Contract Source Code:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {ReentrancyGuard} from "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
import {Pausable} from "@openzeppelin/contracts/utils/Pausable.sol";
import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {SafeERC20} from "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

/**
 * @title ShadowSettlement
 * @notice Privacy-preserving cross-chain settlement contract (EVM side)
 * @dev Bidirectional — acts as SOURCE (commitment storage) and DESTINATION (token release)
 *
 * ARCHITECTURE:
 * - Source side: Relayer batches commitments into Merkle tree for anonymity set
 * - Destination side: NEAR 1Click bridges tokens TO this contract via standard
 *   ERC20 transfer, then relayer verifies delivery and calls settleAndRelease
 * - Cross-chain sync: Stores remote chain Merkle roots for auditability
 * - Per-user view keys for private tracking (derived from wallet signature)
 *
 * TOKEN FLOW (when this chain is DESTINATION):
 * 1. User initiates swap on source chain → commitment stored in source Merkle tree
 * 2. User sends tokens to NEAR 1Click via unique depositAddress
 * 3. NEAR 1Click swaps + bridges → tokens arrive at THIS contract via standard ERC20 transfer
 * 4. Relayer polls NEAR status API → gets destinationChainTxHashes
 * 5. Relayer verifies Transfer event on-chain (correct amount to this contract)
 * 6. Relayer calls settleAndRelease(nullifier, recipient, token, amount)
 *    → Contract verifies nullifier, transfers ERC20 to user
 * 7. Relayer calls markSettled(commitment, nullifier) on SOURCE chain contract
 *
 * TRUST MODEL:
 * - Relayer trusted to verify NEAR delivery before releasing (centralized MVP)
 * - Relayer cannot double-spend (nullifier prevents)
 * - Relayer cannot release more than contract balance (safeTransfer reverts)
 * - Owner can pause in emergencies and manage relayers
 *
 * PRIVACY:
 * - View keys are NEVER exposed on-chain or in events
 * - NEAR intent IDs stored internally, not publicly queryable
 * - Commitment tree position not leaked in events
 * - Batch fill level not leaked in events
 * - settleAndRelease reveals recipient but NOT linked to source commitment
 *   (same model as Tornado Cash withdrawals)
 *
 * COMMITMENT FORMULA (enforced client-side):
 * Frontend MUST generate commitments as:
 *   commitment = keccak256(abi.encodePacked(secret, nullifier, amount, token, destChain))
 *
 * Including amount, token, and destChain prevents:
 * - Cross-swap attacks (same secret can't be reused for different amounts/chains)
 * - Commitment reuse across different swap parameters
 * - This is the industry standard (Tornado Cash, Aztec, etc.)
 *
 * Note: Contract does NOT validate the commitment formula (it's a hash).
 *       Security comes from frontend generating correctly + Merkle proof verification.
 */
contract ShadowSettlement is ReentrancyGuard, Ownable, Pausable {
    using SafeERC20 for IERC20;

    // ===== STRUCTS =====

    /// @dev Internal struct — never returned to external callers with viewKey
    struct Intent {
        bytes32 commitment;
        bytes32 nearIntentsId;
        bytes32 viewKey;
        uint64 submittedAt;
        bool settled;
    }

    /// @notice Public-safe intent data (no viewKey, no nearIntentsId)
    struct IntentPublic {
        bytes32 commitment;
        uint64 submittedAt;
        bool settled;
    }

    /// @notice Full intent data returned to view key holder
    struct IntentDetail {
        bytes32 commitment;
        bytes32 nearIntentsId;
        uint64 submittedAt;
        bool settled;
    }

    /// @notice Remote chain Merkle root snapshot
    struct RemoteRootSnapshot {
        bytes32 root;
        uint256 leafCount;
        uint64 syncedAt;
        bool verified;
    }

    // ===== STATE VARIABLES =====

    // --- Source side (commitment storage) ---

    /// @dev Internal — use getIntent() which strips sensitive fields
    mapping(bytes32 => Intent) internal intents;
    mapping(bytes32 => bool) public usedNullifiers;

    /// @dev Internal — only queryable by providing the correct view key
    mapping(bytes32 => bytes32[]) internal viewKeyToCommitments;

    uint256 public constant TREE_HEIGHT = 20;
    uint256 public nextLeafIndex;
    mapping(uint256 => bytes32) internal filledSubtrees;
    bytes32 public currentRoot;
    bytes32[TREE_HEIGHT] internal zeros;

    /// @dev Internal — tree position is privacy-sensitive
    mapping(bytes32 => uint256) internal commitmentToIndex;

    /// @dev Mapping-based batch avoids gas bomb on delete
    mapping(uint256 => bytes32) internal batchCommitments;
    mapping(uint256 => bytes32) internal batchNearIntentsIds;
    mapping(uint256 => bytes32) internal batchViewKeys;
    uint256 public batchCount;
    uint64 public batchFirstSubmissionTime;

    // --- Cross-chain sync ---

    /// @notice Remote chain identifier → root snapshot history
    /// @dev chainId examples: "starknet-mainnet", "starknet-sepolia"
    mapping(string => RemoteRootSnapshot[]) public remoteRootHistory;

    /// @notice Quick lookup: chainId → latest root index
    mapping(string => uint256) public latestRemoteRootIndex;

    /// @notice Trusted root verifiers (can mark roots as verified)
    mapping(address => bool) public rootVerifiers;

