// File: contracts/stake/StakeRegistry.sol



//SPDX-License-Identifier: Unlicense
pragma solidity ^0.7.6;

import "../interfaces/IStakeRegistry.sol";
import "../libraries/LibTokenStake1.sol";
import "../common/AccessibleCommon.sol";

/// @title Stake Registry
/// @notice Manage the vault list by phase. Manage the list of staking contracts in the vault.
contract StakeRegistry is AccessibleCommon, IStakeRegistry {
    bytes32 public constant ZERO_HASH =
        0x0000000000000000000000000000000000000000000000000000000000000000;

    /// @dev TOS address
    address public tos;

    /// @dev TON address in Tokamak
    address public ton;

    /// @dev WTON address in Tokamak
    address public wton;

    /// @dev Depositmanager address in Tokamak
    address public depositManager;

    /// @dev SeigManager address in Tokamak
    address public seigManager;

    /// @dev swapProxy address in Tokamak
    address public swapProxy;

    /// Contracts included in the phase
    mapping(uint256 => address[]) public phases;

    /// Vault address mapping with vault name hash
    mapping(bytes32 => address) public vaults;

    /// Vault name hash mapping with vault address
    mapping(address => bytes32) public vaultNames;

    /// List of staking contracts included in the vault
    mapping(address => address[]) public stakeContractsOfVault;

    /// Vault address of staking contract
    mapping(address => address) public stakeContractVault;

    /// Defi Info
    mapping(bytes32 => LibTokenStake1.DefiInfo) public override defiInfo;

    modifier nonZero(address _addr) {
        require(_addr != address(0), "StakeRegistry: zero address");
        _;
    }

    /// @dev event on add the vault
    /// @param vault the vault address
    /// @param phase the phase of TOS platform
    event AddedVault(address indexed vault, uint256 phase);

    /// @dev event on add the stake contract in vault
    /// @param vault the vault address
    /// @param stakeContract the stake contract address created
    event AddedStakeContract(
        address indexed vault,
        address indexed stakeContract
    );

    /// @dev event on set the addresses related to tokamak
    /// @param ton the TON address
    /// @param wton the WTON address
    /// @param depositManager the DepositManager address
    /// @param seigManager the SeigManager address
    /// @param swapProxy the SwapProxy address
    event SetTokamak(
        address ton,
        address wton,
        address depositManager,
        address seigManager,
        address swapProxy
    );

    /// @dev event on add the information related to defi.
    /// @param nameHash the name hash
    /// @param name the name of defi identify
    /// @param router the entry address
    /// @param ex1 the extra 1 addres
    /// @param ex2 the extra 2 addres
    /// @param fee fee
    /// @param routerV2 the uniswap2 router address
    event AddedDefiInfo(
        bytes32 nameHash,
        string name,
        address router,
        address ex1,
        address ex2,
        uint256 fee,
        address routerV2
    );

    /// @dev constructor of StakeRegistry
    /// @param _tos TOS address
    constructor(address _tos) {
        _setRoleAdmin(ADMIN_ROLE, ADMIN_ROLE);
        _setupRole(ADMIN_ROLE, msg.sender);
        tos = _tos;
    }

    /// @dev Set addresses for Tokamak integration
    /// @param _ton TON address
    /// @param _wton WTON address
    /// @param _depositManager DepositManager address
    /// @param _seigManager SeigManager address
    function setTokamak(
        address _ton,
        address _wton,
        address _depositManager,
        address _seigManager,
        address _swapProxy
    )
        external
        override
        onlyOwner
        nonZero(_ton)
        nonZero(_wton)
        nonZero(_depositManager)
        nonZero(_seigManager)
        nonZero(_swapProxy)
    {
        ton = _ton;
        wton = _wton;
        depositManager = _depositManager;
        seigManager = _seigManager;
        swapProxy = _swapProxy;

