// Contract: MerkleDistributor
// Target function: function verifyClaim(Claim memory _claim) public view returns (bool valid)
leaves` array, then goes onto the
        // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
        // the merkle tree.
        uint256 leavesLen = leaves.length;
        uint256 totalHashes = proofFlags.length;

        // Check proof validity.
        require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");

        // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
        // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
        bytes32[] memory hashes = new bytes32[](totalHashes);
        uint256 leafPos = 0;
        uint256 hashPos = 0;
        uint256 proofPos = 0;
        // At each step, we compute the next hash using two values:
        // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
        //   get the next hash.
        // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
        //   `proof` array.
        for (uint256 i = 0; i < totalHashes; i++) {
            bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
            bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
            hashes[i] = _hashPair(a, b);
        }

        if (totalHashes > 0) {
            return hashes[totalHashes - 1];
        } else if (leavesLen > 0) {
            return leaves[0];
        } else {
            return proof[0];
        }
    }

    /**
     * @dev Calldata version of {processMultiProof}.
     *
     * CAUTION: Not all merkle trees admit multiproofs. See {processMultiProof} for details.
     *
     * _Available since v4.7._
     */
    function processMultiProofCalldata(
        bytes32[] calldata proof,
        bool[] calldata proofFlags,
        bytes32[] memory leaves
    ) internal pure returns (bytes32 merkleRoot) {
        // This function rebuild the root hash by traversing the tree up from the leaves. The root is rebuilt by
        // consuming and producing values on a queue. The queue starts with the `leaves` array, then goes onto the
        // `hashes` array. At the end of the process, the last hash in the `hashes` array should contain the root of
        // the merkle tree.
        uint256 leavesLen = leaves.length;
        uint256 totalHashes = proofFlags.length;

        // Check proof validity.
        require(leavesLen + proof.length - 1 == totalHashes, "MerkleProof: invalid multiproof");

        // The xxxPos values are "pointers" to the next value to consume in each array. All accesses are done using
        // `xxx[xxxPos++]`, which return the current value and increment the pointer, thus mimicking a queue's "pop".
        bytes32[] memory hashes = new bytes32[](totalHashes);
        uint256 leafPos = 0;
        uint256 hashPos = 0;
        uint256 proofPos = 0;
        // At each step, we compute the next hash using two values:
        // - a value from the "main queue". If not all leaves have been consumed, we get the next leaf, otherwise we
        //   get the next hash.
        // - depending on the flag, either another value for the "main queue" (merging branches) or an element from the
        //   `proof` array.
        for (uint256 i = 0; i < totalHashes; i++) {
            bytes32 a = leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++];
            bytes32 b = proofFlags[i] ? leafPos < leavesLen ? leaves[leafPos++] : hashes[hashPos++] : proof[proofPos++];
            hashes[i] = _hashPair(a, b);
        }

        if (totalHashes > 0) {
            return hashes[totalHashes - 1];
        } else if (leavesLen > 0) {
            return leaves[0];
        } else {
            return proof[0];
        }
    }

    function _hashPair(bytes32 a, bytes32 b) private pure returns (bytes32) {
        return a < b ? _efficientHash(a, b) : _efficientHash(b, a);
    }

    function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, a)
            mstore(0x20, b)
            value := keccak256(0x00, 0x40)
        }
    }
}

// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// -> Forked from https://github.com/UMAprotocol/protocol/blob/master/packages/core/contracts/merkle-distributor/implementation/MerkleDistributor.sol

/**
 * @notice Concise list of functions in MerkleDistributor implementation that would be called by
 * a consuming external contract (such as the Across Protocol's AcceleratingDistributor).
 */
interface IMerkleDistributor {
    // A Window maps a Merkle root to a reward token address.
    struct Window {
        // Merkle root describing the distribution.
        bytes32 merkleRoot;
        // Remaining amount of deposited rewards that have not yet been claimed.
        uint256 remainingAmount;
        // Currency in which reward is processed.
        IERC20 rewardToken;
        // IPFS hash of the merkle tree. Can be used to independently fetch recipient proofs and tree. Note that the canonical
        // data type for storing an IPFS hash is a multihash which is the concatenation of  <varint hash function code>
        // <varint digest size in bytes><hash function output>. We opted to store this in a string type to make it easier
        // for users to query the ipfs data without needing to reconstruct the multihash. to view the IPFS data simply
        // go to https://cloudflare-ipfs.com/ipfs/<IPFS-HASH>.
        string ipfsHash;
    }

