// File: contracts/modules/distributor/Distributor.sol



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

pragma solidity ^0.8.0;

import "@openzeppelin/contracts-v4/access/Ownable.sol";
import "@openzeppelin/contracts-v4/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts-v4/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts-v4/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts-v4/token/ERC721/ERC721.sol";
import "../../interfaces/IGateway.sol";
import "../../interfaces/INXMMaster.sol";
import "../../interfaces/IPool.sol";

contract Distributor is ERC721, Ownable, ReentrancyGuard {
  using SafeERC20 for IERC20;

  address public constant ETH = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

  event ClaimPayoutRedeemed (
    uint indexed coverId,
    uint indexed claimId,
    address indexed receiver,
    uint amountPaid,
    address coverAsset
  );

  event ClaimSubmitted (
    uint indexed coverId,
    uint indexed claimId,
    address indexed submitter
  );

  event CoverBought (
    uint indexed coverId,
    address indexed buyer,
    address indexed contractAddress,
    uint feePercentage,
    uint coverPrice
  );

  event FeePercentageChanged (
    uint feePercentage
  );

  event BuysAllowedChanged (
    bool buysAllowed
  );

  event TreasuryChanged (
    address treasury
  );

  /*
   feePercentage applied to every cover premium. has 2 decimals. eg.: 10.00% stored as 1000
  */
  uint public feePercentage;
  bool public buysAllowed = true;
  /*
    address where `buyCover` distributor fees and `ethOut` from `sellNXM` are sent. Controlled by Owner.
  */
  address payable public treasury;

  /*
    NexusMutual contracts
  */
  IGateway immutable public gateway;
  IERC20 immutable public nxmToken;
  INXMMaster immutable public master;

  modifier onlyTokenApprovedOrOwner(uint256 tokenId) {
    require(_isApprovedOrOwner(msg.sender, tokenId), "Distributor: Not approved or owner");
    _;
  }

  constructor(
    address gatewayAddress,
    address nxmTokenAddress,
    address masterAddress,
    uint _feePercentage,
    address payable _treasury,
    string memory tokenName,
    string memory tokenSymbol
  )
  ERC721(tokenName, tokenSymbol)
  {

    require(_treasury != address(0), "Distributor: treasury address is 0");
    feePercentage = _feePercentage;
    treasury = _treasury;
    gateway = IGateway(gatewayAddress);
    nxmToken = IERC20(nxmTokenAddress);
    master = INXMMaster(masterAddress);
  }

  /**
  * @dev buy cover for a coverable identified by its contractAddress
  * @param contractAddress contract address of coverable
  * @param coverAsset asset of the premium and of the sum assured.
  * @param sumAssured amount payable if claim is submitted and considered valid
  * @param coverType cover type determining how the data parameter is decoded
  * @param maxPriceWithFee max price (including fee) to be spent on the cover.
  * @param data abi-encoded field with additional cover data fields
  * @return token id
  */
  function buyCover (
    address contractAddress,
    address coverAsset,
    uint sumAssured,
    uint16 coverPeriod,
    uint8 coverType,
    uint maxPriceWithFee,
    bytes calldata data
  )
    external
    payable
    nonReentrant
    returns (uint)
  {
    require(buysAllowed, "Distributor: buys not allowed");

    uint coverPrice = gateway.getCoverPrice(contractAddress, coverAsset, sumAssured, coverPeriod, IGateway.CoverType(coverType), data);
    uint coverPriceWithFee = feePercentage * coverPrice / 10000 + coverPrice;
    require(coverPriceWithFee <= maxPriceWithFee, "Distributor: cover price with fee exceeds max");

    uint buyCoverValue = 0;
    if (coverAsset == ETH) {
      require(msg.value >= coverPriceWithFee, "Distributor: Insufficient ETH sent");
      uint remainder = msg.value - coverPriceWithFee;

      if (remainder > 0) {
        // solhint-disable-next-line avoid-low-level-calls
        (bool ok, /* data */) = address(msg.sender).call{value: remainder}("");
        require(ok, "Distributor: Returning ETH remainder to sender failed.");
      }

      buyCoverValue = coverPrice;
    } else {
      IERC20 token = IERC20(coverAsset);
      token.safeTransferFrom(msg.sender, address(this), coverPriceWithFee);
      token.approve(address(gateway), coverPrice);
    }

    uint coverId = gateway.buyCover{value: buyCoverValue }(
      contractAddress,
      coverAsset,
      sumAssured,
      coverPeriod,
      IGateway.CoverType(coverType),
      data
    );

    transferToTreasury(coverPriceWithFee - coverPrice, coverAsset);

