Cryo Explorer Ethereum Mainnet

// 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 v5.0.0) (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * ==== Security Considerations
 *
 * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
 * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
 * considered as an intention to spend the allowance in any specific way. The second is that because permits have
 * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
 * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
 * generally recommended is:
 *
 * ```solidity
 * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
 *     try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
 *     doThing(..., value);
 * }
 *
 * function doThing(..., uint256 value) public {
 *     token.safeTransferFrom(msg.sender, address(this), value);
 *     ...
 * }
 * ```
 *
 * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
 * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
 * {SafeERC20-safeTransferFrom}).
 *
 * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
 * contracts should have entry points that don't rely on permit.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     *
     * CAUTION: See Security Considerations above.
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
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 v5.0.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.20;

import {IERC20} from "../IERC20.sol";
import {IERC20Permit} from "../extensions/IERC20Permit.sol";
import {Address} from "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 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 {
    using Address for address;

    /**
     * @dev An operation with an ERC20 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 {
        _callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value)));
    }

    /**
     * @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 {
        _callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value)));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    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.
     */
    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.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0)));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), 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 data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data);
        if (returndata.length != 0 && !abi.decode(returndata, (bool))) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), 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 data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return success && (returndata.length == 0 || abi.decode(returndata, (bool))) && address(token).code.length > 0;
    }
}

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

pragma solidity ^0.8.20;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev The ETH balance of the account is not enough to perform the operation.
     */
    error AddressInsufficientBalance(address account);

    /**
     * @dev There's no code at `target` (it is not a contract).
     */
    error AddressEmptyCode(address target);

    /**
     * @dev A call to an address target failed. The target may have reverted.
     */
    error FailedInnerCall();

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.8.20/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        if (address(this).balance < amount) {
            revert AddressInsufficientBalance(address(this));
        }

        (bool success, ) = recipient.call{value: amount}("");
        if (!success) {
            revert FailedInnerCall();
        }
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason or custom error, it is bubbled
     * up by this function (like regular Solidity function calls). However, if
     * the call reverted with no returned reason, this function reverts with a
     * {FailedInnerCall} error.
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        if (address(this).balance < value) {
            revert AddressInsufficientBalance(address(this));
        }
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and reverts if the target
     * was not a contract or bubbling up the revert reason (falling back to {FailedInnerCall}) in case of an
     * unsuccessful call.
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata
    ) internal view returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            // only check if target is a contract if the call was successful and the return data is empty
            // otherwise we already know that it was a contract
            if (returndata.length == 0 && target.code.length == 0) {
                revert AddressEmptyCode(target);
            }
            return returndata;
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and reverts if it wasn't, either by bubbling the
     * revert reason or with a default {FailedInnerCall} error.
     */
    function verifyCallResult(bool success, bytes memory returndata) internal pure returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            return returndata;
        }
    }

    /**
     * @dev Reverts with returndata if present. Otherwise reverts with {FailedInnerCall}.
     */
    function _revert(bytes memory returndata) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert FailedInnerCall();
        }
    }
}

// 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 v5.0.0) (utils/math/Math.sol)

pragma solidity ^0.8.20;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Muldiv operation overflow.
     */
    error MathOverflowedMulDiv();

    enum Rounding {
        Floor, // Toward negative infinity
        Ceil, // Toward positive infinity
        Trunc, // Toward zero
        Expand // Away from zero
    }

    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, with an overflow flag.
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds towards infinity instead
     * of rounding towards zero.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        if (b == 0) {
            // Guarantee the same behavior as in a regular Solidity division.
            return a / b;
        }

        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or
     * denominator == 0.
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv) with further edits by
     * Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0 = x * y; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                // Solidity will revert if denominator == 0, unlike the div opcode on its own.
                // The surrounding unchecked block does not change this fact.
                // See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            if (denominator <= prod1) {
                revert MathOverflowedMulDiv();
            }

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator.
            // Always >= 1. See https://cs.stackexchange.com/q/138556/92363.

            uint256 twos = denominator & (0 - denominator);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also
            // works in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (unsignedRoundsUp(rounding) && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded
     * towards zero.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (unsignedRoundsUp(rounding) && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (unsignedRoundsUp(rounding) && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (unsignedRoundsUp(rounding) && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256 of a positive value rounded towards zero.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (unsignedRoundsUp(rounding) && 1 << (result << 3) < value ? 1 : 0);
        }
    }

    /**
     * @dev Returns whether a provided rounding mode is considered rounding up for unsigned integers.
     */
    function unsignedRoundsUp(Rounding rounding) internal pure returns (bool) {
        return uint8(rounding) % 2 == 1;
    }
}

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

pragma solidity ^0.8.20;

/**
 * @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 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].
 */
abstract contract ReentrancyGuard {
    // 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;

    uint256 private _status;

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

    constructor() {
        _status = 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();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

        // Any calls to nonReentrant after this point will fail
        _status = ENTERED;
    }

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

// SPDX-License-Identifier: MIT

pragma solidity 0.8.20;

import "../admin-panel/PlatformAdminPanel.sol";

/**
 * @title Abstract contract from which platform contracts with admin function are inherited
 * @dev Contains the platform admin panel
 * Contains modifier that checks whether sender is platform admin, use platform admin panel
 */
abstract contract PlatformAccessController {
    address public _panel;

    error CallerNotAdmin();
    error AlreadyInitialized();

    function _initiatePlatformAccessController(address adminPanel) internal {
        if(address(_panel) != address(0))
            revert AlreadyInitialized();

        _panel = adminPanel;
    }

    /**
     * @dev Modifier that makes function available for platform admins only
     */
    modifier onlyPlatformAdmin() {
        if(!PlatformAdminPanel(_panel).isAdmin(msgSender()))
            revert CallerNotAdmin();
        _;
    }

    function _isAdmin() internal view returns (bool) {
        return PlatformAdminPanel(_panel).isAdmin(msgSender());
    }

    function msgSender() internal view virtual returns (address) {
        return msg.sender;
    }
}

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

import "../interfaces/IPlatformAdminPanel.sol";

/**
 * @title Platform admins holder contract
 * @notice Used to check accessibility of senders to admin functions in platform contracts
 */
contract PlatformAdminPanel is IPlatformAdminPanel {
    /**
     * @notice Emit during root admin set and reset
     */
    event SetRootAdmin(address indexed wallet);

    event InsertAdminList(address[] adminList);

    event RemoveAdminList(address[] adminList);

    mapping(address => bool) private _adminMap;
    address private _rootAdmin;

    modifier onlyRootAdmin() {
        require(_rootAdmin == msg.sender, "sender is not root admin");
        _;
    }

    /**
     * @notice Specify the root admin, only he has the rights to add and remove admins
     */
    constructor(address rootAdminWallet) {
        _setRootAdmin(rootAdminWallet);
    }

    /**
     * @notice Needed to determine if the user has admin rights for platform contracts
     */
    function isAdmin(address wallet)
        external
        view
        virtual
        override
        returns (bool)
    {
        return wallet == _rootAdmin || _adminMap[wallet];
    }

    function rootAdmin() external view returns (address) {
        return _rootAdmin;
    }