    // --- Destination side (token release) ---

    /// @notice Whitelisted tokens for settlement
    mapping(address => bool) public whitelistedTokens;

    // --- Config ---

    uint256 public batchSize;
    uint256 public batchTimeout;
    mapping(address => bool) public authorizedRelayers;

    // ===== CONSTANTS =====

    uint256 public constant MIN_BATCH_SIZE = 1;
    uint256 public constant MAX_BATCH_SIZE = 100;
    uint256 public constant DEFAULT_BATCH_SIZE = 10;
    uint256 public constant DEFAULT_TIMEOUT = 30;

    /// @notice Sentinel address representing native ETH (industry standard)
    address public constant ETH = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

    // ===== EVENTS =====

    // --- Source side events ---

    /// @notice Emits only commitment hash — no tree position, no batch info
    event CommitmentAdded(bytes32 indexed commitment);

    event BatchProcessed(
        uint256 indexed batchId,
        uint256 commitmentsCount,
        ProcessReason reason
    );

    event MerkleRootUpdated(bytes32 indexed newRoot);

    /// @notice Source-side: commitment marked settled after dest-side release
    event IntentMarkedSettled(
        bytes32 indexed nullifierHash,
        bytes32 indexed commitment,
        uint64 timestamp
    );

    // --- Cross-chain sync events ---

    event RemoteRootSynced(
        string indexed chainId,
        bytes32 indexed root,
        uint256 leafCount,
        uint256 snapshotIndex
    );

    event RemoteRootVerified(
        string indexed chainId,
        uint256 indexed snapshotIndex,
        address verifier
    );

    // --- Destination side events ---

    /// @notice Emitted when tokens are released to user
    /// @dev recipient is visible but NOT linked to source commitment on-chain
    event IntentSettled(
        bytes32 indexed intentId,
        bytes32 indexed nullifierHash,
        address token,
        uint256 amount,
        uint64 timestamp
    );

    // --- Admin events ---

    event BatchConfigUpdated(uint256 newBatchSize, uint256 newTimeout);
    event RelayerStatusChanged(address indexed relayer, bool authorized);
    event RootVerifierStatusChanged(address indexed verifier, bool authorized);
    event TokenWhitelistUpdated(address indexed token, bool whitelisted);

    // ===== ENUMS =====

    enum ProcessReason {
        BATCH_FULL,
        TIMEOUT_REACHED
    }

    // ===== ERRORS =====

    error Unauthorized();
    error InvalidBatchSize();
    error InvalidTimeout();
    error CommitmentExists();
    error CommitmentNotFound();
    error NullifierUsed();
    error BatchEmpty();
    error InvalidCommitment();
    error TreeFull();
    error TimeoutNotReached();
    error TokenNotWhitelisted();
    error InvalidAmount();
    error InvalidRecipient();
    error InvalidChainId();
    error InvalidRoot();
    error RootAlreadyVerified();
    error SnapshotNotFound();
    error TokenWhitelistUnchanged();
    error TransferFailed();

    // ===== MODIFIERS =====

    modifier onlyRelayer() {
        if (!authorizedRelayers[msg.sender]) revert Unauthorized();
        _;
    }

    modifier onlyRootVerifier() {
        if (!rootVerifiers[msg.sender]) revert Unauthorized();
        _;
    }

    // ===== CONSTRUCTOR =====

    constructor(address _owner, address _initialRelayer) Ownable(_owner) {
        authorizedRelayers[_initialRelayer] = true;
        rootVerifiers[_initialRelayer] = true;
        batchSize = DEFAULT_BATCH_SIZE;
        batchTimeout = DEFAULT_TIMEOUT;

        zeros[0] = bytes32(0);
        for (uint256 i = 1; i < TREE_HEIGHT; i++) {
            zeros[i] = _hashPair(zeros[i - 1], zeros[i - 1]);
        }
    }

    /// @notice Accept native ETH — NEAR bridge delivers ETH directly to this contract
    receive() external payable {}

    /// @notice Reject unknown calls with calldata
    fallback() external {
        revert("Unknown function");
    }

    // ==============================================================
    //                     SOURCE SIDE FUNCTIONS
    //         (when this chain is where the user starts)
    // ==============================================================

    /**
     * @notice Add commitment to pending batch
     * @dev Called by relayer when user submits intent via API.
     *      Commitment is opaque bytes32 generated client-side:
     *      commitment = Poseidon(secret, nullifier, amount, destChain)
     *
     * @param commitment Privacy commitment (opaque bytes32 from client)
     * @param nearIntentsId NEAR Intents tracking ID (internal, not publicly exposed)
     * @param viewKey Optional per-user view key (bytes32(0) to skip)
     */
    function addToPendingBatch(
        bytes32 commitment,
        bytes32 nearIntentsId,
        bytes32 viewKey
    ) external onlyRelayer whenNotPaused {
        if (commitment == bytes32(0)) revert InvalidCommitment();
        if (intents[commitment].commitment != bytes32(0))
            revert CommitmentExists();
        if (nextLeafIndex >= (uint256(1) << TREE_HEIGHT)) revert TreeFull();

        uint256 count = batchCount;

        if (count == 0) {
            batchFirstSubmissionTime = uint64(block.timestamp);
        }

        batchCommitments[count] = commitment;
        batchNearIntentsIds[count] = nearIntentsId;
        batchViewKeys[count] = viewKey;
        batchCount = count + 1;

        emit CommitmentAdded(commitment);

        if (count + 1 >= batchSize) {
            _processBatch(ProcessReason.BATCH_FULL);
        }
    }

