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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 () internal {
        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/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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: @openzeppelin/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

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

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

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

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

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

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

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

// File: @openzeppelin/contracts/token/ERC1155/IERC1155.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

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

/**
 * @dev Required interface of an ERC1155 compliant contract, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1155[EIP].
 *
 * _Available since v3.1._
 */
interface IERC1155 is IERC165 {
    /**
     * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
     */
    event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);

    /**
     * @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
     * transfers.
     */
    event TransferBatch(address indexed operator, address indexed from, address indexed to, uint256[] ids, uint256[] values);

    /**
     * @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
     * `approved`.
     */
    event ApprovalForAll(address indexed account, address indexed operator, bool approved);

    /**
     * @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
     *
     * If an {URI} event was emitted for `id`, the standard
     * https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
     * returned by {IERC1155MetadataURI-uri}.
     */
    event URI(string value, uint256 indexed id);

    /**
     * @dev Returns the amount of tokens of token type `id` owned by `account`.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function balanceOf(address account, uint256 id) external view returns (uint256);

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
     *
     * Requirements:
     *
     * - `accounts` and `ids` must have the same length.
     */
    function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids) external view returns (uint256[] memory);

    /**
     * @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
     *
     * Emits an {ApprovalForAll} event.
     *
     * Requirements:
     *
     * - `operator` cannot be the caller.
     */
    function setApprovalForAll(address operator, bool approved) external;

    /**
     * @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
     *
     * See {setApprovalForAll}.
     */
    function isApprovedForAll(address account, address operator) external view returns (bool);

    /**
     * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
     *
     * Emits a {TransferSingle} event.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
     * - `from` must have a balance of tokens of type `id` of at least `amount`.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
     * acceptance magic value.
     */
    function safeTransferFrom(address from, address to, uint256 id, uint256 amount, bytes calldata data) external;

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
     *
     * Emits a {TransferBatch} event.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
     * acceptance magic value.
     */
    function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, uint256[] calldata amounts, bytes calldata data) external;
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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/token/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC20.sol";
import "../../math/SafeMath.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 SafeMath for uint256;
    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).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _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/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <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/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <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 GSN 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 payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: contracts/src/cfolio/interfaces/ICFolioItemHandler.sol



/*
 * Copyright (C) 2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See LICENSE.txt for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

import '../../token/interfaces/ICFolioItemCallback.sol';

/**
 * @dev Interface to C-folio item contracts
 */
interface ICFolioItemHandler is ICFolioItemCallback {
  /**
   * @dev Called when a SFT tokens grade needs re-evaluation
   *
   * @param tokenId The ERC-1155 token ID. Rate is in 1E6 convention: 1E6 = 100%
   * @param newRate The new value rate
   */
  function sftUpgrade(uint256 tokenId, uint32 newRate) external;

  /**
   * @dev Called from SFTMinter after an Investment SFT is minted
   *
   * @param payer The approved address to get investment from
   * @param sftTokenId The sftTokenId whose c-folio is the owner of investment
   * @param amounts The amounts of invested assets
   */
  function setupCFolio(
    address payer,
    uint256 sftTokenId,
    uint256[] calldata amounts
  ) external;

  //////////////////////////////////////////////////////////////////////////////
  // Asset access
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Adds investments into a cFolioItem SFT
   *
   * Transfers amounts of assets from users wallet to the contract. In general,
   * an Approval call is required before the function is called.
   *
   * @param baseTokenId cFolio tokenId, must be unlocked, or -1
   * @param tokenId cFolioItem tokenId, must be unlocked if not in unlocked cFolio
   * @param amounts Investment amounts, implementation specific
   */
  function deposit(
    uint256 baseTokenId,
    uint256 tokenId,
    uint256[] calldata amounts
  ) external;

  /**
   * @dev Removes investments from a cFolioItem SFT
   *
   * Withdrawn token are transfered back to msg.sender.
   *
   * @param baseTokenId cFolio tokenId, must be unlocked, or -1
   * @param tokenId cFolioItem tokenId, must be unlocked if not in unlocked cFolio
   * @param amounts Investment amounts, implementation specific
   */
  function withdraw(
    uint256 baseTokenId,
    uint256 tokenId,
    uint256[] calldata amounts
  ) external;

  /**
   * @dev Get the rewards collected by an SFT base card
   *
   * @param recipient Recipient of the rewards (- fees)
   * @param tokenId SFT base card tokenId, must be unlocked
   */
  function getRewards(address recipient, uint256 tokenId) external;