        emit SetTokamak(ton, wton, depositManager, seigManager, swapProxy);
    }

    /// @dev Add information related to Defi
    /// @param _name name . ex) UNISWAP_V3
    /// @param _router entry point of defi
    /// @param _ex1  additional variable . ex) positionManagerAddress in Uniswap V3
    /// @param _ex2  additional variable . ex) WETH Address in Uniswap V3
    /// @param _fee  fee
    /// @param _routerV2 In case of uniswap, router address of uniswapV2
    function addDefiInfo(
        string calldata _name,
        address _router,
        address _ex1,
        address _ex2,
        uint256 _fee,
        address _routerV2
    ) external override onlyOwner nonZero(_router) {
        bytes32 nameHash = keccak256(abi.encodePacked(_name));
        require(nameHash != ZERO_HASH, "StakeRegistry: nameHash zero");

        LibTokenStake1.DefiInfo storage _defiInfo = defiInfo[nameHash];
        _defiInfo.name = _name;
        _defiInfo.router = _router;
        _defiInfo.ext1 = _ex1;
        _defiInfo.ext2 = _ex2;
        _defiInfo.fee = _fee;
        _defiInfo.routerV2 = _routerV2;

        emit AddedDefiInfo(
            nameHash,
            _name,
            _router,
            _ex1,
            _ex2,
            _fee,
            _routerV2
        );
    }

    /// @dev Add Vault
    /// @dev It is excuted by proxy
    /// @param _vault vault address
    /// @param _phase phase ex) 1,2,3
    /// @param _vaultName  hash of vault's name
    function addVault(
        address _vault,
        uint256 _phase,
        bytes32 _vaultName
    ) external override onlyOwner {
        require(
            vaultNames[_vault] == ZERO_HASH || vaults[_vaultName] == address(0),
            "StakeRegistry: addVault input value is not zero"
        );
        vaults[_vaultName] = _vault;
        vaultNames[_vault] = _vaultName;
        phases[_phase].push(_vault);

        emit AddedVault(_vault, _phase);
    }

    /// @dev Add StakeContract in vault
    /// @dev It is excuted by proxy
    /// @param _vault vault address
    /// @param _stakeContract  StakeContract address
    function addStakeContract(address _vault, address _stakeContract)
        external
        override
        onlyOwner
    {
        require(
            vaultNames[_vault] != ZERO_HASH &&
                stakeContractVault[_stakeContract] == address(0),
            "StakeRegistry: input is zero"
        );
        stakeContractVault[_stakeContract] = _vault;
        stakeContractsOfVault[_vault].push(_stakeContract);

        emit AddedStakeContract(_vault, _stakeContract);
    }

    /// @dev Get addresses for Tokamak interface
    /// @return (ton, wton, depositManager, seigManager)
    function getTokamak()
        external
        view
        override
        returns (
            address,
            address,
            address,
            address,
            address
        )
    {
        return (ton, wton, depositManager, seigManager, swapProxy);
    }

    /// @dev Get indos for UNISWAP_V3 interface
    /// @return (uniswapRouter, npm, wethAddress, fee)
    function getUniswap()
        external
        view
        override
        returns (
            address,
            address,
            address,
            uint256,
            address
        )
    {
        bytes32 nameHash = keccak256(abi.encodePacked("UNISWAP_V3"));
        return (
            defiInfo[nameHash].router,
            defiInfo[nameHash].ext1,
            defiInfo[nameHash].ext2,
            defiInfo[nameHash].fee,
            defiInfo[nameHash].routerV2
        );
    }

    /// @dev Get addresses of vaults of index phase
    /// @param _index the phase number
    /// @return the list of vaults of phase[_index]
    function phasesAll(uint256 _index)
        external
        view
        override
        returns (address[] memory)
    {
        return phases[_index];
    }

    /// @dev Get addresses of staker of _vault
    /// @param _vault the vault's address
    /// @return the list of stakeContracts of vault
    function stakeContractsOfVaultAll(address _vault)
        external
        view
        override
        returns (address[] memory)
    {
        return stakeContractsOfVault[_vault];
    }

