// File: contracts/BetaOTC.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.8.7;

import './interfaces/Decimals.sol';
import './libraries/TransferHelper.sol';
import './libraries/NFTHelper.sol';
import '@openzeppelin/contracts/token/ERC721/IERC721.sol';
import '@openzeppelin/contracts/security/ReentrancyGuard.sol';

/**
 * @title BetaOTC
 * @notice BetaOTC is an over the counter peer to peer trading contract
 * @notice This contract allows for a seller to generate a unique public over the counter deal
 */
contract BetaOTC is ReentrancyGuard {
  using SafeERC20 for IERC20;
  address payable public weth;
  uint256 public dealId;
  address public futuresContract;

  /// @notice Creates a BetaOTC instance
  /// @param _weth The address for the weth contract, weth is used to wrap and unwrap ETH sending to and from the smart contract
  /// @param _fc The address for the futures contract, used to generate the future NFT
  constructor(
    address payable _weth,
    address _fc
  ) {
    require(_weth != address(0));
    require(_fc != address(0));
    weth = _weth;
    futuresContract = _fc;
  }

  /// Deal is the struct that defines a single OTC offer, created by a seller
  /// @param seller This is the creator and seller of the deal
  /// @param token This is the token that the seller is selling! Must be a standard ERC20 token, parameter is the contract address of the ERC20, 
  /// the ERC20 contract is required to have a public call function decimals() that returns a uint. This is required to price the amount of tokens being purchase
  /// @param paymentCurrency This is also an ERC20 which the seller will get paid in during the act of a buyer buying tokens - also the ERC20 contract address
  /// @param remainingAmount This initially is the entire deposit the seller is selling, but as people purchase chunks of the deal, the remaining amount is decreased to 0
  /// @param minimumPurchase This is the minimum chunk size that a buyer can purchase, defined by the seller, must be greater than 0
  /// @param price The Price is the per token cost which buyers pay to the seller, denominated in the payment currency. This is not the total price of the deal
  /// the total price is calculated by the remainingAmount * price (then adjusting for the decimals of the payment currency)
  /// @param maturity This is the unix time defining the period in which the deal is valid. After the maturity no purchases can be made
  /// @param _unlockDates these are the dates in which tokens will be locked, multiple dates can be passed in for a series of vesting cliffs
  /// @param _nfts is a special option to make this deal require that the buyers hold a specific other NFT to participate in the buy
  struct Deal {
    address seller;
    address token;
    address paymentCurrency;
    uint256 remainingAmount;
    uint256 minimumPurchase;
    uint256 price;
    uint256 maturity;
    uint256[] unlockDates;
    address[] nfts;
  }

  /// Mapping of index to deal
  mapping(uint256 => Deal) public deals;

  /// Method to allow this contract receive ETH 
  receive() external payable {}

  /// Event emitted when a deal is created
  event NewNFTGatedDeal(
    uint256 indexed _dealId,
    address indexed _seller,
    address _token,
    address _paymentCurrency,
    uint256 _remainingAmount,
    uint256 _minimumPurchase,
    uint256 _price,
    uint256 _maturity,
    uint256[] _unlockDates,
    address[] _nfts
  );

  /// Event emitted when tokens are bought
  /// @param _dealId The deal index
  /// @param _amount The amount of tokens bought
  /// @param _remainingAmount The remaining number of tokens in the deal
  event TokensBought(uint256 indexed _dealId, uint256 _amount, uint256 _remainingAmount);

  /// Event emitted when the deal is closed
  /// @param _dealId The deal index
  event DealClosed(uint256 indexed _dealId);
  
  /// Event emitted when a future NFT is created
  /// @param _owner The address that bought tokens from the deal and owns the future NFT
  /// @param _token The address of the token contract
  /// @param _amount The amount of tokens locked
  /// @param _unlockDate The date when the future NFT is unlocked
  event FutureCreated(address indexed _owner, address _token, uint256 _amount, uint256 _unlockDate);
  
