// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity ^0.6.2;

/**
 * @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) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @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");
    }
}

// File: @openzeppelin/contracts/token/ERC777/IERC777.sol

pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC777Token standard as defined in the EIP.
 *
 * This contract uses the
 * https://eips.ethereum.org/EIPS/eip-1820[ERC1820 registry standard] to let
 * token holders and recipients react to token movements by using setting implementers
 * for the associated interfaces in said registry. See {IERC1820Registry} and
 * {ERC1820Implementer}.
 */
interface IERC777 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the smallest part of the token that is not divisible. This
     * means all token operations (creation, movement and destruction) must have
     * amounts that are a multiple of this number.
     *
     * For most token contracts, this value will equal 1.
     */
    function granularity() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by an account (`owner`).
     */
    function balanceOf(address owner) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * If send or receive hooks are registered for the caller and `recipient`,
     * the corresponding functions will be called with `data` and empty
     * `operatorData`. See {IERC777Sender} and {IERC777Recipient}.
     *
     * Emits a {Sent} event.
     *
     * Requirements
     *
     * - the caller must have at least `amount` tokens.
     * - `recipient` cannot be the zero address.
     * - if `recipient` is a contract, it must implement the {IERC777Recipient}
     * interface.
     */
    function send(address recipient, uint256 amount, bytes calldata data) external;

    /**
     * @dev Destroys `amount` tokens from the caller's account, reducing the
     * total supply.
     *
     * If a send hook is registered for the caller, the corresponding function
     * will be called with `data` and empty `operatorData`. See {IERC777Sender}.
     *
     * Emits a {Burned} event.
     *
     * Requirements
     *
     * - the caller must have at least `amount` tokens.
     */
    function burn(uint256 amount, bytes calldata data) external;

    /**
     * @dev Returns true if an account is an operator of `tokenHolder`.
     * Operators can send and burn tokens on behalf of their owners. All
     * accounts are their own operator.
     *
     * See {operatorSend} and {operatorBurn}.
     */
    function isOperatorFor(address operator, address tokenHolder) external view returns (bool);

    /**
     * @dev Make an account an operator of the caller.
     *
     * See {isOperatorFor}.
     *
     * Emits an {AuthorizedOperator} event.
     *
     * Requirements
     *
     * - `operator` cannot be calling address.
     */
    function authorizeOperator(address operator) external;

    /**
     * @dev Revoke an account's operator status for the caller.
     *
     * See {isOperatorFor} and {defaultOperators}.
     *
     * Emits a {RevokedOperator} event.
     *
     * Requirements
     *
     * - `operator` cannot be calling address.
     */
    function revokeOperator(address operator) external;

    /**
     * @dev Returns the list of default operators. These accounts are operators
     * for all token holders, even if {authorizeOperator} was never called on
     * them.
     *
     * This list is immutable, but individual holders may revoke these via
     * {revokeOperator}, in which case {isOperatorFor} will return false.
     */
    function defaultOperators() external view returns (address[] memory);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient`. The caller must
     * be an operator of `sender`.
     *
     * If send or receive hooks are registered for `sender` and `recipient`,
     * the corresponding functions will be called with `data` and
     * `operatorData`. See {IERC777Sender} and {IERC777Recipient}.
     *
     * Emits a {Sent} event.
     *
     * Requirements
     *
     * - `sender` cannot be the zero address.
     * - `sender` must have at least `amount` tokens.
     * - the caller must be an operator for `sender`.
     * - `recipient` cannot be the zero address.
     * - if `recipient` is a contract, it must implement the {IERC777Recipient}
     * interface.
     */
    function operatorSend(
        address sender,
        address recipient,
        uint256 amount,
        bytes calldata data,
        bytes calldata operatorData
    ) external;

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the total supply.
     * The caller must be an operator of `account`.
     *
     * If a send hook is registered for `account`, the corresponding function
     * will be called with `data` and `operatorData`. See {IERC777Sender}.
     *
     * Emits a {Burned} event.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     * - the caller must be an operator for `account`.
     */
    function operatorBurn(
        address account,
        uint256 amount,
        bytes calldata data,
        bytes calldata operatorData
    ) external;

    event Sent(
        address indexed operator,
        address indexed from,
        address indexed to,
        uint256 amount,
        bytes data,
        bytes operatorData
    );

    event Minted(address indexed operator, address indexed to, uint256 amount, bytes data, bytes operatorData);

    event Burned(address indexed operator, address indexed from, uint256 amount, bytes data, bytes operatorData);

    event AuthorizedOperator(address indexed operator, address indexed tokenHolder);

    event RevokedOperator(address indexed operator, address indexed tokenHolder);
}

// File: @openzeppelin/contracts/token/ERC777/IERC777Recipient.sol

pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC777TokensRecipient standard as defined in the EIP.
 *
 * Accounts can be notified of {IERC777} tokens being sent to them by having a
 * contract implement this interface (contract holders can be their own
 * implementer) and registering it on the
 * https://eips.ethereum.org/EIPS/eip-1820[ERC1820 global registry].
 *
 * See {IERC1820Registry} and {ERC1820Implementer}.
 */
interface IERC777Recipient {
    /**
     * @dev Called by an {IERC777} token contract whenever tokens are being
     * moved or created into a registered account (`to`). The type of operation
     * is conveyed by `from` being the zero address or not.
     *
     * This call occurs _after_ the token contract's state is updated, so
     * {IERC777-balanceOf}, etc., can be used to query the post-operation state.
     *
     * This function may revert to prevent the operation from being executed.
     */
    function tokensReceived(
        address operator,
        address from,
        address to,
        uint256 amount,
        bytes calldata userData,
        bytes calldata operatorData
    ) external;
}

