// File: contracts/modules/capital/SwapOperator.sol



// SPDX-License-Identifier: GPL-3.0-only

pragma solidity ^0.8.0;

import "@openzeppelin/contracts-v4/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts-v4/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts-v4/token/ERC20/utils/SafeERC20.sol";
import "../../external/uniswap/IUniswapV2Pair.sol";
import "../../external/uniswap/IUniswapV2Router02.sol";
import "../../interfaces/INXMMaster.sol";
import "../../interfaces/IPool.sol";
import "../../interfaces/ITwapOracle.sol";

contract SwapOperator is ReentrancyGuard {
  using SafeERC20 for IERC20;

  struct AssetData {
    uint112 minAmount;
    uint112 maxAmount;
    uint32 lastSwapTime;
    // 18 decimals of precision. 0.01% -> 0.0001 -> 1e14
    uint maxSlippageRatio;
  }

  /* storage */
  bool public communityFundTransferExecuted;

  /* immutables */
  ITwapOracle immutable public twapOracle;
  address immutable public swapController;
  INXMMaster immutable master;
  address immutable public stETH;

  /* constants */
  address constant public ETH = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
  IUniswapV2Router02 constant public router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
  uint constant public MAX_LIQUIDITY_RATIO = 0.015 ether;
  uint constant public MIN_TIME_BETWEEN_SWAPS = 10 minutes;

  /* events */
  event Swapped(address indexed fromAsset, address indexed toAsset, uint amountIn, uint amountOut);

  /* logic */
  modifier onlySwapController {
    require(msg.sender == swapController, "SwapOperator: not swapController");
    _;
  }

  constructor(address payable _master, address _twapOracle, address _swapController, address _stETH) {
    master = INXMMaster(_master);
    twapOracle = ITwapOracle(_twapOracle);
    swapController = _swapController;
    stETH = _stETH;
  }

  function swapETHForAsset(
    address toTokenAddress,
    uint amountIn,
    uint amountOutMin
  ) external onlySwapController {

    IPool pool = _pool();
    (
    uint112 min,
    uint112 max,
    uint32 lastAssetSwapTime,
    uint maxSlippageRatio
    ) = pool.getAssetDetails(toTokenAddress);

    AssetData memory assetDetails = AssetData(min, max, lastAssetSwapTime, maxSlippageRatio);
    require(assetIsEnabled(assetDetails), "SwapOperator: asset is not enabled");

    pool.transferAssetToSwapOperator(ETH, amountIn);
    pool.setAssetDataLastSwapTime(toTokenAddress, uint32(block.timestamp));
    uint amountOut = _swapETHForAsset(
      assetDetails,
      toTokenAddress,
      amountIn,
      amountOutMin,
      pool.minPoolEth()
    );
    transferAssetTo(toTokenAddress, address(pool), amountOut);

    emit Swapped(ETH, toTokenAddress, amountIn, amountOut);
  }

  function swapAssetForETH(
    address fromTokenAddress,
    uint amountIn,
    uint amountOutMin
  ) external onlySwapController {

    IPool pool = _pool();
    (
    uint112 min,
    uint112 max,
    uint32 lastAssetSwapTime,
    uint maxSlippageRatio
    ) = pool.getAssetDetails(fromTokenAddress);

    AssetData memory assetDetails = AssetData(min, max, lastAssetSwapTime, maxSlippageRatio);
    require(assetIsEnabled(assetDetails), "SwapOperator: asset is not enabled");

    pool.transferAssetToSwapOperator(fromTokenAddress, amountIn);
    pool.setAssetDataLastSwapTime(fromTokenAddress, uint32(block.timestamp));
    uint amountOut = _swapAssetForETH(
      assetDetails,
      fromTokenAddress,
      amountIn,
      amountOutMin
    );
    transferAssetTo(ETH, address(pool), amountOut);
    emit Swapped(fromTokenAddress, ETH, amountIn, amountOut);
  }

  function getSwapQuote(
    uint tokenAmountIn,
    IERC20 fromToken,
    IERC20 toToken
  ) public view returns (uint tokenAmountOut) {

    address[] memory path = new address[](2);
    path[0] = address(fromToken);
    path[1] = address(toToken);
    uint[] memory amountsOut = router.getAmountsOut(tokenAmountIn, path);

    return amountsOut[1];
  }

  function _swapETHForAsset(
    AssetData memory assetData,
    address toTokenAddress,
    uint amountIn,
    uint amountOutMin,
    uint minLeftETH
  ) internal returns (uint) {