  /// This function is what the seller uses to create a new OTC offering, Once this function has been completed 
  /// buyers can purchase tokens from the seller based on the price and parameters set
  /// @param _token is the ERC20 contract address that the seller is going to create the over the counter offering for
  /// @param _paymentCurrency is the ERC20 contract address of the opposite ERC20 that the seller wants to get paid in when selling the token (use WETH for ETH)
  /// this can also be used for a token SWAP - where the ERC20 address of the token being swapped to is input as the paymentCurrency
  /// @param _amount is the amount of tokens that you as the seller want to sell
  /// @param _min is the minimum amount of tokens that a buyer can purchase from you. this should be less than or equal to the total amount
  /// @param _price is the price per token which the seller will get paid, denominated in the payment currency
  /// if this is a token SWAP, then the _price needs to be set as the ratio of the tokens being swapped - ie 10 for 10 paymentCurrency tokens to 1 token
  /// @param _maturity is how long you would like to allow buyers to purchase tokens from this deal, in unix time. this needs to be beyond current block time
  /// @param _unlockDates is the dates in which the tokens will be cliff vested
  /// @param _nfts is a special option to make this deal require that the buyers hold a specific other NFT to participate in the buy
  function createNFTGatedDeal(
    address _token,
    address _paymentCurrency,
    uint256 _amount,
    uint256 _min,
    uint256 _price,
    uint256 _maturity,
    uint256[] memory _unlockDates,
    address[] memory _nfts
  ) external payable nonReentrant {
    require(_maturity > block.timestamp, 'OTC01');
    require(_amount >= _min, 'OTC02');
    require((_min * _price) / (10**Decimals(_token).decimals()) > 0, 'OTC03');
    deals[dealId++] = Deal(
      msg.sender,
      _token,
      _paymentCurrency,
      _amount,
      _min,
      _price,
      _maturity,
      _unlockDates,
      _nfts
    );
    
    emit NewNFTGatedDeal(
      dealId - 1,
      msg.sender,
      _token,
      _paymentCurrency,
      _amount,
      _min,
      _price,
      _maturity,
      _unlockDates,
      _nfts
    );

    TransferHelper.transferPayment(weth, _token, payable(msg.sender), payable(address(this)), _amount);
  }

  /// @notice This function lets a seller cancel their existing deal anytime they if they want to, including before the maturity date, 
  /// all that is required is that the deal has not been closed, and that there is still a reamining balance
  /// @param _dealId is the dealID that is mapped to the Struct Deal
  function close(uint256 _dealId) external nonReentrant {
    Deal memory deal = deals[_dealId];
    require(msg.sender == deal.seller, 'OTC04');
    require(deal.remainingAmount > 0, 'OTC05');
    delete deals[_dealId];
    emit DealClosed(_dealId);
    TransferHelper.withdrawPayment(weth, deal.token, payable(msg.sender), deal.remainingAmount);
  }

  /// @notice Checks if the address owns one of the NFTs configured for the deal
  /// @param _dealId The deal index
  /// @param buyer The buyer address
  function isNFTOwner(uint256 _dealId, address buyer) public view returns (bool canBuy) {
    Deal memory deal = deals[_dealId];
    if (deal.nfts.length == 0) {
      canBuy = true;
    } else {
      for (uint256 i; i < deal.nfts.length; i++) {
        if (IERC721(deal.nfts[i]).balanceOf(buyer) > 0) {
          canBuy = true;
        }
      }
    }
  }