    /// @dev Checks if a vault is withing the given phase
    /// @param _phase the phase number
    /// @param _vault the vault's address
    /// @return valid true or false
    function validVault(uint256 _phase, address _vault)
        external
        view
        override
        returns (bool valid)
    {
        require(phases[_phase].length > 0, "StakeRegistry: validVault is fail");

        for (uint256 i = 0; i < phases[_phase].length; i++) {
            if (_vault == phases[_phase][i]) {
                return true;
            }
        }
    }
}

// File: contracts/interfaces/IStakeRegistry.sol



//SPDX-License-Identifier: Unlicense
pragma solidity ^0.7.6;

interface IStakeRegistry {
    /// @dev Set addresses for Tokamak integration
    /// @param _ton TON address
    /// @param _wton WTON address
    /// @param _depositManager DepositManager address
    /// @param _seigManager SeigManager address
    /// @param _swapProxy Proxy address that can swap TON and WTON
    function setTokamak(
        address _ton,
        address _wton,
        address _depositManager,
        address _seigManager,
        address _swapProxy
    ) external;

    /// @dev Add information related to Defi
    /// @param _name name . ex) UNISWAP_V3
    /// @param _router entry point of defi
    /// @param _ex1  additional variable . ex) positionManagerAddress in Uniswap V3
    /// @param _ex2  additional variable . ex) WETH Address in Uniswap V3
    /// @param _fee  fee
    /// @param _routerV2 In case of uniswap, router address of uniswapV2
    function addDefiInfo(
        string calldata _name,
        address _router,
        address _ex1,
        address _ex2,
        uint256 _fee,
        address _routerV2
    ) external;

    /// @dev Add Vault
    /// @dev It is excuted by proxy
    /// @param _vault vault address
    /// @param _phase phase ex) 1,2,3
    /// @param _vaultName  hash of vault's name
    function addVault(
        address _vault,
        uint256 _phase,
        bytes32 _vaultName
    ) external;

    /// @dev Add StakeContract in vault
    /// @dev It is excuted by proxy
    /// @param _vault vault address
    /// @param _stakeContract  StakeContract address
    function addStakeContract(address _vault, address _stakeContract) external;

    /// @dev Get addresses for Tokamak interface
    /// @return (ton, wton, depositManager, seigManager)
    function getTokamak()
        external
        view
        returns (
            address,
            address,
            address,
            address,
            address
        );

    /// @dev Get indos for UNISWAP_V3 interface
    /// @return (uniswapRouter, npm, wethAddress, fee)
    function getUniswap()
        external
        view
        returns (
            address,
            address,
            address,
            uint256,
            address
        );

    /// @dev Checks if a vault is withing the given phase
    /// @param _phase the phase number
    /// @param _vault the vault's address
    /// @return valid true or false
    function validVault(uint256 _phase, address _vault)
        external
        view
        returns (bool valid);

    function phasesAll(uint256 _index) external view returns (address[] memory);

    function stakeContractsOfVaultAll(address _vault)
        external
        view
        returns (address[] memory);

    /// @dev view defi info
    /// @param _name  hash name : keccak256(abi.encodePacked(_name));
    /// @return name  _name ex) UNISWAP_V3, UNISWAP_V3_token0_token1
    /// @return router entry point of defi
    /// @return ext1  additional variable . ex) positionManagerAddress in Uniswap V3
    /// @return ext2  additional variable . ex) WETH Address in Uniswap V3
    /// @return fee  fee
    /// @return routerV2 In case of uniswap, router address of uniswapV2

    function defiInfo(bytes32 _name)
        external
        returns (
            string calldata name,
            address router,
            address ext1,
            address ext2,
            uint256 fee,
            address routerV2
        );
}