    /**
     * @notice Only root admin can call
     */
    function insertAdminList(address[] calldata adminList)
        external
        onlyRootAdmin
    {
        require(0 < adminList.length, "empty admin list");
        require(20 >= adminList.length, "list too large");

        uint256 index = adminList.length;
        while (0 < index) {
            --index;

            _adminMap[adminList[index]] = true;
        }

        emit InsertAdminList(adminList);
    }

    /**
     * @notice Only root admin can call
     */
    function removeAdminList(address[] calldata adminList)
        external
        onlyRootAdmin
    {
        require(0 < adminList.length, "empty admin list");
        require(20 >= adminList.length, "list too large");

        uint256 index = adminList.length;
        while (0 < index) {
            --index;

            _adminMap[adminList[index]] = false;
        }

        emit RemoveAdminList(adminList);
    }

    /**
     * @notice Only root admin can call
     */
    function setRootAdmin(address rootAdminWallet) external onlyRootAdmin {
        _setRootAdmin(rootAdminWallet);
    }

    function _setRootAdmin(address wallet) private {
        require(wallet != address(0), "wallet is zero address");

        _rootAdmin = wallet;

        emit SetRootAdmin(wallet);
    }
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.20;

interface IPlatformAdminPanel {
    function isAdmin(address wallet) external view returns (bool);
}

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

/**
 * @author Yash Gupta (Propchain) (GitHub: @theyashgupta)
 */

import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import '@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol';
import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/utils/ReentrancyGuard.sol';
import '@openzeppelin/contracts/utils/math/Math.sol';
import '../access-controller/PlatformAccessController.sol';

/**
 * @title PropchainStakingV3
 * @dev Staking contract with dynamic APYs, reward caps, checkpoints, and migration support
 */
contract PropchainStakingV3 is PlatformAccessController, ReentrancyGuard {
    using SafeERC20 for IERC20;

    /// @dev Constants for precision and calculations
    uint256 private constant PRECISION = 1e18;
    uint256 private constant BASIS_POINTS = 10000;
    uint256 private constant SECONDS_PER_MONTH = 30 days;
    uint256 private constant MAX_REWARD_CAP = 1e36; // Maximum safe reward cap to prevent overflow
    uint16 private constant MAX_PENALTY_BPS = 4000; // Maximum penalty in basis points (40%)

    /// @notice Checkpoint for tracking reward rate changes over time
    struct Checkpoint {
        uint256 timestamp;
        uint256 totalStaked;
        uint256 rewardRatePerSec;
        uint256 cumulativeRewardPerToken;
    }

    /// @notice Pool configuration and state (optimized for storage packing)
    struct PoolInfo {
        uint256 rewardCap;           // total reward tokens allocated
        uint256 totalStaked;         // current TVL
        uint256 rewardRatePerSec;    // computed per-second rate
        uint256 lastCheckpoint;      // last APY update timestamp
        uint256 minAPY;              // minimum APY in basis points
        uint256 maxAPY;              // maximum APY in basis points
        uint256 endTime;             // pool end time (0 = infinite)
        uint256 currentAPY;          // current effective APY in basis points
        uint256 totalRewardsPaid;    // total rewards paid out from this pool
        uint64 lockupSeconds;        // lockup duration (packed slot)
        uint16 initialPenaltyBps;    // early withdrawal penalty bps (packed slot)
        bool isPaused;               // pool pause state (packed slot)
        string name;                 // pool name
    }

    /// @notice Individual stake information
    struct StakeInfo {
        uint256 amount;
        uint256 unlockTimestamp;
        uint256 lastClaimTimestamp;
        uint256 stakeTimestamp;
        uint256 totalClaimedRewards;
    }

    /// @notice Stake information with pending rewards (for view functions)
    struct StakeInfoWithRewards {
        uint256 amount;
        uint256 unlockTimestamp;
        uint256 lastClaimTimestamp;
        uint256 stakeTimestamp;
        uint256 pendingRewards;
        uint256 totalClaimedRewardsWithPendingRewards;
    }

    /// @notice Pool configuration for migration mode restoration
    struct PoolConfig {
        uint256 minAPY;              // minimum APY in basis points
        uint256 maxAPY;              // maximum APY in basis points
        uint16 initialPenaltyBps;    // early withdrawal penalty bps (max 4000 = 40%)
    }

    /// @dev Core contract state
    IERC20 public immutable stakingToken;
    address public rewardsWallet;
    address public penaltyWallet;
    uint256 public minStakeAmount = 1 ether;
    bool public migrationMode;

    /// @dev Pool and stake data
    PoolInfo[] public pools;
    mapping(uint256 => mapping(address => StakeInfo[])) public stakes;
    mapping(uint256 => Checkpoint[]) public poolCheckpoints;
    
    /// @dev Migration epoch counter - incremented each time migration mode is enabled
    uint256 private migrationEpoch;
    
    /// @dev Tracks per-user progress during migration to allow chunked processing
    mapping(address => uint256) private userMigrationCursor;
    
    /// @dev Tracks which migration epoch each user's cursor belongs to
    mapping(address => uint256) private userMigrationEpoch;
    
    /// @dev Tracks owed rewards when rewardsWallet transfer fails
    mapping(address => uint256) public owedRewards;

    /// @dev User action events
    event Staked(uint256 indexed poolId, address indexed user, uint256 stakeIndex, uint256 amount);
    event RewardClaimed(uint256 indexed poolId, address indexed user, uint256 stakeIndex, uint256 amount);
    event Withdrawn(uint256 indexed poolId, address indexed user, uint256 stakeIndex, uint256 amount, uint256 penalty);
    event UserMigrated(address indexed user, uint256 totalStaked, uint256 totalRewards);
    event RewardsOwed(address indexed user, uint256 amount, string reason);
    event OwedRewardsClaimed(address indexed user, uint256 amount);

    /// @dev Pool management events
    event PoolAdded(uint256 indexed poolId, string name);
    event PoolPaused(uint256 indexed poolId, bool isPaused);
    event CheckpointCreated(uint256 indexed poolId, uint256 timestamp, uint256 totalStaked, uint256 rewardRatePerSec);
    event CheckpointsCleanedUp(uint256 indexed poolId, uint256 oldCount, uint256 newCount);

    /// @dev Configuration events
    event PenaltyWalletUpdated(address indexed oldWallet, address indexed newWallet);
    event RewardsWalletUpdated(address indexed oldWallet, address indexed newWallet);
    event MinStakeUpdated(uint256 oldAmount, uint256 newAmount);
    event APYLimitsUpdated(uint256 indexed poolId, uint256 minAPY, uint256 maxAPY);
    event PoolEndTimeUpdated(uint256 indexed poolId, uint256 endTime);
    event PoolRewardCapSet(uint256 indexed poolId, uint256 oldCap, uint256 newCap);
    event PoolNameUpdated(uint256 indexed poolId, string oldName, string newName);
    event PoolPenaltyUpdated(uint256 indexed poolId, uint16 oldPenalty, uint16 newPenalty);
    event MigrationModeEnabled();
    event MigrationModeDisabled();