  /**
   * @dev Get amounts (handler specific) for a cfolioItem
   *
   * @param cfolioItem address of CFolioItem contract
   */
  function getAmounts(address cfolioItem)
    external
    view
    returns (uint256[] memory);

  /**
   * @dev Get information obout the rewardFarm
   *
   * @param tokenIds List of basecard tokenIds
   * @return bytes of uint256[]: total, rewardDur, rewardRateForDur, [share, earned]
   */
  function getRewardInfo(uint256[] calldata tokenIds)
    external
    view
    returns (bytes memory);
}

// File: contracts/src/cfolio/interfaces/ISFTEvaluator.sol



/*
 * Copyright (C) 2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See LICENSE.txt for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

// BOIS feature bitmask
uint256 constant LEVEL2BOIS = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF0000000000000000000000000000000F;
uint256 constant LEVEL2WOLF = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF000000000000000000000000000000F0;

interface ISFTEvaluator {
  /**
   * @dev Returns the reward in 1e6 factor notation (1e6 = 100%)
   */
  function rewardRate(uint256 sftTokenId) external view returns (uint32);

  /**
   * @dev Returns the cFolioItemType of a given cFolioItem tokenId
   */
  function getCFolioItemType(uint256 tokenId) external view returns (uint256);

  /**
   * @dev Calculate the current reward rate, and notify TFC in case of change
   *
   * Optional revert on unchange to save gas on external calls.
   */
  function setRewardRate(uint256 tokenId, bool revertUnchanged) external;

  /**
   * @dev Sets the cfolioItemType of a cfolioItem tokenId, not yet used
   * sftHolder tokenId expected (without hash)
   */
  function setCFolioItemType(uint256 tokenId, uint256 cfolioItemType_) external;
}

// File: contracts/src/crowdsale/WOWSSftMinter.sol



/*
 * Copyright (C) 2020-2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See the file LICENSES/README.md for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

import '@openzeppelin/contracts/access/Ownable.sol';
import '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import '@openzeppelin/contracts/token/ERC20/SafeERC20.sol';
import '@openzeppelin/contracts/utils/Context.sol';

import '../cfolio/interfaces/ICFolioItemHandler.sol';
import '../cfolio/interfaces/ISFTEvaluator.sol';
import '../investment/interfaces/IRewardHandler.sol';
import '../token/interfaces/IERC1155BurnMintable.sol';
import '../token/interfaces/ITradeFloor.sol';
import '../token/interfaces/IWOWSCryptofolio.sol';
import '../token/interfaces/IWOWSERC1155.sol';
import '../utils/TokenIds.sol';

contract WOWSSftMinter is Context, Ownable {
  using TokenIds for uint256;
  using SafeERC20 for IERC20;

  //////////////////////////////////////////////////////////////////////////////
  // State
  //////////////////////////////////////////////////////////////////////////////

  // PricePerlevel, customLevel start at 0xFF
  mapping(uint16 => uint256) public _pricePerLevel;

  struct CFolioItemSft {
    ICFolioItemHandler handler;
    uint256 price;
    uint128 numMinted;
    uint128 maxMintable;
  }
  mapping(uint256 => CFolioItemSft) public cfolioItemSfts; // C-folio type to c-folio data
  ICFolioItemHandler[] private cfolioItemHandlers;

  uint256 public nextCFolioItemNft = (1 << 64);

  // The ERC1155 contract we are minting from
  IWOWSERC1155 private immutable _sftContract;

  // WOWS token contract
  IERC20 private immutable _wowsToken;

  // Reward handler which distributes WOWS
  IRewardHandler public rewardHandler;

  // TradeFloor Proxy contract
  address public tradeFloor;

  // SFTEvaluator to store the cfolioItemType
  ISFTEvaluator public sftEvaluator;

  // Set while minting CFolioToken
  bool private _setupCFolio;

  // 1.0 of the rewards go to distribution
  uint32 private constant ALL = 1 * 1e6;

  //////////////////////////////////////////////////////////////////////////////
  // Events
  //////////////////////////////////////////////////////////////////////////////

  // Emitted if a new SFT is minted
  event Mint(
    address indexed recipient,
    uint256 tokenId,
    uint256 price,
    uint256 cfolioType
  );

  // Emitted if cFolio mint specifications (e.g. limits / price) have changed
  event CFolioSpecChanged(uint256[] ids, WOWSSftMinter upgradeFrom);

  // Emitted if the contract gets destroyed
  event Destruct();