    // mint token using the coverId as a tokenId (guaranteed unique)
    _mint(msg.sender, coverId);

    emit CoverBought(coverId, msg.sender, contractAddress, feePercentage, coverPrice);
    return coverId;
  }

  /**
  * @notice Submit a claim for the cover
  * @param tokenId cover token id
  * @param data abi-encoded field with additional claim data fields
  */
  function submitClaim(
    uint tokenId,
    bytes calldata data
  )
    external
    onlyTokenApprovedOrOwner(tokenId)
    returns (uint)
  {
    // coverId = tokenId
    uint claimId = gateway.submitClaim(tokenId, data);
    emit ClaimSubmitted(tokenId, claimId, msg.sender);
    return claimId;
  }

  /**
  * @notice Submit a claim for the cover
  * @param tokenId cover token id
  * @param incidentId id of the incident
  * @param coveredTokenAmount amount of yield tokens covered
  * @param coverAsset yield token that is covered
  */
  function claimTokens(
    uint tokenId,
    uint incidentId,
    uint coveredTokenAmount,
    address coverAsset
  )
    external
    onlyTokenApprovedOrOwner(tokenId)
    returns (uint claimId, uint payoutAmount, address payoutToken)
  {
    IERC20 token = IERC20(coverAsset);
    token.safeTransferFrom(msg.sender, address(this), coveredTokenAmount);
    token.approve(address(gateway), coveredTokenAmount);
    // coverId = tokenId
    (claimId, payoutAmount, payoutToken) = gateway.claimTokens(
      tokenId,
      incidentId,
      coveredTokenAmount,
      coverAsset
    );
    _burn(tokenId);
    if (payoutToken == ETH) {
      (bool ok, /* data */) = address(msg.sender).call{value: payoutAmount}("");
      require(ok, "Distributor: ETH transfer to sender failed.");
    } else {
      IERC20(payoutToken).safeTransfer(msg.sender, payoutAmount);
    }
    emit ClaimSubmitted(tokenId, claimId, msg.sender);
  }

  /**
  * @notice Redeem the claim to the cover. Requires that the payout is completed.
  * @param tokenId cover token id
  */
  function redeemClaim(
    uint256 tokenId,
    uint claimId
  )
    public
    onlyTokenApprovedOrOwner(tokenId)
    nonReentrant
  {
    uint coverId = gateway.getClaimCoverId(claimId);
    require(coverId == tokenId, "Distributor: coverId claimId mismatch");
    (IGateway.ClaimStatus status, uint amountPaid, address coverAsset) = gateway.getPayoutOutcome(claimId);
    require(status == IGateway.ClaimStatus.ACCEPTED, "Distributor: Claim not accepted");

    _burn(tokenId);
    if (coverAsset == ETH) {
      (bool ok, /* data */) = msg.sender.call{value: amountPaid}("");
      require(ok, "Distributor: Transfer to NFT owner failed");
    } else {
      IERC20 erc20 = IERC20(coverAsset);
      erc20.safeTransfer(msg.sender, amountPaid);
    }

    emit ClaimPayoutRedeemed(tokenId, claimId, msg.sender, amountPaid, coverAsset);
  }

  /**
  * @notice Execute an action on a specific cover token. The action is identified by an `action` id.
      Allows for an ETH transfer or an ERC20 transfer.
      If less than the supplied assetAmount is needed, it is returned to `msg.sender`.
  * @dev The purpose of this function is future-proofing for updates to the cover buy->claim cycle.
  * @param tokenId id of the cover token
  * @param assetAmount optional asset amount to be transferred along with the action executed
  * @param asset optional asset to be transferred along with the action executed
  * @param action action identifier
  * @param data abi-encoded field with action parameters
  * @return response (abi-encoded response, amount withheld from the original asset amount supplied)
  */
  function executeCoverAction(uint tokenId, uint assetAmount, address asset, uint8 action, bytes calldata data)
    external
    payable
    onlyTokenApprovedOrOwner(tokenId)
    nonReentrant
    returns (bytes memory response, uint withheldAmount)
  {
    if (assetAmount == 0) {
      return gateway.executeCoverAction(tokenId, action, data);
    }
    uint remainder;
    if (asset == ETH) {
      require(msg.value >= assetAmount, "Distributor: Insufficient ETH sent");
      (response, withheldAmount) = gateway.executeCoverAction{ value: msg.value }(tokenId, action, data);
      remainder = assetAmount - withheldAmount;
      (bool ok, /* data */) = address(msg.sender).call{value: remainder}("");
      require(ok, "Distributor: Returning ETH remainder to sender failed.");
      return (response, withheldAmount);
    }

