// File: contracts/utils/DoseVoucherRedeemer.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

import "@animoca/ethereum-contracts-assets/contracts/token/ERC1155/ERC1155TokenReceiver.sol";
import "@animoca/ethereum-contracts-assets/contracts/token/ERC1155/IERC1155InventoryBurnable.sol";
import "@animoca/ethereum-contracts-core/contracts/utils/Recoverable.sol";
import "@animoca/ethereum-contracts-core/contracts/lifecycle/Pausable.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";


contract DoseVoucherRedeemer is Recoverable, Pausable, ERC1155TokenReceiver{
    
    using ERC20Wrapper for IWrappedERC20;
    using SafeMath for uint256;

    IERC1155InventoryBurnable public immutable vouchersContract;
    IWrappedERC20 public immutable tokenContract;
    address public tokenHolder;

    mapping (uint256 => uint256) private _voucherTokenAmount;

    /**
     * Constructor.
     * @param _vouchersContract the address of the vouchers contract.
     * @param _tokenContract the address of the ERC20 token contract.
     * @param _tokenHolder the address of the ERC20 token holder.
     */
    constructor(
        IERC1155InventoryBurnable _vouchersContract,
        IWrappedERC20 _tokenContract,
        address _tokenHolder
    ) Ownable(msg.sender) Pausable(true){
        vouchersContract = _vouchersContract;
        tokenContract = _tokenContract;
        tokenHolder = _tokenHolder;
    }

    /**
     * Sets the ERC20 token value for voucher.
     * @dev Reverts if the sender is not the contract owner.
     * @param tokenIds the id of the voucher.
     * @param amounts value of the voucher in ERC20 token.
     */
    function setVoucherValues(uint256[] memory tokenIds, uint256[] memory amounts) external virtual{
        _requireOwnership(_msgSender());
        require(tokenIds.length == amounts.length, "DoseVoucherRedeemer: invalid length of array");
        for(uint256 i; i < tokenIds.length; ++i){
            uint256 amount = amounts[i];
            require(amount > 0, "DoseVoucherRedeemer: invalid amount");
            _voucherTokenAmount[tokenIds[i]] = amount;
        }
    }

    /**
     * Gets the ERC20 token value for voucher.
     * @param tokenId the id of the voucher.
     */
    function getVoucherValue(uint256 tokenId) external view virtual returns (uint256){
        return _voucherTokenAmount[tokenId];
    }

    /**
     * Validates the validity of the voucher and returns its value.
     * @dev Reverts if the voucher is not a valid voucher.
     * @param tokenId the id of the voucher.
     * @return the value of the voucher in ERC20 token.
     */
    function _voucherValue(uint256 tokenId) internal view virtual returns (uint256) {
        uint256 tokenValue = _voucherTokenAmount[tokenId];
        require(tokenValue > 0, "DoseVoucherRedeemer: invalid voucher");
        return tokenValue;
    }

    /**
     * Sets the token holder address.
     * @dev Reverts if the sender is not the contract owner.
     * @param _tokenHolder the new address for the token holder.
     */
    function setTokenHolder(address _tokenHolder) external virtual {
        _requireOwnership(_msgSender());
        tokenHolder = _tokenHolder;
    }

    /**
     * Pause the redeem function.
     * @dev Reverts if the sender is not the contract owner.
     */
    function pause() public{
        _requireOwnership(_msgSender());
        _pause();
    }

    /**
     * Unpause the redeem function.
     * @dev Reverts if the sender is not the contract owner.
     */
    function unpause() public{
        _requireOwnership(_msgSender());
        _unpause();
    }

    /**
     * Handle the receipt of a single ERC1155 token type.
     * @dev See {IERC1155TokenReceiver-onERC1155Received(address,address,uint256,uint256,bytes)}.
     */
    function onERC1155Received(
        address, /*operator*/
        address from,
        uint256 id,
        uint256 value,
        bytes calldata /*data*/
    ) external virtual override returns (bytes4) {
        _requireNotPaused();
        require(msg.sender == address(vouchersContract), "DoseVoucherRedeemer: wrong sender");
        vouchersContract.burnFrom(address(this), id, value);
        uint256 tokenAmount = _voucherValue(id).mul(value);
        tokenContract.wrappedTransferFrom(tokenHolder, from, tokenAmount);
        return _ERC1155_RECEIVED;
    }