// File: @openzeppelin/contracts/introspection/IERC1820Registry.sol

pragma solidity ^0.6.0;

/**
 * @dev Interface of the global ERC1820 Registry, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1820[EIP]. Accounts may register
 * implementers for interfaces in this registry, as well as query support.
 *
 * Implementers may be shared by multiple accounts, and can also implement more
 * than a single interface for each account. Contracts can implement interfaces
 * for themselves, but externally-owned accounts (EOA) must delegate this to a
 * contract.
 *
 * {IERC165} interfaces can also be queried via the registry.
 *
 * For an in-depth explanation and source code analysis, see the EIP text.
 */
interface IERC1820Registry {
    /**
     * @dev Sets `newManager` as the manager for `account`. A manager of an
     * account is able to set interface implementers for it.
     *
     * By default, each account is its own manager. Passing a value of `0x0` in
     * `newManager` will reset the manager to this initial state.
     *
     * Emits a {ManagerChanged} event.
     *
     * Requirements:
     *
     * - the caller must be the current manager for `account`.
     */
    function setManager(address account, address newManager) external;

    /**
     * @dev Returns the manager for `account`.
     *
     * See {setManager}.
     */
    function getManager(address account) external view returns (address);

    /**
     * @dev Sets the `implementer` contract as ``account``'s implementer for
     * `interfaceHash`.
     *
     * `account` being the zero address is an alias for the caller's address.
     * The zero address can also be used in `implementer` to remove an old one.
     *
     * See {interfaceHash} to learn how these are created.
     *
     * Emits an {InterfaceImplementerSet} event.
     *
     * Requirements:
     *
     * - the caller must be the current manager for `account`.
     * - `interfaceHash` must not be an {IERC165} interface id (i.e. it must not
     * end in 28 zeroes).
     * - `implementer` must implement {IERC1820Implementer} and return true when
     * queried for support, unless `implementer` is the caller. See
     * {IERC1820Implementer-canImplementInterfaceForAddress}.
     */
    function setInterfaceImplementer(address account, bytes32 interfaceHash, address implementer) external;

    /**
     * @dev Returns the implementer of `interfaceHash` for `account`. If no such
     * implementer is registered, returns the zero address.
     *
     * If `interfaceHash` is an {IERC165} interface id (i.e. it ends with 28
     * zeroes), `account` will be queried for support of it.
     *
     * `account` being the zero address is an alias for the caller's address.
     */
    function getInterfaceImplementer(address account, bytes32 interfaceHash) external view returns (address);

    /**
     * @dev Returns the interface hash for an `interfaceName`, as defined in the
     * corresponding
     * https://eips.ethereum.org/EIPS/eip-1820#interface-name[section of the EIP].
     */
    function interfaceHash(string calldata interfaceName) external pure returns (bytes32);

    /**
     *  @notice Updates the cache with whether the contract implements an ERC165 interface or not.
     *  @param account Address of the contract for which to update the cache.
     *  @param interfaceId ERC165 interface for which to update the cache.
     */
    function updateERC165Cache(address account, bytes4 interfaceId) external;

    /**
     *  @notice Checks whether a contract implements an ERC165 interface or not.
     *  If the result is not cached a direct lookup on the contract address is performed.
     *  If the result is not cached or the cached value is out-of-date, the cache MUST be updated manually by calling
     *  {updateERC165Cache} with the contract address.
     *  @param account Address of the contract to check.
     *  @param interfaceId ERC165 interface to check.
     *  @return True if `account` implements `interfaceId`, false otherwise.
     */
    function implementsERC165Interface(address account, bytes4 interfaceId) external view returns (bool);

    /**
     *  @notice Checks whether a contract implements an ERC165 interface or not without using nor updating the cache.
     *  @param account Address of the contract to check.
     *  @param interfaceId ERC165 interface to check.
     *  @return True if `account` implements `interfaceId`, false otherwise.
     */
    function implementsERC165InterfaceNoCache(address account, bytes4 interfaceId) external view returns (bool);

    event InterfaceImplementerSet(address indexed account, bytes32 indexed interfaceHash, address indexed implementer);

    event ManagerChanged(address indexed account, address indexed newManager);
}

// File: contracts/Receiver.sol

pragma solidity >=0.6.2 <0.7.0;




abstract contract Receiver is IERC777Recipient {
  mapping(address => bool) internal canReceive;

  IERC1820Registry constant internal ERC1820_REGISTRY = IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);

  constructor() internal {
    ERC1820_REGISTRY.setInterfaceImplementer(address(this), keccak256("ERC777TokensRecipient"), address(this));
  }

  function _tokensReceived(IERC777 token, address from, uint256 amount, bytes memory data) internal virtual;

  function tokensReceived(
    address /*operator*/,
    address from,
    address /*to*/,
    uint256 amount,
    bytes calldata userData,
    bytes calldata /*operatorData*/
  ) external override {
    // require(canReceive[msg.sender]);
    _tokensReceived(IERC777(msg.sender), from, amount, userData);
  }

  function recover(address token) external /*onlyOwner*/ {
    // require(!canReceive[address(token)]);