    /**
     * @notice Process batch if timeout reached
     * @dev Anyone can call — ensures liveness even if relayer is slow.
     *      Processes even single-item batches (liveness > privacy).
     */
    function processBatchIfTimeout() external whenNotPaused {
        if (batchCount == 0) revert BatchEmpty();

        uint256 timeSinceFirst = block.timestamp - batchFirstSubmissionTime;
        if (timeSinceFirst < batchTimeout) revert TimeoutNotReached();

        _processBatch(ProcessReason.TIMEOUT_REACHED);
    }

    /**
     * @notice Internal batch processing
     * @dev Registers all pending commitments in Merkle tree.
     *      View key mapping is written here
     *      to ensure Intent struct exists before viewKey queries work.
     */
    function _processBatch(ProcessReason reason) internal {
        uint256 count = batchCount;
        if (count == 0) revert BatchEmpty();

        for (uint256 i = 0; i < count; i++) {
            bytes32 commitment = batchCommitments[i];
            bytes32 nearIntentsId = batchNearIntentsIds[i];
            bytes32 viewKey = batchViewKeys[i];

            intents[commitment] = Intent({
                commitment: commitment,
                nearIntentsId: nearIntentsId,
                viewKey: viewKey,
                submittedAt: uint64(block.timestamp),
                settled: false
            });

            _insertCommitment(commitment);

            if (viewKey != bytes32(0)) {
                viewKeyToCommitments[viewKey].push(commitment);
            }
        }

        emit BatchProcessed(nextLeafIndex, count, reason);
        emit MerkleRootUpdated(currentRoot);

        batchCount = 0;
    }

    /**
     * @notice Mark a source-side commitment as settled
     * @dev Called by relayer AFTER tokens were released on the destination chain.
     *      This updates the source-side intent status so view key queries
     *      reflect the completed settlement. Runs on the chain where the
     *      commitment was originally stored (source chain).
     *
     *      Flow: settleAndRelease (dest) → relayer confirms → markSettled (source)
     *
     * @param commitment Intent commitment (must exist in this contract's tree)
     * @param nullifierHash Hash of nullifier (prevents double-marking)
     */
    function markSettled(
        bytes32 commitment,
        bytes32 nullifierHash
    ) external onlyRelayer whenNotPaused {
        Intent storage intent = intents[commitment];
        if (intent.commitment == bytes32(0)) revert CommitmentNotFound();
        if (usedNullifiers[nullifierHash]) revert NullifierUsed();

        intent.settled = true;
        usedNullifiers[nullifierHash] = true;

        emit IntentMarkedSettled(
            nullifierHash,
            commitment,
            uint64(block.timestamp)
        );
    }

    // ==============================================================
    //                   CROSS-CHAIN SYNC FUNCTIONS
    // ==============================================================

    /**
     * @notice Sync Merkle root from remote chain (e.g., StarkNet)
     * @dev Called by relayer to store remote chain state for auditability.
     *      Enables cross-verification that commitments exist on both chains.
     *
     * @param chainId Remote chain identifier (e.g., "starknet-mainnet")
     * @param root Merkle root from remote chain
     * @param leafCount Number of commitments in remote tree at time of sync
     */
    function syncMerkleRoot(
        string calldata chainId,
        bytes32 root,
        uint256 leafCount
    ) external onlyRelayer whenNotPaused {
        if (bytes(chainId).length == 0) revert InvalidChainId();
        if (root == bytes32(0)) revert InvalidRoot();
        if (leafCount == 0) revert InvalidAmount();

        RemoteRootSnapshot memory snapshot = RemoteRootSnapshot({
            root: root,
            leafCount: leafCount,
            syncedAt: uint64(block.timestamp),
            verified: false
        });

        remoteRootHistory[chainId].push(snapshot);
        uint256 newIndex = remoteRootHistory[chainId].length - 1;
        latestRemoteRootIndex[chainId] = newIndex;

        emit RemoteRootSynced(chainId, root, leafCount, newIndex);
    }

    /**
     * @notice Mark a synced root as verified
     * @dev Called by trusted verifier (could be oracle, bridge, or multi-sig).
     *      Once verified, root is considered authoritative.
     *
     * @param chainId Remote chain identifier
     * @param snapshotIndex Index in remoteRootHistory array
     */
    function verifyRemoteRoot(
        string calldata chainId,
        uint256 snapshotIndex
    ) external onlyRootVerifier whenNotPaused {
        RemoteRootSnapshot[] storage snapshots = remoteRootHistory[chainId];
        if (snapshotIndex >= snapshots.length) revert SnapshotNotFound();

        RemoteRootSnapshot storage snapshot = snapshots[snapshotIndex];
        if (snapshot.verified) revert RootAlreadyVerified();

        snapshot.verified = true;

        emit RemoteRootVerified(chainId, snapshotIndex, msg.sender);
    }

    // ==============================================================
    //                   DESTINATION SIDE FUNCTIONS
    //        (when this chain is where the user receives)
    // ==============================================================

