add needed state of enforcing mkt based fees

/*
    Copyright 2017-2019 Phillip A. Elsasser

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

pragma solidity 0.4.25;

import "./libraries/MathLib.sol";
import "./MarketContract.sol";
import "./tokens/PositionToken.sol";
import "./MarketContractRegistryInterface.sol";

import "openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol";
import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
import "openzeppelin-solidity/contracts/ownership/Ownable.sol";

/// @title MarketCollateralPool
/// @notice This collateral pool houses all of the collateral for all market contracts currently in circulation.
/// This pool facilitates locking of collateral and minting / redemption of position tokens for that collateral.
/// @author Phil Elsasser <phil@marketprotocol.io>
contract MarketCollateralPool is Ownable {
    using MathLib for uint;
    using MathLib for int;
    using SafeERC20 for ERC20;

    enum MarketSide { Long, Short, Both}
    address public marketContractRegistry;
    address public mktToken;

    mapping(address => uint) public contractAddressToCollateralPoolBalance;                 // current balance of all collateral committed
    mapping(address => uint) public feesCollectedByTokenAddress;

    event TokensMinted(
        address indexed marketContract,
        address indexed user,
        address indexed feeToken,
        uint qtyMinted,
        uint collateralLocked,
        uint feesPaid
    );

    event TokensRedeemed(
        address indexed marketContract,
        address indexed user,
        uint qtyRedeemed,
        uint collateralUnlocked,
        uint8 marketSide
    );

    constructor(address marketContractRegistryAddress, address mktTokenAddress) public {
        marketContractRegistry = marketContractRegistryAddress;
        mktToken = mktTokenAddress;
    }

    /*
    // EXTERNAL METHODS
    */

    /// @notice Called by a user that would like to mint a new set of long and short token for a specified
    /// market contract.  This will transfer and lock the correct amount of collateral into the pool
    /// and issue them the requested qty of long and short tokens
    /// @param marketContractAddress            address of the market contract to redeem tokens for
    /// @param qtyToMint                      quantity of long / short tokens to mint.
    /// @param isAttemptToPayInMKT            if possible, attempt to pay fee's in MKT rather than collateral tokens
    function mintPositionTokens(
        address marketContractAddress,
        uint qtyToMint,
        bool isAttemptToPayInMKT
    ) external onlyWhiteListedAddress(marketContractAddress)
    {

        MarketContract marketContract = MarketContract(marketContractAddress);
        require(!marketContract.isSettled(), "Contract is already settled");

        address collateralTokenAddress = marketContract.COLLATERAL_TOKEN_ADDRESS();
        uint neededCollateral = MathLib.multiply(qtyToMint, marketContract.COLLATERAL_PER_UNIT());
        // the user has selected to pay fees in MKT and those fees are non zero (allowed) OR
        // the user has selected not to pay fees in MKT, BUT the collateral token fees are disabled (0) AND the
        // MKT fees are enabled (non zero).  (If both are zero, no fee exists)
        bool isPayFeesInMKT = (isAttemptToPayInMKT &&
            marketContract.MKT_TOKEN_FEE_PER_UNIT() != 0) ||
            (!isAttemptToPayInMKT &&
            marketContract.MKT_TOKEN_FEE_PER_UNIT() != 0 &&
            marketContract.COLLATERAL_TOKEN_FEE_PER_UNIT() == 0);

        uint feeAmount;
        uint totalCollateralTokenTransferAmount;
        address feeToken;
        if (isPayFeesInMKT) { // fees are able to be paid in MKT
            feeAmount = MathLib.multiply(qtyToMint, marketContract.MKT_TOKEN_FEE_PER_UNIT());
            totalCollateralTokenTransferAmount = neededCollateral;

            // EXTERNAL CALL - transferring ERC20 tokens from sender to this contract.  User must have called
            // ERC20.approve in order for this call to succeed.
            ERC20(mktToken).safeTransferFrom(msg.sender, address(this), feeAmount);
            feeToken = mktToken;
        } else { // fee are either zero, or being paid in the collateral token
            feeAmount = MathLib.multiply(qtyToMint, marketContract.COLLATERAL_TOKEN_FEE_PER_UNIT());
            totalCollateralTokenTransferAmount = neededCollateral.add(feeAmount);
            feeToken = collateralTokenAddress;
            // we will transfer collateral and fees all at once below.
        }