    IPool pool = _pool();
    uint balanceBefore = IERC20(toTokenAddress).balanceOf(address(pool));
    address WETH = router.WETH();

    {
      // scope for swap frequency check
      uint timeSinceLastTrade = block.timestamp - uint(assetData.lastSwapTime);
      require(timeSinceLastTrade > MIN_TIME_BETWEEN_SWAPS, "SwapOperator: too fast");
    }

    {
      // scope for liquidity check
      address pairAddress = twapOracle.pairFor(WETH, toTokenAddress);
      IUniswapV2Pair pair = IUniswapV2Pair(pairAddress);
      (uint112 reserve0, uint112 reserve1, /* time */) = pair.getReserves();

      uint ethReserve = WETH < toTokenAddress ? reserve0 : reserve1;
      uint maxTradable = ethReserve * MAX_LIQUIDITY_RATIO / 1e18;

      require(amountIn <= maxTradable, "SwapOperator: exceeds max tradable amount");
    }

    {
      // scope for ether checks
      uint ethBalanceAfter = address(pool).balance;
      require(ethBalanceAfter >= minLeftETH, "SwapOperator: insufficient ether left");
    }

    {
      // scope for token checks
      uint avgAmountOut = twapOracle.consult(WETH, amountIn, toTokenAddress);
      uint maxSlippageAmount = avgAmountOut * assetData.maxSlippageRatio / 1e18;
      uint minOutOnMaxSlippage = avgAmountOut - maxSlippageAmount;

      // gas optimisation: reads both values using a single SLOAD
      (uint minAssetAmount, uint maxAssetAmount) = (assetData.minAmount, assetData.maxAmount);

      require(amountOutMin >= minOutOnMaxSlippage, "SwapOperator: amountOutMin < minOutOnMaxSlippage");
      require(balanceBefore < minAssetAmount, "SwapOperator: balanceBefore >= min");
      require(balanceBefore + amountOutMin <= maxAssetAmount, "SwapOperator: balanceAfter > max");
    }

    address[] memory path = new address[](2);
    path[0] = WETH;
    path[1] = toTokenAddress;
    router.swapExactETHForTokens{ value: amountIn }(amountOutMin, path, address(this), block.timestamp);

    uint amountOut = IERC20(toTokenAddress).balanceOf(address(this));

    return amountOut;
  }

  function _swapAssetForETH(
    AssetData memory assetData,
    address fromTokenAddress,
    uint amountIn,
    uint amountOutMin
  ) internal returns (uint) {

    IPool pool = _pool();
    uint tokenBalanceBefore = IERC20(fromTokenAddress).balanceOf(address(pool)) + amountIn;
    address WETH = router.WETH();

    {
      // scope for swap frequency check
      uint timeSinceLastTrade = block.timestamp - uint(assetData.lastSwapTime);
      require(timeSinceLastTrade > MIN_TIME_BETWEEN_SWAPS, "SwapOperator: too fast");
    }

    {
      // scope for liquidity check
      address pairAddress = twapOracle.pairFor(fromTokenAddress, WETH);
      IUniswapV2Pair pair = IUniswapV2Pair(pairAddress);
      (uint112 reserve0, uint112 reserve1, /* time */) = pair.getReserves();

      uint tokenReserve = fromTokenAddress < WETH ? reserve0 : reserve1;
      uint maxTradable = tokenReserve * MAX_LIQUIDITY_RATIO / 1e18;

      require(amountIn <= maxTradable, "SwapOperator: exceeds max tradable amount");
    }