    /**
     * @notice Release tokens to user after NEAR bridge delivery is verified
     * @dev Called by relayer after confirming token arrival via:
     *      1. Poll NEAR status API → get destinationChainTxHashes
     *      2. Verify Transfer event on-chain (amount + recipient = this contract)
     *      3. Call this function to release tokens to user
     *
     *      No on-chain deposit tracking — tokens arrive via standard ERC20
     *      transfer from NEAR 1Click bridge infrastructure. Relayer verifies
     *      the exact amount off-chain before calling.
     *
     * PRIVACY:
     * - recipient address visible on-chain in this call
     * - NOT linked to any source-chain commitment on-chain
     * - Link exists only in relayer's off-chain DB
     * - Same model as Tornado Cash withdrawals
     *
     * @param nullifierHash Hash of nullifier (prevents double-settlement)
     * @param recipient User's destination address on this chain
     * @param token ERC20 token to release
     * @param amount Amount to release (verified by relayer against NEAR status)
     */
    function settleAndRelease(
        bytes32 intentId,
        bytes32 nullifierHash,
        address recipient,
        address token,
        uint256 amount
    ) external onlyRelayer nonReentrant whenNotPaused {
        if (usedNullifiers[nullifierHash]) revert NullifierUsed();
        if (recipient == address(0)) revert InvalidRecipient();
        if (!whitelistedTokens[token]) revert TokenNotWhitelisted();
        if (amount == 0) revert InvalidAmount();

        usedNullifiers[nullifierHash] = true;

        if (token == ETH) {
            (bool ok, ) = payable(recipient).call{value: amount}("");
            if (!ok) revert TransferFailed();
        } else {
            IERC20(token).safeTransfer(recipient, amount);
        }

        emit IntentSettled(
            intentId,
            nullifierHash,
            token,
            amount,
            uint64(block.timestamp)
        );
    }

    // ===== MERKLE TREE FUNCTIONS =====

    /**
     * @notice Insert commitment into incremental Merkle tree
     * @dev Relayer replicates this logic off-chain for proof generation.
     *      Uses sorted hashing to prevent sibling-position leaks.
     */
    function _insertCommitment(bytes32 commitment) internal {
        uint256 index = nextLeafIndex;
        commitmentToIndex[commitment] = index;
        nextLeafIndex++;

        bytes32 currentHash = commitment;
        bytes32 left;
        bytes32 right;

        for (uint256 height = 0; height < TREE_HEIGHT; height++) {
            if (index & 1 == 0) {
                left = currentHash;
                right = zeros[height];
                filledSubtrees[height] = currentHash;
            } else {
                left = filledSubtrees[height];
                right = currentHash;
            }

            currentHash = _hashPair(left, right);
            index >>= 1;
        }

        currentRoot = currentHash;
    }

    function getMerkleRoot() external view returns (bytes32) {
        return currentRoot;
    }

    /**
     * @notice Hash pair of nodes with deterministic ordering
     * @dev Sorted to prevent sibling-position information leaks
     */
    function _hashPair(bytes32 a, bytes32 b) internal pure returns (bytes32) {
        return
            a < b
                ? keccak256(abi.encodePacked(a, b))
                : keccak256(abi.encodePacked(b, a));
    }

    // ===== VIEW KEY FUNCTIONS =====

    /**
     * @notice Get intents for a view key with pagination (full details)
     * @dev View key IS the auth — if you have it, you see everything.
     *      Returns empty array if view key has no intents (prevents existence probing).
     *      Compliance responsibility lies with the user via their view key.
     *
     * @param viewKey Per-user view key (derived from wallet signature client-side)
     * @param offset Start index (0-based)
     * @param limit Max results to return (0 = all from offset)
     * @return userIntents Array of intent details for the requested page
     * @return total Total number of intents for this view key
     */
    function getIntentsByViewKey(
        bytes32 viewKey,
        uint256 offset,
        uint256 limit
    ) external view returns (IntentDetail[] memory userIntents, uint256 total) {
        bytes32[] storage commitments = viewKeyToCommitments[viewKey];
        total = commitments.length;

        if (total == 0 || offset >= total) {
            userIntents = new IntentDetail[](0);
            return (userIntents, total);
        }

        uint256 remaining = total - offset;
        uint256 count = (limit == 0 || limit > remaining) ? remaining : limit;

        userIntents = new IntentDetail[](count);

        for (uint256 i = 0; i < count; i++) {
            Intent storage intent = intents[commitments[offset + i]];
            userIntents[i] = IntentDetail({
                commitment: intent.commitment,
                nearIntentsId: intent.nearIntentsId,
                submittedAt: intent.submittedAt,
                settled: intent.settled
            });
        }

        return (userIntents, total);
    }

    // ===== PUBLIC VIEW FUNCTIONS =====

    function getIntent(
        bytes32 commitment
    ) external view returns (IntentPublic memory info) {
        Intent storage intent = intents[commitment];
        if (intent.commitment == bytes32(0)) revert CommitmentNotFound();

        info = IntentPublic({
            commitment: intent.commitment,
            submittedAt: intent.submittedAt,
            settled: intent.settled
        });
    }

    function commitmentExists(
        bytes32 commitment
    ) external view returns (bool exists) {
        return intents[commitment].commitment != bytes32(0);
    }

    function isNullifierUsed(bytes32 nullifier) external view returns (bool) {
        return usedNullifiers[nullifier];
    }

    function getPendingBatchInfo()
        external
        view
        returns (
            uint256 count,
            uint64 firstSubmissionTime,
            uint256 timeRemaining
        )
    {
        count = batchCount;
        firstSubmissionTime = batchFirstSubmissionTime;

        if (count > 0) {
            uint256 elapsed = block.timestamp - firstSubmissionTime;
            timeRemaining = elapsed >= batchTimeout
                ? 0
                : batchTimeout - elapsed;
        }
    }