    /**
     * Handle the receipt of multiple ERC1155 token types.
     * @dev See {IERC1155TokenReceiver-onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)}.
     */
    function onERC1155BatchReceived(
        address, /*operator*/
        address from,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata /*data*/
    ) external virtual override returns (bytes4) {
        _requireNotPaused();
        require(msg.sender == address(vouchersContract), "DoseVoucherRedeemer: wrong sender");
        vouchersContract.batchBurnFrom(address(this), ids, values);
        uint256 tokenAmount;
        for (uint256 i; i != ids.length; ++i) {
            uint256 id = ids[i];
            tokenAmount = tokenAmount.add(_voucherValue(id).mul(values[i]));
        }
        tokenContract.wrappedTransferFrom(tokenHolder, from, tokenAmount);
        return _ERC1155_BATCH_RECEIVED;
    }
}
// File: @animoca/ethereum-contracts-assets/contracts/token/ERC1155/ERC1155TokenReceiver.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

import {IERC1155TokenReceiver} from "./IERC1155TokenReceiver.sol";
import {IERC165} from "@animoca/ethereum-contracts-core-1.1.1/contracts/introspection/IERC165.sol";

abstract contract ERC1155TokenReceiver is IERC1155TokenReceiver, IERC165 {
    bytes4 private constant _ERC165_INTERFACE_ID = type(IERC165).interfaceId;
    bytes4 private constant _ERC1155_TOKEN_RECEIVER_INTERFACE_ID = type(IERC1155TokenReceiver).interfaceId;

    // bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))
    bytes4 internal constant _ERC1155_RECEIVED = 0xf23a6e61;

    // bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))
    bytes4 internal constant _ERC1155_BATCH_RECEIVED = 0xbc197c81;

    bytes4 internal constant _ERC1155_REJECTED = 0xffffffff;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == _ERC165_INTERFACE_ID || interfaceId == _ERC1155_TOKEN_RECEIVER_INTERFACE_ID;
    }
}

// File: @animoca/ethereum-contracts-assets/contracts/token/ERC1155/IERC1155InventoryBurnable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

/**
 * @title ERC-1155 Inventory additional burning interface
 * @dev See https://eips.ethereum.org/EIPS/eip-1155
 */
interface IERC1155InventoryBurnable {
    /**
     * Burns some token.
     * @dev Reverts if the sender is not approved.
     * @dev Reverts if `id` does not represent a token.
     * @dev Reverts if `id` represents a fungible token and `value` is 0.
     * @dev Reverts if `id` represents a fungible token and `value` is higher than `from`'s balance.
     * @dev Reverts if `id` represents a non-fungible token and `value` is not 1.
     * @dev Reverts if `id` represents a non-fungible token which is not owned by `from`.
     * @dev Emits an {IERC1155-TransferSingle} event.
     * @param from Address of the current token owner.
     * @param id Identifier of the token to burn.
     * @param value Amount of token to burn.
     */
    function burnFrom(
        address from,
        uint256 id,
        uint256 value
    ) external;

    /**
     * Burns multiple tokens.
     * @dev Reverts if `ids` and `values` have different lengths.
     * @dev Reverts if the sender is not approved.
     * @dev Reverts if one of `ids` does not represent a token.
     * @dev Reverts if one of `ids` represents a fungible token and `value` is 0.
     * @dev Reverts if one of `ids` represents a fungible token and `value` is higher than `from`'s balance.
     * @dev Reverts if one of `ids` represents a non-fungible token and `value` is not 1.
     * @dev Reverts if one of `ids` represents a non-fungible token which is not owned by `from`.
     * @dev Emits an {IERC1155-TransferBatch} event.
     * @param from Address of the current tokens owner.
     * @param ids Identifiers of the tokens to burn.
     * @param values Amounts of tokens to burn.
     */
    function batchBurnFrom(
        address from,
        uint256[] calldata ids,
        uint256[] calldata values
    ) external;
}

// File: @animoca/ethereum-contracts-core/contracts/utils/Recoverable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

import {ManagedIdentity} from "../metatx/ManagedIdentity.sol";
import {Ownable} from "../access/Ownable.sol";
import {IWrappedERC20, ERC20Wrapper} from "./ERC20Wrapper.sol";

abstract contract Recoverable is ManagedIdentity, Ownable {
    using ERC20Wrapper for IWrappedERC20;

