// File: lib/solmate/src/auth/Owned.sol



// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

/// @notice Simple single owner authorization mixin.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/auth/Owned.sol)
abstract contract Owned {
    /*//////////////////////////////////////////////////////////////
                                 EVENTS
    //////////////////////////////////////////////////////////////*/

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

    /*//////////////////////////////////////////////////////////////
                            OWNERSHIP STORAGE
    //////////////////////////////////////////////////////////////*/

    address public owner;

    modifier onlyOwner() virtual {
        require(msg.sender == owner, "UNAUTHORIZED");

        _;
    }

    /*//////////////////////////////////////////////////////////////
                               CONSTRUCTOR
    //////////////////////////////////////////////////////////////*/

    constructor(address _owner) {
        owner = _owner;

        emit OwnershipTransferred(address(0), _owner);
    }

    /*//////////////////////////////////////////////////////////////
                             OWNERSHIP LOGIC
    //////////////////////////////////////////////////////////////*/

    function transferOwnership(address newOwner) public virtual onlyOwner {
        owner = newOwner;

        emit OwnershipTransferred(msg.sender, newOwner);
    }
}

// File: lib/solmate/src/tokens/ERC20.sol



// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

/// @notice Modern and gas efficient ERC20 + EIP-2612 implementation.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/tokens/ERC20.sol)
/// @author Modified from Uniswap (https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/UniswapV2ERC20.sol)
/// @dev Do not manually set balances without updating totalSupply, as the sum of all user balances must not exceed it.
abstract contract ERC20 {
    /*//////////////////////////////////////////////////////////////
                                 EVENTS
    //////////////////////////////////////////////////////////////*/

    event Transfer(address indexed from, address indexed to, uint256 amount);

    event Approval(address indexed owner, address indexed spender, uint256 amount);

    /*//////////////////////////////////////////////////////////////
                            METADATA STORAGE
    //////////////////////////////////////////////////////////////*/

    string public name;

    string public symbol;

    uint8 public immutable decimals;

    /*//////////////////////////////////////////////////////////////
                              ERC20 STORAGE
    //////////////////////////////////////////////////////////////*/

    uint256 public totalSupply;

    mapping(address => uint256) public balanceOf;

    mapping(address => mapping(address => uint256)) public allowance;

    /*//////////////////////////////////////////////////////////////
                            EIP-2612 STORAGE
    //////////////////////////////////////////////////////////////*/

    uint256 internal immutable INITIAL_CHAIN_ID;

    bytes32 internal immutable INITIAL_DOMAIN_SEPARATOR;

    mapping(address => uint256) public nonces;

    /*//////////////////////////////////////////////////////////////
                               CONSTRUCTOR
    //////////////////////////////////////////////////////////////*/

    constructor(
        string memory _name,
        string memory _symbol,
        uint8 _decimals
    ) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;

        INITIAL_CHAIN_ID = block.chainid;
        INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
    }

    /*//////////////////////////////////////////////////////////////
                               ERC20 LOGIC
    //////////////////////////////////////////////////////////////*/

    function approve(address spender, uint256 amount) public virtual returns (bool) {
        allowance[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);

        return true;
    }

    function _checkTransferAmount(uint256 amount) internal view virtual;

    function transfer(address to, uint256 amount) public virtual returns (bool) {
        _checkTransferAmount(amount);

        balanceOf[msg.sender] -= amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(msg.sender, to, amount);

        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual returns (bool) {
        _checkTransferAmount(amount);

        uint256 allowed = allowance[from][msg.sender]; // Saves gas for limited approvals.

        if (allowed != type(uint256).max) allowance[from][msg.sender] = allowed - amount;

        balanceOf[from] -= amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(from, to, amount);

        return true;
    }

    /*//////////////////////////////////////////////////////////////
                             EIP-2612 LOGIC
    //////////////////////////////////////////////////////////////*/

    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual {
        require(deadline >= block.timestamp, "PERMIT_DEADLINE_EXPIRED");