        // EXTERNAL CALL - transferring ERC20 tokens from sender to this contract.  User must have called
        // ERC20.approve in order for this call to succeed.
        ERC20(marketContract.COLLATERAL_TOKEN_ADDRESS()).safeTransferFrom(msg.sender, address(this), totalCollateralTokenTransferAmount);

        if (feeAmount != 0) {
            // update the fee's collected balance
            feesCollectedByTokenAddress[feeToken] = feesCollectedByTokenAddress[feeToken].add(feeAmount);
        }

        // Update the collateral pool locked balance.
        contractAddressToCollateralPoolBalance[marketContractAddress] = contractAddressToCollateralPoolBalance[
            marketContractAddress
        ].add(neededCollateral);

        // mint and distribute short and long position tokens to our caller
        marketContract.mintPositionTokens(qtyToMint, msg.sender);

        emit TokensMinted(
            marketContractAddress,
            msg.sender,
            feeToken,
            qtyToMint,
            neededCollateral,
            feeAmount
        );
    }

    /// @notice Called by a user that currently holds both short and long position tokens and would like to redeem them
    /// for their collateral.
    /// @param marketContractAddress            address of the market contract to redeem tokens for
    /// @param qtyToRedeem                      quantity of long / short tokens to redeem.
    function redeemPositionTokens(
        address marketContractAddress,
        uint qtyToRedeem
    ) external onlyWhiteListedAddress(marketContractAddress)
    {
        MarketContract marketContract = MarketContract(marketContractAddress);

        marketContract.redeemLongToken(qtyToRedeem, msg.sender);
        marketContract.redeemShortToken(qtyToRedeem, msg.sender);

        // calculate collateral to return and update pool balance
        uint collateralToReturn = MathLib.multiply(qtyToRedeem, marketContract.COLLATERAL_PER_UNIT());
        contractAddressToCollateralPoolBalance[marketContractAddress] = contractAddressToCollateralPoolBalance[
            marketContractAddress
        ].subtract(collateralToReturn);

        // EXTERNAL CALL
        // transfer collateral back to user
        ERC20(marketContract.COLLATERAL_TOKEN_ADDRESS()).safeTransfer(msg.sender, collateralToReturn);

        emit TokensRedeemed(
            marketContractAddress,
            msg.sender,
            qtyToRedeem,
            collateralToReturn,
            uint8(MarketSide.Both)
        );
    }

    // @notice called by a user after settlement has occurred.  This function will finalize all accounting around any
    // outstanding positions and return all remaining collateral to the caller. This should only be called after
    // settlement has occurred.
    /// @param marketContractAddress address of the MARKET Contract being traded.
    /// @param qtyToRedeem signed qtyToRedeem, positive (+) for long tokens, negative(-) for short tokens
    function settleAndClose(
        address marketContractAddress,
        int qtyToRedeem
    ) external onlyWhiteListedAddress(marketContractAddress)
    {
        MarketContract marketContract = MarketContract(marketContractAddress);
        require(marketContract.isPostSettlementDelay(), "Contract is not past settlement delay");

        // burn tokens being redeemed.
        MarketSide marketSide;
        uint absQtyToRedeem = qtyToRedeem.abs(); // convert to a uint for non signed functions
        if (qtyToRedeem > 0) {
            marketSide = MarketSide.Long;
            marketContract.redeemLongToken(absQtyToRedeem, msg.sender);
        } else {
            marketSide = MarketSide.Short;
            marketContract.redeemShortToken(absQtyToRedeem, msg.sender);
        }

        // calculate amount of collateral to return and update pool balances
        uint collateralToReturn = MathLib.calculateNeededCollateral(
            marketContract.PRICE_FLOOR(),
            marketContract.PRICE_CAP(),
            marketContract.QTY_MULTIPLIER(),
            qtyToRedeem,
            marketContract.settlementPrice()
        );

        contractAddressToCollateralPoolBalance[marketContractAddress] = contractAddressToCollateralPoolBalance[
            marketContractAddress
        ].subtract(collateralToReturn);

        // return collateral tokens
        ERC20(marketContract.COLLATERAL_TOKEN_ADDRESS()).safeTransfer(msg.sender, collateralToReturn);

        emit TokensRedeemed(
            marketContractAddress,
            msg.sender,
            absQtyToRedeem,
            collateralToReturn,
            uint8(marketSide)
        );
    }

