// 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) (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/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) (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) (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
// 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;
    }
}

// contracts/TokenVesting.sol
// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.24;

// OpenZeppelin dependencies
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";

using SafeERC20 for IERC20;

/**
 * @title TokenVesting
 */
contract TokenVesting is Ownable, ReentrancyGuard {
    struct VestingSchedule {
        // beneficiary of tokens after they are released
        address beneficiary;
        // cliff time of the vesting start in seconds since the UNIX epoch
        uint256 cliff;
        // start time of the vesting period in seconds since the UNIX epoch
        uint256 start;
        // duration of the vesting period in seconds
        uint256 duration;
        // duration of a slice period for the vesting in seconds
        uint256 slicePeriodSeconds;
        // whether or not the vesting is revocable
        bool revocable;
        // total amount of tokens to be released at the end of the vesting
        uint256 amountTotal;
        // amount of tokens released
        uint256 released;
        // whether or not the vesting has been revoked
        bool revoked;
    }

    event VestingScheduleCreated(address indexed beneficiary, uint256 amount);

    // address of the ERC20 token
    IERC20 private immutable _token;

    bytes32[] private vestingSchedulesIds;
    mapping(bytes32 => VestingSchedule) private vestingSchedules;
    uint256 private vestingSchedulesTotalAmount;
    mapping(address => uint256) private holdersVestingCount;


    uint256 public START;
    uint256 public DURATION;
    uint256 public CLIFF;
    uint256 public SLICE_PERIOD;

    address public seller;

    /**
     * @dev Reverts if the vesting schedule does not exist or has been revoked.
     */
    modifier onlyIfVestingScheduleNotRevoked(bytes32 vestingScheduleId) {
        require(!vestingSchedules[vestingScheduleId].revoked);
        _;
    }

    /**
     * @dev Creates a vesting contract.
     * @param token_ address of the ERC20 token contract
     */
    constructor(address token_, uint256 _start, uint256 _duration, uint256 _cliff, uint256 _slicePeriodSeconds) Ownable(msg.sender) {
        
        // Check that the token address is not 0x0.
        require(token_ != address(0x0));
        require(_duration > 0, "TokenVesting: duration must be > 0");
        require(
            _slicePeriodSeconds >= 1,
            "TokenVesting: slicePeriodSeconds must be >= 1"
        );
        require(_duration >= _cliff, "TokenVesting: duration must be >= cliff");
        // Set the token address.
        _token = IERC20(token_);
        START = _start;
        DURATION = _duration;
        CLIFF = _cliff;
        SLICE_PERIOD = _slicePeriodSeconds;

    }

    /**
     * @dev This function is called for plain Ether transfers, i.e. for every call with empty calldata.
     */
    receive() external payable {}

    /**
     * @dev Fallback function is executed if none of the other functions match the function
     * identifier or no data was provided with the function call.
     */
    fallback() external payable {}

    function setSeller(address _seller) external onlyOwner {
        seller = _seller;
    }

    /**
     * @notice Creates a new vesting schedule for a beneficiary.
     * @param _beneficiary address of the beneficiary to whom vested tokens are transferred
     * @param _amount total amount of tokens to be released at the end of the vesting
     * @param _revocable whether the vesting is revocable or not
     */
    function createVestingSchedule(
        address _beneficiary,
        uint256 _amount,
        bool _revocable
    ) external {
        
        require(msg.sender == seller || msg.sender == owner(), "Only seller or owner can create vesting schedule");

        require(
            getWithdrawableAmount() >= _amount,
            "TokenVesting: cannot create vesting schedule because not sufficient tokens"
        );
        require(_amount > 0, "TokenVesting: amount must be > 0");
        bytes32 vestingScheduleId = computeNextVestingScheduleIdForHolder(
            _beneficiary
        );