    /// @dev Custom errors
    error InvalidPoolId(uint256 poolId);
    error InvalidStakeIndex(uint256 stakeIndex);
    error InvalidAmount(uint256 amount);
    error InsufficientStake(uint256 requested, uint256 available);
    error InvalidAddress();
    error ArrayLengthMismatch();
    error PoolIsPaused(uint256 poolId);
    error BelowMinStake(uint256 amount, uint256 minStake);
    error PoolEnded(uint256 poolId);
    error MigrationModeActive();
    error MigrationModeNotActive();

    /// @dev Validation modifiers
    modifier validPool(uint256 poolId) {
        if (poolId >= pools.length) revert InvalidPoolId(poolId);
        _;
    }

    modifier validStake(uint256 poolId, address user, uint256 stakeIndex) {
        if (stakeIndex >= stakes[poolId][user].length) revert InvalidStakeIndex(stakeIndex);
        _;
    }

    modifier poolNotPaused(uint256 poolId) {
        if (pools[poolId].isPaused) revert PoolIsPaused(poolId);
        _;
    }

    modifier poolNotEnded(uint256 poolId) {
        if (pools[poolId].endTime > 0 && block.timestamp >= pools[poolId].endTime) {
            revert PoolEnded(poolId);
        }
        _;
    }

    modifier onlyInMigrationMode() {
        if (!migrationMode) revert MigrationModeNotActive();
        _;
    }

    modifier onlyNotInMigrationMode() {
        if (migrationMode) revert MigrationModeActive();
        _;
    }

    /// @notice Initialize the staking contract
    constructor(IERC20 _stakingToken, address _rewardsWallet, address _penaltyWallet, address adminPanel) {
        if (
            address(_stakingToken) == address(0) ||
            _rewardsWallet == address(0) ||
            _penaltyWallet == address(0) ||
            adminPanel == address(0)
        ) revert InvalidAddress();

        stakingToken = _stakingToken;
        rewardsWallet = _rewardsWallet;
        penaltyWallet = _penaltyWallet;
        _initiatePlatformAccessController(adminPanel);
    }

    // ========================================================
    //                    Admin Functions
    // ========================================================

    /**
     * @notice Pause or unpause a pool
     * @param poolId Pool identifier
     * @param isPaused True to pause, false to unpause
     */
    function setPoolPause(uint256 poolId, bool isPaused) external onlyPlatformAdmin validPool(poolId) {
        pools[poolId].isPaused = isPaused;
        emit PoolPaused(poolId, isPaused);
    }

    /**
     * @notice Update penalty wallet address
     * @param newPenaltyWallet New penalty wallet address
     */
    function setPenaltyWallet(address newPenaltyWallet) external onlyPlatformAdmin {
        if (newPenaltyWallet == address(0)) revert InvalidAddress();
        address oldWallet = penaltyWallet;
        penaltyWallet = newPenaltyWallet;
        emit PenaltyWalletUpdated(oldWallet, newPenaltyWallet);
    }

    /**
     * @notice Update minimum stake amount
     * @param newMinStake New minimum stake amount
     */
    function setMinStakeAmount(uint256 newMinStake) external onlyPlatformAdmin {
        uint256 oldAmount = minStakeAmount;
        minStakeAmount = newMinStake;
        emit MinStakeUpdated(oldAmount, newMinStake);
    }

    /**
     * @notice Update APY limits for a pool
     * @param poolId Pool identifier
     * @param minAPY Minimum APY in basis points
     * @param maxAPY Maximum APY in basis points
     */
    function setAPYLimits(uint256 poolId, uint256 minAPY, uint256 maxAPY) external onlyPlatformAdmin validPool(poolId) {
        if (maxAPY > 0 && minAPY > maxAPY) revert InvalidAmount(minAPY);

        pools[poolId].minAPY = minAPY;
        pools[poolId].maxAPY = maxAPY;

        emit APYLimitsUpdated(poolId, minAPY, maxAPY);
    }

    /**
     * @notice Set pool end time
     * @param poolId Pool identifier
     * @param endTime End time (0 = infinite)
     */
    function setPoolEndTime(uint256 poolId, uint256 endTime) external onlyPlatformAdmin validPool(poolId) {
        pools[poolId].endTime = endTime;
        emit PoolEndTimeUpdated(poolId, endTime);
    }

    /**
     * @notice Set reward cap for a pool
     * @param poolId Pool identifier
     * @param newCap New reward cap
     */
    function setRewardCap(uint256 poolId, uint256 newCap) external onlyPlatformAdmin validPool(poolId) {
        if (newCap > MAX_REWARD_CAP) revert InvalidAmount(newCap);
        uint256 oldCap = pools[poolId].rewardCap;
        pools[poolId].rewardCap = newCap;
        _updatePool(poolId);
        _createCheckpoint(poolId);
        emit PoolRewardCapSet(poolId, oldCap, newCap);
    }

    /**
     * @notice Set pool name
     * @param poolId Pool identifier
     * @param newName New pool name
     */
    function setPoolName(uint256 poolId, string calldata newName) external onlyPlatformAdmin validPool(poolId) {
        string memory oldName = pools[poolId].name;
        pools[poolId].name = newName;
        emit PoolNameUpdated(poolId, oldName, newName);
    }

    /**
     * @notice Set initial penalty BPS for a pool
     * @param poolId Pool identifier
     * @param newPenaltyBps New penalty BPS (max 4000 = 40%)
     */
    function setInitialPenaltyBps(uint256 poolId, uint16 newPenaltyBps) external onlyPlatformAdmin validPool(poolId) {
        if (newPenaltyBps > MAX_PENALTY_BPS) revert InvalidAmount(newPenaltyBps);
        
        uint16 oldPenalty = pools[poolId].initialPenaltyBps;
        pools[poolId].initialPenaltyBps = newPenaltyBps;
        emit PoolPenaltyUpdated(poolId, oldPenalty, newPenaltyBps);
    }

    /**
     * @notice Set rewards wallet address
     * @param newRewardsWallet New rewards wallet address
     */
    function setRewardsWallet(address newRewardsWallet) external onlyPlatformAdmin {
        if (newRewardsWallet == address(0)) revert InvalidAddress();
        address oldWallet = rewardsWallet;
        rewardsWallet = newRewardsWallet;
        emit RewardsWalletUpdated(oldWallet, newRewardsWallet);
    }