    /// @dev allows the owner to remove the fees paid into this contract for minting
    /// @param feeTokenAddress - address of the erc20 token fees have been paid in
    /// @param feeRecipient - Recipient address of fees
    function withdrawFees(address feeTokenAddress, address feeRecipient) public onlyOwner {
        uint feesAvailableForWithdrawal = feesCollectedByTokenAddress[feeTokenAddress];
        require(feesAvailableForWithdrawal != 0, "No fees available for withdrawal");
        require(feeRecipient != address(0), "Cannot send fees to null address");
        feesCollectedByTokenAddress[feeTokenAddress] = 0;
        // EXTERNAL CALL
        ERC20(feeTokenAddress).transfer(feeRecipient, feesAvailableForWithdrawal);
    }

    /// @dev allows the owner to update the mkt token address in use for fees
    /// @param mktTokenAddress address of new MKT token
    function setMKTTokenAddress(address mktTokenAddress) public onlyOwner {
        require(mktTokenAddress != address(0), "Cannot set MKT Token Address To Null");
        mktToken = mktTokenAddress;
    }

    /// @dev allows the owner to update the mkt token address in use for fees
    /// @param marketContractRegistryAddress address of new contract registry
    function setMarketContractRegistryAddress(address marketContractRegistryAddress) public onlyOwner {
        require(marketContractRegistryAddress != address(0), "Cannot set Market Contract Registry Address To Null");
        marketContractRegistry = marketContractRegistryAddress;
    }

    /*
    // MODIFIERS
    */

    /// @notice only can be called with a market contract address that currently exists in our whitelist
    /// this ensure's it is a market contract that has been created by us and therefore has a uniquely created
    /// long and short token address.  If it didn't we could have spoofed contracts minting tokens with a
    /// collateral token that wasn't the same as the intended token.
    modifier onlyWhiteListedAddress(address marketContractAddress) {
        require(
            MarketContractRegistryInterface(marketContractRegistry).isAddressWhiteListed(marketContractAddress),
            "Contract is not whitelisted"
        );
        _;
    }
}

/*
    Copyright 2017-2019 Phillip A. Elsasser

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

pragma solidity 0.4.25;

import "./libraries/MathLib.sol";
import "./MarketContract.sol";
import "./tokens/PositionToken.sol";
import "./MarketContractRegistryInterface.sol";

import "openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol";
import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
import "openzeppelin-solidity/contracts/ownership/Ownable.sol";

/// @title MarketCollateralPool
/// @notice This collateral pool houses all of the collateral for all market contracts currently in circulation.
/// This pool facilitates locking of collateral and minting / redemption of position tokens for that collateral.
/// @author Phil Elsasser <phil@marketprotocol.io>
contract MarketCollateralPool is Ownable {
    using MathLib for uint;
    using MathLib for int;
    using SafeERC20 for ERC20;

    enum MarketSide { Long, Short, Both}
    address public marketContractRegistry;
    address public mktToken;

    mapping(address => uint) public contractAddressToCollateralPoolBalance;                 // current balance of all collateral committed
    mapping(address => uint) public feesCollectedByTokenAddress;

    event TokensMinted(
        address indexed marketContract,
        address indexed user,
        address indexed feeToken,
        uint qtyMinted,
        uint collateralLocked,
        uint feesPaid
    );

    event TokensRedeemed(
        address indexed marketContract,
        address indexed user,
        uint qtyRedeemed,
        uint collateralUnlocked,
        uint8 marketSide
    );

    constructor(address marketContractRegistryAddress, address mktTokenAddress) public {
        marketContractRegistry = marketContractRegistryAddress;
        mktToken = mktTokenAddress;
    }

    /*
    // EXTERNAL METHODS
    */

    /// @notice Called by a user that would like to mint a new set of long and short token for a specified
    /// market contract.  This will transfer and lock the correct amount of collateral into the pool
    /// and issue them the requested qty of long and short tokens
    /// @param marketContractAddress            address of the market contract to redeem tokens for
    /// @param qtyToMint                      quantity of long / short tokens to mint.
    /// @param isAttemptToPayInMKT            if possible, attempt to pay fee's in MKT rather than collateral tokens
    function mintPositionTokens(
        address marketContractAddress,
        uint qtyToMint,
        bool isAttemptToPayInMKT
    ) external onlyWhiteListedAddress(marketContractAddress)
    {