  /// This function is what buyers use to make purchases from the sellers
  /// @param _dealId is the index of the deal that a buyer wants to participate in and make a purchase
  /// @param _amount is the amount of tokens the buyer is purchasing, which must be at least the minimumPurchase and at 
  /// most the remainingAmount for this deal (or the remainingAmount if that is less than the minimum)
  /// @dev this function can also be used to execute a token SWAP function, where the swap is executed through this function
  function buy(uint256 _dealId, uint256 _amount) external payable nonReentrant {
    Deal memory deal = deals[_dealId];
    require(deal.maturity >= block.timestamp, 'OTC07');
    require(isNFTOwner(_dealId, msg.sender), 'OTC08');
    require(
      (_amount >= deal.minimumPurchase || _amount == deal.remainingAmount) && deal.remainingAmount >= _amount,
      'OTC09'
    );
    uint256 decimals = Decimals(deal.token).decimals();
    uint256 purchase = (_amount * deal.price) / (10**decimals);
    TransferHelper.transferPayment(weth, deal.paymentCurrency, msg.sender, payable(deal.seller), purchase);
    deal.remainingAmount -= _amount;
    emit TokensBought(_dealId, _amount, deal.remainingAmount);
    if (deal.unlockDates.length > 0) {
      uint256 proRataLockAmount = _amount / deal.unlockDates.length;
      for (uint256 i; i < deal.unlockDates.length; i++) {
        NFTHelper.lockTokens(futuresContract, msg.sender, deal.token, proRataLockAmount, deal.unlockDates[i]);
        emit FutureCreated(msg.sender, deal.token, proRataLockAmount, deal.unlockDates[i]);
      }
    } else {
      TransferHelper.withdrawPayment(weth, deal.token, payable(msg.sender), _amount);
    }
    if (deal.remainingAmount == 0) {
      delete deals[_dealId];
    } else {
      deals[_dealId].remainingAmount = deal.remainingAmount;
    }
  }
}

// File: contracts/interfaces/Decimals.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.8.7;

/// @dev this interface is a critical addition that is not part of the standard ERC-20 specifications
/// @dev this is required to do the calculation of the total price required, when pricing things in the payment currency
/// @dev only the payment currency is required to have a decimals impelementation on the ERC20 contract, otherwise it will fail
interface Decimals {
  function decimals() external view returns (uint256);
}

// File: contracts/libraries/TransferHelper.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.8.7;

import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import '@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol';
import '../interfaces/IWETH.sol';

/// @notice Library to help safely transfer tokens and handle ETH wrapping and unwrapping of WETH
library TransferHelper {
  using SafeERC20 for IERC20;

  /// @notice Internal function used for standard ERC20 transferFrom method
  /// @notice it contains a pre and post balance check
  /// @notice as well as a check on the msg.senders balance
  /// @param token is the address of the ERC20 being transferred
  /// @param from is the remitting address
  /// @param to is the location where they are being delivered
  function transferTokens(
    address token,
    address from,
    address to,
    uint256 amount
  ) internal {
    uint256 priorBalance = IERC20(token).balanceOf(address(to));
    require(IERC20(token).balanceOf(msg.sender) >= amount, 'THL01');
    SafeERC20.safeTransferFrom(IERC20(token), from, to, amount);
    uint256 postBalance = IERC20(token).balanceOf(address(to));
    require(postBalance - priorBalance == amount, 'THL02');
  }

  /// @notice Internal function is used with standard ERC20 transfer method
  /// @notice this function ensures that the amount received is the amount sent with pre and post balance checking
  /// @param token is the ERC20 contract address that is being transferred
  /// @param to is the address of the recipient
  /// @param amount is the amount of tokens that are being transferred
  function withdrawTokens(
    address token,
    address to,
    uint256 amount
  ) internal {
    uint256 priorBalance = IERC20(token).balanceOf(address(to));
    SafeERC20.safeTransfer(IERC20(token), to, amount);
    uint256 postBalance = IERC20(token).balanceOf(address(to));
    require(postBalance - priorBalance == amount, 'THL02');
  }