    /**
     * @notice Add a new staking pool
     * @param lockupSeconds Duration tokens must be locked up for
     * @param rewardCap Total reward tokens allocated to this pool
     * @param initialPenaltyBps Early withdrawal penalty in basis points (max 4000 = 40%)
     * @param name Name identifier for the pool
     * @param minAPY Minimum APY in basis points
     * @param maxAPY Maximum APY in basis points
     * @param endTime When the pool ends (0 = no end)
     */
    function addPool(
        uint64 lockupSeconds,
        uint256 rewardCap,
        uint16 initialPenaltyBps,
        string calldata name,
        uint256 minAPY,
        uint256 maxAPY,
        uint256 endTime
    ) external onlyPlatformAdmin {
        if (rewardCap > MAX_REWARD_CAP) revert InvalidAmount(rewardCap);
        if (initialPenaltyBps > MAX_PENALTY_BPS) revert InvalidAmount(initialPenaltyBps);
        
        pools.push(
            PoolInfo({
                rewardCap: rewardCap,
                totalStaked: 0,
                rewardRatePerSec: 0,
                lastCheckpoint: block.timestamp,
                minAPY: minAPY,
                maxAPY: maxAPY,
                endTime: endTime,
                currentAPY: 0,
                totalRewardsPaid: 0,
                lockupSeconds: lockupSeconds,
                initialPenaltyBps: initialPenaltyBps,
                isPaused: false,
                name: name
            })
        );
        uint256 poolId = pools.length - 1;
        poolCheckpoints[poolId].push(
            Checkpoint({ timestamp: block.timestamp, totalStaked: 0, rewardRatePerSec: 0, cumulativeRewardPerToken: 0 })
        );
        emit PoolAdded(poolId, name);
    }

    

    // ========================================================
    //                   Migration Functions
    // ========================================================

    /**
     * @notice Enable migration mode - pauses all pools, zeros penalties and locks APY at zero
     */
    function enableMigrationMode() external onlyPlatformAdmin {
        // Pause all pools and lock rewards at zero BEFORE setting migration mode
        for (uint256 poolId = 0; poolId < pools.length; poolId++) {
            pools[poolId].isPaused = true;
            pools[poolId].initialPenaltyBps = 0; // No withdrawal penalties

            // LOCK APY at zero - these won't change during migration
            pools[poolId].rewardRatePerSec = 0;
            pools[poolId].currentAPY = 0;
            pools[poolId].minAPY = 0;
            pools[poolId].maxAPY = 0;

            emit PoolPaused(poolId, true);
        }

        unchecked { ++migrationEpoch; }

        // Set migration mode AFTER updating pools
        migrationMode = true;

        // Create final checkpoints with zero rewards
        for (uint256 poolId = 0; poolId < pools.length; poolId++) {
            // Force create checkpoint with current zero values
            Checkpoint[] storage checkpoints = poolCheckpoints[poolId];
            checkpoints.push(
                Checkpoint({
                    timestamp: block.timestamp,
                    totalStaked: pools[poolId].totalStaked,
                    rewardRatePerSec: 0, // Explicitly zero
                    cumulativeRewardPerToken: _calculateNewCumulativeReward(poolId, checkpoints)
                })
            );
            emit CheckpointCreated(poolId, block.timestamp, pools[poolId].totalStaked, 0);
        }

        emit MigrationModeEnabled();
    }

    /**
     * @notice Disable migration mode and restore pool configurations
     * @param poolConfigs Array of pool configurations to restore after migration
     */
    function disableMigrationMode(
        PoolConfig[] calldata poolConfigs
    ) external onlyPlatformAdmin {
        if (poolConfigs.length != pools.length) revert ArrayLengthMismatch();
        
        migrationMode = false;

        for (uint256 poolId = 0; poolId < pools.length; poolId++) {
            PoolConfig memory config = poolConfigs[poolId];
            
            if (config.initialPenaltyBps > MAX_PENALTY_BPS) revert InvalidAmount(config.initialPenaltyBps);
            
            pools[poolId].isPaused = false;
            pools[poolId].minAPY = config.minAPY;
            pools[poolId].maxAPY = config.maxAPY;
            pools[poolId].initialPenaltyBps = config.initialPenaltyBps;
            
            _updatePool(poolId);
            _createCheckpoint(poolId);
            
            emit PoolPaused(poolId, false);
            emit APYLimitsUpdated(poolId, config.minAPY, config.maxAPY);
            emit PoolPenaltyUpdated(poolId, 0, config.initialPenaltyBps);
        }

        emit MigrationModeDisabled();
    }

    /**
     * @notice Batch withdraw all stakes for migration (only in migration mode)
     */
    function migrateWithdrawAll(uint256 maxPools) external nonReentrant onlyInMigrationMode {
        if (maxPools == 0) revert InvalidAmount(maxPools);
        uint256 poolCount = pools.length;
        uint256 totalWithdrawn;
        uint256 totalRewards;

        if (userMigrationEpoch[msg.sender] != migrationEpoch) {
            userMigrationCursor[msg.sender] = 0;
            userMigrationEpoch[msg.sender] = migrationEpoch;
        }

        uint256 startPoolId = userMigrationCursor[msg.sender];
        if (startPoolId >= poolCount) {
            return;
        }

        uint256 poolsToProcess = maxPools;
        uint256 remaining = poolCount - startPoolId;
        if (poolsToProcess > remaining) poolsToProcess = remaining;

        uint256 endPoolExclusive = startPoolId + poolsToProcess;

        for (uint256 poolId = startPoolId; poolId < endPoolExclusive;) {
            StakeInfo[] storage userStakes = stakes[poolId][msg.sender];
            uint256 stakeCount = userStakes.length;

            if (stakeCount > 0) {
                uint256 poolStakeAmount;

                for (uint256 i = stakeCount; i > 0;) {
                    unchecked { --i; }
                    StakeInfo storage userStake = userStakes[i];

                    if (userStake.amount > 0) {
                        uint256 pending = _calculatePendingRewardsWithCheckpoints(poolId, userStake);

                        unchecked {
                            totalWithdrawn += userStake.amount;
                            totalRewards += pending;
                            poolStakeAmount += userStake.amount;
                        }

                        if (pending > 0) {
                            unchecked { userStake.totalClaimedRewards += pending; }
                            userStake.lastClaimTimestamp = block.timestamp;

                            unchecked { pools[poolId].totalRewardsPaid += pending; }
                            emit RewardClaimed(poolId, msg.sender, i, pending);
                        }
                        emit Withdrawn(poolId, msg.sender, i, userStake.amount, 0);
                    }
                }

                unchecked { pools[poolId].totalStaked -= poolStakeAmount; }
                delete stakes[poolId][msg.sender];
            }

            unchecked { ++poolId; }
        }

        userMigrationCursor[msg.sender] = endPoolExclusive;

        if (totalWithdrawn > 0) stakingToken.safeTransfer(msg.sender, totalWithdrawn);
        if (totalRewards > 0) {
            if (_tryTransferRewards(msg.sender, totalRewards)) {
            } else {
                owedRewards[msg.sender] += totalRewards;
                emit RewardsOwed(msg.sender, totalRewards, "RewardsWallet transfer failed during migration");
            }
        }

        emit UserMigrated(msg.sender, totalWithdrawn, totalRewards);
    }

    /**
     * @notice Get user's total migration data
     * @param user User address
     * @return totalStaked Total staked amount across all pools
     * @return totalPendingRewards Total pending rewards across all pools
     * @return totalStakes Total number of stakes
     */
    function getUserMigrationSummary(address user) external view returns (
        uint256 totalStaked,
        uint256 totalPendingRewards,
        uint256 totalStakes
    ) {
        uint256 poolCount = pools.length;

        for (uint256 poolId = 0; poolId < poolCount; poolId++) {
            StakeInfo[] memory userStakes = stakes[poolId][user];
            uint256 stakeCount = userStakes.length;

            if (stakeCount == 0) continue; // Skip empty pools

            totalStakes += stakeCount;

            for (uint256 i = 0; i < stakeCount; i++) {
                StakeInfo memory stakeInfo = userStakes[i];
                if (stakeInfo.amount > 0) { // Only process non-zero stakes
                    totalStaked += stakeInfo.amount;
                    totalPendingRewards += _calculatePendingRewardsWithCheckpoints(poolId, stakeInfo);
                }
            }
        }
    }