        MarketContract marketContract = MarketContract(marketContractAddress);
        require(!marketContract.isSettled(), "Contract is already settled");

        address collateralTokenAddress = marketContract.COLLATERAL_TOKEN_ADDRESS();
        uint neededCollateral = MathLib.multiply(qtyToMint, marketContract.COLLATERAL_PER_UNIT());
        bool isPayFeesInMKT = isAttemptToPayInMKT && marketContract.MKT_TOKEN_FEE_PER_UNIT() != 0;

        uint feeAmount;
        uint totalCollateralTokenTransferAmount;
        address feeToken;
        if (isPayFeesInMKT) { // fees are able to be paid in MKT
            feeAmount = MathLib.multiply(qtyToMint, marketContract.MKT_TOKEN_FEE_PER_UNIT());
            totalCollateralTokenTransferAmount = neededCollateral;

            // EXTERNAL CALL - transferring ERC20 tokens from sender to this contract.  User must have called
            // ERC20.approve in order for this call to succeed.
            ERC20(mktToken).safeTransferFrom(msg.sender, address(this), feeAmount);
            feeToken = mktToken;
        } else { // fee are either zero, or being paid in the collateral token
            feeAmount = MathLib.multiply(qtyToMint, marketContract.COLLATERAL_TOKEN_FEE_PER_UNIT());
            totalCollateralTokenTransferAmount = neededCollateral.add(feeAmount);
            feeToken = collateralTokenAddress;
            // we will transfer collateral and fees all at once below.
        }

        // EXTERNAL CALL - transferring ERC20 tokens from sender to this contract.  User must have called
        // ERC20.approve in order for this call to succeed.
        ERC20(marketContract.COLLATERAL_TOKEN_ADDRESS()).safeTransferFrom(msg.sender, address(this), totalCollateralTokenTransferAmount);

        if (feeAmount != 0) {
            // update the fee's collected balance
            feesCollectedByTokenAddress[feeToken] = feesCollectedByTokenAddress[feeToken].add(feeAmount);
        }

        // Update the collateral pool locked balance.
        contractAddressToCollateralPoolBalance[marketContractAddress] = contractAddressToCollateralPoolBalance[
            marketContractAddress
        ].add(neededCollateral);

        // mint and distribute short and long position tokens to our caller
        marketContract.mintPositionTokens(qtyToMint, msg.sender);

        emit TokensMinted(
            marketContractAddress,
            msg.sender,
            feeToken,
            qtyToMint,
            neededCollateral,
            feeAmount
        );
    }

    /// @notice Called by a user that currently holds both short and long position tokens and would like to redeem them
    /// for their collateral.
    /// @param marketContractAddress            address of the market contract to redeem tokens for
    /// @param qtyToRedeem                      quantity of long / short tokens to redeem.
    function redeemPositionTokens(
        address marketContractAddress,
        uint qtyToRedeem
    ) external onlyWhiteListedAddress(marketContractAddress)
    {
        MarketContract marketContract = MarketContract(marketContractAddress);

        marketContract.redeemLongToken(qtyToRedeem, msg.sender);
        marketContract.redeemShortToken(qtyToRedeem, msg.sender);

        // calculate collateral to return and update pool balance
        uint collateralToReturn = MathLib.multiply(qtyToRedeem, marketContract.COLLATERAL_PER_UNIT());
        contractAddressToCollateralPoolBalance[marketContractAddress] = contractAddressToCollateralPoolBalance[
            marketContractAddress
        ].subtract(collateralToReturn);

        // EXTERNAL CALL
        // transfer collateral back to user
        ERC20(marketContract.COLLATERAL_TOKEN_ADDRESS()).safeTransfer(msg.sender, collateralToReturn);

        emit TokensRedeemed(
            marketContractAddress,
            msg.sender,
            qtyToRedeem,
            collateralToReturn,
            uint8(MarketSide.Both)
        );
    }

    // @notice called by a user after settlement has occurred.  This function will finalize all accounting around any
    // outstanding positions and return all remaining collateral to the caller. This should only be called after
    // settlement has occurred.
    /// @param marketContractAddress address of the MARKET Contract being traded.
    /// @param qtyToRedeem signed qtyToRedeem, positive (+) for long tokens, negative(-) for short tokens
    function settleAndClose(
        address marketContractAddress,
        int qtyToRedeem
    ) external onlyWhiteListedAddress(marketContractAddress)
    {
        MarketContract marketContract = MarketContract(marketContractAddress);
        require(marketContract.isPostSettlementDelay(), "Contract is not past settlement delay");