  /// @dev Internal function that handles transfering payments from buyers to sellers with special WETH handling
  /// @dev this function assumes that if the recipient address is a contract, it cannot handle ETH - so we always deliver WETH
  /// @dev special care needs to be taken when using contract addresses to sell deals - to ensure it can handle WETH properly when received
  function transferPayment(
    address weth,
    address token,
    address from,
    address payable to,
    uint256 amount
  ) internal {
    if (token == weth) {
      require(msg.value == amount, 'THL03');
      if (!Address.isContract(to)) {
        (bool success, ) = to.call{value: amount}('');
        require(success, 'THL04');
      } else {
        /// @dev we want to deliver WETH from ETH here for better handling at contract
        IWETH(weth).deposit{value: amount}();
        require(IWETH(weth).transfer(to, amount));
      }
    } else {
      transferTokens(token, from, to, amount);
    }
  }

  /// @dev Internal funciton that handles withdrawing tokens and WETH that are up for sale to buyers
  /// @dev this function is only called if the tokens are not timelocked
  /// @dev this function handles weth specially and delivers ETH to the recipient
  function withdrawPayment(
    address weth,
    address token,
    address payable to,
    uint256 amount
  ) internal {
    if (token == weth) {
      IWETH(weth).withdraw(amount);
      (bool success, ) = to.call{value: amount}('');
      require(success, 'THL04');
    } else {
      withdrawTokens(token, to, amount);
    }
  }
}

// File: contracts/libraries/NFTHelper.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.8.7;
import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import '@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol';
import '../interfaces/INFT.sol';

/// @notice Library to lock tokens and mint an NFT
/// @notice this NFTHelper is used by the HedgeyOTC contract to lock tokens and instruct the Hedgeys contract to mint an NFT
library NFTHelper {
  /// @dev internal function that handles the locking of the tokens in the NFT Futures contract
  /// @param futureContract is the address of the NFT contract that will mint the NFT and lock tokens
  /// @param _holder address here becomes the owner of the newly minted NFT
  /// @param _token address here is the ERC20 contract address of the tokens being locked by the NFT contract
  /// @param _amount is the amount of tokens that will be locked
  /// @param _unlockDate provides the unlock date which is the expiration date for the Future generated
  function lockTokens(
    address futureContract,
    address _holder,
    address _token,
    uint256 _amount,
    uint256 _unlockDate
  ) internal {
    /// @dev ensure that the _unlockDate is in the future compared to the current block timestamp
    require(_unlockDate > block.timestamp, 'NHL01');
    /// @dev similar to checking the balances for the OTC contract when creating a new deal - we check the current and post balance in the NFT contract
    /// @dev to ensure that 100% of the amount of tokens to be locked are in fact locked in the contract address
    uint256 currentBalance = IERC20(_token).balanceOf(futureContract);
    /// @dev increase allowance so that the NFT contract can pull the total funds
    /// @dev this is a safer way to ensure that the entire amount is delivered to the NFT contract
    SafeERC20.safeIncreaseAllowance(IERC20(_token), futureContract, _amount);
    /// @dev this function points to the NFT Futures contract and calls its function to mint an NFT and generate the locked tokens future struct
    INFT(futureContract).createNFT(_holder, _amount, _token, _unlockDate);
    /// @dev check to make sure that _holder is received by the futures contract equals the total amount we have delivered
    /// @dev this prevents functionality with deflationary or tax tokens that have not whitelisted these address
    uint256 postBalance = IERC20(_token).balanceOf(futureContract);
    require(postBalance - currentBalance == _amount, 'NHL02');
  }

