[wip] Add exploratory xGNANA contracts

contracts/xGNANA.sol

@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-3.0-only
+pragma solidity 0.8.17;
+
+/*
+  ______                     ______                                 
+ /      \                   /      \                                
+|  ▓▓▓▓▓▓\ ______   ______ |  ▓▓▓▓▓▓\__   __   __  ______   ______  
+| ▓▓__| ▓▓/      \ /      \| ▓▓___\▓▓  \ |  \ |  \|      \ /      \ 
+| ▓▓    ▓▓  ▓▓▓▓▓▓\  ▓▓▓▓▓▓\\▓▓    \| ▓▓ | ▓▓ | ▓▓ \▓▓▓▓▓▓\  ▓▓▓▓▓▓\
+| ▓▓▓▓▓▓▓▓ ▓▓  | ▓▓ ▓▓    ▓▓_\▓▓▓▓▓▓\ ▓▓ | ▓▓ | ▓▓/      ▓▓ ▓▓  | ▓▓
+| ▓▓  | ▓▓ ▓▓__/ ▓▓ ▓▓▓▓▓▓▓▓  \__| ▓▓ ▓▓_/ ▓▓_/ ▓▓  ▓▓▓▓▓▓▓ ▓▓__/ ▓▓
+| ▓▓  | ▓▓ ▓▓    ▓▓\▓▓     \\▓▓    ▓▓\▓▓   ▓▓   ▓▓\▓▓    ▓▓ ▓▓    ▓▓
+ \▓▓   \▓▓ ▓▓▓▓▓▓▓  \▓▓▓▓▓▓▓ \▓▓▓▓▓▓  \▓▓▓▓▓\▓▓▓▓  \▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓ 
+         | ▓▓                                             | ▓▓      
+         | ▓▓                                             | ▓▓      
+          \▓▓                                              \▓▓         
+ * App:             https://ApeSwap.finance
+ * Medium:          https://ape-swap.medium.com
+ * Twitter:         https://twitter.com/ape_swap
+ * Telegram:        https://t.me/ape_swap
+ * Announcements:   https://t.me/ape_swap_news
+ * Reddit:          https://reddit.com/r/ApeSwap
+ * Instagram:       https://instagram.com/ApeSwap.finance
+ * GitHub:          https://github.com/ApeSwapFinance
+ */
+
+import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import "@openzeppelin/contracts/token/ERC20/extensions/draft-ERC20Permit.sol";
+import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Votes.sol";
+
+interface IxToken {
+    event Redeem(address indexed to, uint256 xGnanaAmount, uint256 gnanaAmount);
+    event Deposit(address indexed from, uint256 xGnanaAmount, uint256 gnanaActualAmount);
+
+    function exchangeRate() external returns (uint256);
+    function redeem(uint256 amount) external;
+    function deposit(uint256 amount) external;
+}
+
+contract xGNANA is IxToken, ERC20, ERC20Permit, ERC20Votes {
+    using SafeERC20 for ERC20;
+
+    ERC20 public immutable gnana;
+    mapping(address => address) private _delegates;
+
+
+    constructor(ERC20 gnana_) ERC20("X Golden Banana", "xGNANA") ERC20Permit("X Golden Banana") {
+        gnana = gnana_;
+    }
+
+    function gnanaBalance() public view returns (uint256) {
+        return gnana.balanceOf(address(this));
+    }
+
+    function exchangeRate() public view returns (uint256) {
+        return gnanaBalance() * 1e18 / totalSupply();
+    }
+
+    function redeem(uint256 xGnanaAmount) external {
+        uint256 gnanaAmount = (xGnanaAmount * exchangeRate()) / 1e18;
+        _burn(msg.sender, xGnanaAmount);
+        gnana.safeTransfer(msg.sender, gnanaAmount);
+        emit Redeem(msg.sender, xGnanaAmount, gnanaAmount); 
+    }
+
+    function deposit(uint256 gnanaGrossAmount) external {
+        uint256 currentExchangeRate = exchangeRate();
+        uint256 gnanaActualAmount = _transferGnanaFrom(msg.sender, gnanaGrossAmount);
+
+        uint256 xGnanaAmount = (gnanaActualAmount * 1e18) / currentExchangeRate;
+        _mint(msg.sender, xGnanaAmount);
+        emit Deposit(msg.sender, xGnanaAmount, gnanaActualAmount); 
+    }
+
+    function _transferGnanaFrom(address from, uint256 gnanaGrossAmount) internal returns (uint256 gnanaActualAmount) {
+        uint256 previousGnanaBalance = gnanaBalance();
+        gnana.safeTransferFrom(from, address(this), gnanaGrossAmount);
+        gnanaActualAmount = gnanaBalance() - previousGnanaBalance;
+    }
+
+    /**
+     * @dev Override _transfer and prevent transferability.