        // burn tokens being redeemed.
        MarketSide marketSide;
        uint absQtyToRedeem = qtyToRedeem.abs(); // convert to a uint for non signed functions
        if (qtyToRedeem > 0) {
            marketSide = MarketSide.Long;
            marketContract.redeemLongToken(absQtyToRedeem, msg.sender);
        } else {
            marketSide = MarketSide.Short;
            marketContract.redeemShortToken(absQtyToRedeem, msg.sender);
        }

        // calculate amount of collateral to return and update pool balances
        uint collateralToReturn = MathLib.calculateNeededCollateral(
            marketContract.PRICE_FLOOR(),
            marketContract.PRICE_CAP(),
            marketContract.QTY_MULTIPLIER(),
            qtyToRedeem,
            marketContract.settlementPrice()
        );

        contractAddressToCollateralPoolBalance[marketContractAddress] = contractAddressToCollateralPoolBalance[
            marketContractAddress
        ].subtract(collateralToReturn);

        // return collateral tokens
        ERC20(marketContract.COLLATERAL_TOKEN_ADDRESS()).safeTransfer(msg.sender, collateralToReturn);

        emit TokensRedeemed(
            marketContractAddress,
            msg.sender,
            absQtyToRedeem,
            collateralToReturn,
            uint8(marketSide)
        );
    }

    /// @dev allows the owner to remove the fees paid into this contract for minting
    /// @param feeTokenAddress - address of the erc20 token fees have been paid in
    /// @param feeRecipient - Recipient address of fees
    function withdrawFees(address feeTokenAddress, address feeRecipient) public onlyOwner {
        uint feesAvailableForWithdrawal = feesCollectedByTokenAddress[feeTokenAddress];
        require(feesAvailableForWithdrawal != 0, "No fees available for withdrawal");
        require(feeRecipient != address(0), "Cannot send fees to null address");
        feesCollectedByTokenAddress[feeTokenAddress] = 0;
        // EXTERNAL CALL
        ERC20(feeTokenAddress).transfer(feeRecipient, feesAvailableForWithdrawal);
    }

    /// @dev allows the owner to update the mkt token address in use for fees
    /// @param mktTokenAddress address of new MKT token
    function setMKTTokenAddress(address mktTokenAddress) public onlyOwner {
        require(mktTokenAddress != address(0), "Cannot set MKT Token Address To Null");
        mktToken = mktTokenAddress;
    }

    /// @dev allows the owner to update the mkt token address in use for fees
    /// @param marketContractRegistryAddress address of new contract registry
    function setMarketContractRegistryAddress(address marketContractRegistryAddress) public onlyOwner {
        require(marketContractRegistryAddress != address(0), "Cannot set Market Contract Registry Address To Null");
        marketContractRegistry = marketContractRegistryAddress;
    }

    /*
    // MODIFIERS
    */

    /// @notice only can be called with a market contract address that currently exists in our whitelist
    /// this ensure's it is a market contract that has been created by us and therefore has a uniquely created
    /// long and short token address.  If it didn't we could have spoofed contracts minting tokens with a
    /// collateral token that wasn't the same as the intended token.
    modifier onlyWhiteListedAddress(address marketContractAddress) {
        require(
            MarketContractRegistryInterface(marketContractRegistry).isAddressWhiteListed(marketContractAddress),
            "Contract is not whitelisted"
        );
        _;
    }
}


Fix typo: snapshoted

Fix typo: snapshoted

pragma solidity ^0.5.2;

import "../math/SafeMath.sol";
import "../utils/Arrays.sol";
import "../drafts/Counters.sol";
import "../token/ERC20/ERC20.sol";

/**
 * @title ERC20 token with snapshots.
 * inspired by Jordi Baylina's MiniMeToken to record historical balances
 * Snapshots store a value at the time a snapshot is taken (and a new snapshot id created), and the corresponding
 * snapshot id. Each account has individual snapshots taken on demand, as does the token's total supply.
 * @author Validity Labs AG <info@validitylabs.org>
 */
contract ERC20Snapshot is ERC20 {
    using SafeMath for uint256;
    using Arrays for uint256[];
    using Counters for Counters.Counter;

    // Snapshotted values have arrays of ids and the value corresponding to that id. These could be an array of a
    // Snapshot struct, but that would impede usage of functions that work on an array.
    struct Snapshots {
        uint256[] ids;
        uint256[] values;
    }

    mapping (address => Snapshots) private _accountBalanceSnapshots;
    Snapshots private _totalSupplySnaphots;