    IERC20 token = IERC20(asset);
    token.safeTransferFrom(msg.sender, address(this), assetAmount);
    token.approve(address(gateway), assetAmount);
    (response, withheldAmount) = gateway.executeCoverAction(tokenId, action, data);
    remainder = assetAmount - withheldAmount;
    token.safeTransfer(msg.sender, remainder);
    return (response, withheldAmount);
  }

  /**
  * @notice get cover data
  * @param tokenId cover token id
  */
  function getCover(uint tokenId)
  public
  view
  returns (
    uint8 status,
    uint sumAssured,
    uint16 coverPeriod,
    uint validUntil,
    address contractAddress,
    address coverAsset,
    uint premiumInNXM,
    address memberAddress
  ) {
    return gateway.getCover(tokenId);
  }

  /**
  * @notice get state of a claim payout. Returns
  * status of cover,  amount paid as part of the payout, address of the cover asset)
  * @param claimId id of claim
  */
  function getPayoutOutcome(uint claimId)
  public
  view
  returns (IGateway.ClaimStatus status, uint amountPaid, address coverAsset)
  {
    (status, amountPaid, coverAsset) = gateway.getPayoutOutcome(claimId);
  }

  /**
  * @notice Set `amount` as the allowance of `spender` over the distributor's NXM tokens.
  * @param spender approved spender
  * @param amount amount approved
  */
  function approveNXM(address spender, uint256 amount) public onlyOwner {
    nxmToken.approve(spender, amount);
  }

  /**
  * @notice Moves `amount` tokens from the distributor to `recipient`.
  * @param recipient recipient of NXM
  * @param amount amount of NXM
  */
  function withdrawNXM(address recipient, uint256 amount) public onlyOwner {
    nxmToken.safeTransfer(recipient, amount);
  }

  /**
  * @notice Switch NexusMutual membership to `newAddress`.
  * @param newAddress address
  */
  function switchMembership(address newAddress) external onlyOwner {
    nxmToken.approve(address(gateway), type(uint).max);
    gateway.switchMembership(newAddress);
  }

  /**
  * @notice Sell Distributor-owned NXM tokens for ETH
  * @param nxmIn Amount of NXM to sell
  * @param minEthOut minimum expected Eth received
  */
  function sellNXM(uint nxmIn, uint minEthOut) external onlyOwner {

    address poolAddress = master.getLatestAddress("P1");
    nxmToken.approve(poolAddress, nxmIn);
    uint balanceBefore = address(this).balance;
    IPool(poolAddress).sellNXM(nxmIn, minEthOut);
    uint balanceAfter = address(this).balance;

    transferToTreasury(balanceAfter - balanceBefore, ETH);
  }

  /**
  * @notice Set if buyCover calls are allowed (true) or not (false).
  * @param _buysAllowed value set for buysAllowed
  */
  function setBuysAllowed(bool _buysAllowed) external onlyOwner {
    buysAllowed = _buysAllowed;
    emit BuysAllowedChanged(_buysAllowed);
  }

  /**
  * @notice Set treasury address where `buyCover` distributor fees and `ethOut` from `sellNXM` are sent.
  * @param _treasury new treasury address
  */
  function setTreasury(address payable _treasury) external onlyOwner {
    require(_treasury != address(0), "Distributor: treasury address is 0");
    treasury = _treasury;
    emit TreasuryChanged(_treasury);
  }