// File: contracts/libraries/LibTokenStake1.sol



//SPDX-License-Identifier: Unlicense
pragma solidity ^0.7.6;

library LibTokenStake1 {
    enum DefiStatus {
        NONE,
        APPROVE,
        DEPOSITED,
        REQUESTWITHDRAW,
        REQUESTWITHDRAWALL,
        WITHDRAW,
        END
    }
    struct DefiInfo {
        string name;
        address router;
        address ext1;
        address ext2;
        uint256 fee;
        address routerV2;
    }
    struct StakeInfo {
        string name;
        uint256 startBlock;
        uint256 endBlock;
        uint256 balance;
        uint256 totalRewardAmount;
        uint256 claimRewardAmount;
    }

    struct StakedAmount {
        uint256 amount;
        uint256 claimedBlock;
        uint256 claimedAmount;
        uint256 releasedBlock;
        uint256 releasedAmount;
        uint256 releasedTOSAmount;
        bool released;
    }

    struct StakedAmountForSTOS {
        uint256 amount;
        uint256 startBlock;
        uint256 periodBlock;
        uint256 rewardPerBlock;
        uint256 claimedBlock;
        uint256 claimedAmount;
        uint256 releasedBlock;
        uint256 releasedAmount;
    }
}

// File: contracts/common/AccessibleCommon.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.7.6;
import "@openzeppelin/contracts/access/AccessControl.sol";
import "./AccessRoleCommon.sol";

contract AccessibleCommon is AccessRoleCommon, AccessControl {
    modifier onlyOwner() {
        require(isAdmin(msg.sender), "Accessible: Caller is not an admin");
        _;
    }

    /// @dev add admin
    /// @param account  address to add
    function addAdmin(address account) public virtual onlyOwner {
        grantRole(ADMIN_ROLE, account);
    }

    /// @dev remove admin
    /// @param account  address to remove
    function removeAdmin(address account) public virtual onlyOwner {
        renounceRole(ADMIN_ROLE, account);
    }

    /// @dev transfer admin
    /// @param newAdmin new admin address
    function transferAdmin(address newAdmin) external virtual onlyOwner {
        require(newAdmin != address(0), "Accessible: zero address");
        require(msg.sender != newAdmin, "Accessible: same admin");

        grantRole(ADMIN_ROLE, newAdmin);
        renounceRole(ADMIN_ROLE, msg.sender);
    }

    /// @dev whether admin
    /// @param account  address to check
    function isAdmin(address account) public view virtual returns (bool) {
        return hasRole(ADMIN_ROLE, account);
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../utils/EnumerableSet.sol";
import "../utils/Address.sol";
import "../GSN/Context.sol";

/**
 * @dev Contract module that allows children to implement role-based access
 * control mechanisms.
 *
 * Roles are referred to by their `bytes32` identifier. These should be exposed
 * in the external API and be unique. The best way to achieve this is by
 * using `public constant` hash digests:
 *
 * ```
 * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
 * ```
 *
 * Roles can be used to represent a set of permissions. To restrict access to a
 * function call, use {hasRole}:
 *
 * ```
 * function foo() public {
 *     require(hasRole(MY_ROLE, msg.sender));
 *     ...
 * }
 * ```
 *
 * Roles can be granted and revoked dynamically via the {grantRole} and
 * {revokeRole} functions. Each role has an associated admin role, and only
 * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
 *
 * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
 * that only accounts with this role will be able to grant or revoke other
 * roles. More complex role relationships can be created by using
 * {_setRoleAdmin}.
 *
 * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
 * grant and revoke this role. Extra precautions should be taken to secure
 * accounts that have been granted it.
 */
abstract contract AccessControl is Context {
    using EnumerableSet for EnumerableSet.AddressSet;
    using Address for address;

    struct RoleData {
        EnumerableSet.AddressSet members;
        bytes32 adminRole;
    }

    mapping (bytes32 => RoleData) private _roles;

    bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;

    /**
     * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
     *
     * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
     * {RoleAdminChanged} not being emitted signaling this.
     *
     * _Available since v3.1._
     */
    event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);

    /**
     * @dev Emitted when `account` is granted `role`.
     *
     * `sender` is the account that originated the contract call, an admin role
     * bearer except when using {_setupRole}.
     */
    event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Emitted when `account` is revoked `role`.
     *
     * `sender` is the account that originated the contract call:
     *   - if using `revokeRole`, it is the admin role bearer
     *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
     */
    event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);