    {
      // scope for token checks
      uint avgAmountOut = twapOracle.consult(fromTokenAddress, amountIn, WETH);
      uint maxSlippageAmount = avgAmountOut * assetData.maxSlippageRatio / 1e18;
      uint minOutOnMaxSlippage = avgAmountOut - maxSlippageAmount;

      // gas optimisation: reads both values using a single SLOAD
      (uint minAssetAmount, uint maxAssetAmount) = (assetData.minAmount, assetData.maxAmount);

      require(amountOutMin >= minOutOnMaxSlippage, "SwapOperator: amountOutMin < minOutOnMaxSlippage");
      require(tokenBalanceBefore > maxAssetAmount, "SwapOperator: tokenBalanceBefore <= max");
      require(tokenBalanceBefore - amountIn >= minAssetAmount, "SwapOperator: tokenBalanceAfter < min");
    }

    address[] memory path = new address[](2);
    path[0] = fromTokenAddress;
    path[1] = router.WETH();
    IERC20(fromTokenAddress).approve(address(router), amountIn);
    router.swapExactTokensForETH(amountIn, amountOutMin, path, address(this), block.timestamp);

    uint amountOut = address(this).balance;

    return amountOut;
  }

  function transferAssetTo (address asset, address to, uint amount) internal {

    if (asset == ETH) {
      (bool ok, /* data */) = to.call{ value: amount }("");
      require(ok, "SwapOperator: Eth transfer failed");
      return;
    }

    IERC20 token = IERC20(asset);
    token.safeTransfer(to, amount);
  }

  function swapETHForStETH(uint amountIn) external onlySwapController {

    IPool pool = _pool();
    address toTokenAddress = stETH;
    (
    uint112 minAmount,
    uint112 maxAmount,
    /* uint32 lastAssetSwapTime */,
    /* uint maxSlippageRatio */
    ) = pool.getAssetDetails(toTokenAddress);

    require(!(minAmount == 0 && maxAmount == 0), "SwapOperator: asset is not enabled");

    uint amountOutMin;
    if (amountIn > 10000) {
      amountOutMin = amountIn - 10000; // allow for precision error
    }

    uint balanceBefore = IERC20(toTokenAddress).balanceOf(address(pool));

    pool.transferAssetToSwapOperator(ETH, amountIn);

    (bool ok, /* data */) = toTokenAddress.call{ value: amountIn }("");
    require(ok, "SwapOperator: stEth transfer failed");

    pool.setAssetDataLastSwapTime(toTokenAddress, uint32(block.timestamp));

    uint amountOut = IERC20(toTokenAddress).balanceOf(address(this));

    require(amountOut >= amountOutMin, "SwapOperator: amountOut < amountOutMin");
    require(balanceBefore < minAmount, "SwapOperator: balanceBefore >= min");
    require(balanceBefore + amountOutMin <= maxAmount, "SwapOperator: balanceAfter > max");
    {
      uint ethBalanceAfter = address(pool).balance;
      require(ethBalanceAfter >= pool.minPoolEth(), "SwapOperator: insufficient ether left");
    }

    transferAssetTo(stETH, address(pool), amountOut);

    emit Swapped(ETH, stETH, amountIn, amountOut);
  }

  function transferToCommunityFund() external onlySwapController {

    // amount, destination, deadline
    uint amount = 8000 ether;
    address communityFund = 0x586b9b2F8010b284A0197f392156f1A7Eb5e86e9;
    uint deadline = 1638057600; // Sun Nov 28 2021 00:00:00 GMT+0000

    // perform checks and mark as paid
    require(block.timestamp < deadline, "SwapOperator: the deadline has passed");
    require(!communityFundTransferExecuted, "SwapOperator: already executed");
    communityFundTransferExecuted = true;

    // transfer
    _pool().transferAssetToSwapOperator(ETH, amount);
    (bool ok, /* data */) = communityFund.call{ value: amount }("");
    require(ok, "SwapOperator: transfer failed");
  }

  function assetIsEnabled(AssetData memory assetData) internal pure returns (bool) {
    return !(assetData.minAmount == 0 && assetData.maxAmount == 0);
  }

  function _pool() internal view returns (IPool) {
    return IPool(master.getLatestAddress('P1'));
  }

  receive() external payable {}
}

// File: @openzeppelin/contracts-v4/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