    /**
     * @notice Check if migration mode is active
     * @return True if migration mode is active
     */
    function isMigrationMode() external view returns (bool) {
        return migrationMode;
    }

    // ========================================================
    //                   Staking Functions
    // ========================================================

    /// @notice Stake tokens in a specific pool
    function stake(uint256 poolId, uint256 amount) 
        external 
        nonReentrant 
        validPool(poolId) 
        onlyNotInMigrationMode 
        poolNotPaused(poolId) 
        poolNotEnded(poolId) 
    {
        if (amount == 0) revert InvalidAmount(amount);
        if (amount < minStakeAmount) revert BelowMinStake(amount, minStakeAmount);

        // Cache timestamp and calculate unlock time
        uint256 currentTime = block.timestamp;
        uint256 unlockTime = currentTime + pools[poolId].lockupSeconds;

        // Create stake
        stakes[poolId][msg.sender].push(
            StakeInfo({
                amount: amount,
                unlockTimestamp: unlockTime,
                lastClaimTimestamp: currentTime,
                stakeTimestamp: currentTime,
                totalClaimedRewards: 0
            })
        );

        // Update pool state
        unchecked { pools[poolId].totalStaked += amount; }
        _updatePool(poolId);
        _createCheckpoint(poolId);

        uint256 stakeIndex = stakes[poolId][msg.sender].length - 1;
        emit Staked(poolId, msg.sender, stakeIndex, amount);

        stakingToken.safeTransferFrom(msg.sender, address(this), amount);
    }

    /**
     * @notice Claim rewards from a specific stake
     * @param poolId Pool identifier
     * @param stakeIndex Index of the stake
     */
    function claim(
        uint256 poolId,
        uint256 stakeIndex
    ) external nonReentrant validPool(poolId) validStake(poolId, msg.sender, stakeIndex) {
        StakeInfo storage userStake = stakes[poolId][msg.sender][stakeIndex];

        // If pool has ended, ensure pool state is updated and checkpointed
        if (pools[poolId].endTime > 0 && block.timestamp >= pools[poolId].endTime) {
            _updatePool(poolId);
            _createCheckpoint(poolId);
        }
        
        uint256 pending = _calculatePendingRewardsWithCheckpoints(poolId, userStake);

        if (pending > 0) {
            userStake.lastClaimTimestamp = block.timestamp;
            userStake.totalClaimedRewards += pending;

            // Track total rewards paid for cap enforcement
            pools[poolId].totalRewardsPaid += pending;

            // Check if reward cap exceeded and update pool if needed
            if (pools[poolId].rewardCap > 0 && pools[poolId].totalRewardsPaid >= pools[poolId].rewardCap) {
                _updatePool(poolId);
                _createCheckpoint(poolId);
            }

            if (_tryTransferRewards(msg.sender, pending)) {
                emit RewardClaimed(poolId, msg.sender, stakeIndex, pending);
            } else {
                owedRewards[msg.sender] += pending;
                emit RewardsOwed(msg.sender, pending, "RewardsWallet transfer failed");
            }
        }
    }

    /// @notice Batch claim rewards for all stakes in all pools for the caller
    function batchClaim() external nonReentrant {
        uint256 poolCount = pools.length;
        uint256 currentTime = block.timestamp;

        for (uint256 poolId; poolId < poolCount;) {
            if (pools[poolId].endTime > 0 && block.timestamp >= pools[poolId].endTime) {
                _updatePool(poolId);
                _createCheckpoint(poolId);
            }
            StakeInfo[] storage userStakes = stakes[poolId][msg.sender];
            uint256 stakeCount = userStakes.length;

            for (uint256 stakeIndex; stakeIndex < stakeCount;) {
                StakeInfo storage userStake = userStakes[stakeIndex];
                uint256 pending = _calculatePendingRewardsWithCheckpoints(poolId, userStake);

                if (pending > 0) {
                    userStake.lastClaimTimestamp = currentTime;
                    unchecked { userStake.totalClaimedRewards += pending; }
                    unchecked { pools[poolId].totalRewardsPaid += pending; }

                    // Check if reward cap exceeded and update pool if needed
                    if (pools[poolId].totalRewardsPaid >= pools[poolId].rewardCap && pools[poolId].rewardCap > 0) {
                        _updatePool(poolId);
                        _createCheckpoint(poolId);
                    }

                    if (_tryTransferRewards(msg.sender, pending)) {
                        emit RewardClaimed(poolId, msg.sender, stakeIndex, pending);
                    } else {
                        owedRewards[msg.sender] += pending;
                        emit RewardsOwed(msg.sender, pending, "RewardsWallet transfer failed");
                    }
                }

                unchecked { ++stakeIndex; }
            }

            unchecked { ++poolId; }
        }
    }

    /// @notice Withdraw entire stake (with penalty if before unlock)
    function withdraw(uint256 poolId, uint256 stakeIndex) 
        external 
        nonReentrant 
        validPool(poolId) 
        validStake(poolId, msg.sender, stakeIndex) 
    {
        StakeInfo storage userStake = stakes[poolId][msg.sender][stakeIndex];
        uint256 stakeAmount = userStake.amount;
        if (stakeAmount == 0) revert InvalidAmount(0);

        uint256 currentTime = block.timestamp;

        // If pool has ended, ensure pool state is updated and checkpointed
        if (pools[poolId].endTime > 0 && currentTime >= pools[poolId].endTime) {
            _updatePool(poolId);
            _createCheckpoint(poolId);
        }

        // Calculate and claim pending rewards
        uint256 pending = _calculatePendingRewardsWithCheckpoints(poolId, userStake);
        if (pending > 0) {
            userStake.lastClaimTimestamp = currentTime;
            unchecked { userStake.totalClaimedRewards += pending; }
            unchecked { pools[poolId].totalRewardsPaid += pending; }

            if (_tryTransferRewards(msg.sender, pending)) {
                emit RewardClaimed(poolId, msg.sender, stakeIndex, pending);
            } else {
                owedRewards[msg.sender] += pending;
                emit RewardsOwed(msg.sender, pending, "RewardsWallet transfer failed");
            }
        }

        // Calculate early withdrawal penalty
        uint256 penalty;
        if (currentTime < userStake.unlockTimestamp) {
            penalty = _calculatePenalty(poolId, userStake, stakeAmount);
            if (penalty > stakeAmount) penalty = stakeAmount;
        }

        // Update pool state and remove stake
        unchecked { pools[poolId].totalStaked -= stakeAmount; }
        _updatePool(poolId);
        _createCheckpoint(poolId);
        _removeStake(poolId, msg.sender, stakeIndex);