  //////////////////////////////////////////////////////////////////////////////
  // Constructor
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Contruct WOWSSftMinter
   *
   * @param owner Owner of this contract
   * @param wowsToken The WOWS ERC-20 token contract
   * @param rewardHandler_ Handler which distributes
   * @param sftContract Cryptofolio SFT source
   */
  constructor(
    address owner,
    IERC20 wowsToken,
    IRewardHandler rewardHandler_,
    IWOWSERC1155 sftContract
  ) {
    // Validate parameters
    require(owner != address(0), 'O: 0 address');
    require(address(wowsToken) != address(0), 'WT: 0 address');
    require(address(rewardHandler_) != address(0), 'RH: 0 address');
    require(address(sftContract) != address(0), 'SFT: 0 address');

    // Initialize {Ownable}
    transferOwnership(owner);

    // Initialize state
    _sftContract = sftContract;
    _wowsToken = wowsToken;
    rewardHandler = rewardHandler_;
  }

  //////////////////////////////////////////////////////////////////////////////
  // State modifiers
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Set prices for the given levels
   */
  function setPrices(uint16[] memory levels, uint256[] memory prices)
    external
    onlyOwner
  {
    // Validate parameters
    require(levels.length == prices.length, 'Length mismatch');

    // Update state
    for (uint256 i = 0; i < levels.length; ++i)
      _pricePerLevel[levels[i]] = prices[i];
  }

  /**
   * @dev Set new reward handler
   *
   * RewardHandler is by concept upgradeable / see investment::Controller.sol.
   */
  function setRewardHandler(IRewardHandler newRewardHandler)
    external
    onlyOwner
  {
    // Update state
    rewardHandler = newRewardHandler;
  }

  /**
   * @dev Set Trade Floor
   */
  function setTradeFloor(address tradeFloor_) external onlyOwner {
    // Validate parameters
    require(tradeFloor_ != address(0), 'Invalid TF');

    // Update state
    tradeFloor = tradeFloor_;
  }

  /**
   * @dev Set SFT evaluator
   */
  function setSFTEvaluator(ISFTEvaluator sftEvaluator_) external onlyOwner {
    // Validate parameters
    require(address(sftEvaluator_) != address(0), 'Invalid TF');

    // Update state
    sftEvaluator = sftEvaluator_;
  }

  /**
   * @dev Set the limitations, the price and the handlers for CFolioItem SFT's
   */
  function setCFolioSpec(
    uint256[] calldata cFolioTypes,
    address[] calldata handlers,
    uint128[] calldata maxMint,
    uint256[] calldata prices,
    WOWSSftMinter oldMinter
  ) external onlyOwner {
    // Validate parameters
    require(
      cFolioTypes.length == handlers.length &&
        handlers.length == maxMint.length &&
        maxMint.length == prices.length,
      'Length mismatch'
    );

    // Update state
    for (uint256 i = 0; i < cFolioTypes.length; ++i) {
      CFolioItemSft storage cfi = cfolioItemSfts[cFolioTypes[i]];
      cfi.handler = ICFolioItemHandler(handlers[i]);
      cfi.maxMintable = maxMint[i];
      cfi.price = prices[i];

      uint256 j = 0;
      for (; j < cfolioItemHandlers.length; ++j) {
        if (address(cfolioItemHandlers[j]) == handlers[i]) break;
      }
      if (j == cfolioItemHandlers.length) {
        cfolioItemHandlers.push(ICFolioItemHandler(handlers[i]));
      }
    }
    if (address(oldMinter) != address(0)) {
      for (uint256 i = 0; i < cFolioTypes.length; ++i) {
        (, , uint128 numMinted, ) = oldMinter.cfolioItemSfts(cFolioTypes[i]);
        cfolioItemSfts[cFolioTypes[i]].numMinted = numMinted;
      }
      nextCFolioItemNft = oldMinter.nextCFolioItemNft();
    }
    emit CFolioSpecChanged(cFolioTypes, oldMinter);
  }

  /**
   * @dev upgrades state from an existing WOWSSFTMinter
   */
  function destructContract() external onlyOwner {
    emit Destruct();
    selfdestruct(msg.sender);
  }

  /**
   * @dev Mint one of our stock card SFTs
   *
   * Approval of WOWS token required before the call.
   */
  function mintWowsSFT(
    address recipient,
    uint8 level,
    uint8 cardId
  ) external {
    // Validate parameters
    require(recipient != address(0), 'Invalid recipient');

    // Load state
    uint256 price = _pricePerLevel[level];

    // Validate state
    require(price > 0, 'No price available');

    // Get the next free mintable token for level / cardId
    (bool success, uint256 tokenId) =
      _sftContract.getNextMintableTokenId(level, cardId);
    require(success, 'Unsufficient cards');

