refactor(NODLMigration): prepare to create GrantsMigration (#45)

src/bridge/BridgeBase.sol

@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: BSD-3-Clause-Clear
+
+pragma solidity 0.8.23;
+
+import {NODL} from "../NODL.sol";
+
+/// @title BridgeBase
+/// @notice Abstract contract for bridging free or vested tokens with the help of oracles.
+/// @dev This contract provides basic functionalities for voting on proposals
+/// to bridge tokens and ensuring certain constraints such as voting thresholds and delays.
+abstract contract BridgeBase {
+    /// @notice Token contract address for the NODL token.
+    NODL public nodl;
+
+    /// @notice Mapping to track whether an address is an oracle.
+    mapping(address => bool) public isOracle;
+
+    /// @notice Minimum number of votes needed to execute a proposal.
+    uint8 public threshold;
+
+    /// @notice Number of blocks to delay before a proposal can be executed after reaching the voting threshold.
+    uint256 public delay;
+
+    /// @notice Maximum number of oracles allowed.
+    uint8 public constant MAX_ORACLES = 10;
+
+    /// @notice Mapping of oracles to proposals to track which oracle has voted on which proposal.
+    mapping(address => mapping(bytes32 => bool)) public voted;
+
+    /// @notice Emitted when the first vote a proposal has been cast.
+    event VoteStarted(bytes32 indexed proposal, address oracle, address indexed user, uint256 amount);
+
+    /// @notice Emitted when an oracle votes on a proposal which is already created.
+    event Voted(bytes32 indexed proposal, address oracle);
+
+    /// @notice Error to indicate an oracle has already voted on a proposal.
+    error AlreadyVoted(bytes32 proposal, address oracle);
+
+    /// @notice Error to indicate a proposal has already been executed.
+    error AlreadyExecuted(bytes32 proposal);
+
+    /// @notice Error to indicate parameters of a proposal have been changed after initiation.
+    error ParametersChanged(bytes32 proposal);
+
+    /// @notice Error to indicate an address is not recognized as an oracle.
+    error NotAnOracle(address user);
+
+    /// @notice Error to indicate it's too soon to execute a proposal.
+    /// Please note `withdraw` here refers to a function for free tokens where they are minted for the user.
+    /// We have kept the name for API compatibility.
+    error NotYetWithdrawable(bytes32 proposal);
+
+    /// @notice Error to indicate insufficient votes to execute a proposal.
+    error NotEnoughVotes(bytes32 proposal);
+
+    /// @notice Error to indicate that the number of oracles exceeds the allowed maximum.
+    error MaxOraclesExceeded();
+
+    /// @notice Initializes the contract with specified parameters.
+    /// @param bridgeOracles Array of oracle accounts.
+    /// @param token Contract address of the NODL token.
+    /// @param minVotes Minimum required votes to consider a proposal valid.
+    /// @param minDelay Blocks to wait before a passed proposal can be executed.
+    constructor(address[] memory bridgeOracles, NODL token, uint8 minVotes, uint256 minDelay) {
+        require(bridgeOracles.length >= minVotes, "Not enough oracles");
+        require(minVotes > 0, "Votes must be more than zero");
+
+        _mustNotExceedMaxOracles(bridgeOracles.length);
+
+        for (uint256 i = 0; i < bridgeOracles.length; i++) {
+            isOracle[bridgeOracles[i]] = true;
+        }
+
+        nodl = token;
+        threshold = minVotes;
+        delay = minDelay;
+    }
+
+    /// @notice Creates a new vote on a proposal.
+    /// @dev Sets initial values and emits a VoteStarted event.
+    /// @param proposal The hash identifier of the proposal.
+    /// @param oracle The oracle address initiating the vote.
+    /// @param user The user address associated with the vote.
+    /// @param amount The amount of tokens being bridged.
+    function _createVote(bytes32 proposal, address oracle, address user, uint256 amount) internal virtual {
+        _mustNotHaveVotedYet(proposal, oracle);
+
+        voted[oracle][proposal] = true;
+        _incTotalVotes(proposal);
+        _updateLastVote(proposal, block.number);
+        emit VoteStarted(proposal, oracle, user, amount);
+    }
+
+    /// @notice Records a vote for a proposal by an oracle.
+    /// @param proposal The hash identifier of the proposal.
+    /// @param oracle The oracle casting the vote.
+    function _recordVote(bytes32 proposal, address oracle) internal virtual {
+        _mustNotHaveVotedYet(proposal, oracle);
+
+        voted[oracle][proposal] = true;
+        _incTotalVotes(proposal);
+        _updateLastVote(proposal, block.number);
+        emit Voted(proposal, oracle);
+    }
+
+    /// @notice Executes a proposal after all conditions are met.
+    /// @param proposal The hash identifier of the proposal.
+    function _execute(bytes32 proposal) internal {
+        _mustNotHaveExecutedYet(proposal);
+        _mustHaveEnoughVotes(proposal);
+        _mustBePastSafetyDelay(proposal);
+
+        _flagAsExecuted(proposal);
+    }
+
+    /**
+     * @dev Updates the last vote value for a given proposal.
+     * @param proposal The identifier of the proposal.
+     * @param value The new value for the last vote.
+     */
+    function _updateLastVote(bytes32 proposal, uint256 value) internal virtual;
+
+    /**
+     * @dev Increments the total votes count for a given proposal.
+     * @param proposal The identifier of the proposal.
+     */
+    function _incTotalVotes(bytes32 proposal) internal virtual;
+
+    /**
+     * @dev Flags a proposal as executed.
+     * @param proposal The identifier of the proposal.
+     */
+    function _flagAsExecuted(bytes32 proposal) internal virtual;
+
+    /**
+     * @dev Retrieves the last vote value for a given proposal.
+     * @param proposal The identifier of the proposal.
+     * @return The last vote value.
+     */
+    function _lastVote(bytes32 proposal) internal view virtual returns (uint256);
+
+    /**
+     * @dev Retrieves the total votes count for a given proposal.
+     * @param proposal The identifier of the proposal.
+     * @return The total votes count.
+     */
+    function _totalVotes(bytes32 proposal) internal view virtual returns (uint8);
+
+    /**
+     * @dev Checks if a proposal has been executed.
+     * @param proposal The identifier of the proposal.
+     * @return A boolean indicating if the proposal has been executed.
+     */
+    function _executed(bytes32 proposal) internal view virtual returns (bool);
+
+    function _mustNotHaveExecutedYet(bytes32 proposal) internal view {
+        if (_executed(proposal)) {
+            revert AlreadyExecuted(proposal);
+        }
+    }
+
+    function _mustBePastSafetyDelay(bytes32 proposal) internal view {
+        if (block.number - _lastVote(proposal) < delay) {
+            revert NotYetWithdrawable(proposal);
+        }
+    }
+
+    function _mustHaveEnoughVotes(bytes32 proposal) internal view {
+        if (_totalVotes(proposal) < threshold) {
+            revert NotEnoughVotes(proposal);
+        }
+    }
+
+    function _mustBeAnOracle(address maybeOracle) internal view {
+        if (!isOracle[maybeOracle]) {
+            revert NotAnOracle(maybeOracle);
+        }
+    }
+
+    function _mustNotExceedMaxOracles(uint256 length) internal pure {
+        if (length > MAX_ORACLES) {
+            revert MaxOraclesExceeded();
+        }
+    }
+
+    function _mustNotHaveVotedYet(bytes32 proposal, address oracle) internal view {
+        if (voted[oracle][proposal]) {
+            revert AlreadyVoted(proposal, oracle);
+        }
+    }
+}