    /**
     * @dev Returns `true` if `account` has been granted `role`.
     */
    function hasRole(bytes32 role, address account) public view returns (bool) {
        return _roles[role].members.contains(account);
    }

    /**
     * @dev Returns the number of accounts that have `role`. Can be used
     * together with {getRoleMember} to enumerate all bearers of a role.
     */
    function getRoleMemberCount(bytes32 role) public view returns (uint256) {
        return _roles[role].members.length();
    }

    /**
     * @dev Returns one of the accounts that have `role`. `index` must be a
     * value between 0 and {getRoleMemberCount}, non-inclusive.
     *
     * Role bearers are not sorted in any particular way, and their ordering may
     * change at any point.
     *
     * WARNING: When using {getRoleMember} and {getRoleMemberCount}, make sure
     * you perform all queries on the same block. See the following
     * https://forum.openzeppelin.com/t/iterating-over-elements-on-enumerableset-in-openzeppelin-contracts/2296[forum post]
     * for more information.
     */
    function getRoleMember(bytes32 role, uint256 index) public view returns (address) {
        return _roles[role].members.at(index);
    }

    /**
     * @dev Returns the admin role that controls `role`. See {grantRole} and
     * {revokeRole}.
     *
     * To change a role's admin, use {_setRoleAdmin}.
     */
    function getRoleAdmin(bytes32 role) public view returns (bytes32) {
        return _roles[role].adminRole;
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function grantRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to grant");

        _grantRole(role, account);
    }

    /**
     * @dev Revokes `role` from `account`.
     *
     * If `account` had been granted `role`, emits a {RoleRevoked} event.
     *
     * Requirements:
     *
     * - the caller must have ``role``'s admin role.
     */
    function revokeRole(bytes32 role, address account) public virtual {
        require(hasRole(_roles[role].adminRole, _msgSender()), "AccessControl: sender must be an admin to revoke");

        _revokeRole(role, account);
    }

    /**
     * @dev Revokes `role` from the calling account.
     *
     * Roles are often managed via {grantRole} and {revokeRole}: this function's
     * purpose is to provide a mechanism for accounts to lose their privileges
     * if they are compromised (such as when a trusted device is misplaced).
     *
     * If the calling account had been granted `role`, emits a {RoleRevoked}
     * event.
     *
     * Requirements:
     *
     * - the caller must be `account`.
     */
    function renounceRole(bytes32 role, address account) public virtual {
        require(account == _msgSender(), "AccessControl: can only renounce roles for self");

        _revokeRole(role, account);
    }

    /**
     * @dev Grants `role` to `account`.
     *
     * If `account` had not been already granted `role`, emits a {RoleGranted}
     * event. Note that unlike {grantRole}, this function doesn't perform any
     * checks on the calling account.
     *
     * [WARNING]
     * ====
     * This function should only be called from the constructor when setting
     * up the initial roles for the system.
     *
     * Using this function in any other way is effectively circumventing the admin
     * system imposed by {AccessControl}.
     * ====
     */
    function _setupRole(bytes32 role, address account) internal virtual {
        _grantRole(role, account);
    }

    /**
     * @dev Sets `adminRole` as ``role``'s admin role.
     *
     * Emits a {RoleAdminChanged} event.
     */
    function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
        emit RoleAdminChanged(role, _roles[role].adminRole, adminRole);
        _roles[role].adminRole = adminRole;
    }

    function _grantRole(bytes32 role, address account) private {
        if (_roles[role].members.add(account)) {
            emit RoleGranted(role, account, _msgSender());
        }
    }

    function _revokeRole(bytes32 role, address account) private {
        if (_roles[role].members.remove(account)) {
            emit RoleRevoked(role, account, _msgSender());
        }
    }
}

// File: contracts/common/AccessRoleCommon.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.7.6;

contract AccessRoleCommon {
    bytes32 public constant ADMIN_ROLE = keccak256("ADMIN");
    bytes32 public constant MINTER_ROLE = keccak256("MINTER");
    bytes32 public constant BURNER_ROLE = keccak256("BURNER");
}

