[DRAFT] V2 => V3 Contract Upgrade

contracts/ZeroDAOTokenV3.sol

@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.3;
+
+// Slight modifiations from base Open Zeppelin Contracts
+// Consult /oz/README.md for more information
+import "./oz/ERC20Upgradeable.sol";
+import "./oz/ERC20SnapshotUpgradeable.sol";
+import "./oz/ERC20PausableUpgradeable.sol";
+
+import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
+import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
+
+import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+
+contract ZeroDAOTokenV3 is
+  OwnableUpgradeable,
+  ERC20Upgradeable,
+  ERC20PausableUpgradeable,
+  ERC20SnapshotUpgradeable
+{
+  using SafeERC20 for IERC20;
+
+  event AuthorizedSnapshotter(address account);
+  event DeauthorizedSnapshotter(address account);
+  event ERC20TokenWithdrawn(
+    IERC20 indexed token,
+    address indexed to,
+    uint256 indexed amount
+  );
+
+  // Mapping which stores all addresses allowed to snapshot
+  mapping(address => bool) authorizedToSnapshot;
+
+  function initialize(
+    string memory name,
+    string memory symbol
+  ) public initializer {
+    __ERC20_init(name, symbol);
+  }
+
+  // Call this on the implementation contract (not the proxy)
+  function initializeImplementation() public initializer {}
+
+  /**
+   * Utility function to transfer tokens to many addresses at once.
+   * @param recipients The addresses to send tokens to
+   * @param amount The amount of tokens to send
+   * @return Boolean if the transfer was a success
+   */
+  function transferBulk(
+    address[] calldata recipients,
+    uint256 amount
+  ) external returns (bool) {
+    address sender = _msgSender();
+
+    uint256 total = amount * recipients.length;
+    require(
+      _balances[sender] >= total,
+      "ERC20: transfer amount exceeds balance"
+    );
+
+    _balances[sender] -= total;
+
+    for (uint256 i = 0; i < recipients.length; ++i) {
+      address recipient = recipients[i];
+      require(recipient != address(0), "ERC20: transfer to the zero address");
+
+      // Note: _beforeTokenTransfer isn't called here
+      // This function emulates what it would do
+
+      _balances[recipient] += amount;
+
+      emit Transfer(sender, recipient, amount);
+    }
+
+    return true;
+  }
+
+  /**
+   * Utility function to transfer tokens to many addresses at once.
+   * @param sender The address to send the tokens from
+   * @param recipients The addresses to send tokens to
+   * @param amount The amount of tokens to send
+   * @return Boolean if the transfer was a success
+   */
+  function transferFromBulk(
+    address sender,
+    address[] calldata recipients,
+    uint256 amount
+  ) external returns (bool) {
+    uint256 total = amount * recipients.length;
+    require(
+      _balances[sender] >= total,
+      "ERC20: transfer amount exceeds balance"
+    );
+
+    // Ensure enough allowance
+    uint256 currentAllowance = _allowances[sender][_msgSender()];
+    require(
+      currentAllowance >= total,
+      "ERC20: transfer total exceeds allowance"
+    );
+    _approve(sender, _msgSender(), currentAllowance - total);
+
+    _balances[sender] -= total;
+
+    for (uint256 i = 0; i < recipients.length; ++i) {
+      address recipient = recipients[i];
+      require(recipient != address(0), "ERC20: transfer to the zero address");
+
+      // Note: _beforeTokenTransfer isn't called here
+      // This function emulates what it would do (paused and snapshot)
+
+      _balances[recipient] += amount;
+
+      emit Transfer(sender, recipient, amount);
+    }
+
+    return true;
+  }
+
+  function _beforeTokenTransfer(
+    address from,
+    address to,
+    uint256 amount
+  )
+    internal
+    virtual
+    override(
+      ERC20PausableUpgradeable,
+      ERC20SnapshotUpgradeable,
+      ERC20Upgradeable
+    )
+  {
+    super._beforeTokenTransfer(from, to, amount);
+  }
+
+  function _transfer(
+    address from,
+    address to,
+    uint256 amount
+  ) internal override {
+    super._transfer(from, to, amount);
+
+    if (to == address(this)) {
+      _burn(to, amount);
+    }
+  }
+}