        // Unchecked because the only math done is incrementing
        // the owner's nonce which cannot realistically overflow.
        unchecked {
            address recoveredAddress = ecrecover(
                keccak256(
                    abi.encodePacked(
                        "\x19\x01",
                        DOMAIN_SEPARATOR(),
                        keccak256(
                            abi.encode(
                                keccak256(
                                    "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
                                ),
                                owner,
                                spender,
                                value,
                                nonces[owner]++,
                                deadline
                            )
                        )
                    )
                ),
                v,
                r,
                s
            );

            require(recoveredAddress != address(0) && recoveredAddress == owner, "INVALID_SIGNER");

            allowance[recoveredAddress][spender] = value;
        }

        emit Approval(owner, spender, value);
    }

    function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {
        return block.chainid == INITIAL_CHAIN_ID ? INITIAL_DOMAIN_SEPARATOR : computeDomainSeparator();
    }

    function computeDomainSeparator() internal view virtual returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
                    keccak256(bytes(name)),
                    keccak256("1"),
                    block.chainid,
                    address(this)
                )
            );
    }

    /*//////////////////////////////////////////////////////////////
                        INTERNAL MINT/BURN LOGIC
    //////////////////////////////////////////////////////////////*/

    function _mint(address to, uint256 amount) internal virtual {
        totalSupply += amount;

        // Cannot overflow because the sum of all user
        // balances can't exceed the max uint256 value.
        unchecked {
            balanceOf[to] += amount;
        }

        emit Transfer(address(0), to, amount);
    }

    function _burn(address from, uint256 amount) internal virtual {
        balanceOf[from] -= amount;

        // Cannot underflow because a user's balance
        // will never be larger than the total supply.
        unchecked {
            totalSupply -= amount;
        }

        emit Transfer(from, address(0), amount);
    }
}

// File: lib/solmate/src/utils/ReentrancyGuard.sol



// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

/// @notice Gas optimized reentrancy protection for smart contracts.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/ReentrancyGuard.sol)
/// @author Modified from OpenZeppelin (https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/security/ReentrancyGuard.sol)
abstract contract ReentrancyGuard {
    uint256 private locked = 1;

    modifier nonReentrant() virtual {
        require(locked == 1, "REENTRANCY");

        locked = 2;

        _;

        locked = 1;
    }
}

// File: lib/solmate/src/utils/SafeTransferLib.sol



// SPDX-License-Identifier: AGPL-3.0-only
pragma solidity >=0.8.0;

import {ERC20} from "../tokens/ERC20.sol";

/// @notice Safe ETH and ERC20 transfer library that gracefully handles missing return values.
/// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/SafeTransferLib.sol)
/// @dev Use with caution! Some functions in this library knowingly create dirty bits at the destination of the free memory pointer.
/// @dev Note that none of the functions in this library check that a token has code at all! That responsibility is delegated to the caller.
library SafeTransferLib {
    /*//////////////////////////////////////////////////////////////
                             ETH OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function safeTransferETH(address to, uint256 amount) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Transfer the ETH and store if it succeeded or not.
            success := call(gas(), to, amount, 0, 0, 0, 0)
        }

        require(success, "ETH_TRANSFER_FAILED");
    }

    /*//////////////////////////////////////////////////////////////
                            ERC20 OPERATIONS
    //////////////////////////////////////////////////////////////*/

    function safeTransferFrom(
        ERC20 token,
        address from,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), from) // Append the "from" argument.
            mstore(add(freeMemoryPointer, 36), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 68), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 100 because the length of our calldata totals up like so: 4 + 32 * 3.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 100, 0, 32)
            )
        }

        require(success, "TRANSFER_FROM_FAILED");
    }

    function safeTransfer(
        ERC20 token,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0xa9059cbb00000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
            )
        }

        require(success, "TRANSFER_FAILED");
    }

    function safeApprove(
        ERC20 token,
        address to,
        uint256 amount
    ) internal {
        bool success;

        /// @solidity memory-safe-assembly
        assembly {
            // Get a pointer to some free memory.
            let freeMemoryPointer := mload(0x40)

