LoanRepaid(msg.sender, repaymentAmount);
+    }
+
+    // Liquidate overdue loan and seize collateral
+    function liquidateOverdueLoan(address borrower) external {
+        Loan storage loan = loans[borrower];
+        require(loan.amountBorrowed > 0, "No active loan");
+        require(block.timestamp > loan.dueDate, "Loan is not overdue");
+        require(!loan.isRepaid, "Loan already repaid");
+
+        deposits[address(this)] += loan.collateralAmount; // Lenders take the collateral
+        delete loans[borrower]; // Remove loan record
+        emit CollateralLiquidated(borrower, loan.collateralAmount);
+    }
+
+    // Check lender balance
+    function getLenderBalance() external view returns (uint256) {
+        return deposits[msg.sender];
+    }
+
+    // Check borrower loan details
+    function getLoanDetails(address borrower) external view returns (Loan memory) {
+        return loans[borrower];
+    }
+}