    // Update state
    _mint(recipient, tokenId, price, 0);
  }

  /**
   * @dev Mint a custom token
   *
   * Approval of WOWS token required before the call.
   */
  function mintCustomSFT(
    address recipient,
    uint8 level,
    string memory uri
  ) external {
    // Validate parameters
    require(recipient != address(0), 'Invalid recipient');

    // Load state
    uint256 price = _pricePerLevel[0x100 + level];

    // Validate state
    require(price > 0, 'No price available');

    // Get the next free mintable token for level / cardId
    uint256 tokenId = _sftContract.getNextMintableCustomToken();

    // Custom baseToken only allowed < 64Bit
    require(tokenId.isBaseCard(), 'Max tokenId reached');

    // Set card level and uri
    _sftContract.setCustomCardLevel(tokenId, level);
    _sftContract.setCustomURI(tokenId, uri);

    // Update state
    _mint(recipient, tokenId, price, 0);
  }

  /**
   * @dev Mint a CFolioItem token
   *
   * Approval of WOWS token required before the call.
   *
   * Post-condition: `_setupCFolio` must be false.
   *
   * @param recipient Recipient of the SFT, unused if sftTokenId is != -1
   * @param cfolioItemType The item type of the SFT
   * @param sftTokenId If <> -1 recipient is the SFT c-folio / handler must be called
   * @param investAmounts Arguments needed for the handler (in general investments).
   * Investments may be zero if the user is just buying an SFT.
   */
  function mintCFolioItemSFT(
    address recipient,
    uint256 cfolioItemType,
    uint256 sftTokenId,
    uint256[] calldata investAmounts
  ) external {
    // Validate state
    require(!_setupCFolio, 'Already setting up');
    require(tradeFloor != address(0), 'TF not set');
    require(address(sftEvaluator) != address(0), 'SFTE not set');

    // Validate parameters
    require(recipient != address(0), 'Invalid recipient');

    // Load state
    CFolioItemSft storage sftData = cfolioItemSfts[cfolioItemType];

    // Validate state
    require(address(sftData.handler) != address(0), 'CFI Minter: Invalid type');
    require(sftData.numMinted < sftData.maxMintable, 'CFI Minter: sold out');

    address sftCFolio = address(0);
    if (sftTokenId != uint256(-1)) {
      require(sftTokenId.isBaseCard(), 'Invalid sftTokenId');

      // Get the CFolio contract address, it will be the final recipient
      sftCFolio = _sftContract.tokenIdToAddress(sftTokenId);
      require(sftCFolio != address(0), 'Bad sftTokenId');

      // Intermediate owner of the minted SFT
      recipient = address(this);

      // Allow this contract to be an ERC1155 holder
      _setupCFolio = true;
    }

    uint256 tokenId = nextCFolioItemNft++;
    require(tokenId.isCFolioCard(), 'Invalid cfolioItem tokenId');

    sftEvaluator.setCFolioItemType(tokenId, cfolioItemType);

    // Update state, mint SFT token
    sftData.numMinted += 1;
    _mint(recipient, tokenId, sftData.price, cfolioItemType);

    // Let CFolioHandler setup the new minted token
    sftData.handler.setupCFolio(_msgSender(), tokenId, investAmounts);

    // Check-effects-interaction not needed, as `_setupCFolio` can't be mutated
    // outside this function.

    // If the SFT's c-folio is final recipient of c-folio item, we call the
    // handler and lock the c-folio item in the TradeFloor contract before we transfer
    // it to the SFT
    if (sftCFolio != address(0)) {
      // Lock the SFT into the TradeFloor contract
      IERC1155BurnMintable(address(_sftContract)).safeTransferFrom(
        address(this),
        tradeFloor,
        tokenId,
        1,
        abi.encodePacked(sftCFolio)
      );

      // Reset the temporary state which allows holding ERC1155 token
      _setupCFolio = false;
    }
  }

  /**
   * @dev Claim rewards from all c-folio farms
   *
   * @param sftTokenId valid SFT tokenId, must not be locked in TF
   */
  function claimSFTRewards(uint256 sftTokenId) external {
    for (uint256 i = 0; i < cfolioItemHandlers.length; ++i) {
      cfolioItemHandlers[i].getRewards(msg.sender, sftTokenId);
    }
  }

  //////////////////////////////////////////////////////////////////////////////
  // ERC1155Holder
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev We are a temorary token holder during CFolioToken mint step
   *
   * Only accept ERC1155 tokens during this setup.
   */
  function onERC1155Received(
    address,
    address,
    uint256,
    uint256,
    bytes memory
  ) external view returns (bytes4) {
    // Validate state
    require(_setupCFolio, 'Only during setup');