        // Transfer tokens
        unchecked {
            uint256 withdrawAmount = stakeAmount - penalty;
            if (withdrawAmount > 0) stakingToken.safeTransfer(msg.sender, withdrawAmount);
            if (penalty > 0) stakingToken.safeTransfer(penaltyWallet, penalty);
        }

        emit Withdrawn(poolId, msg.sender, stakeIndex, stakeAmount, penalty);
    }

    /// @notice Claim owed rewards that failed to transfer during withdrawal
    function claimOwedRewards(uint256 amount) external nonReentrant {
        uint256 userOwedRewards = owedRewards[msg.sender];
        if (userOwedRewards == 0) revert InvalidAmount(0);

        uint256 claimAmount = amount == 0 ? userOwedRewards : amount;
        if (claimAmount > userOwedRewards) revert InvalidAmount(claimAmount);

        if (_tryTransferRewards(msg.sender, claimAmount)) {
            owedRewards[msg.sender] -= claimAmount;
            emit OwedRewardsClaimed(msg.sender, claimAmount);
        } else {
            revert("RewardsWallet transfer failed");
        }
    }

    // ========================================================
    //                  Internal Functions
    // ========================================================

    /// @notice Update pool reward rate based on current state
    function _updatePool(uint256 poolId) internal {
        PoolInfo storage pool = pools[poolId];

        // Early returns for special states
        if (migrationMode) {
            pool.rewardRatePerSec = 0;
            pool.currentAPY = 0;
            pool.lastCheckpoint = block.timestamp;
            return;
        }

        if (pool.endTime > 0 && block.timestamp >= pool.endTime) {
            pool.rewardRatePerSec = 0;
            pool.currentAPY = 0;
            pool.lastCheckpoint = block.timestamp;
            return;
        }

        // Cache pool values to reduce storage reads
        uint256 totalStaked = pool.totalStaked;
        uint256 rewardCap = pool.rewardCap;
        uint256 totalRewardsPaid = pool.totalRewardsPaid;
        uint256 minAPY = pool.minAPY;
        uint256 maxAPY = pool.maxAPY;

        uint256 newAPY;

        // Calculate APY based on current state
        if (totalRewardsPaid >= rewardCap && rewardCap > 0) {
            newAPY = minAPY; // Cap exceeded
        } else if (totalStaked == 0) {
            newAPY = 0; // No stakes, freeze rewards
        } else if (rewardCap > 0) {
            // Calculate theoretical APY from original reward cap (fixed allocation)
            uint256 annualFactor = (365 days * BASIS_POINTS) / pool.lockupSeconds;
            uint256 theoreticalAPY = Math.mulDiv(rewardCap, annualFactor, totalStaked);

            // Apply limits
            newAPY = theoreticalAPY;
            if (minAPY > 0 && newAPY < minAPY) newAPY = minAPY;
            if (maxAPY > 0 && newAPY > maxAPY) newAPY = maxAPY;
        } else {
            // No cap, use min APY but check for zero stakes first
            if (totalStaked == 0) {
                newAPY = 0; // No stakes, freeze rewards
            } else {
                newAPY = minAPY; // No cap, use min APY
            }
        }

        // Update pool state
        pool.currentAPY = newAPY;
        pool.rewardRatePerSec = Math.mulDiv(newAPY, PRECISION, 365 days * BASIS_POINTS);
        pool.lastCheckpoint = block.timestamp;
    }

    /**
     * @notice Create a new checkpoint for APY tracking
     * @param poolId Pool identifier
     */
    function _createCheckpoint(uint256 poolId) internal {
        PoolInfo memory pool = pools[poolId];
        Checkpoint[] storage checkpoints = poolCheckpoints[poolId];

        // CRITICAL: Don't create new checkpoints during migration mode
        // The final checkpoint was created when migration mode was enabled
        if (migrationMode && checkpoints.length > 0) {
            return; // Skip checkpoint creation entirely
        }

        // Only create checkpoint if rate or stake amount changed
        if (
            checkpoints.length == 0 ||
            checkpoints[checkpoints.length - 1].rewardRatePerSec != pool.rewardRatePerSec ||
            checkpoints[checkpoints.length - 1].totalStaked != pool.totalStaked
        ) {
            checkpoints.push(
                Checkpoint({
                    timestamp: block.timestamp,
                    totalStaked: pool.totalStaked,
                    rewardRatePerSec: pool.rewardRatePerSec,
                    cumulativeRewardPerToken: _calculateNewCumulativeReward(poolId, checkpoints)
                })
            );

            emit CheckpointCreated(poolId, block.timestamp, pool.totalStaked, pool.rewardRatePerSec);
        }
    }

    /// @notice Calculate new cumulative reward per token for a checkpoint
    function _calculateNewCumulativeReward(
        uint256 poolId,
        Checkpoint[] storage checkpoints
    ) internal view returns (uint256) {
        if (checkpoints.length == 0) {
            return 0;
        }

        Checkpoint memory lastCheckpoint = checkpoints[checkpoints.length - 1];
        // Cap accrual at pool end time if set
        uint256 effectiveNow = block.timestamp;
        uint256 poolEnd = pools[poolId].endTime;
        if (poolEnd > 0 && effectiveNow > poolEnd) {
            effectiveNow = poolEnd;
        }
        if (effectiveNow <= lastCheckpoint.timestamp) {
            return lastCheckpoint.cumulativeRewardPerToken;
        }
        uint256 timeDelta = effectiveNow - lastCheckpoint.timestamp;

        if (timeDelta == 0) {
            return lastCheckpoint.cumulativeRewardPerToken;
        }

        return lastCheckpoint.cumulativeRewardPerToken + lastCheckpoint.rewardRatePerSec * timeDelta;
    }

    /**
     * @notice Calculate pending rewards using optimized prefix sum approach
     * @param poolId Pool identifier
     * @param userStake Stake information
     * @return pending Pending reward amount
     */
    function _calculatePendingRewardsWithCheckpoints(
        uint256 poolId,
        StakeInfo memory userStake
    ) internal view returns (uint256 pending) {
        Checkpoint[] memory checkpoints = poolCheckpoints[poolId];
        if (checkpoints.length == 0) return 0;

        uint256 lastClaimTime = userStake.lastClaimTimestamp;
        uint256 currentTime = block.timestamp;

        // Cap calculation window at pool end time if set
        uint256 poolEnd = pools[poolId].endTime;
        uint256 effectiveNow = currentTime;
        if (poolEnd > 0 && effectiveNow > poolEnd) {
            effectiveNow = poolEnd;
        }
        if (lastClaimTime > effectiveNow) {
            // Nothing to accrue after end time
            return 0;
        }

        // Find checkpoint at last claim time using binary search
        uint256 startIdx = _findCheckpointAtTimestamp(checkpoints, lastClaimTime);

        // Get cumulative reward per token at last claim time
        uint256 startCumulative = checkpoints[startIdx].cumulativeRewardPerToken;