    IERC777(token).send(msg.sender, IERC777(token).balanceOf(address(this)), "");
  }
}

// File: contracts/protocols/aave/ILendingPoolCore.sol

pragma solidity >=0.6.2 <0.7.0;

interface ILendingPoolCore {
  function getReserveATokenAddress(address _reserve) external /*view*/ returns (address);

  function getReserveNormalizedIncome(address _reserve) external view returns (uint256);
}

// File: contracts/protocols/aave/ILendingPool.sol

pragma solidity >=0.6.2 <0.7.0;


interface ILendingPool {
  function core() external view returns (ILendingPoolCore);

  function deposit(address _reserve, uint256 _amount, uint16 _referralCode) external payable;
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.6.0;

/**
 * @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: contracts/protocols/aave/IAToken.sol

pragma solidity >=0.6.2 <0.7.0;


interface IAToken is IERC20 {

    // function underlyingAssetAddress() external view returns (address);

    /**
    * @dev redirects the interest generated to a target address.
    * when the interest is redirected, the user balance is added to
    * the recepient redirected balance.
    * @param _to the address to which the interest will be redirected
    **/
    // function redirectInterestStream(address _to) external;

    /**
    * @dev redirects the interest generated by _from to a target address.
    * when the interest is redirected, the user balance is added to
    * the recepient redirected balance. The caller needs to have allowance on
    * the interest redirection to be able to execute the function.
    * @param _from the address of the user whom interest is being redirected
    * @param _to the address to which the interest will be redirected
    **/
    // function redirectInterestStreamOf(address _from, address _to) external;

    /**
    * @dev gives allowance to an address to execute the interest redirection
    * on behalf of the caller.
    * @param _to the address to which the interest will be redirected. Pass address(0) to reset
    * the allowance.
    **/
    // function allowInterestRedirectionTo(address _to) external;

    /**
    * @dev redeems aToken for the underlying asset
    * @param _amount the amount being redeemed
    **/
    function redeem(uint256 _amount) external;

    /**
     * @dev mints token in the event of users depositing the underlying asset into the lending pool
     * only lending pools can call this function
     * @param _account the address receiving the minted tokens
     * @param _amount the amount of tokens to mint
     */
    // function mintOnDeposit(address _account, uint256 _amount) external;

    /**
     * @dev transfers tokens in the event of a borrow being liquidated, in case the liquidators reclaims the aToken
     *      only lending pools can call this function
     * @param _from the address from which transfer the aTokens
     * @param _to the destination address
     * @param _value the amount to transfer
     **/
    // function transferOnLiquidation(address _from, address _to, uint256 _value) external;

    /**
    * @dev returns the principal balance of the user. The principal balance is the last
    * updated stored balance, which does not consider the perpetually accruing interest.
    * @param _user the address of the user
    * @return the principal balance of the user
    **/
    // function principalBalanceOf(address _user) external view returns(uint256);


    /**
     * @dev Used to validate transfers before actually executing them.
     * @param _user address of the user to check
     * @param _amount the amount to check
     * @return true if the _user can transfer _amount, false otherwise
     **/
    // function isTransferAllowed(address _user, uint256 _amount) external view returns (bool);

    /**
    * @dev returns the last index of the user, used to calculate the balance of the user
    * @param _user address of the user
    * @return the last user index
    **/
    // function getUserIndex(address _user) external view returns(uint256);


    /**
    * @dev returns the address to which the interest is redirected
    * @param _user address of the user
    * @return 0 if there is no redirection, an address otherwise
    **/
    // function getInterestRedirectionAddress(address _user) external view returns(address);

    /**
    * @dev returns the redirected balance of the user. The redirected balance is the balance
    * redirected by other accounts to the user, that is accrueing interest for him.
    * @param _user address of the user
    * @return the total redirected balance
    **/
    // function getRedirectedBalance(address _user) external view returns(uint256);
}

// File: @openzeppelin/contracts/math/SafeMath.sol

pragma solidity ^0.6.0;

/**
 * @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, 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) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * 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);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/GSN/Context.sol

pragma solidity ^0.6.0;

/*
 * @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.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }

    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: @openzeppelin/contracts/token/ERC20/ERC20.sol

pragma solidity ^0.6.0;





/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20MinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;
    using Address for address;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name, string memory symbol) public {
        _name = name;
        _symbol = symbol;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
     *
     * This is internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

// File: contracts/tokens/IWrapped777.sol

pragma solidity >=0.6.2 <0.7.0;



interface IWrapped777 is IERC777 {
  function factory() external view returns (address);

  function token() external view returns (ERC20);

  function wrap(uint256 amount) external returns (uint256);
}

// File: @openzeppelin/contracts/token/ERC777/IERC777Sender.sol

pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC777TokensSender standard as defined in the EIP.
 *
 * {IERC777} Token holders can be notified of operations performed on their
 * tokens by having a contract implement this interface (contract holders can be
 *  their own implementer) and registering it on the
 * https://eips.ethereum.org/EIPS/eip-1820[ERC1820 global registry].
 *
 * See {IERC1820Registry} and {ERC1820Implementer}.
 */
interface IERC777Sender {
    /**
     * @dev Called by an {IERC777} token contract whenever a registered holder's
     * (`from`) tokens are about to be moved or destroyed. The type of operation
     * is conveyed by `to` being the zero address or not.
     *
     * This call occurs _before_ the token contract's state is updated, so
     * {IERC777-balanceOf}, etc., can be used to query the pre-operation state.
     *
     * This function may revert to prevent the operation from being executed.
     */
    function tokensToSend(
        address operator,
        address from,
        address to,
        uint256 amount,
        bytes calldata userData,
        bytes calldata operatorData
    ) external;
}