    /**
     * Extract ERC20 tokens which were accidentally sent to the contract to a list of accounts.
     * Warning: this function should be overriden for contracts which are supposed to hold ERC20 tokens
     * so that the extraction is limited to only amounts sent accidentally.
     * @dev Reverts if the sender is not the contract owner.
     * @dev Reverts if `accounts`, `tokens` and `amounts` do not have the same length.
     * @dev Reverts if one of `tokens` is does not implement the ERC20 transfer function.
     * @dev Reverts if one of the ERC20 transfers fail for any reason.
     * @param accounts the list of accounts to transfer the tokens to.
     * @param tokens the list of ERC20 token addresses.
     * @param amounts the list of token amounts to transfer.
     */
    function recoverERC20s(
        address[] calldata accounts,
        address[] calldata tokens,
        uint256[] calldata amounts
    ) external virtual {
        _requireOwnership(_msgSender());
        uint256 length = accounts.length;
        require(length == tokens.length && length == amounts.length, "Recov: inconsistent arrays");
        for (uint256 i = 0; i != length; ++i) {
            IWrappedERC20(tokens[i]).wrappedTransfer(accounts[i], amounts[i]);
        }
    }

    /**
     * Extract ERC721 tokens which were accidentally sent to the contract to a list of accounts.
     * Warning: this function should be overriden for contracts which are supposed to hold ERC721 tokens
     * so that the extraction is limited to only tokens sent accidentally.
     * @dev Reverts if the sender is not the contract owner.
     * @dev Reverts if `accounts`, `contracts` and `amounts` do not have the same length.
     * @dev Reverts if one of `contracts` is does not implement the ERC721 transferFrom function.
     * @dev Reverts if one of the ERC721 transfers fail for any reason.
     * @param accounts the list of accounts to transfer the tokens to.
     * @param contracts the list of ERC721 contract addresses.
     * @param tokenIds the list of token ids to transfer.
     */
    function recoverERC721s(
        address[] calldata accounts,
        address[] calldata contracts,
        uint256[] calldata tokenIds
    ) external virtual {
        _requireOwnership(_msgSender());
        uint256 length = accounts.length;
        require(length == contracts.length && length == tokenIds.length, "Recov: inconsistent arrays");
        for (uint256 i = 0; i != length; ++i) {
            IRecoverableERC721(contracts[i]).transferFrom(address(this), accounts[i], tokenIds[i]);
        }
    }
}

interface IRecoverableERC721 {
    /// See {IERC721-transferFrom(address,address,uint256)}
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;
}

// File: @animoca/ethereum-contracts-core/contracts/lifecycle/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

import {ManagedIdentity} from "../metatx/ManagedIdentity.sol";

/**
 * @dev Contract which allows children to implement pausability.
 */
abstract contract Pausable is ManagedIdentity {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool public paused;

    constructor(bool paused_) {
        paused = paused_;
    }

    function _requireNotPaused() internal view {
        require(!paused, "Pausable: paused");
    }

    function _requirePaused() internal view {
        require(paused, "Pausable: not paused");
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual {
        _requireNotPaused();
        paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual {
        _requirePaused();
        paused = false;
        emit Unpaused(_msgSender());
    }
}

// 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: @animoca/ethereum-contracts-assets/contracts/token/ERC1155/IERC1155TokenReceiver.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

/**
 * @title ERC-1155 Multi Token Standard, token receiver
 * @dev See https://eips.ethereum.org/EIPS/eip-1155
 * Interface for any contract that wants to support transfers from ERC1155 asset contracts.
 * Note: The ERC-165 identifier for this interface is 0x4e2312e0.
 */
interface IERC1155TokenReceiver {
    /**
     * @notice Handle the receipt of a single ERC1155 token type.
     * An ERC1155 contract MUST call this function on a recipient contract, at the end of a `safeTransferFrom` after the balance update.
     * This function MUST return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
     *  (i.e. 0xf23a6e61) to accept the transfer.
     * Return of any other value than the prescribed keccak256 generated value MUST result in the transaction being reverted by the caller.
     * @param operator  The address which initiated the transfer (i.e. msg.sender)
     * @param from      The address which previously owned the token
     * @param id        The ID of the token being transferred
     * @param value     The amount of tokens being transferred
     * @param data      Additional data with no specified format
     * @return bytes4   `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
     */
    function onERC1155Received(
        address operator,
        address from,
        uint256 id,
        uint256 value,
        bytes calldata data
    ) external returns (bytes4);

    /**
     * @notice Handle the receipt of multiple ERC1155 token types.
     * An ERC1155 contract MUST call this function on a recipient contract, at the end of a `safeBatchTransferFrom` after the balance updates.
     * This function MUST return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
     *  (i.e. 0xbc197c81) if to accept the transfer(s).
     * Return of any other value than the prescribed keccak256 generated value MUST result in the transaction being reverted by the caller.
     * @param operator  The address which initiated the batch transfer (i.e. msg.sender)
     * @param from      The address which previously owned the token
     * @param ids       An array containing ids of each token being transferred (order and length must match _values array)
     * @param values    An array containing amounts of each token being transferred (order and length must match _ids array)
     * @param data      Additional data with no specified format
     * @return          `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
     */
    function onERC1155BatchReceived(
        address operator,
        address from,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    ) external returns (bytes4);
}