  /**
  * @notice Send `amount` of `asset`  to treasury address
  * @param amount amount of asset
  * @param asset ERC20 token address or ETH
  */
  function transferToTreasury(uint amount, address asset) internal {
    if (asset == ETH) {
      (bool ok, /* data */) = treasury.call{value: amount}("");
      require(ok, "Distributor: Transfer to treasury failed");
    } else {
      IERC20 erc20 = IERC20(asset);
      erc20.safeTransfer(treasury, amount);
    }
  }

  /**
  * @notice Set fee percentage for buyCover premiums.
  *  `_feePercentage` has 2 decimals of precision ( 5000 is 50%)
  * @param _feePercentage fee percentage to be set
  */
  function setFeePercentage(uint _feePercentage) external onlyOwner {
    feePercentage = _feePercentage;
    emit FeePercentageChanged(_feePercentage);
  }

  /**
  * @dev required to be allow for receiving ETH claim payouts
  */
  receive () payable external {
  }
}

// File: @openzeppelin/contracts-v4/access/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

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

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

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

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

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

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

// 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/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/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'
        // solhint-disable-next-line max-line-length
        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
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: @openzeppelin/contracts-v4/token/ERC721/ERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping (uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping (address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping (uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping (address => mapping (address => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor (string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return interfaceId == type(IERC721).interfaceId
            || interfaceId == type(IERC721Metadata).interfaceId
            || super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0
            ? string(abi.encodePacked(baseURI, tokenId.toString()))
            : '';
    }

    /**
     * @dev Base URI for computing {tokenURI}. Empty by default, can be overriden
     * in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        require(operator != _msgSender(), "ERC721: approve to caller");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(address from, address to, uint256 tokenId) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**
     * @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.
     *
     * `_data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(address from, address to, uint256 tokenId, bytes memory _data) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(address to, uint256 tokenId, bytes memory _data) internal virtual {
        _mint(to, tokenId);
        require(_checkOnERC721Received(address(0), to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

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

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(address from, address to, uint256 tokenId) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits a {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
        private returns (bool)
    {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver(to).onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual { }
}

// File: contracts/interfaces/IGateway.sol



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

pragma solidity >=0.5.0;

interface IGateway {

  enum ClaimStatus { IN_PROGRESS, ACCEPTED, REJECTED }

  enum CoverType { SIGNED_QUOTE_CONTRACT_COVER }

  function buyCover (
    address contractAddress,
    address coverAsset,
    uint sumAssured,
    uint16 coverPeriod,
    CoverType coverType,
    bytes calldata data
  ) external payable returns (uint);

  function getCoverPrice (
    address contractAddress,
    address coverAsset,
    uint sumAssured,
    uint16 coverPeriod,
    CoverType coverType,
    bytes calldata data
  ) external view returns (uint coverPrice);

  function getCover(uint coverId)
  external
  view
  returns (
    uint8 status,
    uint sumAssured,
    uint16 coverPeriod,
    uint validUntil,
    address contractAddress,
    address coverAsset,
    uint premiumInNXM,
    address memberAddress
  );

  function submitClaim(uint coverId, bytes calldata data) external returns (uint);

  function claimTokens(
    uint coverId,
    uint incidentId,
    uint coveredTokenAmount,
    address coverAsset
  ) external returns (uint claimId, uint payoutAmount, address payoutToken);

  function getClaimCoverId(uint claimId) external view returns (uint);

  function getPayoutOutcome(uint claimId) external view returns (ClaimStatus status, uint paidAmount, address asset);

  function executeCoverAction(uint tokenId, uint8 action, bytes calldata data) external payable returns (bytes memory, uint);

  function switchMembership(address _newAddress) 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 pauseTime() external view returns (uint);

  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 updatePauseTime(uint _time) external;

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

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

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

// 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: @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) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        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;
        // solhint-disable-next-line no-inline-assembly
        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");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (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");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private 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

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts-v4/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT

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

    /**
     * @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 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);

    /**
      * @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;
}

// File: @openzeppelin/contracts-v4/token/ERC721/IERC721Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(address operator, address from, uint256 tokenId, bytes calldata data) external returns (bytes4);
}

// File: @openzeppelin/contracts-v4/token/ERC721/extensions/IERC721Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {

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

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

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant alphabet = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = alphabet[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

}

// File: @openzeppelin/contracts-v4/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts-v4/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

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);
}

// 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);

}