// File: contracts/tokens/Granularity.sol

pragma solidity >=0.6.2 <0.7.0;

contract Granularity {
  uint256 internal _decimals;

  function setDecimals(uint decimals) internal {
    _decimals = decimals;
  }

  function getGranularity() internal view returns (uint256) {
    return 10 ** (18 - _decimals);
  }

  function from777to20(uint amount) internal view returns (uint256) {
    return amount / getGranularity();
  }

  function from20to777(uint amount) internal view returns (uint256) {
    return amount * getGranularity();
  }
}

// File: contracts/protocols/aave/ERC777WithoutBalance.sol

pragma solidity ^0.6.0;











/**
 * @dev Copies the OpenZeppelin ERC777, but adds support for Granularity.
 */
abstract contract ERC777WithoutBalance is Context, IERC777, IERC20, Granularity {
    using SafeMath for uint256;
    using Address for address;

    IERC1820Registry constant internal _ERC1820_REGISTRY = IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);

    // mapping(address => uint256) private _balances;

    string internal _name;
    string internal _symbol;

    // We inline the result of the following hashes because Solidity doesn't resolve them at compile time.
    // See https://github.com/ethereum/solidity/issues/4024.

    // keccak256("ERC777TokensSender")
    bytes32 constant private _TOKENS_SENDER_INTERFACE_HASH =
        0x29ddb589b1fb5fc7cf394961c1adf5f8c6454761adf795e67fe149f658abe895;

    // keccak256("ERC777TokensRecipient")
    bytes32 constant private _TOKENS_RECIPIENT_INTERFACE_HASH =
        0xb281fc8c12954d22544db45de3159a39272895b169a852b314f9cc762e44c53b;

    // This isn't ever read from - it's only used to respond to the defaultOperators query.
    address[] private _defaultOperatorsArray;

    // Immutable, but accounts may revoke them (tracked in __revokedDefaultOperators).
    mapping(address => bool) private _defaultOperators;

    // For each account, a mapping of its operators and revoked default operators.
    mapping(address => mapping(address => bool)) private _operators;
    mapping(address => mapping(address => bool)) private _revokedDefaultOperators;

    // ERC20-allowances
    mapping (address => mapping (address => uint256)) private _allowances;

    /**
     * @dev `defaultOperators` may be an empty array.
     */
    constructor(
        // string memory name,
        // string memory symbol,
        // address[] memory defaultOperators
    ) public {
        // _name = name;
        // _symbol = symbol;

        // _defaultOperatorsArray = defaultOperators;
        // for (uint256 i = 0; i < _defaultOperatorsArray.length; i++) {
        //     _defaultOperators[_defaultOperatorsArray[i]] = true;
        // }

        // register interfaces
        _ERC1820_REGISTRY.setInterfaceImplementer(address(this), keccak256("ERC777Token"), address(this));
        _ERC1820_REGISTRY.setInterfaceImplementer(address(this), keccak256("ERC20Token"), address(this));
    }

    /**
     * @dev See {IERC777-name}.
     */
    function name() public view override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC777-symbol}.
     */
    function symbol() public view override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {ERC20-decimals}.
     *
     * Always returns 18, as per the
     * [ERC777 EIP](https://eips.ethereum.org/EIPS/eip-777#backward-compatibility).
     */
    function decimals() public pure returns (uint8) {
        return 18;
    }

    /**
     * @dev See {IERC777-granularity}.
     *
     * This implementation always returns `1`.
     */
    function granularity() public view override returns (uint256) {
        return getGranularity();
    }

    /**
     * @dev See {IERC777-totalSupply}.
     */
    function totalSupply() public view override(IERC20, IERC777) virtual returns (uint256);

    function balanceOf(address account) external view override(IERC20, IERC777) virtual returns (uint256);

    /**
     * @dev See {IERC777-send}.
     *
     * Also emits a {IERC20-Transfer} event for ERC20 compatibility.
     */
    function send(address recipient, uint256 amount, bytes memory data) public override  {
        _send(_msgSender(), recipient, amount, data, "", true);
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Unlike `send`, `recipient` is _not_ required to implement the {IERC777Recipient}
     * interface if it is a contract.
     *
     * Also emits a {Sent} event.
     */
    function transfer(address recipient, uint256 amount) public override returns (bool) {
        require(recipient != address(0), "ERC777: transfer to the zero address");

        address from = _msgSender();

        _callTokensToSend(from, from, recipient, amount, "", "");

        _move(from, from, recipient, amount, "", "");

        _callTokensReceived(from, from, recipient, amount, "", "", false);

        return true;
    }

    /**
     * @dev See {IERC777-burn}.
     *
     * Also emits a {IERC20-Transfer} event for ERC20 compatibility.
     */
    function burn(uint256 amount, bytes memory data) public override  {
        _burn(_msgSender(), amount, data, "");
    }