        VestingSchedule memory vestingSchedule = vestingSchedules[vestingScheduleId];

        if(vestingSchedule.amountTotal == 0) {
            uint256 cliff = START + CLIFF;
            vestingSchedule = VestingSchedule(
                _beneficiary,
                cliff,
                START,
                DURATION,
                SLICE_PERIOD,
                _revocable,
                _amount,
                0,
                false
            );
        } else {
            vestingSchedule.amountTotal = vestingSchedule.amountTotal + _amount;
        }
        vestingSchedules[vestingScheduleId] = vestingSchedule;

        vestingSchedulesTotalAmount = vestingSchedulesTotalAmount + _amount;
        vestingSchedulesIds.push(vestingScheduleId);
        uint256 currentVestingCount = holdersVestingCount[_beneficiary];
        holdersVestingCount[_beneficiary] = currentVestingCount + 1;
        emit VestingScheduleCreated(_beneficiary, _amount);
    }

    /**
     * @notice Revokes the vesting schedule for given identifier.
     * @param vestingScheduleId the vesting schedule identifier
     */
    function revoke(
        bytes32 vestingScheduleId
    ) external onlyOwner onlyIfVestingScheduleNotRevoked(vestingScheduleId) {
        VestingSchedule storage vestingSchedule = vestingSchedules[
            vestingScheduleId
        ];
        require(
            vestingSchedule.revocable,
            "TokenVesting: vesting is not revocable"
        );
        uint256 vestedAmount = _computeReleasableAmount(vestingSchedule);
        if (vestedAmount > 0) {
            release(vestingScheduleId, vestedAmount);
        }
        uint256 unreleased = vestingSchedule.amountTotal -
            vestingSchedule.released;
        vestingSchedulesTotalAmount = vestingSchedulesTotalAmount - unreleased;
        vestingSchedule.revoked = true;
    }

    /**
     * @notice Withdraw the specified amount if possible.
     * @param amount the amount to withdraw
     */
    function withdraw(uint256 amount) external nonReentrant onlyOwner {
        require(
            getWithdrawableAmount() >= amount,
            "TokenVesting: not enough withdrawable funds"
        );
        /*
         * @dev Replaced owner() with msg.sender => address of WITHDRAWER_ROLE
         */
        _token.safeTransfer(msg.sender, amount);
    }

    /**
     * @notice Release vested amount of tokens.
     * @param vestingScheduleId the vesting schedule identifier
     * @param amount the amount to release
     */
    function release(
        bytes32 vestingScheduleId,
        uint256 amount
    ) public nonReentrant onlyIfVestingScheduleNotRevoked(vestingScheduleId) {
        VestingSchedule storage vestingSchedule = vestingSchedules[
            vestingScheduleId
        ];
        bool isBeneficiary = msg.sender == vestingSchedule.beneficiary;

        bool isReleasor = (msg.sender == owner());
        require(
            isBeneficiary || isReleasor,
            "TokenVesting: only beneficiary and owner can release vested tokens"
        );
        uint256 vestedAmount = _computeReleasableAmount(vestingSchedule);
        require(
            vestedAmount >= amount,
            "TokenVesting: cannot release tokens, not enough vested tokens"
        );
        vestingSchedule.released = vestingSchedule.released + amount;
        address payable beneficiaryPayable = payable(
            vestingSchedule.beneficiary
        );
        vestingSchedulesTotalAmount = vestingSchedulesTotalAmount - amount;
        _token.safeTransfer(beneficiaryPayable, amount);
    }

    /**
     * @dev Returns the vesting schedule id at the given index.
     * @return the vesting id
     */
    function getVestingIdAtIndex(
        uint256 index
    ) external view returns (bytes32) {
        require(
            index < getVestingSchedulesCount(),
            "TokenVesting: index out of bounds"
        );
        return vestingSchedulesIds[index];
    }

    /**
     * @notice Returns the vesting schedule information for a given holder.
     * @return the vesting schedule structure information
     */
    function getVestingScheduleByAddress(
        address holder
    ) external view returns (VestingSchedule memory) {
        return
            getVestingSchedule(
                computeVestingScheduleIdForAddress(holder)
            );
    }

