A sample smart contract for the base chain

docs/base-chain/sample.sol

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+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+/**
+ * @title SimpleVault
+ * @dev A basic vault contract for Base L2 that allows users to deposit and withdraw ETH
+ * @notice This demonstrates common patterns for Base L2 smart contracts
+ */
+contract SimpleVault {
+    // State variables
+    mapping(address => uint256) public balances;
+    uint256 public totalDeposits;
+    address public owner;
+    bool public isPaused;
+
+    // Events
+    event Deposit(address indexed user, uint256 amount, uint256 timestamp);
+    event Withdrawal(address indexed user, uint256 amount, uint256 timestamp);
+    event EmergencyWithdraw(address indexed user, uint256 amount);
+    event PauseToggled(bool isPaused);
+
+    // Modifiers
+    modifier onlyOwner() {
+        require(msg.sender == owner, "Not authorized");
+        _;
+    }
+
+    modifier whenNotPaused() {
+        require(!isPaused, "Contract is paused");
+        _;
+    }
+
+    // Constructor
+    constructor() {
+        owner = msg.sender;
+        isPaused = false;
+    }
+
+    /**
+     * @dev Deposit ETH into the vault
+     * @notice Sends ETH to this function to deposit
+     */
+    function deposit() external payable whenNotPaused {
+        require(msg.value > 0, "Deposit must be greater than 0");
+
+        balances[msg.sender] += msg.value;
+        totalDeposits += msg.value;
+
+        emit Deposit(msg.sender, msg.value, block.timestamp);
+    }
+
+    /**
+     * @dev Withdraw ETH from the vault
+     * @param amount The amount to withdraw in wei
+     */
+    function withdraw(uint256 amount) external whenNotPaused {
+        require(amount > 0, "Amount must be greater than 0");
+        require(balances[msg.sender] >= amount, "Insufficient balance");
+        require(address(this).balance >= amount, "Insufficient contract balance");
+
+        balances[msg.sender] -= amount;
+        totalDeposits -= amount;
+
+        (bool success, ) = msg.sender.call{value: amount}("");
+        require(success, "Transfer failed");
+
+        emit Withdrawal(msg.sender, amount, block.timestamp);
+    }
+
+    /**
+     * @dev Emergency withdraw - allows users to withdraw even when paused
+     */
+    function emergencyWithdraw() external {
+        uint256 balance = balances[msg.sender];
+        require(balance > 0, "No balance to withdraw");
+
+        balances[msg.sender] = 0;
+        totalDeposits -= balance;
+
+        (bool success, ) = msg.sender.call{value: balance}("");
+        require(success, "Transfer failed");
+
+        emit EmergencyWithdraw(msg.sender, balance);
+    }
+
+    /**
+     * @dev Get the balance of a specific user
+     * @param user The address to check
+     * @return The balance of the user
+     */
+    function getBalance(address user) external view returns (uint256) {
+        return balances[user];
+    }
+
+    /**
+     * @dev Get the contract's total ETH balance
+     * @return The total ETH held by the contract
+     */
+    function getContractBalance() external view returns (uint256) {
+        return address(this).balance;
+    }
+
+    /**
+     * @dev Toggle pause state (owner only)
+     */
+    function togglePause() external onlyOwner {
+        isPaused = !isPaused;
+        emit PauseToggled(isPaused);
+    }
+
+    /**
+     * @dev Transfer ownership (owner only)
+     * @param newOwner The address of the new owner
+     */
+    function transferOwnership(address newOwner) external onlyOwner {
+        require(newOwner != address(0), "Invalid address");
+        owner = newOwner;
+    }
+
+    // Fallback function to receive ETH
+    receive() external payable {
+        balances[msg.sender] += msg.value;
+        totalDeposits += msg.value;
+        emit Deposit(msg.sender, msg.value, block.timestamp);
+    }
+}