        // Create a fresh checkpoint to get accurate current cumulative reward
        // This eliminates precision issues with manual partial calculations
        uint256 endCumulative;
        uint256 endIdx = _findCheckpointAtTimestamp(checkpoints, effectiveNow);
        
        if (effectiveNow > checkpoints[endIdx].timestamp) {
            // Calculate end cumulative with current timestamp
            uint256 timeDelta = effectiveNow - checkpoints[endIdx].timestamp;
            endCumulative = checkpoints[endIdx].cumulativeRewardPerToken + 
                           checkpoints[endIdx].rewardRatePerSec * timeDelta;
        } else {
            endCumulative = checkpoints[endIdx].cumulativeRewardPerToken;
        }
        
        // For start cumulative, if lastClaimTime is after the checkpoint, calculate accordingly
        if (lastClaimTime > checkpoints[startIdx].timestamp) {
            uint256 timeDelta = lastClaimTime - checkpoints[startIdx].timestamp;
            startCumulative = checkpoints[startIdx].cumulativeRewardPerToken + 
                             checkpoints[startIdx].rewardRatePerSec * timeDelta;
        }

        // Calculate pending rewards: amount * (endCumulative - startCumulative) / PRECISION
        if (endCumulative > startCumulative) {
            pending = (userStake.amount * (endCumulative - startCumulative)) / PRECISION;
        }
    }

    /**
     * @notice Binary search to find the checkpoint at or before a given timestamp
     * @param checkpoints Array of checkpoints
     * @param timestamp Target timestamp
     * @return Index of the checkpoint
     */
    function _findCheckpointAtTimestamp(
        Checkpoint[] memory checkpoints,
        uint256 timestamp
    ) internal pure returns (uint256) {
        if (checkpoints.length == 0) {
            return 0;
        }

        uint256 left = 0;
        uint256 right = checkpoints.length - 1;

        // If timestamp is before first checkpoint, return 0
        if (timestamp < checkpoints[0].timestamp) {
            return 0;
        }

        // If timestamp is after last checkpoint, return last index
        if (timestamp >= checkpoints[right].timestamp) {
            return right;
        }

        // Binary search for the last checkpoint with timestamp <= target
        while (left < right) {
            uint256 mid = (left + right + 1) / 2;
            if (checkpoints[mid].timestamp <= timestamp) {
                left = mid;
            } else {
                right = mid - 1;
            }
        }

        return left;
    }

    /**
     * @notice Calculate penalty for early withdrawal
     * @param poolId Pool identifier
     * @param userStake Stake information
     * @param withdrawAmount Amount being withdrawn
     * @return penalty Penalty amount
     */
    function _calculatePenalty(
        uint256 poolId,
        StakeInfo memory userStake,
        uint256 withdrawAmount
    ) internal view returns (uint256 penalty) {
        PoolInfo memory pool = pools[poolId];

        if (pool.lockupSeconds == 0) return 0;

        // Calculate elapsed time since stake start
        uint256 stakeStartTime = userStake.stakeTimestamp;
        uint256 elapsed = block.timestamp - stakeStartTime;

        if (elapsed >= pool.lockupSeconds) return 0;

        // Linear penalty reduction: penaltyBps = initialPenaltyBps * (lockupSeconds - elapsed) / lockupSeconds
        uint256 penaltyBps = (pool.initialPenaltyBps * (pool.lockupSeconds - elapsed)) / pool.lockupSeconds;
        penalty = (withdrawAmount * penaltyBps) / BASIS_POINTS;

        if (penalty > withdrawAmount) {
            penalty = withdrawAmount;
        }
    }

    /**
     * @notice Remove a stake from user's stakes array
     * @param poolId Pool identifier
     * @param user User address
     * @param stakeIndex Index of stake to remove
     */
    function _removeStake(uint256 poolId, address user, uint256 stakeIndex) internal {
        StakeInfo[] storage userStakes = stakes[poolId][user];

        if (userStakes.length == 0) return;
        if (stakeIndex >= userStakes.length) return;

        if (stakeIndex != userStakes.length - 1) {
            userStakes[stakeIndex] = userStakes[userStakes.length - 1];
        }
        userStakes.pop();
    }

    /**
     * @notice Internal function to try transferring rewards from rewardsWallet
     * @param to Recipient address
     * @param amount Amount to transfer
     * @return success True if transfer succeeded, false otherwise
     */
    function _tryTransferRewards(address to, uint256 amount) internal returns (bool success) {
        (bool callSuccess, bytes memory returnData) = address(stakingToken).call(
            abi.encodeWithSelector(
                stakingToken.transferFrom.selector,
                rewardsWallet,
                to,
                amount
            )
        );

        if (!callSuccess) {
            return false;
        }

        if (returnData.length > 0) {
            bool transferSuccess;
            if (returnData.length >= 32) {
                assembly {
                    transferSuccess := mload(add(returnData, 32))
                }
                return transferSuccess;
            }
            return true;
        }

        return true;
    }

    // ========================================================
    //                    View Functions
    // ========================================================

    /// @notice Get pool information
    function getPoolInfo(uint256 poolId) external view validPool(poolId) returns (PoolInfo memory) {
        return pools[poolId];
    }

    /// @notice Get all stakes for a user in a pool with pending rewards
    function getUserStakes(uint256 poolId, address user) 
        external 
        view 
        validPool(poolId) 
        returns (StakeInfoWithRewards[] memory) 
    {
        StakeInfo[] memory userStakes = stakes[poolId][user];
        uint256 stakeCount = userStakes.length;
        StakeInfoWithRewards[] memory stakesWithRewards = new StakeInfoWithRewards[](stakeCount);

        for (uint256 i; i < stakeCount;) {
            StakeInfo memory currentStake = userStakes[i];
            uint256 pendingRewards = _calculatePendingRewardsWithCheckpoints(poolId, currentStake);

            stakesWithRewards[i] = StakeInfoWithRewards({
                amount: currentStake.amount,
                unlockTimestamp: currentStake.unlockTimestamp,
                lastClaimTimestamp: currentStake.lastClaimTimestamp,
                stakeTimestamp: currentStake.stakeTimestamp,
                pendingRewards: pendingRewards,
                totalClaimedRewardsWithPendingRewards: currentStake.totalClaimedRewards + pendingRewards
            });

            unchecked { ++i; }
        }

        return stakesWithRewards;
    }

    /// @notice Get pending rewards for all stakes of a user in a pool
    function getPendingRewards(uint256 poolId, address user) 
        external 
        view 
        validPool(poolId) 
        returns (uint256[] memory) 
    {
        StakeInfo[] memory userStakes = stakes[poolId][user];
        uint256 stakeCount = userStakes.length;
        uint256[] memory pendingRewards = new uint256[](stakeCount);

        for (uint256 i; i < stakeCount;) {
            pendingRewards[i] = _calculatePendingRewardsWithCheckpoints(poolId, userStakes[i]);
            unchecked { ++i; }
        }

        return pendingRewards;
    }

    /// @notice Get total pending rewards for a user across all pools
    function getTotalPendingRewards(address user) external view returns (uint256 totalPending) {
        uint256 poolCount = pools.length;
        for (uint256 poolId; poolId < poolCount;) {
            StakeInfo[] memory userStakes = stakes[poolId][user];
            uint256 stakeCount = userStakes.length;

            for (uint256 i; i < stakeCount;) {
                unchecked {
                    totalPending += _calculatePendingRewardsWithCheckpoints(poolId, userStakes[i]);
                    ++i;
                }
            }
            unchecked { ++poolId; }
        }
    }