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



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Library for managing
 * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
 * types.
 *
 * Sets have the following properties:
 *
 * - Elements are added, removed, and checked for existence in constant time
 * (O(1)).
 * - Elements are enumerated in O(n). No guarantees are made on the ordering.
 *
 * ```
 * contract Example {
 *     // Add the library methods
 *     using EnumerableSet for EnumerableSet.AddressSet;
 *
 *     // Declare a set state variable
 *     EnumerableSet.AddressSet private mySet;
 * }
 * ```
 *
 * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
 * and `uint256` (`UintSet`) are supported.
 */
library EnumerableSet {
    // To implement this library for multiple types with as little code
    // repetition as possible, we write it in terms of a generic Set type with
    // bytes32 values.
    // The Set implementation uses private functions, and user-facing
    // implementations (such as AddressSet) are just wrappers around the
    // underlying Set.
    // This means that we can only create new EnumerableSets for types that fit
    // in bytes32.

    struct Set {
        // Storage of set values
        bytes32[] _values;

        // Position of the value in the `values` array, plus 1 because index 0
        // means a value is not in the set.
        mapping (bytes32 => uint256) _indexes;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function _add(Set storage set, bytes32 value) private returns (bool) {
        if (!_contains(set, value)) {
            set._values.push(value);
            // The value is stored at length-1, but we add 1 to all indexes
            // and use 0 as a sentinel value
            set._indexes[value] = set._values.length;
            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function _remove(Set storage set, bytes32 value) private returns (bool) {
        // We read and store the value's index to prevent multiple reads from the same storage slot
        uint256 valueIndex = set._indexes[value];

        if (valueIndex != 0) { // Equivalent to contains(set, value)
            // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
            // the array, and then remove the last element (sometimes called as 'swap and pop').
            // This modifies the order of the array, as noted in {at}.

            uint256 toDeleteIndex = valueIndex - 1;
            uint256 lastIndex = set._values.length - 1;

            // When the value to delete is the last one, the swap operation is unnecessary. However, since this occurs
            // so rarely, we still do the swap anyway to avoid the gas cost of adding an 'if' statement.

            bytes32 lastvalue = set._values[lastIndex];

            // Move the last value to the index where the value to delete is
            set._values[toDeleteIndex] = lastvalue;
            // Update the index for the moved value
            set._indexes[lastvalue] = toDeleteIndex + 1; // All indexes are 1-based

            // Delete the slot where the moved value was stored
            set._values.pop();

            // Delete the index for the deleted slot
            delete set._indexes[value];

            return true;
        } else {
            return false;
        }
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function _contains(Set storage set, bytes32 value) private view returns (bool) {
        return set._indexes[value] != 0;
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function _length(Set storage set) private view returns (uint256) {
        return set._values.length;
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function _at(Set storage set, uint256 index) private view returns (bytes32) {
        require(set._values.length > index, "EnumerableSet: index out of bounds");
        return set._values[index];
    }

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _add(set._inner, value);
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
        return _remove(set._inner, value);
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
        return _contains(set._inner, value);
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(Bytes32Set storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
        return _at(set._inner, index);
    }

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(value)));
    }

    /**
     * @dev Returns the number of values in the set. O(1).
     */
    function length(AddressSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint256(_at(set._inner, index)));
    }


    // UintSet

    struct UintSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(UintSet storage set, uint256 value) internal returns (bool) {
        return _add(set._inner, bytes32(value));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(UintSet storage set, uint256 value) internal returns (bool) {
        return _remove(set._inner, bytes32(value));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(UintSet storage set, uint256 value) internal view returns (bool) {
        return _contains(set._inner, bytes32(value));
    }

    /**
     * @dev Returns the number of values on the set. O(1).
     */
    function length(UintSet storage set) internal view returns (uint256) {
        return _length(set._inner);
    }

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(UintSet storage set, uint256 index) internal view returns (uint256) {
        return uint256(_at(set._inner, index));
    }
}

// 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);
    }

    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/GSN/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;
    }
}