// File: @animoca/ethereum-contracts-core-1.1.1/contracts/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165.
 */
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: @animoca/ethereum-contracts-core/contracts/metatx/ManagedIdentity.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

/*
 * 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.
 */
abstract contract ManagedIdentity {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

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

// File: @animoca/ethereum-contracts-core/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

import {ManagedIdentity} from "../metatx/ManagedIdentity.sol";
import {IERC173} from "./IERC173.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 ManagedIdentity, IERC173 {
    address internal _owner;

    /**
     * Initializes the contract, setting the deployer as the initial owner.
     * @dev Emits an {IERC173-OwnershipTransferred(address,address)} event.
     */
    constructor(address owner_) {
        _owner = owner_;
        emit OwnershipTransferred(address(0), owner_);
    }

    /**
     * Gets the address of the current contract owner.
     */
    function owner() public view virtual override returns (address) {
        return _owner;
    }

    /**
     * See {IERC173-transferOwnership(address)}
     * @dev Reverts if the sender is not the current contract owner.
     * @param newOwner the address of the new owner. Use the zero address to renounce the ownership.
     */
    function transferOwnership(address newOwner) public virtual override {
        _requireOwnership(_msgSender());
        _owner = newOwner;
        emit OwnershipTransferred(_owner, newOwner);
    }

    /**
     * @dev Reverts if `account` is not the contract owner.
     * @param account the account to test.
     */
    function _requireOwnership(address account) internal virtual {
        require(account == this.owner(), "Ownable: not the owner");
    }
}

// File: @animoca/ethereum-contracts-core/contracts/utils/ERC20Wrapper.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

import {AddressIsContract} from "./types/AddressIsContract.sol";

/**
 * @title ERC20Wrapper
 * Wraps ERC20 functions to support non-standard implementations which do not return a bool value.
 * Calls to the wrapped functions revert only if they throw or if they return false.
 */
library ERC20Wrapper {
    using AddressIsContract for address;

    function wrappedTransfer(
        IWrappedERC20 token,
        address to,
        uint256 value
    ) internal {
        _callWithOptionalReturnData(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function wrappedTransferFrom(
        IWrappedERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callWithOptionalReturnData(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function wrappedApprove(
        IWrappedERC20 token,
        address spender,
        uint256 value
    ) internal {
        _callWithOptionalReturnData(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function _callWithOptionalReturnData(IWrappedERC20 token, bytes memory callData) internal {
        address target = address(token);
        require(target.isContract(), "ERC20Wrapper: non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory data) = target.call(callData);
        if (success) {
            if (data.length != 0) {
                require(abi.decode(data, (bool)), "ERC20Wrapper: operation failed");
            }
        } else {
            // revert using a standard revert message
            if (data.length == 0) {
                revert("ERC20Wrapper: operation failed");
            }

            // revert using the revert message coming from the call
            assembly {
                let size := mload(data)
                revert(add(32, data), size)
            }
        }
    }
}

interface IWrappedERC20 {
    function transfer(address to, uint256 value) external returns (bool);

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external returns (bool);

    function approve(address spender, uint256 value) external returns (bool);
}

// File: @animoca/ethereum-contracts-core/contracts/access/IERC173.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.7.6 <0.8.0;

/**
 * @title ERC-173 Contract Ownership Standard
 * Note: the ERC-165 identifier for this interface is 0x7f5828d0
 */
interface IERC173 {
    /**
     * Event emited when ownership of a contract changes.
     * @param previousOwner the previous owner.
     * @param newOwner the new owner.
     */
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * Get the address of the owner
     * @return The address of the owner.
     */
    function owner() external view returns (address);

    /**
     * Set the address of the new owner of the contract
     * Set newOwner to address(0) to renounce any ownership.
     * @dev Emits an {OwnershipTransferred} event.
     * @param newOwner The address of the new owner of the contract. Using the zero address means renouncing ownership.
     */
    function transferOwnership(address newOwner) external;
}

// File: @animoca/ethereum-contracts-core/contracts/utils/types/AddressIsContract.sol



// SPDX-License-Identifier: MIT

// Partially derived from OpenZeppelin:
// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/406c83649bd6169fc1b578e08506d78f0873b276/contracts/utils/Address.sol

pragma solidity >=0.7.6 <0.8.0;

/**
 * @dev Upgrades the address type to check if it is a contract.
 */
library AddressIsContract {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }
}