    /**
     * @dev See {IERC777-isOperatorFor}.
     */
    function isOperatorFor(
        address operator,
        address tokenHolder
    ) public view override returns (bool) {
        return operator == tokenHolder ||
            (_defaultOperators[operator] && !_revokedDefaultOperators[tokenHolder][operator]) ||
            _operators[tokenHolder][operator];
    }

    /**
     * @dev See {IERC777-authorizeOperator}.
     */
    function authorizeOperator(address operator) public override  {
        require(_msgSender() != operator, "ERC777: authorizing self as operator");

        if (_defaultOperators[operator]) {
            delete _revokedDefaultOperators[_msgSender()][operator];
        } else {
            _operators[_msgSender()][operator] = true;
        }

        emit AuthorizedOperator(operator, _msgSender());
    }

    /**
     * @dev See {IERC777-revokeOperator}.
     */
    function revokeOperator(address operator) public override  {
        require(operator != _msgSender(), "ERC777: revoking self as operator");

        if (_defaultOperators[operator]) {
            _revokedDefaultOperators[_msgSender()][operator] = true;
        } else {
            delete _operators[_msgSender()][operator];
        }

        emit RevokedOperator(operator, _msgSender());
    }

    /**
     * @dev See {IERC777-defaultOperators}.
     */
    function defaultOperators() public view override returns (address[] memory) {
        return _defaultOperatorsArray;
    }

    /**
     * @dev See {IERC777-operatorSend}.
     *
     * Emits {Sent} and {IERC20-Transfer} events.
     */
    function operatorSend(
        address sender,
        address recipient,
        uint256 amount,
        bytes memory data,
        bytes memory operatorData
    )
    public override
    {
        require(isOperatorFor(_msgSender(), sender), "ERC777: caller is not an operator for holder");
        _send(sender, recipient, amount, data, operatorData, true);
    }

    /**
     * @dev See {IERC777-operatorBurn}.
     *
     * Emits {Burned} and {IERC20-Transfer} events.
     */
    function operatorBurn(address account, uint256 amount, bytes memory data, bytes memory operatorData) public override {
        require(isOperatorFor(_msgSender(), account), "ERC777: caller is not an operator for holder");
        _burn(account, amount, data, operatorData);
    }

    /**
     * @dev See {IERC20-allowance}.
     *
     * Note that operator and allowance concepts are orthogonal: operators may
     * not have allowance, and accounts with allowance may not be operators
     * themselves.
     */
    function allowance(address holder, address spender) public view override returns (uint256) {
        return _allowances[holder][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Note that accounts cannot have allowance issued by their operators.
     */
    function approve(address spender, uint256 value) public override returns (bool) {
        address holder = _msgSender();
        _approve(holder, spender, value);
        return true;
    }

   /**
    * @dev See {IERC20-transferFrom}.
    *
    * Note that operator and allowance concepts are orthogonal: operators cannot
    * call `transferFrom` (unless they have allowance), and accounts with
    * allowance cannot call `operatorSend` (unless they are operators).
    *
    * Emits {Sent}, {IERC20-Transfer} and {IERC20-Approval} events.
    */
    function transferFrom(address holder, address recipient, uint256 amount) public override returns (bool) {
        require(recipient != address(0), "ERC777: transfer to the zero address");
        require(holder != address(0), "ERC777: transfer from the zero address");

        address spender = _msgSender();

        _callTokensToSend(spender, holder, recipient, amount, "", "");

        _move(spender, holder, recipient, amount, "", "");
        _approve(holder, spender, _allowances[holder][spender].sub(amount, "ERC777: transfer amount exceeds allowance"));

        _callTokensReceived(spender, holder, recipient, amount, "", "", false);

        return true;
    }

    /**
     * @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * If a send hook is registered for `account`, the corresponding function
     * will be called with `operator`, `data` and `operatorData`.
     *
     * See {IERC777Sender} and {IERC777Recipient}.
     *
     * Emits {Minted} and {IERC20-Transfer} events.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - if `account` is a contract, it must implement the {IERC777Recipient}
     * interface.
     */
    function _mint(
        address account,
        uint256 amount,
        bytes memory userData,
        bytes memory operatorData
    )
    internal virtual
    {
        require(account != address(0), "ERC777b: mint to the zero address");
        require(amount % getGranularity() == 0, "ERC777: Invalid granularity");

        address operator = _msgSender();

        _beforeTokenTransfer(operator, address(0), account, amount);

        // Update state variables
        // _totalSupply = _totalSupply.add(amount);
        // _balances[account] = _balances[account].add(amount);

        _callTokensReceived(operator, address(0), account, amount, userData, operatorData, true);

        emit Minted(operator, account, amount, userData, operatorData);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Send tokens
     * @param from address token holder address
     * @param to address recipient address
     * @param amount uint256 amount of tokens to transfer
     * @param userData bytes extra information provided by the token holder (if any)
     * @param operatorData bytes extra information provided by the operator (if any)
     * @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient
     */
    function _send(
        address from,
        address to,
        uint256 amount,
        bytes memory userData,
        bytes memory operatorData,
        bool requireReceptionAck
    )
        internal
    {
        require(from != address(0), "ERC777: send from the zero address");
        require(to != address(0), "ERC777: send to the zero address");

        address operator = _msgSender();

        _callTokensToSend(operator, from, to, amount, userData, operatorData);

        _move(operator, from, to, amount, userData, operatorData);

        _callTokensReceived(operator, from, to, amount, userData, operatorData, requireReceptionAck);
    }