    function isRelayerAuthorized(address relayer) external view returns (bool) {
        return authorizedRelayers[relayer];
    }

    function isRootVerifier(address verifier) external view returns (bool) {
        return rootVerifiers[verifier];
    }

    function getLatestRemoteRoot(
        string calldata chainId
    ) external view returns (RemoteRootSnapshot memory snapshot) {
        RemoteRootSnapshot[] storage snapshots = remoteRootHistory[chainId];
        if (snapshots.length == 0) revert SnapshotNotFound();
        return snapshots[latestRemoteRootIndex[chainId]];
    }

    function getLatestVerifiedRemoteRoot(
        string calldata chainId
    ) external view returns (RemoteRootSnapshot memory snapshot, uint256 index) {
        RemoteRootSnapshot[] storage snapshots = remoteRootHistory[chainId];
        if (snapshots.length == 0) revert SnapshotNotFound();

        for (uint256 i = snapshots.length; i > 0; i--) {
            if (snapshots[i - 1].verified) {
                return (snapshots[i - 1], i - 1);
            }
        }

        revert SnapshotNotFound();
    }

    function getRemoteRootSnapshot(
        string calldata chainId,
        uint256 snapshotIndex
    ) external view returns (RemoteRootSnapshot memory snapshot) {
        RemoteRootSnapshot[] storage snapshots = remoteRootHistory[chainId];
        if (snapshotIndex >= snapshots.length) revert SnapshotNotFound();
        return snapshots[snapshotIndex];
    }

    function getRemoteRootCount(
        string calldata chainId
    ) external view returns (uint256 count) {
        return remoteRootHistory[chainId].length;
    }

    // ===== ADMIN FUNCTIONS =====

    function updateBatchConfig(
        uint256 newBatchSize,
        uint256 newTimeout
    ) external onlyOwner {
        if (newBatchSize < MIN_BATCH_SIZE || newBatchSize > MAX_BATCH_SIZE) {
            revert InvalidBatchSize();
        }
        if (newTimeout == 0) revert InvalidTimeout();

        batchSize = newBatchSize;
        batchTimeout = newTimeout;

        emit BatchConfigUpdated(newBatchSize, newTimeout);
    }

    function setRelayerStatus(
        address relayer,
        bool authorized
    ) external onlyOwner {
        authorizedRelayers[relayer] = authorized;
        emit RelayerStatusChanged(relayer, authorized);
    }

    function setRootVerifierStatus(
        address verifier,
        bool authorized
    ) external onlyOwner {
        rootVerifiers[verifier] = authorized;
        emit RootVerifierStatusChanged(verifier, authorized);
    }

    /**
     * @notice Whitelist or delist a token for settlement
     * @param token ERC20 token address
     * @param whitelisted True to whitelist, false to delist
     */
    function setTokenWhitelist(
        address token,
        bool whitelisted
    ) external onlyOwner {
        if (whitelistedTokens[token] == whitelisted) revert TokenWhitelistUnchanged();
        whitelistedTokens[token] = whitelisted;
        emit TokenWhitelistUpdated(token, whitelisted);
    }

    /**
     * @notice Emergency rescue stuck tokens
     * @dev Only callable by owner. For recovering tokens from failed NEAR
     *      bridge transfers or tokens sent to contract by mistake.
     *
     * @param token ERC20 token address
     * @param to Recipient address
     * @param amount Amount to rescue
     */
    function rescueTokens(
        address token,
        address to,
        uint256 amount
    ) external onlyOwner {
        if (token == ETH) {
            (bool ok, ) = payable(to).call{value: amount}("");
            if (!ok) revert TransferFailed();
        } else {
            IERC20(token).safeTransfer(to, amount);
        }
    }

    function pause() external onlyOwner {
        _pause();
    }

    function unpause() external onlyOwner {
        _unpause();
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.5.0) (utils/ReentrancyGuard.sol)

pragma solidity ^0.8.20;

import {StorageSlot} from "./StorageSlot.sol";

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If EIP-1153 (transient storage) is available on the chain you're deploying at,
 * consider using {ReentrancyGuardTransient} instead.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 *
 * IMPORTANT: Deprecated. This storage-based reentrancy guard will be removed and replaced
 * by the {ReentrancyGuardTransient} variant in v6.0.
 *
 * @custom:stateless
 */
abstract contract ReentrancyGuard {
    using StorageSlot for bytes32;

    // keccak256(abi.encode(uint256(keccak256("openzeppelin.storage.ReentrancyGuard")) - 1)) & ~bytes32(uint256(0xff))
    bytes32 private constant REENTRANCY_GUARD_STORAGE =
        0x9b779b17422d0df92223018b32b4d1fa46e071723d6817e2486d003becc55f00;

    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant NOT_ENTERED = 1;
    uint256 private constant ENTERED = 2;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    constructor() {
        _reentrancyGuardStorageSlot().getUint256Slot().value = NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    /**
     * @dev A `view` only version of {nonReentrant}. Use to block view functions
     * from being called, preventing reading from inconsistent contract state.
     *
     * CAUTION: This is a "view" modifier and does not change the reentrancy
     * status. Use it only on view functions. For payable or non-payable functions,
     * use the standard {nonReentrant} modifier instead.
     */
    modifier nonReentrantView() {
        _nonReentrantBeforeView();
        _;
    }

    function _nonReentrantBeforeView() private view {
        if (_reentrancyGuardEntered()) {
            revert ReentrancyGuardReentrantCall();
        }
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        _nonReentrantBeforeView();