    // Represents an account's claim for `amount` within the Merkle root located at the `windowIndex`.
    struct Claim {
        uint256 windowIndex;
        uint256 amount;
        uint256 accountIndex; // Used only for bitmap. Assumed to be unique for each claim.
        address account;
        bytes32[] merkleProof;
    }

    function claim(Claim memory _claim) external;

    function claimMulti(Claim[] memory claims) external;

    function getRewardTokenForWindow(uint256 windowIndex) external view returns (address);
}

// -> Forked from https://github.com/UMAprotocol/protocol/blob/master/packages/core/contracts/merkle-distributor/implementation/MerkleDistributor.sol

/**
 * Inspired by:
 * - https://github.com/pie-dao/vested-token-migration-app
 * - https://github.com/Uniswap/merkle-distributor
 * - https://github.com/balancer-labs/erc20-redeemable
 *
 * @title  MerkleDistributor contract.
 * @notice Allows an owner to distribute any reward ERC20 to claimants according to Merkle roots. The owner can specify
 *         multiple Merkle roots distributions with customized reward currencies.
 * @dev    The Merkle trees are not validated in any way, so the system assumes the contract owner behaves honestly.
 */
contract MerkleDistributor is IMerkleDistributor, Ownable {
    using SafeERC20 for IERC20;

    // Windows are mapped to arbitrary indices.
    mapping(uint256 => Window) public merkleWindows;

    // Index of next created Merkle root.
    uint256 public nextCreatedIndex;

    // Track which accounts have claimed for each window index.
    // Note: uses a packed array of bools for gas optimization on tracking certain claims. Copied from Uniswap's contract.
    mapping(uint256 => mapping(uint256 => uint256)) private claimedBitMap;

    /**
     *
     *                EVENTS
     *
     */
    event Claimed(
        address indexed caller,
        uint256 windowIndex,
        address indexed account,
        uint256 accountIndex,
        uint256 amount,
        address indexed rewardToken
    );
    event CreatedWindow(
        uint256 indexed windowIndex, uint256 rewardsDeposited, address indexed rewardToken, address owner
    );
    event WithdrawRewards(address indexed owner, uint256 amount, address indexed currency);
    event DeleteWindow(uint256 indexed windowIndex, address owner);

    /**
     *
     *      ADMIN FUNCTIONS
     *
     */

    /**
     * @notice Set merkle root for the next available window index and seed allocations.
     * @notice Callable only by owner of this contract. Caller must have approved this contract to transfer
     *      `rewardsToDeposit` amount of `rewardToken` or this call will fail. Importantly, we assume that the
     *      owner of this contract correctly chooses an amount `rewardsToDeposit` that is sufficient to cover all
     *      claims within the `merkleRoot`.
     * @param rewardsToDeposit amount of rewards to deposit to seed this allocation.
     * @param rewardToken ERC20 reward token.
     * @param merkleRoot merkle root describing allocation.
     * @param ipfsHash hash of IPFS object, conveniently stored for clients
     */
    function setWindow(uint256 rewardsToDeposit, address rewardToken, bytes32 merkleRoot, string calldata ipfsHash)
        external
        onlyOwner
    {
        uint256 indexToSet = nextCreatedIndex;
        nextCreatedIndex = indexToSet + 1;

        _setWindow(indexToSet, rewardsToDeposit, rewardToken, merkleRoot, ipfsHash);
    }

    /**
     * @notice Delete merkle root at window index.
     * @dev Callable only by owner. Likely to be followed by a withdrawRewards call to clear contract state.
     * @param windowIndex merkle root index to delete.
     */
    function deleteWindow(uint256 windowIndex) external onlyOwner {
        delete merkleWindows[windowIndex];
        emit DeleteWindow(windowIndex, msg.sender);
    }