    /**
     * @dev Burn tokens
     * @param from address token holder address
     * @param amount uint256 amount of tokens to burn
     * @param data bytes extra information provided by the token holder
     * @param operatorData bytes extra information provided by the operator (if any)
     */
    function _burn(
        address from,
        uint256 amount,
        bytes memory data,
        bytes memory operatorData
    )
        internal virtual
    {
        require(from != address(0), "ERC777: burn from the zero address");
        require(amount % getGranularity() == 0, "ERC777: Invalid granularity");

        address operator = _msgSender();

        _beforeTokenTransfer(operator, from, address(0), amount);

        _callTokensToSend(operator, from, address(0), amount, data, operatorData);

        // Update state variables
        // _balances[from] = _balances[from].sub(amount, "ERC777: burn amount exceeds balance");
        // _totalSupply = _totalSupply.sub(amount);

        emit Burned(operator, from, amount, data, operatorData);
        emit Transfer(from, address(0), amount);
    }

    function _move(
        address operator,
        address from,
        address to,
        uint256 amount,
        bytes memory userData,
        bytes memory operatorData
    ) internal virtual;

    function _approve(address holder, address spender, uint256 value) internal {
        // TODO: restore this require statement if this function becomes internal, or is called at a new callsite. It is
        // currently unnecessary.
        //require(holder != address(0), "ERC777: approve from the zero address");
        require(spender != address(0), "ERC777: approve to the zero address");

        _allowances[holder][spender] = value;
        emit Approval(holder, spender, value);
    }

    /**
     * @dev Call from.tokensToSend() if the interface is registered
     * @param operator address operator requesting the transfer
     * @param from address token holder address
     * @param to address recipient address
     * @param amount uint256 amount of tokens to transfer
     * @param userData bytes extra information provided by the token holder (if any)
     * @param operatorData bytes extra information provided by the operator (if any)
     */
    function _callTokensToSend(
        address operator,
        address from,
        address to,
        uint256 amount,
        bytes memory userData,
        bytes memory operatorData
    )
        private
    {
        address implementer = _ERC1820_REGISTRY.getInterfaceImplementer(from, _TOKENS_SENDER_INTERFACE_HASH);
        if (implementer != address(0)) {
            IERC777Sender(implementer).tokensToSend(operator, from, to, amount, userData, operatorData);
        }
    }

    /**
     * @dev Call to.tokensReceived() if the interface is registered. Reverts if the recipient is a contract but
     * tokensReceived() was not registered for the recipient
     * @param operator address operator requesting the transfer
     * @param from address token holder address
     * @param to address recipient address
     * @param amount uint256 amount of tokens to transfer
     * @param userData bytes extra information provided by the token holder (if any)
     * @param operatorData bytes extra information provided by the operator (if any)
     * @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient
     */
    function _callTokensReceived(
        address operator,
        address from,
        address to,
        uint256 amount,
        bytes memory userData,
        bytes memory operatorData,
        bool requireReceptionAck
    )
        private
    {
        address implementer = _ERC1820_REGISTRY.getInterfaceImplementer(to, _TOKENS_RECIPIENT_INTERFACE_HASH);
        if (implementer != address(0)) {
            IERC777Recipient(implementer).tokensReceived(operator, from, to, amount, userData, operatorData);
        } else if (requireReceptionAck) {
            require(!to.isContract(), "ERC777: token recipient contract has no implementer for ERC777TokensRecipient");
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes
     * calls to {send}, {transfer}, {operatorSend}, minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - when `from` is zero, `tokenId` will be minted for `to`.
     * - when `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address operator, address from, address to, uint256 tokenId) internal virtual { }
}

// File: contracts/protocols/aave/WadRayMath.sol

pragma solidity >=0.5.0;


/******************
@title WadRayMath library
@author Aave
@dev Provides mul and div function for wads (decimal numbers with 18 digits precision) and rays (decimals with 27 digits)
 */

library WadRayMath {
    using SafeMath for uint256;

    uint256 internal constant WAD = 1e18;
    uint256 internal constant halfWAD = WAD / 2;

    uint256 internal constant RAY = 1e27;
    uint256 internal constant halfRAY = RAY / 2;

    uint256 internal constant WAD_RAY_RATIO = 1e9;

    function ray() internal pure returns (uint256) {
        return RAY;
    }
    function wad() internal pure returns (uint256) {
        return WAD;
    }

    function halfRay() internal pure returns (uint256) {
        return halfRAY;
    }

    function halfWad() internal pure returns (uint256) {
        return halfWAD;
    }

    function wadMul(uint256 a, uint256 b) internal pure returns (uint256) {
        return halfWAD.add(a.mul(b)).div(WAD);
    }

    function wadDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 halfB = b / 2;

        return halfB.add(a.mul(WAD)).div(b);
    }

    function rayMul(uint256 a, uint256 b) internal pure returns (uint256) {
        return halfRAY.add(a.mul(b)).div(RAY);
    }

    function rayDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 halfB = b / 2;

        return halfB.add(a.mul(RAY)).div(b);
    }

    function rayToWad(uint256 a) internal pure returns (uint256) {
        uint256 halfRatio = WAD_RAY_RATIO / 2;

        return halfRatio.add(a).div(WAD_RAY_RATIO);
    }

    function wadToRay(uint256 a) internal pure returns (uint256) {
        return a.mul(WAD_RAY_RATIO);
    }