        // Any calls to nonReentrant after this point will fail
        _reentrancyGuardStorageSlot().getUint256Slot().value = ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _reentrancyGuardStorageSlot().getUint256Slot().value = NOT_ENTERED;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _reentrancyGuardStorageSlot().getUint256Slot().value == ENTERED;
    }

    function _reentrancyGuardStorageSlot() internal pure virtual returns (bytes32) {
        return REENTRANCY_GUARD_STORAGE;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (access/Ownable.sol)

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @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.
 *
 * The initial owner is set to the address provided by the deployer. 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;

    /**
     * @dev The caller account is not authorized to perform an operation.
     */
    error OwnableUnauthorizedAccount(address account);

    /**
     * @dev The owner is not a valid owner account. (eg. `address(0)`)
     */
    error OwnableInvalidOwner(address owner);

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the address provided by the deployer as the initial owner.
     */
    constructor(address initialOwner) {
        if (initialOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _transferOwnership(initialOwner);
    }

    /**
     * @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 {
        if (owner() != _msgSender()) {
            revert OwnableUnauthorizedAccount(_msgSender());
        }
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling 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 {
        if (newOwner == address(0)) {
            revert OwnableInvalidOwner(address(0));
        }
        _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);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.3.0) (utils/Pausable.sol)

pragma solidity ^0.8.20;

import {Context} from "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    bool private _paused;

    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    /**
     * @dev The operation failed because the contract is paused.
     */
    error EnforcedPause();

    /**
     * @dev The operation failed because the contract is not paused.
     */
    error ExpectedPause();

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        if (paused()) {
            revert EnforcedPause();
        }
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        if (!paused()) {
            revert ExpectedPause();
        }
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.4.0) (token/ERC20/IERC20.sol)

pragma solidity >=0.4.16;

/**
 * @dev Interface of the ERC-20 standard as defined in the ERC.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the value of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 value) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 value) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.5.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.20;

import {IERC20} from "../IERC20.sol";
import {IERC1363} from "../../../interfaces/IERC1363.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC-20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    /**
     * @dev An operation with an ERC-20 token failed.
     */
    error SafeERC20FailedOperation(address token);

    /**
     * @dev Indicates a failed `decreaseAllowance` request.
     */
    error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease);

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        if (!_safeTransfer(token, to, value, true)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        if (!_safeTransferFrom(token, from, to, value, true)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Variant of {safeTransfer} that returns a bool instead of reverting if the operation is not successful.
     */
    function trySafeTransfer(IERC20 token, address to, uint256 value) internal returns (bool) {
        return _safeTransfer(token, to, value, false);
    }

    /**
     * @dev Variant of {safeTransferFrom} that returns a bool instead of reverting if the operation is not successful.
     */
    function trySafeTransferFrom(IERC20 token, address from, address to, uint256 value) internal returns (bool) {
        return _safeTransferFrom(token, from, to, value, false);
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     *
     * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client"
     * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using
     * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract
     * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        forceApprove(token, spender, oldAllowance + value);
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
     * value, non-reverting calls are assumed to be successful.
     *
     * IMPORTANT: If the token implements ERC-7674 (ERC-20 with temporary allowance), and if the "client"
     * smart contract uses ERC-7674 to set temporary allowances, then the "client" smart contract should avoid using
     * this function. Performing a {safeIncreaseAllowance} or {safeDecreaseAllowance} operation on a token contract
     * that has a non-zero temporary allowance (for that particular owner-spender) will result in unexpected behavior.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal {
        unchecked {
            uint256 currentAllowance = token.allowance(address(this), spender);
            if (currentAllowance < requestedDecrease) {
                revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease);
            }
            forceApprove(token, spender, currentAllowance - requestedDecrease);
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     *
     * NOTE: If the token implements ERC-7674, this function will not modify any temporary allowance. This function
     * only sets the "standard" allowance. Any temporary allowance will remain active, in addition to the value being
     * set here.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        if (!_safeApprove(token, spender, value, false)) {
            if (!_safeApprove(token, spender, 0, true)) revert SafeERC20FailedOperation(address(token));
            if (!_safeApprove(token, spender, value, true)) revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} transferAndCall, with a fallback to the simple {ERC20} transfer if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that relies on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
        if (to.code.length == 0) {
            safeTransfer(token, to, value);
        } else if (!token.transferAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} transferFromAndCall, with a fallback to the simple {ERC20} transferFrom if the target
     * has no code. This can be used to implement an {ERC721}-like safe transfer that relies on {ERC1363} checks when
     * targeting contracts.
     *
     * Reverts if the returned value is other than `true`.
     */
    function transferFromAndCallRelaxed(
        IERC1363 token,
        address from,
        address to,
        uint256 value,
        bytes memory data
    ) internal {
        if (to.code.length == 0) {
            safeTransferFrom(token, from, to, value);
        } else if (!token.transferFromAndCall(from, to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Performs an {ERC1363} approveAndCall, with a fallback to the simple {ERC20} approve if the target has no
     * code. This can be used to implement an {ERC721}-like safe transfer that rely on {ERC1363} checks when
     * targeting contracts.
     *
     * NOTE: When the recipient address (`to`) has no code (i.e. is an EOA), this function behaves as {forceApprove}.
     * Oppositely, when the recipient address (`to`) has code, this function only attempts to call {ERC1363-approveAndCall}
     * once without retrying, and relies on the returned value to be true.
     *
     * Reverts if the returned value is other than `true`.
     */
    function approveAndCallRelaxed(IERC1363 token, address to, uint256 value, bytes memory data) internal {
        if (to.code.length == 0) {
            forceApprove(token, to, value);
        } else if (!token.approveAndCall(to, value, data)) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Imitates a Solidity `token.transfer(to, value)` call, relaxing the requirement on the return value: the
     * return value is optional (but if data is returned, it must not be false).
     *
     * @param token The token targeted by the call.
     * @param to The recipient of the tokens
     * @param value The amount of token to transfer
     * @param bubble Behavior switch if the transfer call reverts: bubble the revert reason or return a false boolean.
     */
    function _safeTransfer(IERC20 token, address to, uint256 value, bool bubble) private returns (bool success) {
        bytes4 selector = IERC20.transfer.selector;