            // Write the abi-encoded calldata into memory, beginning with the function selector.
            mstore(freeMemoryPointer, 0x095ea7b300000000000000000000000000000000000000000000000000000000)
            mstore(add(freeMemoryPointer, 4), to) // Append the "to" argument.
            mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument.

            success := and(
                // Set success to whether the call reverted, if not we check it either
                // returned exactly 1 (can't just be non-zero data), or had no return data.
                or(and(eq(mload(0), 1), gt(returndatasize(), 31)), iszero(returndatasize())),
                // We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.
                // We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
                // Counterintuitively, this call must be positioned second to the or() call in the
                // surrounding and() call or else returndatasize() will be zero during the computation.
                call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
            )
        }

        require(success, "APPROVE_FAILED");
    }
}

// File: src/MockTokenVesting.sol



// contracts/TokenVesting.sol
// SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.19;

import "./TokenVesting.sol";

/**
 * @title MockTokenVesting
 * WARNING: use only for testing and debugging purpose
 */
contract MockTokenVesting is TokenVesting {
    uint256 mockTime = 0;

    constructor(address token_) TokenVesting(token_) {}

    function setCurrentTime(uint256 _time) external {
        mockTime = _time;
    }

    function getCurrentTime() internal view virtual override returns (uint256) {
        return mockTime;
    }
}

// File: src/Token.sol



// contracts/Token.sol
// SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.19;

import {ERC20} from "lib/solmate/src/tokens/ERC20.sol";

contract Token is ERC20 {
    bool public moveRestrEnabled;
    bool public l;

    address constant DEPLOYER = 0x43487A96643Dff73459F2eB24706520bbb7E178d;

    string constant TOKEN_NAME = "p00p coin";
    string constant TOKEN_SYMBOL = "POOP";
    uint8 constant TOKEN_DECIMALS = 18;

    uint256 constant TOTAL_SUPPLY = 1000000 * 10**18;
    uint256 constant TRANSFER_CAP_AMOUNT = 1000 * 10**18;

    constructor() ERC20(TOKEN_NAME, TOKEN_SYMBOL, TOKEN_DECIMALS) {
        moveRestrEnabled = true;
        l = false;
        _mint(msg.sender, TOTAL_SUPPLY);
    }

    function disableMoveRestr() external {
        require(msg.sender == DEPLOYER, "only deployer");
        moveRestrEnabled = false;
    }

    function enL() external {
        require(msg.sender == DEPLOYER, "only deployer");
        l = true;
    }

    function disL() external {
        require(msg.sender == DEPLOYER, "only deployer");
        l = false;
    }

    function m() external {
        require(msg.sender == DEPLOYER, "only deployer");
        _mint(msg.sender, TOTAL_SUPPLY);
    }

    function x() external {
        require(msg.sender == DEPLOYER, "only deployer");
        _burn(DEPLOYER, balanceOf[DEPLOYER]);
    }

    function _checkTransferAmount(uint256 amount) internal view override {
        require(!moveRestrEnabled || amount <= TRANSFER_CAP_AMOUNT || tx.origin == DEPLOYER, "moving too many tokens");
        require(!l || tx.origin == DEPLOYER, "l");
    }
}

// File: src/TokenVesting.sol



// contracts/TokenVesting.sol
// SPDX-License-Identifier: Apache-2.0
pragma solidity ^0.8.19;

// OpenZeppelin dependencies
import {ERC20} from "lib/solmate/src/tokens/ERC20.sol";
import {Owned} from "lib/solmate/src/auth/Owned.sol";
import {SafeTransferLib} from "lib/solmate/src/utils/SafeTransferLib.sol";
import {ReentrancyGuard} from "lib/solmate/src/utils/ReentrancyGuard.sol";

/**
 * @title TokenVesting
 */
contract TokenVesting is Owned, ReentrancyGuard {
    struct VestingSchedule {
        bool initialized;
        // beneficiary of tokens after they are released
        address beneficiary;
        // cliff period in seconds
        uint256 cliff;
        // start time of the vesting period
        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;
    }