    /**
     * @notice Emergency method that transfers rewards out of the contract if the contract was configured improperly.
     * @dev Callable only by owner.
     * @param rewardCurrency rewards to withdraw from contract.
     * @param amount amount of rewards to withdraw.
     */
    function withdrawRewards(IERC20 rewardCurrency, uint256 amount) external onlyOwner {
        rewardCurrency.safeTransfer(msg.sender, amount);
        emit WithdrawRewards(msg.sender, amount, address(rewardCurrency));
    }

    /**
     *
     *    NON-ADMIN FUNCTIONS
     *
     */

    /**
     * @notice Batch claims to reduce gas versus individual submitting all claims. Method will fail
     *         if any individual claims within the batch would fail.
     * @dev    Optimistically tries to batch together consecutive claims for the same account and same
     *         reward token to reduce gas. Therefore, the most gas-cost-optimal way to use this method
     *         is to pass in an array of claims sorted by account and reward currency. It also reverts
     *         when any of individual `_claim`'s `amount` exceeds `remainingAmount` for its window.
     * @param claims array of claims to claim.
     */
    function claimMulti(Claim[] memory claims) public virtual override {
        uint256 batchedAmount;
        uint256 claimCount = claims.length;
        for (uint256 i = 0; i < claimCount; i++) {
            Claim memory _claim = claims[i];
            _verifyAndMarkClaimed(_claim);
            batchedAmount += _claim.amount;

            // If the next claim is NOT the same account or the same token (or this claim is the last one),
            // then disburse the `batchedAmount` to the current claim's account for the current claim's reward token.
            uint256 nextI = i + 1;
            IERC20 currentRewardToken = merkleWindows[_claim.windowIndex].rewardToken;
            if (
                nextI == claimCount
                // This claim is last claim.
                || claims[nextI].account != _claim.account
                // Next claim account is different than current one.
                || merkleWindows[claims[nextI].windowIndex].rewardToken != currentRewardToken
            ) {
                // Next claim reward token is different than current one.

                currentRewardToken.safeTransfer(_claim.account, batchedAmount);
                batchedAmount = 0;
            }
        }
    }

    /**
     * @notice Claim amount of reward tokens for account, as described by Claim input object.
     * @dev    If the `_claim`'s `amount`, `accountIndex`, and `account` do not exactly match the
     *         values stored in the merkle root for the `_claim`'s `windowIndex` this method
     *         will revert. It also reverts when `_claim`'s `amount` exceeds `remainingAmount` for the window.
     * @param _claim claim object describing amount, accountIndex, account, window index, and merkle proof.
     */
    function claim(Claim memory _claim) public virtual override {
        _verifyAndMarkClaimed(_claim);
        merkleWindows[_claim.windowIndex].rewardToken.safeTransfer(_claim.account, _claim.amount);
    }

    /**
     * @notice Returns True if the claim for `accountIndex` has already been completed for the Merkle root at
     *         `windowIndex`.
     * @dev    This method will only work as intended if all `accountIndex`'s are unique for a given `windowIndex`.
     *         The onus is on the Owner of this contract to submit only valid Merkle roots.
     * @param windowIndex merkle root to check.
     * @param accountIndex account index to check within window index.
     * @return True if claim has been executed already, False otherwise.
     */
    function isClaimed(uint256 windowIndex, uint256 accountIndex) public view returns (bool) {
        uint256 claimedWordIndex = accountIndex / 256;
        uint256 claimedBitIndex = accountIndex % 256;
        uint256 claimedWord = claimedBitMap[windowIndex][claimedWordIndex];
        uint256 mask = (1 << claimedBitIndex);
        return claimedWord & mask == mask;
    }

    /**
     * @notice Returns rewardToken set by admin for windowIndex.
     * @param windowIndex merkle root to check.
     * @return address Reward token address
     */
    function getRewardTokenForWindow(uint256 windowIndex) public view override returns (address) {
        return address(merkleWindows[windowIndex].rewardToken);
    }