    // Call ancestor
    return this.onERC1155Received.selector;
  }

  //////////////////////////////////////////////////////////////////////////////
  // Getters
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Query prices for given levels
   */
  function getPrices(uint16[] memory levels)
    external
    view
    returns (uint256[] memory)
  {
    uint256[] memory result = new uint256[](levels.length);
    for (uint256 i = 0; i < levels.length; ++i)
      result[i] = _pricePerLevel[levels[i]];
    return result;
  }

  /**
   * @dev retrieve mint information about cfolioItem
   */
  function getCFolioSpec(uint256[] calldata cFolioTypes)
    external
    view
    returns (
      uint256[] memory prices,
      uint128[] memory numMinted,
      uint128[] memory maxMintable
    )
  {
    uint256 length = cFolioTypes.length;
    prices = new uint256[](length);
    numMinted = new uint128[](length);
    maxMintable = new uint128[](length);

    for (uint256 i; i < length; ++i) {
      CFolioItemSft storage cfi = cfolioItemSfts[cFolioTypes[i]];
      prices[i] = cfi.price;
      numMinted[i] = cfi.numMinted;
      maxMintable[i] = cfi.maxMintable;
    }
  }

  /**
   * @dev See {IWOWSSftMinter-tradeFloorTokenId}.
   */
  function tradeFloorTokenId(uint256 sftTokenId)
    external
    view
    returns (uint256)
  {
    bytes memory hashData;
    uint256[] memory tokenIds;
    uint256 tokenIdsLength;
    if (sftTokenId.isBaseCard()) {
      // It's a base card, calculate hash using all cfolioItems
      address cfolio = _sftContract.tokenIdToAddress(sftTokenId);
      require(cfolio != address(0), 'WSM: src token invalid');
      (tokenIds, tokenIdsLength) = IWOWSCryptofolio(cfolio).getCryptofolio(
        address(this)
      );
      hashData = abi.encodePacked(address(this), sftTokenId);
    } else {
      // It's a cfolioItem itself, only calculate underlying value
      tokenIds = new uint256[](1);
      tokenIds[0] = sftTokenId;
      tokenIdsLength = 1;
    }

    // Run through all cfolioItems and add let their single CFolioItemHandler
    // append hashable data
    for (uint256 i = 0; i < tokenIdsLength; ++i) {
      address cfolio =
        _sftContract.tokenIdToAddress(tokenIds[i].toSftTokenId());
      require(cfolio != address(0), 'WSM: item token invalid');

      address handler = IWOWSCryptofolio(cfolio)._tradefloors(0);
      require(handler != address(0), 'WSM: item handler invalid');

      hashData = ICFolioItemCallback(handler).appendHash(cfolio, hashData);
    }

    uint256 hashNum = uint256(keccak256(hashData));
    return (hashNum ^ (hashNum << 128)).maskHash() | sftTokenId;
  }

  /**
   * @dev Get all tokenIds from SFT and TF contract owned by account.
   */
  function getTokenIds(address account)
    external
    view
    returns (uint256[] memory sftTokenIds, uint256[] memory tfTokenIds)
  {
    require(account != address(0), 'Null address');
    sftTokenIds = _sftContract.getTokenIds(account);
    tfTokenIds = ITradeFloor(tradeFloor).getTokenIds(account);
  }

  /**
   * @dev Get underlying information (cFolioItems / value) for given tokenIds.
   *
   * @param tokenIds the tokenIds information should be queried
   * @return result [%,MintTime,NumItems,[tokenId,type,numAssetValues,[assetValue]]]...
   */
  function getTokenInformation(uint256[] calldata tokenIds)
    external
    view
    returns (bytes memory result)
  {
    uint256[] memory cFolioItems;
    uint256[] memory oneCFolioItem = new uint256[](1);
    uint256 cfolioLength;
    uint256 rewardRate;
    uint256 timestamp;

    for (uint256 i = 0; i < tokenIds.length; ++i) {
      if (tokenIds[i].isBaseCard()) {
        // Only main TradeFloor supported
        uint256 sftTokenId = tokenIds[i].toSftTokenId();
        address cfolio = _sftContract.tokenIdToAddress(sftTokenId);
        if (address(cfolio) != address(0)) {
          (cFolioItems, cfolioLength) = IWOWSCryptofolio(cfolio).getCryptofolio(
            tradeFloor
          );
        } else {
          cFolioItems = oneCFolioItem;
          cfolioLength = 0;
        }