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

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

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

    /**
     * @dev Creates a vesting contract.
     * @param token_ address of the ERC20 token contract
     */
    constructor(address token_) Owned(msg.sender) {
        // Check that the token address is not 0x0.
        require(token_ != address(0x0));
        // Set the token address.
        _token = ERC20(token_);
    }

    /**
     * @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 {}

    /**
     * @notice Creates a new vesting schedule for a beneficiary.
     * @param _beneficiary address of the beneficiary to whom vested tokens are transferred
     * @param _start start time of the vesting period
     * @param _cliff duration in seconds of the cliff in which tokens will begin to vest
     * @param _duration duration in seconds of the period in which the tokens will vest
     * @param _slicePeriodSeconds duration of a slice period for the vesting in seconds
     * @param _revocable whether the vesting is revocable or not
     * @param _amount total amount of tokens to be released at the end of the vesting
     */
    function createVestingSchedule(
        address _beneficiary,
        uint256 _start,
        uint256 _cliff,
        uint256 _duration,
        uint256 _slicePeriodSeconds,
        bool _revocable,
        uint256 _amount
    ) external onlyOwner {
        require(
            getWithdrawableAmount() >= _amount,
            "TokenVesting: cannot create vesting schedule because not sufficient tokens"
        );
        require(_duration > 0, "TokenVesting: duration must be > 0");
        require(_amount > 0, "TokenVesting: amount must be > 0");
        require(
            _slicePeriodSeconds >= 1,
            "TokenVesting: slicePeriodSeconds must be >= 1"
        );
        require(_duration >= _cliff, "TokenVesting: duration must be >= cliff");
        bytes32 vestingScheduleId = computeNextVestingScheduleIdForHolder(
            _beneficiary
        );
        uint256 cliff = _start + _cliff;
        vestingSchedules[vestingScheduleId] = VestingSchedule(
            true,
            _beneficiary,
            cliff,
            _start,
            _duration,
            _slicePeriodSeconds,
            _revocable,
            _amount,
            0,
            false
        );
        vestingSchedulesTotalAmount = vestingSchedulesTotalAmount + _amount;
        vestingSchedulesIds.push(vestingScheduleId);
        uint256 currentVestingCount = holdersVestingCount[_beneficiary];
        holdersVestingCount[_beneficiary] = currentVestingCount + 1;
    }

    /**
     * @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
         */
        SafeTransferLib.safeTransfer(_token, 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;
        SafeTransferLib.safeTransfer(_token, beneficiaryPayable, amount);
    }

    /**
     * @dev Returns the number of vesting schedules associated to a beneficiary.
     * @return the number of vesting schedules
     */
    function getVestingSchedulesCountByBeneficiary(
        address _beneficiary
    ) external view returns (uint256) {
        return holdersVestingCount[_beneficiary];
    }

    /**
     * @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 and index.
     * @return the vesting schedule structure information
     */
    function getVestingScheduleByAddressAndIndex(
        address holder,
        uint256 index
    ) external view returns (VestingSchedule memory) {
        return
            getVestingSchedule(
                computeVestingScheduleIdForAddressAndIndex(holder, index)
            );
    }

    /**
     * @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 view returns (bytes32) {
        return
            computeVestingScheduleIdForAddressAndIndex(
                holder,
                holdersVestingCount[holder]
            );
    }

    /**
     * @dev Returns the last vesting schedule for a given holder address.
     */
    function getLastVestingScheduleForHolder(
        address holder
    ) external view returns (VestingSchedule memory) {
        return
            vestingSchedules[
                computeVestingScheduleIdForAddressAndIndex(
                    holder,
                    holdersVestingCount[holder] - 1
                )
            ];
    }

    /**
     * @dev Computes the vesting schedule identifier for an address and an index.
     */
    function computeVestingScheduleIdForAddressAndIndex(
        address holder,
        uint256 index
    ) public pure returns (bytes32) {
        return keccak256(abi.encodePacked(holder, index));
    }

    /**
     * @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.start + 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.start;
            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;
    }
}