    /// @notice Calculate penalty for early withdrawal of entire stake
    function calculateWithdrawPenalty(uint256 poolId, address user, uint256 stakeIndex) 
        external 
        view 
        validPool(poolId) 
        validStake(poolId, user, stakeIndex) 
        returns (uint256) 
    {
        StakeInfo memory userStake = stakes[poolId][user][stakeIndex];
        return block.timestamp >= userStake.unlockTimestamp ? 
            0 : _calculatePenalty(poolId, userStake, userStake.amount);
    }

    /**
     * @notice Calculate future rewards for a hypothetical stake at a given timestamp
     * @param poolId Pool identifier
     * @param amount Amount to stake
     * @param futureTimestamp Future timestamp to calculate rewards for
     * @return futureRewards Expected rewards at the future timestamp
     */
    function calculateFutureRewards(
        uint256 poolId,
        uint256 amount,
        uint256 futureTimestamp
    ) external view validPool(poolId) returns (uint256 futureRewards) {
        if (futureTimestamp <= block.timestamp) {
            return 0;
        }
        PoolInfo memory pool = pools[poolId];
        uint256 timeDelta = futureTimestamp - block.timestamp;
        futureRewards = (amount * pool.rewardRatePerSec * timeDelta) / PRECISION;
    }

    /**
     * @notice Get checkpoints for a pool
     * @param poolId Pool identifier
     * @return Array of checkpoints
     */
    function getPoolCheckpoints(uint256 poolId) external view validPool(poolId) returns (Checkpoint[] memory) {
        return poolCheckpoints[poolId];
    }

    /**
     * @notice Get total number of pools
     * @return Number of pools
     */
    function getPoolCount() external view returns (uint256) {
        return pools.length;
    }

    /**
     * @notice Get number of stakes for a user in a pool
     * @param poolId Pool identifier
     * @param user User address
     * @return Number of stakes
     */
    function getUserStakeCount(uint256 poolId, address user) external view validPool(poolId) returns (uint256) {
        return stakes[poolId][user].length;
    }

    /**
     * @notice Get current penalty wallet address
     * @return Penalty wallet address
     */
    function getPenaltyWallet() external view returns (address) {
        return penaltyWallet;
    }

    /**
     * @notice Get minimum stake amount
     * @return Minimum stake amount
     */
    function getMinStakeAmount() external view returns (uint256) {
        return minStakeAmount;
    }

    /**
     * @notice Get APY limits for a pool
     * @param poolId Pool identifier
     * @return minAPY Minimum APY in basis points
     * @return maxAPY Maximum APY in basis points
     */
    function getAPYLimits(uint256 poolId) external view validPool(poolId) returns (uint256 minAPY, uint256 maxAPY) {
        PoolInfo memory pool = pools[poolId];
        return (pool.minAPY, pool.maxAPY);
    }

    /**
     * @notice Get pool end time
     * @param poolId Pool identifier
     * @return endTime Pool end time (0 = infinite)
     */
    function getPoolEndTime(uint256 poolId) external view validPool(poolId) returns (uint256 endTime) {
        return pools[poolId].endTime;
    }

    /**
     * @notice Get current APY for a pool
     * @param poolId Pool identifier
     * @return apy Annual percentage yield in basis points
     */
    function getCurrentAPY(uint256 poolId) external view validPool(poolId) returns (uint256 apy) {
        return pools[poolId].currentAPY;
    }

    /**
     * @notice Check if a specific stake is matured (lockup period is over)
     * @param poolId Pool identifier
     * @param user User address
     * @param stakeIndex Index of the stake
     * @return isMatured True if the stake is matured, false otherwise
     */
    function isStakeMatured(
        uint256 poolId,
        address user,
        uint256 stakeIndex
    ) external view validPool(poolId) validStake(poolId, user, stakeIndex) returns (bool isMatured) {
        StakeInfo memory userStake = stakes[poolId][user][stakeIndex];
        return block.timestamp >= userStake.unlockTimestamp;
    }

    /**
     * @notice Get total earned rewards (claimed + pending) for a specific stake
     * @param poolId Pool identifier
     * @param user User address
     * @param stakeIndex Index of the stake
     * @return totalEarned Total rewards ever earned for this stake
     */
    function getTotalEarnedForStake(
        uint256 poolId,
        address user,
        uint256 stakeIndex
    ) external view validPool(poolId) validStake(poolId, user, stakeIndex) returns (uint256 totalEarned) {
        StakeInfo memory userStake = stakes[poolId][user][stakeIndex];
        uint256 pending = _calculatePendingRewardsWithCheckpoints(poolId, userStake);
        return userStake.totalClaimedRewards + pending;
    }

    /**
     * @notice Get all-time total rewards earned (claimed + pending) for a user in a pool
     * @param poolId Pool identifier
     * @param user User address
     * @return totalEarned All-time total rewards for the user in the pool
     */
    function getTotalEarnedForUserInPool(
        uint256 poolId,
        address user
    ) external view validPool(poolId) returns (uint256 totalEarned) {
        StakeInfo[] memory userStakes = stakes[poolId][user];
        for (uint256 i = 0; i < userStakes.length; i++) {
            uint256 pending = _calculatePendingRewardsWithCheckpoints(poolId, userStakes[i]);
            totalEarned += userStakes[i].totalClaimedRewards + pending;
        }
    }

    /**
     * @notice Get all-time total rewards earned (claimed + pending) for a user across all pools
     * @param user User address
     * @return totalEarned All-time total rewards for the user across all pools
     */
    function getTotalEarnedForUserInAllPools(address user) external view returns (uint256 totalEarned) {
        uint256 poolCount = pools.length;
        for (uint256 poolId = 0; poolId < poolCount; poolId++) {
            StakeInfo[] memory userStakes = stakes[poolId][user];
            for (uint256 i = 0; i < userStakes.length; i++) {
                uint256 pending = _calculatePendingRewardsWithCheckpoints(poolId, userStakes[i]);
                totalEarned += userStakes[i].totalClaimedRewards + pending;
            }
        }
    }

    /**
     * @notice Get total staked amount for a user across all pools
     * @param user User address
     * @return totalStaked Total staked amount across all pools
     */
    function getTotalStakedByUser(address user) external view returns (uint256 totalStaked) {
        uint256 poolCount = pools.length;
        for (uint256 poolId = 0; poolId < poolCount; poolId++) {
            StakeInfo[] memory userStakes = stakes[poolId][user];
            for (uint256 i = 0; i < userStakes.length; i++) {
                totalStaked += userStakes[i].amount;
            }
        }
    }

    /**
     * @notice Get amount of owed rewards for a user
     * @param user User address
     * @return amount Amount of owed rewards
     */
    ...

// [truncated — 50121 bytes total]