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 make 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-v4/token/ERC20/ERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless this function is
     * overridden;
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        unchecked {
            _approve(sender, _msgSender(), currentAllowance - amount);
        }

        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(_msgSender(), spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `sender` to `recipient`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[sender] = senderBalance - amount;
        }
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);

        _afterTokenTransfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

// File: @openzeppelin/contracts-v4/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT

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/external/uniswap/IUniswapV2Pair.sol



// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
  function getReserves() external view returns (uint112, uint112, uint32);
}

// File: contracts/external/uniswap/IUniswapV2Router02.sol



// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.5.0;

import './IUniswapV2Router01.sol';

interface IUniswapV2Router02 is IUniswapV2Router01 {

  function removeLiquidityETHSupportingFeeOnTransferTokens(
    address token,
    uint liquidity,
    uint amountTokenMin,
    uint amountETHMin,
    address to,
    uint deadline
  ) external returns (uint amountETH);

  function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
    address token,
    uint liquidity,
    uint amountTokenMin,
    uint amountETHMin,
    address to,
    uint deadline,
    bool approveMax, uint8 v, bytes32 r, bytes32 s
  ) external returns (uint amountETH);

  function swapExactTokensForTokensSupportingFeeOnTransferTokens(
    uint amountIn,
    uint amountOutMin,
    address[] calldata path,
    address to,
    uint deadline
  ) external;

  function swapExactETHForTokensSupportingFeeOnTransferTokens(
    uint amountOutMin,
    address[] calldata path,
    address to,
    uint deadline
  ) external payable;

  function swapExactTokensForETHSupportingFeeOnTransferTokens(
    uint amountIn,
    uint amountOutMin,
    address[] calldata path,
    address to,
    uint deadline
  ) external;
}

// File: contracts/interfaces/INXMMaster.sol



// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.5.0;

interface INXMMaster {

  function tokenAddress() external view returns (address);

  function owner() external view returns (address);

  function masterInitialized() external view returns (bool);

  function isInternal(address _add) external view returns (bool);

  function isPause() external view returns (bool check);

  function isOwner(address _add) external view returns (bool);

  function isMember(address _add) external view returns (bool);

  function checkIsAuthToGoverned(address _add) external view returns (bool);

  function dAppLocker() external view returns (address _add);

  function getLatestAddress(bytes2 _contractName) external view returns (address payable contractAddress);

  function upgradeMultipleContracts(
    bytes2[] calldata _contractCodes,
    address payable[] calldata newAddresses
  ) external;

  function removeContracts(bytes2[] calldata contractCodesToRemove) external;

  function addNewInternalContracts(
    bytes2[] calldata _contractCodes,
    address payable[] calldata newAddresses,
    uint[] calldata _types
  ) external;

  function updateOwnerParameters(bytes8 code, address payable val) external;
}

// File: contracts/interfaces/IPool.sol



// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.5.0;

import "./IPriceFeedOracle.sol";

interface IPool {
  function sellNXM(uint tokenAmount, uint minEthOut) external;

  function sellNXMTokens(uint tokenAmount) external returns (bool);

  function minPoolEth() external returns (uint);

  function transferAssetToSwapOperator(address asset, uint amount) external;

  function setAssetDataLastSwapTime(address asset, uint32 lastSwapTime) external;

  function getAssetDetails(address _asset) external view returns (
    uint112 min,
    uint112 max,
    uint32 lastAssetSwapTime,
    uint maxSlippageRatio
  );

  function sendClaimPayout (
    address asset,
    address payable payoutAddress,
    uint amount
  ) external returns (bool success);

  function transferAsset(
    address asset,
    address payable destination,
    uint amount
  ) external;

  function upgradeCapitalPool(address payable newPoolAddress) external;

  function priceFeedOracle() external view returns (IPriceFeedOracle);

  function getPoolValueInEth() external view returns (uint);


  function transferAssetFrom(address asset, address from, uint amount) external;