+     */
+    function _transfer(
+        address from,
+        address to,
+        uint256 amount
+    ) internal pure override(ERC20) {
+        revert("xGNANA is non-transferrable");
+    }
+
+    // The following functions are overrides required by Solidity.
+
+    function _afterTokenTransfer(address from, address to, uint256 amount)
+        internal
+        virtual
+        override(ERC20, ERC20Votes)
+    {
+        super._afterTokenTransfer(from, to, amount);
+    }
+
+    function _mint(address to, uint256 amount)
+        internal
+        override(ERC20, ERC20Votes)
+    {
+        super._mint(to, amount);
+    }
+
+    function _burn(address account, uint256 amount)
+        internal
+        override(ERC20, ERC20Votes)
+    {
+        super._burn(account, amount);
+    }
+}

contracts/xGNANABribes.sol

@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-3.0-only
+pragma solidity 0.8.17;
+
+/*
+  ______                     ______                                 
+ /      \                   /      \                                
+|  ▓▓▓▓▓▓\ ______   ______ |  ▓▓▓▓▓▓\__   __   __  ______   ______  
+| ▓▓__| ▓▓/      \ /      \| ▓▓___\▓▓  \ |  \ |  \|      \ /      \ 
+| ▓▓    ▓▓  ▓▓▓▓▓▓\  ▓▓▓▓▓▓\\▓▓    \| ▓▓ | ▓▓ | ▓▓ \▓▓▓▓▓▓\  ▓▓▓▓▓▓\
+| ▓▓▓▓▓▓▓▓ ▓▓  | ▓▓ ▓▓    ▓▓_\▓▓▓▓▓▓\ ▓▓ | ▓▓ | ▓▓/      ▓▓ ▓▓  | ▓▓
+| ▓▓  | ▓▓ ▓▓__/ ▓▓ ▓▓▓▓▓▓▓▓  \__| ▓▓ ▓▓_/ ▓▓_/ ▓▓  ▓▓▓▓▓▓▓ ▓▓__/ ▓▓
+| ▓▓  | ▓▓ ▓▓    ▓▓\▓▓     \\▓▓    ▓▓\▓▓   ▓▓   ▓▓\▓▓    ▓▓ ▓▓    ▓▓
+ \▓▓   \▓▓ ▓▓▓▓▓▓▓  \▓▓▓▓▓▓▓ \▓▓▓▓▓▓  \▓▓▓▓▓\▓▓▓▓  \▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓ 
+         | ▓▓                                             | ▓▓      
+         | ▓▓                                             | ▓▓      
+          \▓▓                                              \▓▓         
+ * App:             https://ApeSwap.finance
+ * Medium:          https://ape-swap.medium.com
+ * Twitter:         https://twitter.com/ape_swap
+ * Telegram:        https://t.me/ape_swap
+ * Announcements:   https://t.me/ape_swap_news
+ * Reddit:          https://reddit.com/r/ApeSwap
+ * Instagram:       https://instagram.com/ApeSwap.finance
+ * GitHub:          https://github.com/ApeSwapFinance
+ */
+
+import "./xGNANA.sol";
+import "@openzeppelin/contracts/utils/structs/EnumerableSet.sol";
+import "@openzeppelin/contracts/access/AccessControlEnumerable.sol";
+
+/**
+    // TODO: Possible features
+    - [x] AccessControl to be able to whitelist IERC20VotesDelegatee from factory contracts
+    - [ ] Factory contract which can deploy bribe contracts with the callback functions below 
+    - [ ] Relevant events
+    - [ ] NatSpec comments
+    - [ ] Some ability to accumulate non GNANA revenue
+          - I would say that my argument still applies that we should perform buy backs at strategic points when there is high value
+             Is there a way we could mix in like stable revenue and with GNANA for xGNANA holders? 
+
+    - [x] Provide an admin role to be able to add new white listers
+    - [x] Be able to remove delegatee contracts
+ */
+
+import "@openzeppelin/contracts/utils/introspection/IERC165.sol";
+interface IERC20VotesDelegatee is IERC165 {
+    function syncDelegatePower(address delegator) external;
+}
+
+/**
+ * The intent here is that a factory contract could be used to deploy bridge contracts
+ * where a protocol can fill up with tokens and distribute tokens to xGNANA holders who 
+ * delegate their voting power.