    // Snapshot ids increase monotonically, with the first value being 1. An id of 0 is invalid.
    Counters.Counter private _currentSnapshotId;

    event Snapshot(uint256 id);

    // Creates a new snapshot id. Balances are only stored in snapshots on demand: unless a snapshot was taken, a
    // balance change will not be recorded. This means the extra added cost of storing snapshotted balances is only paid
    // when required, but is also flexible enough that it allows for e.g. daily snapshots.
    function snapshot() public returns (uint256) {
        _currentSnapshotId.increment();

        uint256 currentId = _currentSnapshotId.current();
        emit Snapshot(currentId);
        return currentId;
    }

    function balanceOfAt(address account, uint256 snapshotId) public view returns (uint256) {
        (bool snapshotted, uint256 value) = _valueAt(snapshotId, _accountBalanceSnapshots[account]);

        return snapshotted ? value : balanceOf(account);
    }

    function totalSupplyAt(uint256 snapshotId) public view returns(uint256) {
        (bool snapshotted, uint256 value) = _valueAt(snapshotId, _totalSupplySnaphots);

        return snapshotted ? value : totalSupply();
    }

    // _transfer, _mint and _burn are the only functions where the balances are modified, so it is there that the
    // snapshots are updated. Note that the update happens _before_ the balance change, with the pre-modified value.
    // The same is true for the total supply and _mint and _burn.
    function _transfer(address from, address to, uint256 value) internal {
        _updateAccountSnapshot(from);
        _updateAccountSnapshot(to);

        super._transfer(from, to, value);
    }

    function _mint(address account, uint256 value) internal {
        _updateAccountSnapshot(account);
        _updateTotalSupplySnapshot();

        super._mint(account, value);
    }

    function _burn(address account, uint256 value) internal {
        _updateAccountSnapshot(account);
        _updateTotalSupplySnapshot();

        super._burn(account, value);
    }

    // When a valid snapshot is queried, there are three possibilities:
    //  a) The queried value was not modified after the snapshot was taken. Therefore, a snapshot entry was never
    //  created for this id, and all stored snapshot ids are smaller than the requested one. The value that corresponds
    //  to this id is the current one.
    //  b) The queried value was modified after the snapshot was taken. Therefore, there will be an entry with the
    //  requested id, and its value is the one to return.
    //  c) More snapshots were created after the requested one, and the queried value was later modified. There will be
    //  no entry for the requested id: the value that corresponds to it is that of the smallest snapshot id that is
    //  larger than the requested one.
    //
    // In summary, we need to find an element in an array, returning the index of the smallest value that is larger if
    // it is not found, unless said value doesn't exist (e.g. when all values are smaller). Arrays.findUpperBound does
    // exactly this.
    function _valueAt(uint256 snapshotId, Snapshots storage snapshots)
        private view returns (bool, uint256)
    {
        require(snapshotId > 0);
        require(snapshotId <= _currentSnapshotId.current());

        uint256 index = snapshots.ids.findUpperBound(snapshotId);

        if (index == snapshots.ids.length) {
            return (false, 0);
        } else {
            return (true, snapshots.values[index]);
        }
    }

    function _updateAccountSnapshot(address account) private {
        _updateSnapshot(_accountBalanceSnapshots[account], balanceOf(account));
    }

    function _updateTotalSupplySnapshot() private {
        _updateSnapshot(_totalSupplySnaphots, totalSupply());
    }

    function _updateSnapshot(Snapshots storage snapshots, uint256 currentValue) private {
        uint256 currentId = _currentSnapshotId.current();
        if (_lastSnapshotId(snapshots.ids) < currentId) {
            snapshots.ids.push(currentId);
            snapshots.values.push(currentValue);
        }
    }

    function _lastSnapshotId(uint256[] storage ids) private view returns (uint256) {
        if (ids.length == 0) {
            return 0;
        } else {
            return ids[ids.length - 1];
        }
    }
}

pragma solidity ^0.5.2;

import "../math/SafeMath.sol";
import "../utils/Arrays.sol";
import "../drafts/Counters.sol";
import "../token/ERC20/ERC20.sol";

/**
 * @title ERC20 token with snapshots.
 * inspired by Jordi Baylina's MiniMeToken to record historical balances
 * Snapshots store a value at the time a snapshot is taken (and a new snapshot id created), and the corresponding
 * snapshot id. Each account has individual snapshots taken on demand, as does the token's total supply.
 * @author Validity Labs AG <info@validitylabs.org>
 */
contract ERC20Snapshot is ERC20 {
    using SafeMath for uint256;
    using Arrays for uint256[];
    using Counters for Counters.Counter;