        assembly ("memory-safe") {
            let fmp := mload(0x40)
            mstore(0x00, selector)
            mstore(0x04, and(to, shr(96, not(0))))
            mstore(0x24, value)
            success := call(gas(), token, 0, 0x00, 0x44, 0x00, 0x20)
            // if call success and return is true, all is good.
            // otherwise (not success or return is not true), we need to perform further checks
            if iszero(and(success, eq(mload(0x00), 1))) {
                // if the call was a failure and bubble is enabled, bubble the error
                if and(iszero(success), bubble) {
                    returndatacopy(fmp, 0x00, returndatasize())
                    revert(fmp, returndatasize())
                }
                // if the return value is not true, then the call is only successful if:
                // - the token address has code
                // - the returndata is empty
                success := and(success, and(iszero(returndatasize()), gt(extcodesize(token), 0)))
            }
            mstore(0x40, fmp)
        }
    }

    /**
     * @dev Imitates a Solidity `token.transferFrom(from, to, value)` call, relaxing the requirement on the return
     * value: the return value is optional (but if data is returned, it must not be false).
     *
     * @param token The token targeted by the call.
     * @param from The sender of the tokens
     * @param to The recipient of the tokens
     * @param value The amount of token to transfer
     * @param bubble Behavior switch if the transfer call reverts: bubble the revert reason or return a false boolean.
     */
    function _safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value,
        bool bubble
    ) private returns (bool success) {
        bytes4 selector = IERC20.transferFrom.selector;

        assembly ("memory-safe") {
            let fmp := mload(0x40)
            mstore(0x00, selector)
            mstore(0x04, and(from, shr(96, not(0))))
            mstore(0x24, and(to, shr(96, not(0))))
            mstore(0x44, value)
            success := call(gas(), token, 0, 0x00, 0x64, 0x00, 0x20)
            // if call success and return is true, all is good.
            // otherwise (not success or return is not true), we need to perform further checks
            if iszero(and(success, eq(mload(0x00), 1))) {
                // if the call was a failure and bubble is enabled, bubble the error
                if and(iszero(success), bubble) {
                    returndatacopy(fmp, 0x00, returndatasize())
                    revert(fmp, returndatasize())
                }
                // if the return value is not true, then the call is only successful if:
                // - the token address has code
                // - the returndata is empty
                success := and(success, and(iszero(returndatasize()), gt(extcodesize(token), 0)))
            }
            mstore(0x40, fmp)
            mstore(0x60, 0)
        }
    }

    /**
     * @dev Imitates a Solidity `token.approve(spender, value)` call, relaxing the requirement on the return value:
     * the return value is optional (but if data is returned, it must not be false).
     *
     * @param token The token targeted by the call.
     * @param spender The spender of the tokens
     * @param value The amount of token to transfer
     * @param bubble Behavior switch if the transfer call reverts: bubble the revert reason or return a false boolean.
     */
    function _safeApprove(IERC20 token, address spender, uint256 value, bool bubble) private returns (bool success) {
        bytes4 selector = IERC20.approve.selector;

        assembly ("memory-safe") {
            let fmp := mload(0x40)
            mstore(0x00, selector)
            mstore(0x04, and(spender, shr(96, not(0))))
            mstore(0x24, value)
            success := call(gas(), token, 0, 0x00, 0x44, 0x00, 0x20)
            // if call success and return is true, all is good.
            // otherwise (not success or return is not true), we need to perform further checks
            if iszero(and(success, eq(mload(0x00), 1))) {
                // if the call was a failure and bubble is enabled, bubble the error
                if and(iszero(success), bubble) {
                    returndatacopy(fmp, 0x00, returndatasize())
                    revert(fmp, returndatasize())
                }
                // if the return value is not true, then the call is only successful if:
                // - the token address has code
                // - the returndata is empty
                success := and(success, and(iszero(returndatasize()), gt(extcodesize(token), 0)))
            }
            mstore(0x40, fmp)
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (utils/StorageSlot.sol)
// This file was procedurally generated from scripts/generate/templates/StorageSlot.js.

pragma solidity ^0.8.20;