        rewardRate = sftEvaluator.rewardRate(tokenIds[i]);
        (timestamp, ) = _sftContract.getTokenData(sftTokenId);
      } else {
        oneCFolioItem[0] = tokenIds[i];
        cfolioLength = 1;
        cFolioItems = oneCFolioItem; // Reference, no copy
        rewardRate = 0;
        timestamp = 0;
      }

      result = abi.encodePacked(result, rewardRate, timestamp, cfolioLength);

      for (uint256 j = 0; j < cfolioLength; ++j) {
        uint256 sftTokenId = cFolioItems[j].toSftTokenId();
        uint256 cfolioType = sftEvaluator.getCFolioItemType(sftTokenId);
        uint256[] memory amounts;

        address cfolio = _sftContract.tokenIdToAddress(sftTokenId);
        if (address(cfolio) != address(0)) {
          address handler = IWOWSCryptofolio(cfolio)._tradefloors(0);
          if (handler != address(0))
            amounts = ICFolioItemHandler(handler).getAmounts(cfolio);
        }

        result = abi.encodePacked(
          result,
          cFolioItems[j],
          cfolioType,
          amounts.length,
          amounts
        );
      }
    }
  }

  /**
   * @dev Get balances of given ERC20 addresses.
   */
  function getErc20Balances(address account, address[] calldata erc20)
    external
    view
    returns (uint256[] memory amounts)
  {
    amounts = new uint256[](erc20.length);
    for (uint256 i = 0; i < erc20.length; ++i)
      amounts[i] = erc20[i] == address(0)
        ? 0
        : IERC20(erc20[i]).balanceOf(account);
  }

  /**
   * @dev Get allowances of given ERC20 addresses.
   */
  function getErc20Allowances(
    address account,
    address[] calldata spender,
    address[] calldata erc20
  ) external view returns (uint256[] memory amounts) {
    // Validate parameters
    require(spender.length == erc20.length, 'Length mismatch');

    amounts = new uint256[](spender.length);
    for (uint256 i = 0; i < spender.length; ++i)
      amounts[i] = erc20[i] == address(0)
        ? 0
        : IERC20(erc20[i]).allowance(account, spender[i]);
  }

  //////////////////////////////////////////////////////////////////////////////
  // Internal functionality
  //////////////////////////////////////////////////////////////////////////////

  function _mint(
    address recipient,
    uint256 tokenId,
    uint256 price,
    uint256 cfolioType
  ) internal {
    // Transfer WOWS from user to reward handler
    if (price > 0)
      _wowsToken.safeTransferFrom(_msgSender(), address(rewardHandler), price);

    // Mint the token
    IERC1155BurnMintable(address(_sftContract)).mint(recipient, tokenId, 1, '');

    // Distribute the rewards
    if (price > 0) rewardHandler.distribute2(recipient, price, ALL);

    // Log event
    emit Mint(recipient, tokenId, price, cfolioType);
  }
}

// File: contracts/src/investment/interfaces/IRewardHandler.sol



/*
 * Copyright (C) 2020-2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See the file LICENSES/README.md for more information.
 */

pragma solidity >=0.6.0 <0.8.0;

interface IRewardHandler {
  /**
   * @dev Transfer reward and distribute the fee
   *
   * This is the new implementation of distribute() which uses internal fees
   * defined in the {RewardHandler} contract.
   *
   * @param recipient The recipient of the reward
   * @param amount The amount of WOWS to transfer to the recipient
   * @param fee The reward fee in 1e6 factor notation
   */

  function distribute2(
    address recipient,
    uint256 amount,
    uint32 fee
  ) external;

  /**
   * @dev Transfer reward and distribute the fee
   *
   * This is the current implementation, needed for backward compatibility.
   *
   * Current ERC1155Minter and Controller call this function, later
   * reward handler clients should call the the new one with internal
   * fees specified in this contract.
   *
   * uint32 values are in 1e6 factor notation.
   */
  function distribute(
    address recipient,
    uint256 amount,
    uint32 fee,
    uint32 toTeam,
    uint32 toMarketing,
    uint32 toBooster,
    uint32 toRewardPool
  ) external;
}

// File: contracts/src/token/interfaces/ICFolioItemCallback.sol



/*
 * Copyright (C) 2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See LICENSE.txt for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

/**
 * @dev Interface to receive callbacks when minted tokens are burnt
 */
interface ICFolioItemCallback {
  /**
   * @dev Called when a TradeFloor CFolioItem is transfered
   *
   * In case of mint `from` is address(0).
   * In case of burn `to` is address(0).
   *
   * cfolioHandlers are passed to let each cfolioHandler filter for its own
   * token. This eliminates the need for creating separate lists.
   *
   * @param from The account sending the token
   * @param to The account receiving the token
   * @param tokenIds The ERC-1155 token IDs
   * @param cfolioHandlers cFolioItem handlers
   */
  function onCFolioItemsTransferedFrom(
    address from,
    address to,
    uint256[] calldata tokenIds,
    address[] calldata cfolioHandlers
  ) external;