    /**
    * @dev calculates base^exp. The code uses the ModExp precompile
    * @return z base^exp, in ray
    */
    //solium-disable-next-line
    function rayPow(uint256 x, uint256 n) internal pure returns (uint256 z) {

        z = n % 2 != 0 ? x : RAY;

        for (n /= 2; n != 0; n /= 2) {
            x = rayMul(x, x);

            if (n % 2 != 0) {
                z = rayMul(z, x);
            }
        }
    }

}

// File: contracts/protocols/aave/AToken777.sol

pragma solidity >=0.6.2 <0.7.0;












contract AToken777 is ERC777WithoutBalance, IWrapped777, Receiver {
  using WadRayMath for uint256;
  using SafeMath for uint256;

  ERC20 public override token;
  address public override factory;

  IWrapped777 public immutable reserveWrapper;
  ERC20 public reserve;
  ILendingPool public lendingPool;

  uint16 constant private referralCode = 45;
  address private silentReceive;
  address constant private ETH_FAKE_TOKEN = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

  mapping(address => uint256) private balance;
  mapping(address => uint256) private userIndexes;

  constructor(ILendingPool _lendingPool, IWrapped777 _reserveWrapper) public {
    lendingPool = _lendingPool;
    reserveWrapper = _reserveWrapper;

    if (address(_reserveWrapper) == ETH_FAKE_TOKEN) {
      reserve = ERC20(ETH_FAKE_TOKEN);
    } else {
      reserve = _reserveWrapper.token();
    }

    canReceive[address(this)] = true;
    canReceive[address(_reserveWrapper)] = true;

    token = ERC20(lendingPool.core().getReserveATokenAddress(address(reserve)));

    _name = string(abi.encodePacked(token.name(), "-777"));
    _symbol = string(abi.encodePacked(token.symbol(), "777"));

    setDecimals(token.decimals());
    _ERC1820_REGISTRY.setInterfaceImplementer(address(this), keccak256("AToken777"), address(this));
  }

  function balanceOf(address tokenHolder) public view override(ERC777WithoutBalance, IERC777) returns (uint256) {
    uint256 reserveNormalizedIncome = lendingPool.core().getReserveNormalizedIncome(address(reserve));
    return from20to777(getReserveBalance(tokenHolder, reserveNormalizedIncome));
  }

  function getReserveBalance(address tokenHolder, uint256 reserveNormalizedIncome) internal view returns (uint256) {
    if (balance[tokenHolder] == 0) {
      return 0;
    }

    return balance[tokenHolder]
      .wadToRay()
      .rayMul(reserveNormalizedIncome)
      .rayDiv(userIndexes[tokenHolder])
      .rayToWad();
  }

  function totalSupply() public view override(ERC777WithoutBalance, IERC777) returns (uint256) {
    return from20to777(token.balanceOf(address(this)));
  }

  function update(address account) internal {
    uint256 reserveNormalizedIncome = lendingPool.core().getReserveNormalizedIncome(address(reserve));
    balance[account] = getReserveBalance(account, reserveNormalizedIncome);
    userIndexes[account] = reserveNormalizedIncome;
  }

  function _move(
    address /*operator*/,
    address from,
    address to,
    uint256 amount,
    bytes memory /*userData*/,
    bytes memory /*operatorData*/
  ) internal override {
    if (to != address(this)) {
      update(from);
      update(to);

      balance[from] = balance[from].sub(amount);
      balance[to] = balance[to].add(amount);
    }
  }

  function wrap(uint256 amount) external override returns (uint256 outAmount) {
    address sender = _msgSender();
    reserve.transferFrom(sender, address(this), amount);

    update(sender);
    balance[sender] = balance[sender].add(amount);

    reserve.approve(address(lendingPool.core()), amount);
    lendingPool.deposit(address(reserve), amount, referralCode);

    outAmount = from20to777(amount);
    _mint(sender, outAmount, "", "");
  }

  receive() external payable {
    if (silentReceive != ETH_FAKE_TOKEN) {
      depositFor(msg.sender);
    }
  }

  function depositFor(address receiver) public payable {
    require(address(reserveWrapper) == ETH_FAKE_TOKEN);
    update(receiver);

    uint256 amount = msg.value;
    balance[receiver] = balance[receiver].add(amount);

    lendingPool.deposit{value: amount}(ETH_FAKE_TOKEN, amount, referralCode);

    require(token.balanceOf(address(this)) == amount, "Didn't receive aTokens");

    _mint(receiver, amount, "", "");
  }

  function _tokensReceived(IERC777 _token, address from, uint256 amount, bytes memory data) internal override {
    if (address(_token) == silentReceive) {
      return;
    }

    update(from);

    address receiver = from;
    if (data.length > 0) {
      (address _receiver) = abi.decode(data, (address));
      if (_receiver != address(0)) {
        receiver = _receiver;
        update(receiver);
      }
    }

    if (address(_token) == address(this)) {
      withdraw(amount, from, receiver);
    } else if (address(_token) == address(reserveWrapper)) {
      deposit(_token, amount, receiver);
    } else {
      revert('Unsupported');
    }
  }

  function withdraw(uint256 amount, address from, address recipient) private {
    uint adjustedAmount = from777to20(amount);

    balance[from] = balance[from].sub(adjustedAmount);
    silentReceive = address(reserveWrapper);
    IAToken(address(token)).redeem(adjustedAmount);