/**
 * @dev Library for reading and writing primitive types to specific storage slots.
 *
 * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
 * This library helps with reading and writing to such slots without the need for inline assembly.
 *
 * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
 *
 * Example usage to set ERC-1967 implementation slot:
 * ```solidity
 * contract ERC1967 {
 *     // Define the slot. Alternatively, use the SlotDerivation library to derive the slot.
 *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
 *
 *     function _getImplementation() internal view returns (address) {
 *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
 *     }
 *
 *     function _setImplementation(address newImplementation) internal {
 *         require(newImplementation.code.length > 0);
 *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
 *     }
 * }
 * ```
 *
 * TIP: Consider using this library along with {SlotDerivation}.
 */
library StorageSlot {
    struct AddressSlot {
        address value;
    }

    struct BooleanSlot {
        bool value;
    }

    struct Bytes32Slot {
        bytes32 value;
    }

    struct Uint256Slot {
        uint256 value;
    }

    struct Int256Slot {
        int256 value;
    }

    struct StringSlot {
        string value;
    }

    struct BytesSlot {
        bytes value;
    }

    /**
     * @dev Returns an `AddressSlot` with member `value` located at `slot`.
     */
    function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
        assembly ("memory-safe") {
            r.slot := slot
        }
    }

    /**
     * @dev Returns a `BooleanSlot` with member `value` located at `slot`.
     */
    function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
        assembly ("memory-safe") {
            r.slot := slot
        }
    }

    /**
     * @dev Returns a `Bytes32Slot` with member `value` located at `slot`.
     */
    function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
        assembly ("memory-safe") {
            r.slot := slot
        }
    }

    /**
     * @dev Returns a `Uint256Slot` with member `value` located at `slot`.
     */
    function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
        assembly ("memory-safe") {
            r.slot := slot
        }
    }

    /**
     * @dev Returns a `Int256Slot` with member `value` located at `slot`.
     */
    function getInt256Slot(bytes32 slot) internal pure returns (Int256Slot storage r) {
        assembly ("memory-safe") {
            r.slot := slot
        }
    }

    /**
     * @dev Returns a `StringSlot` with member `value` located at `slot`.
     */
    function getStringSlot(bytes32 slot) internal pure returns (StringSlot storage r) {
        assembly ("memory-safe") {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `StringSlot` representation of the string storage pointer `store`.
     */
    function getStringSlot(string storage store) internal pure returns (StringSlot storage r) {
        assembly ("memory-safe") {
            r.slot := store.slot
        }
    }

    /**
     * @dev Returns a `BytesSlot` with member `value` located at `slot`.
     */
    function getBytesSlot(bytes32 slot) internal pure returns (BytesSlot storage r) {
        assembly ("memory-safe") {
            r.slot := slot
        }
    }

    /**
     * @dev Returns an `BytesSlot` representation of the bytes storage pointer `store`.
     */
    function getBytesSlot(bytes storage store) internal pure returns (BytesSlot storage r) {
        assembly ("memory-safe") {
            r.slot := store.slot
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @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;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.4.0) (interfaces/IERC1363.sol)

pragma solidity >=0.6.2;

import {IERC20} from "./IERC20.sol";
import {IERC165} from "./IERC165.sol";

/**
 * @title IERC1363
 * @dev Interface of the ERC-1363 standard as defined in the https://eips.ethereum.org/EIPS/eip-1363[ERC-1363].
 *
 * Defines an extension interface for ERC-20 tokens that supports executing code on a recipient contract
 * after `transfer` or `transferFrom`, or code on a spender contract after `approve`, in a single transaction.
 */
interface IERC1363 is IERC20, IERC165 {
    /*
     * Note: the ERC-165 identifier for this interface is 0xb0202a11.
     * 0xb0202a11 ===
     *   bytes4(keccak256('transferAndCall(address,uint256)')) ^
     *   bytes4(keccak256('transferAndCall(address,uint256,bytes)')) ^
     *   bytes4(keccak256('transferFromAndCall(address,address,uint256)')) ^
     *   bytes4(keccak256('transferFromAndCall(address,address,uint256,bytes)')) ^
     *   bytes4(keccak256('approveAndCall(address,uint256)')) ^
     *   bytes4(keccak256('approveAndCall(address,uint256,bytes)'))
     */

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferAndCall(address to, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from the caller's account to `to`
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @param data Additional data with no specified format, sent in call to `to`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferAndCall(address to, uint256 value, bytes calldata data) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferFromAndCall(address from, address to, uint256 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the allowance mechanism
     * and then calls {IERC1363Receiver-onTransferReceived} on `to`.
     * @param from The address which you want to send tokens from.
     * @param to The address which you want to transfer to.
     * @param value The amount of tokens to be transferred.
     * @param data Additional data with no specified format, sent in call to `to`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function transferFromAndCall(address from, address to, uint256 value, bytes calldata data) external returns (bool);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function approveAndCall(address spender, uint256 value) external returns (bool);

    /**
     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
     * caller's tokens and then calls {IERC1363Spender-onApprovalReceived} on `spender`.
     * @param spender The address which will spend the funds.
     * @param value The amount of tokens to be spent.
     * @param data Additional data with no specified format, sent in call to `spender`.
     * @return A boolean value indicating whether the operation succeeded unless throwing.
     */
    function approveAndCall(address spender, uint256 value, bytes calldata data) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.4.0) (interfaces/IERC20.sol)

pragma solidity >=0.4.16;

import {IERC20} from "../token/ERC20/IERC20.sol";

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.4.0) (interfaces/IERC165.sol)

pragma solidity >=0.4.16;

import {IERC165} from "../utils/introspection/IERC165.sol";

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.4.0) (utils/introspection/IERC165.sol)

pragma solidity >=0.4.16;

/**
 * @dev Interface of the ERC-165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[ERC].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[ERC section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}