    /**
     * @notice Returns the total amount of vesting schedules.
     * @return the total amount of vesting schedules
     */
    function getVestingSchedulesTotalAmount() external view returns (uint256) {
        return vestingSchedulesTotalAmount;
    }

    /**
     * @dev Returns the address of the ERC20 token managed by the vesting contract.
     */
    function getToken() external view returns (address) {
        return address(_token);
    }

    /**
     * @dev Returns the number of vesting schedules managed by this contract.
     * @return the number of vesting schedules
     */
    function getVestingSchedulesCount() public view returns (uint256) {
        return vestingSchedulesIds.length;
    }

    /**
     * @notice Computes the vested amount of tokens for the given vesting schedule identifier.
     * @return the vested amount
     */
    function computeReleasableAmount(
        bytes32 vestingScheduleId
    )
        external
        view
        onlyIfVestingScheduleNotRevoked(vestingScheduleId)
        returns (uint256)
    {
        VestingSchedule storage vestingSchedule = vestingSchedules[
            vestingScheduleId
        ];
        return _computeReleasableAmount(vestingSchedule);
    }

    /**
     * @notice Returns the vesting schedule information for a given identifier.
     * @return the vesting schedule structure information
     */
    function getVestingSchedule(
        bytes32 vestingScheduleId
    ) public view returns (VestingSchedule memory) {
        return vestingSchedules[vestingScheduleId];
    }

    /**
     * @dev Returns the amount of tokens that can be withdrawn by the owner.
     * @return the amount of tokens
     */
    function getWithdrawableAmount() public view returns (uint256) {
        return _token.balanceOf(address(this)) - vestingSchedulesTotalAmount;
    }

    /**
     * @dev Computes the next vesting schedule identifier for a given holder address.
     */
    function computeNextVestingScheduleIdForHolder(
        address holder
    ) public pure returns (bytes32) {
        return
            computeVestingScheduleIdForAddress(
                holder
            );
    }

    /**
     * @dev Computes the vesting schedule identifier for an address and an index.
     */
    function computeVestingScheduleIdForAddress(
        address holder
    ) public pure returns (bytes32) {
        return keccak256(abi.encodePacked(holder));
    }

    /**
     * @dev Computes the releasable amount of tokens for a vesting schedule.
     * @return the amount of releasable tokens
     */
    function _computeReleasableAmount(
        VestingSchedule memory vestingSchedule
    ) internal view returns (uint256) {
        // Retrieve the current time.
        uint256 currentTime = getCurrentTime();
        // If the current time is before the cliff, no tokens are releasable.
        if ((currentTime < vestingSchedule.cliff) || vestingSchedule.revoked) {
            return 0;
        }
        // If the current time is after the vesting period, all tokens are releasable,
        // minus the amount already released.
        else if (
            currentTime >= vestingSchedule.cliff + vestingSchedule.duration
        ) {
            return vestingSchedule.amountTotal - vestingSchedule.released;
        }
        // Otherwise, some tokens are releasable.
        else {
            // Compute the number of full vesting periods that have elapsed.
            uint256 timeFromStart = currentTime - vestingSchedule.cliff;
            uint256 secondsPerSlice = vestingSchedule.slicePeriodSeconds;
            uint256 vestedSlicePeriods = timeFromStart / secondsPerSlice;
            uint256 vestedSeconds = vestedSlicePeriods * secondsPerSlice;
            // Compute the amount of tokens that are vested.
            uint256 vestedAmount = (vestingSchedule.amountTotal *
                vestedSeconds) / vestingSchedule.duration;
            // Subtract the amount already released and return.
            return vestedAmount - vestingSchedule.released;
        }
    }

    /**
     * @dev Returns the current time.
     * @return the current timestamp in seconds.
     */
    function getCurrentTime() internal view virtual returns (uint256) {
        return block.timestamp;
    }
}

{
  "compilationTarget": {
    "contracts/TokenVesting.sol": "TokenVesting"
  },
  "evmVersion": "paris",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}