    // Snapshoted values have arrays of ids and the value corresponding to that id. These could be an array of a
    // Snapshot struct, but that would impede usage of functions that work on an array.
    struct Snapshots {
        uint256[] ids;
        uint256[] values;
    }

    mapping (address => Snapshots) private _accountBalanceSnapshots;
    Snapshots private _totalSupplySnaphots;

    // Snapshot ids increase monotonically, with the first value being 1. An id of 0 is invalid.
    Counters.Counter private _currentSnapshotId;

    event Snapshot(uint256 id);

    // Creates a new snapshot id. Balances are only stored in snapshots on demand: unless a snapshot was taken, a
    // balance change will not be recorded. This means the extra added cost of storing snapshotted balances is only paid
    // when required, but is also flexible enough that it allows for e.g. daily snapshots.
    function snapshot() public returns (uint256) {
        _currentSnapshotId.increment();

        uint256 currentId = _currentSnapshotId.current();
        emit Snapshot(currentId);
        return currentId;
    }

    function balanceOfAt(address account, uint256 snapshotId) public view returns (uint256) {
        (bool snapshotted, uint256 value) = _valueAt(snapshotId, _accountBalanceSnapshots[account]);

        return snapshotted ? value : balanceOf(account);
    }

    function totalSupplyAt(uint256 snapshotId) public view returns(uint256) {
        (bool snapshotted, uint256 value) = _valueAt(snapshotId, _totalSupplySnaphots);

        return snapshotted ? value : totalSupply();
    }

    // _transfer, _mint and _burn are the only functions where the balances are modified, so it is there that the
    // snapshots are updated. Note that the update happens _before_ the balance change, with the pre-modified value.
    // The same is true for the total supply and _mint and _burn.
    function _transfer(address from, address to, uint256 value) internal {
        _updateAccountSnapshot(from);
        _updateAccountSnapshot(to);

        super._transfer(from, to, value);
    }

    function _mint(address account, uint256 value) internal {
        _updateAccountSnapshot(account);
        _updateTotalSupplySnapshot();

        super._mint(account, value);
    }

    function _burn(address account, uint256 value) internal {
        _updateAccountSnapshot(account);
        _updateTotalSupplySnapshot();

        super._burn(account, value);
    }

    // When a valid snapshot is queried, there are three possibilities:
    //  a) The queried value was not modified after the snapshot was taken. Therefore, a snapshot entry was never
    //  created for this id, and all stored snapshot ids are smaller than the requested one. The value that corresponds
    //  to this id is the current one.
    //  b) The queried value was modified after the snapshot was taken. Therefore, there will be an entry with the
    //  requested id, and its value is the one to return.
    //  c) More snapshots were created after the requested one, and the queried value was later modified. There will be
    //  no entry for the requested id: the value that corresponds to it is that of the smallest snapshot id that is
    //  larger than the requested one.
    //
    // In summary, we need to find an element in an array, returning the index of the smallest value that is larger if
    // it is not found, unless said value doesn't exist (e.g. when all values are smaller). Arrays.findUpperBound does
    // exactly this.
    function _valueAt(uint256 snapshotId, Snapshots storage snapshots)
        private view returns (bool, uint256)
    {
        require(snapshotId > 0);
        require(snapshotId <= _currentSnapshotId.current());

        uint256 index = snapshots.ids.findUpperBound(snapshotId);

        if (index == snapshots.ids.length) {
            return (false, 0);
        } else {
            return (true, snapshots.values[index]);
        }
    }

    function _updateAccountSnapshot(address account) private {
        _updateSnapshot(_accountBalanceSnapshots[account], balanceOf(account));
    }

    function _updateTotalSupplySnapshot() private {
        _updateSnapshot(_totalSupplySnaphots, totalSupply());
    }

    function _updateSnapshot(Snapshots storage snapshots, uint256 currentValue) private {
        uint256 currentId = _currentSnapshotId.current();
        if (_lastSnapshotId(snapshots.ids) < currentId) {
            snapshots.ids.push(currentId);
            snapshots.values.push(currentValue);
        }
    }

    function _lastSnapshotId(uint256[] storage ids) private view returns (uint256) {
        if (ids.length == 0) {
            return 0;
        } else {
            return ids[ids.length - 1];
        }
    }
}