  function getEthForNXM(uint nxmAmount) external view returns (uint ethAmount);

  function calculateEthForNXM(
    uint nxmAmount,
    uint currentTotalAssetValue,
    uint mcrEth
  ) external pure returns (uint);

  function calculateMCRRatio(uint totalAssetValue, uint mcrEth) external pure returns (uint);

  function calculateTokenSpotPrice(uint totalAssetValue, uint mcrEth) external pure returns (uint tokenPrice);

  function getTokenPrice(address asset) external view returns (uint tokenPrice);

  function getMCRRatio() external view returns (uint);
}

// File: contracts/interfaces/ITwapOracle.sol



// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.5.0;

interface ITwapOracle {
  function pairFor(address tokenA, address tokenB) external view returns (address);
  function consult(address tokenIn, uint amountIn, address tokenOut) external view returns (uint);
  function periodSize() external view returns (uint);
}

// File: @openzeppelin/contracts-v4/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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 `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, 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 `sender` to `recipient` 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 sender,
        address recipient,
        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);
}

// File: @openzeppelin/contracts-v4/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// File: @openzeppelin/contracts-v4/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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;
    }
}

// File: @openzeppelin/contracts-v4/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 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/external/uniswap/IUniswapV2Router01.sol



// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.5.0;

interface IUniswapV2Router01 {

  function factory() external pure returns (address);

  function WETH() external pure returns (address);

  function addLiquidity(
    address tokenA,
    address tokenB,
    uint amountADesired,
    uint amountBDesired,
    uint amountAMin,
    uint amountBMin,
    address to,
    uint deadline
  ) external returns (uint amountA, uint amountB, uint liquidity);

  function addLiquidityETH(
    address token,
    uint amountTokenDesired,
    uint amountTokenMin,
    uint amountETHMin,
    address to,
    uint deadline
  ) external payable returns (uint amountToken, uint amountETH, uint liquidity);

  function removeLiquidity(
    address tokenA,
    address tokenB,
    uint liquidity,
    uint amountAMin,
    uint amountBMin,
    address to,
    uint deadline
  ) external returns (uint amountA, uint amountB);

  function removeLiquidityETH(
    address token,
    uint liquidity,
    uint amountTokenMin,
    uint amountETHMin,
    address to,
    uint deadline
  ) external returns (uint amountToken, uint amountETH);

  function removeLiquidityWithPermit(
    address tokenA,
    address tokenB,
    uint liquidity,
    uint amountAMin,
    uint amountBMin,
    address to,
    uint deadline,
    bool approveMax, uint8 v, bytes32 r, bytes32 s
  ) external returns (uint amountA, uint amountB);

  function removeLiquidityETHWithPermit(
    address token,
    uint liquidity,
    uint amountTokenMin,
    uint amountETHMin,
    address to,
    uint deadline,
    bool approveMax, uint8 v, bytes32 r, bytes32 s
  ) external returns (uint amountToken, uint amountETH);

  function swapExactTokensForTokens(
    uint amountIn,
    uint amountOutMin,
    address[] calldata path,
    address to,
    uint deadline
  ) external returns (uint[] memory amounts);

  function swapTokensForExactTokens(
    uint amountOut,
    uint amountInMax,
    address[] calldata path,
    address to,
    uint deadline
  ) external returns (uint[] memory amounts);

  function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
  external
  payable
  returns (uint[] memory amounts);

  function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
  external
  returns (uint[] memory amounts);

  function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
  external
  returns (uint[] memory amounts);

  function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
  external
  payable
  returns (uint[] memory amounts);

  function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);

  function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);

  function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);

  function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);

  function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

// File: contracts/interfaces/IPriceFeedOracle.sol



// SPDX-License-Identifier: GPL-3.0-only

pragma solidity >=0.5.0;

interface IPriceFeedOracle {

  function daiAddress() external view returns (address);
  function stETH() external view returns (address);
  function ETH() external view returns (address);

  function getAssetToEthRate(address asset) external view returns (uint);
  function getAssetForEth(address asset, uint ethIn) external view returns (uint);

}