// File: @openzeppelin/contracts/math/SafeMath.sol



pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, 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) {
        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/token/ERC20/IERC20.sol



pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @openzeppelin/contracts/utils/Address.sol



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/token/ERC20/SafeERC20.sol



pragma solidity >=0.6.0 <0.8.0;




/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/aave/IFlashLoanReceiver.sol

pragma solidity ^0.6.6;

/**
* @title IFlashLoanReceiver interface
* @notice Interface for the Aave fee IFlashLoanReceiver.
* @author Aave
* @dev implement this interface to develop a flashloan-compatible flashLoanReceiver contract
**/
interface IFlashLoanReceiver {
    function executeOperation(address _reserve, uint256 _amount, uint256 _fee, bytes calldata _params) external;
}

// File: contracts/aave/ILendingPoolAddressesProvider.sol

pragma solidity ^0.6.6;

/**
    @title ILendingPoolAddressesProvider interface
    @notice provides the interface to fetch the LendingPoolCore address
 */

interface ILendingPoolAddressesProvider {
    function getLendingPoolCore() external view returns (address payable);
    function getLendingPool() external view returns (address);
}

// File: @openzeppelin/contracts/GSN/Context.sol



pragma solidity >=0.6.0 <0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol



pragma solidity >=0.6.0 <0.8.0;




/**
 * @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 {ERC20PresetMinterPauser}.
 *
 * 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;

    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 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: @openzeppelin/contracts/access/Ownable.sol



pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

// File: contracts/utils/Withdrawable.sol

pragma solidity ^0.6.6;




/**
    Ensures that any contract that inherits from this contract is able to
    withdraw funds that are accidentally received or stuck.
 */
 
contract Withdrawable is Ownable {
    using SafeERC20 for ERC20;
    address constant ETHER = address(0);

    event LogWithdraw(
        address indexed _from,
        address indexed _assetAddress,
        uint amount
    );

    /**
     * @dev Withdraw asset.
     * @param _assetAddress Asset to be withdrawn.
     */
    function withdraw(address _assetAddress) public onlyOwner {
        uint assetBalance;
        if (_assetAddress == ETHER) {
            address self = address(this); // workaround for a possible solidity bug
            assetBalance = self.balance;
            msg.sender.transfer(assetBalance);
        } else {
            assetBalance = ERC20(_assetAddress).balanceOf(address(this));
            ERC20(_assetAddress).safeTransfer(msg.sender, assetBalance);
        }
        emit LogWithdraw(msg.sender, _assetAddress, assetBalance);
    }
}

// File: contracts/aave/FlashLoanReceiverBase.sol

pragma solidity ^0.6.6;







abstract contract FlashLoanReceiverBase is IFlashLoanReceiver, Withdrawable {

    using SafeERC20 for IERC20;
    using SafeMath for uint256;

    address constant ethAddress = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
    ILendingPoolAddressesProvider public addressesProvider;

    constructor(address _addressProvider) public {
        addressesProvider = ILendingPoolAddressesProvider(_addressProvider);
    }

    receive() payable external {}

    function transferFundsBackToPoolInternal(address _reserve, uint256 _amount) internal {
        address payable core = addressesProvider.getLendingPoolCore();
        transferInternal(core, _reserve, _amount);
    }

    function transferInternal(address payable _destination, address _reserve, uint256 _amount) internal {
        if(_reserve == ethAddress) {
            (bool success, ) = _destination.call{value: _amount}("");
            require(success == true, "Couldn't transfer ETH");
            return;
        }
        IERC20(_reserve).safeTransfer(_destination, _amount);
    }

    function getBalanceInternal(address _target, address _reserve) internal view returns(uint256) {
        if(_reserve == ethAddress) {
            return _target.balance;
        }
        return IERC20(_reserve).balanceOf(_target);
    }
}

// File: contracts/aave/ILendingPool.sol

pragma solidity ^0.6.6;