Create VestingToken.sol

Create VestingToken.sol

// contracts/CFLUTokenVesting.sol
// SPDX-License-Identifier: Apache-2.0
pragma solidity 0.8.11;

// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

    /**
     * @dev Moves `amount` 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 amount) 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 `amount` 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 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` 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 amount
    ) external returns (bool);

    /**
     * @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 Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @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://diligence.consensys.net/posts/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/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @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, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * 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.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @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`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // 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

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

/**
 * @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;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @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, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

/**
 * @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;

    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() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

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

        _;

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

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    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 substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    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.
     *
     * _Available since v3.4._
     */
    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.
     *
     * _Available since v3.4._
     */
    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.
     *
     * _Available since v3.4._
     */
    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 addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

/**
 * @title TokenVesting
 * @dev Self
 */
contract TokenVesting is Ownable, ReentrancyGuard{
    using SafeMath for uint256;
    using SafeERC20 for IERC20;
    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 CFLU BEP20 token
    IERC20 immutable private _cflue_token;

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

    event Released(uint256 amount);
    event Revoked();

    /**
    * @dev Reverts if no vesting schedule matches the passed identifier.
    */
    modifier onlyIfVestingScheduleExists(bytes32 vestingScheduleId) {
        require(vestingSchedules[vestingScheduleId].initialized == true);
        _;
    }

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

    /**
     * @dev Creates a vesting contract.
     * @param token_cflu_ address of the ERC20 token contract
     */
    constructor(address token_cflu_) {
        require(token_cflu_ != address(0x0));
        _cflue_token = IERC20(token_cflu_);
    }

    receive() external payable {}

    fallback() external payable {}

    /**
    * @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(_cflue_token);
    }

    /**
    * @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
    )
        public
        onlyOwner{
        require(
            this.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");
        bytes32 vestingScheduleId = this.computeNextVestingScheduleIdForHolder(_beneficiary);
        uint256 cliff = _start.add(_cliff);
        vestingSchedules[vestingScheduleId] = VestingSchedule(
            true,
            _beneficiary,
            cliff,
            _start,
            _duration,
            _slicePeriodSeconds,
            _revocable,
            _amount,
            0,
            false
        );
        vestingSchedulesTotalAmount = vestingSchedulesTotalAmount.add(_amount);
        vestingSchedulesIds.push(vestingScheduleId);
        uint256 currentVestingCount = holdersVestingCount[_beneficiary];
        holdersVestingCount[_beneficiary] = currentVestingCount.add(1);
    }

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

    /**
    * @notice Withdraw the specified amount if possible.
    * @param amount the amount to withdraw
    */
    function withdraw(uint256 amount)
        public
        nonReentrant
        onlyOwner{
        require(this.getWithdrawableAmount() >= amount, "TokenVesting: not enough withdrawable funds");
        _cflue_token.safeTransfer(owner(), 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 = _msgSender() == vestingSchedule.beneficiary;
        bool isOwner = _msgSender() == owner();
        require(
            isBeneficiary || isOwner,
            "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.add(amount);
        address payable beneficiaryPayable = payable(vestingSchedule.beneficiary);
        vestingSchedulesTotalAmount = vestingSchedulesTotalAmount.sub(amount);
        _cflue_token.safeTransfer(beneficiaryPayable, amount);
    }

    /**
    * @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)
        public
        onlyIfVestingScheduleNotRevoked(vestingScheduleId)
        view
        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 _cflue_token.balanceOf(address(this)).sub(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)
        public
        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){
        uint256 currentTime = getCurrentTime();
        if ((currentTime < vestingSchedule.cliff) || vestingSchedule.revoked == true) {
            return 0;
        } else if (currentTime >= vestingSchedule.start.add(vestingSchedule.duration)) {
            return vestingSchedule.amountTotal.sub(vestingSchedule.released);
        } else {
            uint256 timeFromStart = currentTime.sub(vestingSchedule.start);
            uint secondsPerSlice = vestingSchedule.slicePeriodSeconds;
            uint256 vestedSlicePeriods = timeFromStart.div(secondsPerSlice);
            uint256 vestedSeconds = vestedSlicePeriods.mul(secondsPerSlice);
            uint256 vestedAmount = vestingSchedule.amountTotal.mul(vestedSeconds).div(vestingSchedule.duration);
            vestedAmount = vestedAmount.sub(vestingSchedule.released);
            return vestedAmount;
        }
    }

    function getCurrentTime()
        internal
        virtual
        view
        returns(uint256){
        return block.timestamp;
    }

}

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