  /// @notice function to get the balances for a given wallet
  function getLockedTokenDetails(address futureContract, address holder)
    public
    view
    returns (
      uint256[] memory amounts,
      address[] memory tokens,
      uint256[] memory unlockDates
    )
  {
    uint256 holdersBalance = INFT(futureContract).balanceOf(holder);
    /// @dev for loop going through the holders balance to get each of their token IDs
    for (uint256 i = 0; i < holdersBalance; i++) {
      /// @dev gets the tokenId
      uint256 tokenId = INFT(futureContract).tokenOfOwnerByIndex(holder, i);
      /// @dev now we can use that tokenId to get their time lock details
      (uint256 amount, address token, uint256 unlockDate) = INFT(futureContract).futures(tokenId);
      /// @dev add these to the array
      amounts[i] = amount;
      tokens[i] = token;
      unlockDates[i] = unlockDate;
    }
  }

  function getLockedTokenBalance(address futureContract, address holder, address lockedToken) public view returns (uint256 lockedAmount) {
     uint256 holdersBalance = INFT(futureContract).balanceOf(holder);
    /// @dev for loop going through the holders balance to get each of their token IDs
    for (uint256 i = 0; i < holdersBalance; i++) {
      /// @dev gets the tokenId
      uint256 tokenId = INFT(futureContract).tokenOfOwnerByIndex(holder, i);
      /// @dev now we can use that tokenId to get their time lock details
      (uint256 amount, address token,) = INFT(futureContract).futures(tokenId);
      /// @dev check if the token matches the lockedToken criteria
      if (token == lockedToken) {
        /// @dev if it does - add it to the sum total
        lockedAmount += amount;
      }
    }
  }
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);
}

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @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;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

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

    /**
     * @dev Returns the 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);
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    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");
        }
    }
}

// File: contracts/interfaces/IWETH.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.8.7;

/// @dev used for handling ETH wrapping into WETH to be stored in smart contracts upon deposit,
/// ... and used to unwrap WETH into ETH to deliver when withdrawing from smart contracts
interface IWETH {
  function deposit() external payable;

  function transfer(address to, uint256 value) external returns (bool);

  function withdraw(uint256) external;
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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);
            }
        }
    }
}

// File: contracts/interfaces/INFT.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.8.7;

/// @dev this is the one contract call that the OTC needs to interact with the NFT contract
interface INFT {
  /// @notice function for publicly viewing a lockedToken (future) details
  /// @param _id is the id of the NFT which is mapped to the future struct
  /// @dev this returns the amount of tokens locked, the token address and the date that they are unlocked
  function futures(uint256 _id)
    external
    view
    returns (
      uint256 amount,
      address token,
      uint256 unlockDate
    );
    /// @dev Returns the number of tokens in ``owner``'s account.
    function balanceOf(address owner) external view returns (uint256 balance);
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256);
    function tokenByIndex(uint256 index) external view returns (uint256);

  /// @param _holder is the new owner of the NFT and timelock future - this can be any address
  /// @param _amount is the amount of tokens that are going to be locked
  /// @param _token is the token address to be locked by the NFT. Use WETH address for ETH - but WETH must be held by the msg.sender
  /// ... as there is no automatic wrapping from ETH to WETH for this function.
  /// @param _unlockDate is the date which the tokens become unlocked and available to be redeemed and withdrawn from the contract
  /// @dev this is a public function that anyone can call
  /// @dev the _holder can be defined as your address, or any chose address - and so you can directly mint NFTs to other addresses
  /// ... in a way to airdrop NFTs directly to contributors
  function createNFT(
    address _holder,
    uint256 _amount,
    address _token,
    uint256 _unlockDate
  ) external returns (uint256);

  /// @dev function for redeeming an NFT
  /// @notice this function will burn the NFT and delete the future struct - in return the locked tokens will be delivered
  function redeemNFT(uint256 _id) external returns (bool);

  /// @notice this event spits out the details of the NFT and future struct when a new NFT & Future is minted
  event NFTCreated(uint256 _i, address _holder, uint256 _amount, address _token, uint256 _unlockDate);

  /// @notice this event spits out the details of the NFT and future structe when an existing NFT and Future is redeemed
  event NFTRedeemed(uint256 _i, address _holder, uint256 _amount, address _token, uint256 _unlockDate);

  /// @notice this event is fired the one time when the baseURI is updated
  event URISet(string newURI);
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

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