interface ILendingPool {
  function addressesProvider () external view returns ( address );
  function deposit ( address _reserve, uint256 _amount, uint16 _referralCode ) external payable;
  function redeemUnderlying ( address _reserve, address _user, uint256 _amount ) external;
  function borrow ( address _reserve, uint256 _amount, uint256 _interestRateMode, uint16 _referralCode ) external;
  function repay ( address _reserve, uint256 _amount, address _onBehalfOf ) external payable;
  function swapBorrowRateMode ( address _reserve ) external;
  function rebalanceFixedBorrowRate ( address _reserve, address _user ) external;
  function setUserUseReserveAsCollateral ( address _reserve, bool _useAsCollateral ) external;
  function liquidationCall ( address _collateral, address _reserve, address _user, uint256 _purchaseAmount, bool _receiveAToken ) external payable;
  function flashLoan ( address _receiver, address _reserve, uint256 _amount, bytes calldata _params ) external;
  function getReserveConfigurationData ( address _reserve ) external view returns ( uint256 ltv, uint256 liquidationThreshold, uint256 liquidationDiscount, address interestRateStrategyAddress, bool usageAsCollateralEnabled, bool borrowingEnabled, bool fixedBorrowRateEnabled, bool isActive );
  function getReserveData ( address _reserve ) external view returns ( uint256 totalLiquidity, uint256 availableLiquidity, uint256 totalBorrowsFixed, uint256 totalBorrowsVariable, uint256 liquidityRate, uint256 variableBorrowRate, uint256 fixedBorrowRate, uint256 averageFixedBorrowRate, uint256 utilizationRate, uint256 liquidityIndex, uint256 variableBorrowIndex, address aTokenAddress, uint40 lastUpdateTimestamp );
  function getUserAccountData ( address _user ) external view returns ( uint256 totalLiquidityETH, uint256 totalCollateralETH, uint256 totalBorrowsETH, uint256 availableBorrowsETH, uint256 currentLiquidationThreshold, uint256 ltv, uint256 healthFactor );
  function getUserReserveData ( address _reserve, address _user ) external view returns ( uint256 currentATokenBalance, uint256 currentUnderlyingBalance, uint256 currentBorrowBalance, uint256 principalBorrowBalance, uint256 borrowRateMode, uint256 borrowRate, uint256 liquidityRate, uint256 originationFee, uint256 variableBorrowIndex, uint256 lastUpdateTimestamp, bool usageAsCollateralEnabled );
  function getReserves () external view;
}

// File: contracts/wepiggy/IComptroller.sol

pragma solidity 0.6.12;

interface IComptroller {

    /*** Assets You Are In ***/

    /**
     * PIGGY-MODIFY:
     * @notice Add assets to be included in account liquidity calculation
     * @param pTokens The list of addresses of the cToken markets to be enabled
     * @return Success indicator for whether each corresponding market was entered
     */
    function enterMarkets(address[] calldata pTokens) external returns (uint[] memory);

    /**
     * PIGGY-MODIFY:
     * @notice Removes asset from sender's account liquidity calculation
     * @dev Sender must not have an outstanding borrow balance in the asset,
     *  or be providing necessary collateral for an outstanding borrow.
     * @param pTokenAddress The address of the asset to be removed
     * @return Whether or not the account successfully exited the market
     */
    function exitMarket(address pTokenAddress) external returns (uint);

    /*** Policy Hooks ***/

    /**
     * PIGGY-MODIFY:
     * @notice Checks if the account should be allowed to mint tokens in the given market
     * @param pToken The market to verify the mint against
     * @param minter The account which would get the minted tokens
     * @param mintAmount The amount of underlying being supplied to the market in exchange for tokens
     * @return 0 if the mint is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function mintAllowed(
        address pToken,
        address minter,
        uint mintAmount
    ) external returns (uint);

    /**
     * PIGGY-MODIFY:
     * @notice Validates mint and reverts on rejection. May emit logs.
     * @param pToken Asset being minted
     * @param minter The address minting the tokens
     * @param mintAmount The amount of the underlying asset being minted
     * @param mintTokens The number of tokens being minted
     */
    function mintVerify(
        address pToken,
        address minter,
        uint mintAmount,
        uint mintTokens
    ) external;

    /**
     * PIGGY-MODIFY:
     * @notice Checks if the account should be allowed to redeem tokens in the given market
     * @param pToken The market to verify the redeem against
     * @param redeemer The account which would redeem the tokens
     * @param redeemTokens The number of cTokens to exchange for the underlying asset in the market
     * @return 0 if the redeem is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function redeemAllowed(
        address pToken,
        address redeemer,
        uint redeemTokens
    ) external returns (uint);

    /**
     * PIGGY-MODIFY:
     * @notice Validates redeem and reverts on rejection. May emit logs.
     * @param pToken Asset being redeemed
     * @param redeemer The address redeeming the tokens
     * @param redeemAmount The amount of the underlying asset being redeemed
     * @param redeemTokens The number of tokens being redeemed
     */
    function redeemVerify(
        address pToken,
        address redeemer,
        uint redeemAmount,
        uint redeemTokens
    ) external;