  /**
   * @dev Append data we use later for hashing
   *
   * @param cfolioItem The token ID of the c-folio item
   * @param current The current data being hashes
   *
   * @return The current data, with internal data appended
   */
  function appendHash(address cfolioItem, bytes calldata current)
    external
    view
    returns (bytes memory);

  /**
   * @dev get custom uri for tokenId
   */
  function uri(uint256 tokenId) external view returns (string memory);
}

// File: contracts/src/token/interfaces/IERC1155BurnMintable.sol



/*
 * Copyright (C) 2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See the file LICENSES/README.md for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

import '@openzeppelin/contracts/token/ERC1155/IERC1155.sol';

interface IERC1155BurnMintable is IERC1155 {
  /**
   * @dev Mint amount new tokens at ID `tokenId` (MINTER_ROLE required)
   */
  function mint(
    address to,
    uint256 tokenId,
    uint256 amount,
    bytes memory data
  ) external;

  /**
   * @dev Mint new token amounts at IDs `tokenIds` (MINTER_ROLE required)
   */
  function mintBatch(
    address to,
    uint256[] calldata tokenIds,
    uint256[] calldata amounts,
    bytes memory data
  ) external;

  /**
   * @dev Burn value amount of tokens with ID `tokenId`.
   *
   * Caller must be approvedForAll.
   */
  function burn(
    address account,
    uint256 tokenId,
    uint256 value
  ) external;

  /**
   * @dev Burn `values` amounts of tokens with IDs `tokenIds`.
   *
   * Caller must be approvedForAll.
   */
  function burnBatch(
    address account,
    uint256[] calldata tokenIds,
    uint256[] calldata values
  ) external;
}

// File: contracts/src/token/interfaces/ITradeFloor.sol



/*
 * Copyright (C) 2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See the file LICENSES/README.md for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

/**
 * @notice Cryptofolio and tokenId interface
 */
interface ITradeFloor {
  //////////////////////////////////////////////////////////////////////////////
  // Getters
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Return all tokenIds owned by account
   */
  function getTokenIds(address account)
    external
    view
    returns (uint256[] memory);
}

// File: contracts/src/token/interfaces/IWOWSCryptofolio.sol



/*
 * Copyright (C) 2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See the file LICENSES/README.md for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

/**
 * @notice Cryptofolio interface
 */
interface IWOWSCryptofolio {
  //////////////////////////////////////////////////////////////////////////////
  // Initialization
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Initialize the deployed contract after creation
   *
   * This is a one time call which sets _deployer to msg.sender.
   * Subsequent calls reverts.
   */
  function initialize() external;

  //////////////////////////////////////////////////////////////////////////////
  // Getters
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Return tradefloor at given index
   *
   * @param index The 0-based index in the tradefloor array
   *
   * @return The address of the tradefloor and position index
   */
  function _tradefloors(uint256 index) external view returns (address);

  /**
   * @dev Return array of cryptofolio item token IDs
   *
   * The token IDs belong to the contract TradeFloor.
   *
   * @param tradefloor The TradeFloor that items belong to
   *
   * @return tokenIds The token IDs in scope of operator
   * @return idsLength The number of valid token IDs
   */
  function getCryptofolio(address tradefloor)
    external
    view
    returns (uint256[] memory tokenIds, uint256 idsLength);

  //////////////////////////////////////////////////////////////////////////////
  // State modifiers
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Set the owner of the underlying NFT
   *
   * This function is called if ownership of the parent NFT has changed.
   *
   * The new owner gets allowance to transfer cryptofolio items. The new owner
   * is allowed to transfer / burn cryptofolio items. Make sure that allowance
   * is removed from previous owner.
   *
   * @param owner The new owner of the underlying NFT, or address(0) if the
   * underlying NFT is being burned
   */
  function setOwner(address owner) external;

  /**
   * @dev Allow owner (of parent NFT) to approve external operators to transfer
   * our cryptofolio items
   *
   * The NFT owner is allowed to approve operator to handle cryptofolios.
   *
   * @param operator The operator
   * @param allow True to approve for all NFTs, false to revoke approval
   */
  function setApprovalForAll(address operator, bool allow) external;

  /**
   * @dev Burn all cryptofolio items
   *
   * In case an underlying NFT is burned, we also burn the cryptofolio.
   */
  function burn() external;
}

