Create NexusContract.sol

pi-nexus-blockchain/contracts/NexusContract.sol

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+pragma solidity ^0.8.0;
+
+import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/access/Ownable.sol";
+import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/math/SafeMath.sol";
+import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol";
+import "./NexusToken.sol";
+
+contract NexusContract is Ownable {
+    using SafeMath for uint256;
+    using SafeERC20 for ERC20;
+
+    // Mapping of user addresses to their Nexus token balances
+    mapping (address => uint256) public nexusBalances;
+
+    // Mapping of user addresses to their Nexus token allowances
+    mapping (address => mapping (address => uint256)) public nexusAllowances;
+
+    // Event emitted when a user deposits Nexus tokens
+    event Deposit(address indexed user, uint256 amount);
+
+    // Event emitted when a user withdraws Nexus tokens
+    event Withdrawal(address indexed user, uint256 amount);
+
+    // Event emitted when a user transfers Nexus tokens
+    event Transfer(address indexed from, address indexed to, uint256 amount);
+
+    // Nexus token contract
+    NexusToken public nexusToken;
+
+    // Constructor
+    constructor() public {
+        nexusToken = NexusToken(NEXUS_TOKEN_ADDRESS);
+    }
+
+    // Deposit Nexus tokens
+    function deposit(uint256 amount) public {
+        require(amount > 0, "Deposit amount must be greater than 0");
+        nexusToken.safeTransferFrom(msg.sender, address(this), amount);
+        nexusBalances[msg.sender] = nexusBalances[msg.sender].add(amount);
+        emit Deposit(msg.sender, amount);
+    }
+
+    // Withdraw Nexus tokens
+    function withdraw(uint256 amount) public {
+        require(amount > 0, "Withdrawal amount must be greater than 0");
+        require(nexusBalances[msg.sender] >= amount, "Insufficient balance");
+        nexusToken.safeTransfer(msg.sender, amount);
+        nexusBalances[msg.sender] = nexusBalances[msg.sender].sub(amount);
+        emit Withdrawal(msg.sender, amount);
+    }
+
+    // Transfer Nexus tokens
+    function transfer(address to, uint256 amount) public {
+        require(to != address(0), "Cannot transfer to zero address");
+        require(amount > 0, "Transfer amount must be greater than 0");
+        require(nexusBalances[msg.sender] >= amount, "Insufficient balance");
+        nexusBalances[msg.sender] = nexusBalances[msg.sender].sub(amount);
+        nexusBalances[to] = nexusBalances[to].add(amount);
+        emit Transfer(msg.sender, to, amount);
+    }
+
+    // Approve Nexus token allowance
+    function approve(address spender, uint256 amount) public {
+        require(spender != address(0), "Cannot approve zero address");
+        nexusAllowances[msg.sender][spender] = amount;
+        emit Approval(msg.sender, spender, amount);
+    }
+
+    // Get Nexus token balance
+    function balanceOf(address user) public view returns (uint256) {
+        return nexusBalances[user];
+    }
+
+    // Get Nexus token allowance
+    function allowance(address user, address spender) public view returns (uint256) {
+        return nexusAllowances[user][spender];
+    }
+}