+ */
+interface IxTokenWithBribes {
+    event CallbackDelegateRegistered(IERC20VotesDelegatee indexed delegatee);
+    event CallbackDelegateRemoved(IERC20VotesDelegatee indexed delegatee);
+    function syncDelegateVotingPower(address delegator, address delegatee, bool withRevert) external;
+    function registerCallbackDelegatee(IERC20VotesDelegatee delegateeContract) external;
+    function removeCallbackDelegatee(IERC20VotesDelegatee delegateeContract) external;
+    function getVotesDelegatedTo(address delegator, address delegatee) external returns (uint256);
+}
+
+contract xGNANABribes is IxTokenWithBribes, xGNANA, AccessControlEnumerable {
+    // NOTE: example https://github.com/ApeSwapFinance/apeswap-pool-factory/blob/f24fb874a9f70cedcfadeecd4a6ddacb45ee9752/contracts/PoolManager.sol
+    using EnumerableSet for EnumerableSet.AddressSet;
+
+    EnumerableSet.AddressSet private _registeredCallbackDelegatees;
+
+    bytes32 public constant DELEGATEE_MANAGER_ROLE = keccak256("DELEGATEE_MANAGER_ROLE");
+
+    constructor(ERC20 gnana_, address admin_) xGNANA(gnana_) {
+        _grantRole(DEFAULT_ADMIN_ROLE, admin_);
+        _setRoleAdmin(DELEGATEE_MANAGER_ROLE, DEFAULT_ADMIN_ROLE);
+    }
+
+    function syncDelegateVotingPower(address delegator, address delegatee, bool withRevert) public {
+        bool synced = _syncDelegateVotingPower(delegator, delegatee);
+        if(withRevert && !synced) {
+            revert("delegatee not registered");
+        }
+    }
+
+    function getRegisteredCallbackDelegateesCount() external view returns (uint256) {
+        return _registeredCallbackDelegatees.length();
+    }
+
+    function getRegisteredCallbackDelegateesAt(uint256 index) external view returns (address) {
+        return _registeredCallbackDelegatees.at(index);
+    }
+
+    function getAllRegisteredCallbackDelegatees() external view returns (address[] memory) {
+        return _registeredCallbackDelegatees.values();
+    }
+
+    function registerCallbackDelegatee(IERC20VotesDelegatee callbackDelegatee) external override onlyRole(DELEGATEE_MANAGER_ROLE) {
+        require(callbackDelegatee.supportsInterface(type(IERC20VotesDelegatee).interfaceId), "Does not support interface");
+        if(!_registeredCallbackDelegatees.contains(address(callbackDelegatee))) {
+            _registeredCallbackDelegatees.add(address(callbackDelegatee));
+            emit CallbackDelegateRegistered(callbackDelegatee);
+        }
+    }
+
+    function removeCallbackDelegatee(IERC20VotesDelegatee callbackDelegatee) external override onlyRole(DEFAULT_ADMIN_ROLE) {
+        require(_registeredCallbackDelegatees.contains(address(callbackDelegatee)), "not registered");
+        _registeredCallbackDelegatees.remove(address(callbackDelegatee));
+        emit CallbackDelegateRemoved(callbackDelegatee);
+    }
+
+    function getVotesDelegatedTo(address delegator, address delegatee) external view override returns (uint256) {
+        address currentDelegatee = delegates(delegator);
+        if(currentDelegatee == delegatee) {
+            return balanceOf(delegator);
+        } else {
+            return 0;
+        }
+    }
+
+    /**
+     * @dev This hook is called after _mint and _burn even though
+     *  xGNANA is non-transferrable
+     */
+    function _afterTokenTransfer(
+        address from,
+        address to,
+        uint256 amount
+    ) internal override(xGNANA) {
+        super._afterTokenTransfer(from, to, amount);
+        // After balances are updated, sync external 
+        _syncDelegateVotingPower(delegates(from), from);
+        _syncDelegateVotingPower(delegates(to), to);
+    }
+
+    /**
+     * @dev Change delegation for `delegator` to `delegatee`.
+     *
+     * Sync delegation power with external delegation contract for bribes.
+     */
+    function _delegate(address delegator, address delegatee) internal override(ERC20Votes) {
+        address fromDelegate = delegates(delegator);
+        super._delegate(delegator, delegatee);
+
+        _syncDelegateVotingPower(fromDelegate, delegator);
+        _syncDelegateVotingPower(delegatee, delegator);
+    }
+
+    function _syncDelegateVotingPower(address delegator, address delegatee) internal returns (bool){
+        if(_registeredCallbackDelegatees.contains(delegatee)) {
+            IERC20VotesDelegatee(delegatee).syncDelegatePower(delegator);
+            return true;
+        } else {
+            return false;
+        }
+    }
+}