    _burn(address(this), amount, "", "");
    transferReserveToUser(recipient, amount);
    silentReceive = address(0);
  }

  function deposit(IERC777 wrapper, uint256 amount, address recipient) private {
    wrapper.send(address(wrapper), amount, '');

    uint reserveAmount = reserve.balanceOf(address(this));
    balance[recipient] = balance[recipient].add(reserveAmount);
    reserve.approve(address(lendingPool.core()), reserveAmount);
    lendingPool.deposit(address(reserve), reserveAmount, referralCode);

    userIndexes[recipient] = lendingPool.core().getReserveNormalizedIncome(address(reserve));
    _mint(recipient, from20to777(reserveAmount), "", "");

  }

  function transferReserveToUser(address receiver, uint256 amount) private {
    if (address(reserve) == ETH_FAKE_TOKEN) {
      payable(receiver).transfer(amount);
    } else {
      reserve.approve(address(reserveWrapper), amount);

      reserveWrapper.wrap(amount);
      ERC20(address(reserveWrapper)).transfer(receiver, amount);
    }

  }

}

// File: contracts/protocols/aave/ILendingPoolAddressesProvider.sol

pragma solidity >=0.6.2 <0.7.0;


/**
@title ILendingPoolAddressesProvider interface
@notice provides the interface to fetch the LendingPoolCore address
 */

interface ILendingPoolAddressesProvider {
    function getLendingPool() external view returns (ILendingPool);
    // function setLendingPoolImpl(address _pool) external;

    // function getLendingPoolCore() external view returns (address payable);
    // function setLendingPoolCoreImpl(address _lendingPoolCore) external;

    // function getLendingPoolConfigurator() external view returns (address);
    // function setLendingPoolConfiguratorImpl(address _configurator) external;

    // function getLendingPoolDataProvider() external view returns (address);
    // function setLendingPoolDataProviderImpl(address _provider) external;

    // function getLendingPoolParametersProvider() external view returns (address);
    // function setLendingPoolParametersProviderImpl(address _parametersProvider) external;

    // function getTokenDistributor() external view returns (address);
    // function setTokenDistributor(address _tokenDistributor) external;


    // function getFeeProvider() external view returns (address);
    // function setFeeProviderImpl(address _feeProvider) external;

    // function getLendingPoolLiquidationManager() external view returns (address);
    // function setLendingPoolLiquidationManager(address _manager) external;

    // function getLendingPoolManager() external view returns (address);
    // function setLendingPoolManager(address _lendingPoolManager) external;

    // function getPriceOracle() external view returns (address);
    // function setPriceOracle(address _priceOracle) external;

    // function getLendingRateOracle() external view returns (address);
    // function setLendingRateOracle(address _lendingRateOracle) external;
}

// File: contracts/protocols/aave/Aave777.sol

pragma solidity >=0.6.5 <0.7.0;








contract Aave777 is Receiver {
  using Address for address;

  ILendingPoolAddressesProvider private addressProvider;

  IERC1820Registry constant private _ERC1820_REGISTRY = IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);
  bytes32 immutable private _ATOKEN_777_INTERFACE_HASH;

  address constant private ETH_FAKE_TOKEN = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

  constructor(address lendingPoolAddressProvider) public {
    // mainnet address, for other addresses: https://docs.aave.com/developers/developing-on-aave/deployed-contract-instances
    addressProvider = ILendingPoolAddressesProvider(lendingPoolAddressProvider);

    _ATOKEN_777_INTERFACE_HASH = keccak256("AToken777");
  }

  function createWrapper(address wrapper) public {    
    new AToken777{salt: bytes32(0)}(addressProvider.getLendingPool(), IWrapped777(wrapper));
  }

  function calculateWrapperAddress(address wrapper) public view returns (address calculatedAddress) { 
    calculatedAddress = address(uint(keccak256(abi.encodePacked(
      byte(0xff),
      address(this),
      bytes32(0),
      keccak256(abi.encodePacked(
        type(AToken777).creationCode,
        uint256(address(addressProvider.getLendingPool())),
        uint256(wrapper)
      ))
    ))));
  }

  function getWrapperAddress(address wrappedReserve) public returns (address wrapperAddress) {
    wrapperAddress = calculateWrapperAddress(wrappedReserve);

    if(!wrapperAddress.isContract()) {
      createWrapper(wrappedReserve);
      assert(wrapperAddress.isContract());
    }
  }

  receive() external payable {
    AToken777 atoken = AToken777(payable(getWrapperAddress(ETH_FAKE_TOKEN)));

    atoken.depositFor{value: msg.value}(msg.sender);
  }

  function _tokensReceived(IERC777 _token, address from, uint256 amount, bytes memory /*data*/) internal override {
    address implementer = _ERC1820_REGISTRY.getInterfaceImplementer(address(_token), _ATOKEN_777_INTERFACE_HASH);

    if (implementer != address(0) /* token is wrapped aToken */) {
      _token.send(address(_token), amount, abi.encode(from));
      return;
    }

    address innerToken = address(IWrapped777(address(_token)).token());
    address aToken = addressProvider.getLendingPool().core().getReserveATokenAddress(innerToken);
    if (aToken != address(0)) {
      address wrapper = getWrapperAddress(address(_token));

      _token.send(wrapper, amount, abi.encode(from));
    } else {
      revert("Unsupported token");
    }
  }
}