src/bridge/NODLMigration.sol

@@ -3,11 +3,12 @@
 pragma solidity 0.8.23;
 
 import {NODL} from "../NODL.sol";
+import {BridgeBase} from "./BridgeBase.sol";
 
 /// @title NODLMigration
 /// @notice This contract is used to help migrating the NODL assets from the Nodle Parachain
 /// to the ZkSync contracts.
-contract NODLMigration {
+contract NODLMigration is BridgeBase {
     struct Proposal {
         address target;
         uint256 amount;
@@ -16,43 +17,15 @@ contract NODLMigration {
         bool executed;
     }
 
-    NODL public nodl;
-    mapping(address => bool) public isOracle;
-    uint8 public threshold;
-    uint256 public delay;
-
     // We track votes in a seperate mapping to avoid having to write helper functions to
     // expose the votes for each proposal.
     mapping(bytes32 => Proposal) public proposals;
-    mapping(address => mapping(bytes32 => bool)) public voted;
-
-    error AlreadyVoted(bytes32 proposal, address oracle);
-    error AlreadyExecuted(bytes32 proposal);
-    error ParametersChanged(bytes32 proposal);
-    error NotAnOracle(address user);
-    error NotYetWithdrawable(bytes32 proposal);
-    error NotEnoughVotes(bytes32 proposal);
 
-    event VoteStarted(bytes32 indexed proposal, address oracle, address indexed user, uint256 amount);
-    event Voted(bytes32 indexed proposal, address oracle);
     event Withdrawn(bytes32 indexed proposal, address indexed user, uint256 amount);
 