// File: contracts/src/token/interfaces/IWOWSERC1155.sol



/*
 * Copyright (C) 2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See the file LICENSES/README.md for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

/**
 * @notice Cryptofolio interface
 */
interface IWOWSERC1155 {
  //////////////////////////////////////////////////////////////////////////////
  // Getters
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Check if the specified address is a known tradefloor
   *
   * @param account The address to check
   *
   * @return True if the address is a known tradefloor, false otherwise
   */
  function isTradeFloor(address account) external view returns (bool);

  /**
   * @dev Get the token ID of a given address
   *
   * A cross check is required because token ID 0 is valid.
   *
   * @param tokenAddress The address to convert to a token ID
   *
   * @return The token ID on success, or uint256(-1) if `tokenAddress` does not
   * belong to a token ID
   */
  function addressToTokenId(address tokenAddress)
    external
    view
    returns (uint256);

  /**
   * @dev Get the address for a given token ID
   *
   * @param tokenId The token ID to convert
   *
   * @return The address, or address(0) in case the token ID does not belong
   * to an NFT
   */
  function tokenIdToAddress(uint256 tokenId) external view returns (address);

  /**
   * @dev Get the next mintable token ID for the specified card
   *
   * @param level The level of the card
   * @param cardId The ID of the card
   *
   * @return bool True if a free token ID was found, false otherwise
   * @return uint256 The first free token ID if one was found, or invalid otherwise
   */
  function getNextMintableTokenId(uint8 level, uint8 cardId)
    external
    view
    returns (bool, uint256);

  /**
   * @dev Return the next mintable custom token ID
   */
  function getNextMintableCustomToken() external view returns (uint256);

  /**
   * @dev Return the level and the mint timestamp of tokenId
   *
   * @param tokenId The tokenId to query
   *
   * @return mintTimestamp The timestamp token was minted
   * @return level The level token belongs to
   */
  function getTokenData(uint256 tokenId)
    external
    view
    returns (uint64 mintTimestamp, uint8 level);

  /**
   * @dev Return all tokenIds owned by account
   */
  function getTokenIds(address account)
    external
    view
    returns (uint256[] memory);

  //////////////////////////////////////////////////////////////////////////////
  // State modifiers
  //////////////////////////////////////////////////////////////////////////////

  /**
   * @dev Set the base URI for either predefined cards or custom cards
   * which don't have it's own URI.
   *
   * The resulting uri is baseUri+[hex(tokenId)] + '.json'. where
   * tokenId will be reduces to upper 16 bit (>> 16) before building the hex string.
   *
   */
  function setBaseMetadataURI(string memory baseContractMetadata) external;

  /**
   * @dev Set the contracts metadata URI
   *
   * @param contractMetadataURI The URI which point to the contract metadata file.
   */
  function setContractMetadataURI(string memory contractMetadataURI) external;

  /**
   * @dev Set the URI for a custom card
   *
   * @param tokenId The token ID whose URI is being set.
   * @param customURI The URI which point to an unique metadata file.
   */
  function setCustomURI(uint256 tokenId, string memory customURI) external;

  /**
   * @dev Each custom card has its own level. Level will be used when
   * calculating rewards and raiding power.
   *
   * @param tokenId The ID of the token whose level is being set
   * @param cardLevel The new level of the specified token
   */
  function setCustomCardLevel(uint256 tokenId, uint8 cardLevel) external;
}

// File: contracts/src/utils/TokenIds.sol



/*
 * Copyright (C) 2021 The Wolfpack
 * This file is part of wolves.finance - https://github.com/wolvesofwallstreet/wolves.finance
 *
 * SPDX-License-Identifier: Apache-2.0
 * See LICENSE.txt for more information.
 */

pragma solidity >=0.7.0 <0.8.0;

library TokenIds {
  // 128 bit underlying hash
  uint256 public constant HASH_MASK = (1 << 128) - 1;

  function isBaseCard(uint256 tokenId) internal pure returns (bool) {
    return (tokenId & HASH_MASK) < (1 << 64);
  }

  function isStockCard(uint256 tokenId) internal pure returns (bool) {
    return (tokenId & HASH_MASK) < (1 << 32);
  }

  function isCFolioCard(uint256 tokenId) internal pure returns (bool) {
    return
      (tokenId & HASH_MASK) >= (1 << 64) && (tokenId & HASH_MASK) < (1 << 128);
  }

  function toSftTokenId(uint256 tokenId) internal pure returns (uint256) {
    return tokenId & HASH_MASK;
  }

  function maskHash(uint256 tokenId) internal pure returns (uint256) {
    return tokenId & ~HASH_MASK;
  }
}