-    /// @param bridgeOracles Array of oracle accounts that will be able to bridge the tokens.
-    /// @param token Contract address of the NODL token.
-    /// @param minVotes Minimum number of votes required to bridge the tokens. This needs to be
-    /// less than or equal to the number of oracles and is expected to be above 1.
-    /// @param minDelay Minimum delay in blocks before bridged tokens can be minted.
-    constructor(address[] memory bridgeOracles, NODL token, uint8 minVotes, uint256 minDelay) {
-        assert(bridgeOracles.length >= minVotes);
-        assert(minVotes > 0);
-
-        for (uint256 i = 0; i < bridgeOracles.length; i++) {
-            isOracle[bridgeOracles[i]] = true;
-        }
-        nodl = token;
-        threshold = minVotes;
-        delay = minDelay;
-    }
+    constructor(address[] memory bridgeOracles, NODL token, uint8 minVotes, uint256 minDelay)
+        BridgeBase(bridgeOracles, token, minVotes, minDelay)
+    {}
 
     /// @notice Bridge some tokens from the Nodle Parachain to the ZkSync contracts. This
     /// tracks "votes" from each oracle and unlocks execution after a withdrawal delay.
@@ -76,76 +49,52 @@ contract NODLMigration {
     /// proposal has enough votes and has passed the safety delay.
     /// @param paraTxHash The transaction hash on the Parachain for this transfer.
     function withdraw(bytes32 paraTxHash) external {
-        _mustNotHaveExecutedYet(paraTxHash);
-        _mustHaveEnoughVotes(paraTxHash);
-        _mustBePastSafetyDelay(paraTxHash);
-
+        _execute(paraTxHash);
         _withdraw(paraTxHash, proposals[paraTxHash].target, proposals[paraTxHash].amount);
     }
 
-    function _mustBeAnOracle(address maybeOracle) internal view {
-        if (!isOracle[maybeOracle]) {
-            revert NotAnOracle(maybeOracle);
-        }
-    }
-
-    function _mustNotHaveVotedYet(bytes32 proposal, address oracle) internal view {
-        if (voted[oracle][proposal]) {
-            revert AlreadyVoted(proposal, oracle);
-        }
-    }
-
-    function _mustNotHaveExecutedYet(bytes32 proposal) internal view {
-        if (proposals[proposal].executed) {
-            revert AlreadyExecuted(proposal);
-        }
-    }
-
     function _mustNotBeChangingParameters(bytes32 proposal, address user, uint256 amount) internal view {
         if (proposals[proposal].amount != amount || proposals[proposal].target != user) {
             revert ParametersChanged(proposal);
         }
     }
 
-    function _mustBePastSafetyDelay(bytes32 proposal) internal view {
-        if (block.number - proposals[proposal].lastVote < delay) {
-            revert NotYetWithdrawable(proposal);
-        }
-    }
-
-    function _mustHaveEnoughVotes(bytes32 proposal) internal view {
-        if (proposals[proposal].totalVotes < threshold) {
-            revert NotEnoughVotes(proposal);
-        }
-    }
-
     function _proposalExists(bytes32 proposal) internal view returns (bool) {
         return proposals[proposal].totalVotes > 0 && proposals[proposal].amount > 0;
     }
 
-    function _createVote(bytes32 proposal, address oracle, address user, uint256 amount) internal {
-        voted[oracle][proposal] = true;
+    function _createVote(bytes32 proposal, address oracle, address user, uint256 amount) internal override {
         proposals[proposal].target = user;
         proposals[proposal].amount = amount;
-        proposals[proposal].totalVotes = 1;
-        proposals[proposal].lastVote = block.number;
+        super._createVote(proposal, oracle, user, amount);
+    }
+
+    function _withdraw(bytes32 proposal, address user, uint256 amount) internal {
+        nodl.mint(user, amount);
+        emit Withdrawn(proposal, user, amount);
+    }
 
-        emit VoteStarted(proposal, oracle, user, amount);
+    function _flagAsExecuted(bytes32 proposal) internal override {
+        proposals[proposal].executed = true;
     }
 
-    function _recordVote(bytes32 proposal, address oracle) internal {
-        voted[oracle][proposal] = true;
-        // this is safe since we are unlikely to have maxUint8 oracles to manage
-        proposals[proposal].totalVotes += 1;
-        proposals[proposal].lastVote = block.number;
+    function _incTotalVotes(bytes32 proposal) internal override {
+        proposals[proposal].totalVotes++;
+    }
 
-        emit Voted(proposal, oracle);
+    function _updateLastVote(bytes32 proposal, uint256 value) internal override {
+        proposals[proposal].lastVote = value;
     }
 
-    function _withdraw(bytes32 proposal, address user, uint256 amount) internal {
-        proposals[proposal].executed = true;
-        nodl.mint(user, amount);
+    function _totalVotes(bytes32 proposal) internal view override returns (uint8) {
+        return proposals[proposal].totalVotes;
+    }
 
-        emit Withdrawn(proposal, user, amount);
+    function _lastVote(bytes32 proposal) internal view override returns (uint256) {
+        return proposals[proposal].lastVote;
+    }
+
+    function _executed(bytes32 proposal) internal view override returns (bool) {
+        return proposals[proposal].executed;
     }
 }