    /**
     * PIGGY-MODIFY:
     * @notice Checks if the account should be allowed to borrow the underlying asset of the given market
     * @param pToken The market to verify the borrow against
     * @param borrower The account which would borrow the asset
     * @param borrowAmount The amount of underlying the account would borrow
     * @return 0 if the borrow is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function borrowAllowed(
        address pToken,
        address borrower,
        uint borrowAmount
    ) external returns (uint);

    /**
     * PIGGY-MODIFY:
     * @notice Validates borrow and reverts on rejection. May emit logs.
     * @param pToken Asset whose underlying is being borrowed
     * @param borrower The address borrowing the underlying
     * @param borrowAmount The amount of the underlying asset requested to borrow
     */
    function borrowVerify(
        address pToken,
        address borrower,
        uint borrowAmount
    ) external;

    /**
     * PIGGY-MODIFY:
     * @notice Checks if the account should be allowed to repay a borrow in the given market
     * @param pToken The market to verify the repay against
     * @param payer The account which would repay the asset
     * @param borrower The account which would borrowed the asset
     * @param repayAmount The amount of the underlying asset the account would repay
     * @return 0 if the repay is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function repayBorrowAllowed(
        address pToken,
        address payer,
        address borrower,
        uint repayAmount
    ) external returns (uint);

    /**
     * PIGGY-MODIFY:
     * @notice Validates repayBorrow and reverts on rejection. May emit logs.
     * @param pToken Asset being repaid
     * @param payer The address repaying the borrow
     * @param borrower The address of the borrower
     * @param repayAmount The amount of underlying being repaid
     */
    function repayBorrowVerify(
        address pToken,
        address payer,
        address borrower,
        uint repayAmount,
        uint borrowerIndex
    ) external;

    /**
     * PIGGY-MODIFY:
     * @notice Checks if the liquidation should be allowed to occur
     * @param pTokenBorrowed Asset which was borrowed by the borrower
     * @param pTokenCollateral Asset which was used as collateral and will be seized
     * @param liquidator The address repaying the borrow and seizing the collateral
     * @param borrower The address of the borrower
     * @param repayAmount The amount of underlying being repaid
     */
    function liquidateBorrowAllowed(
        address pTokenBorrowed,
        address pTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount
    ) external returns (uint);

    /**
     * PIGGY-MODIFY:
     * @notice Validates liquidateBorrow and reverts on rejection. May emit logs.
     * @param pTokenBorrowed Asset which was borrowed by the borrower
     * @param pTokenCollateral Asset which was used as collateral and will be seized
     * @param liquidator The address repaying the borrow and seizing the collateral
     * @param borrower The address of the borrower
     * @param repayAmount The amount of underlying being repaid
     */
    function liquidateBorrowVerify(
        address pTokenBorrowed,
        address pTokenCollateral,
        address liquidator,
        address borrower,
        uint repayAmount,
        uint seizeTokens
    ) external;

    /**
     * PIGGY-MODIFY:
     * @notice Checks if the seizing of assets should be allowed to occur
     * @param pTokenCollateral Asset which was used as collateral and will be seized
     * @param pTokenBorrowed Asset which was borrowed by the borrower
     * @param liquidator The address repaying the borrow and seizing the collateral
     * @param borrower The address of the borrower
     * @param seizeTokens The number of collateral tokens to seize
     */
    function seizeAllowed(
        address pTokenCollateral,
        address pTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens
    ) external returns (uint);

    /**
     * PIGGY-MODIFY:
     * @notice Validates seize and reverts on rejection. May emit logs.
     * @param pTokenCollateral Asset which was used as collateral and will be seized
     * @param pTokenBorrowed Asset which was borrowed by the borrower
     * @param liquidator The address repaying the borrow and seizing the collateral
     * @param borrower The address of the borrower
     * @param seizeTokens The number of collateral tokens to seize
     */
    function seizeVerify(
        address pTokenCollateral,
        address pTokenBorrowed,
        address liquidator,
        address borrower,
        uint seizeTokens
    ) external;

    /**
     * PIGGY-MODIFY:
     * @notice Checks if the account should be allowed to transfer tokens in the given market
     * @param pToken The market to verify the transfer against
     * @param src The account which sources the tokens
     * @param dst The account which receives the tokens
     * @param transferTokens The number of pTokens to transfer
     * @return 0 if the transfer is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
     */
    function transferAllowed(
        address pToken,
        address src,
        address dst,
        uint transferTokens
    ) external returns (uint);

    /**
     * PIGGY-MODIFY:
     * @notice Validates transfer and reverts on rejection. May emit logs.
     * @param pToken Asset being transferred
     * @param src The account which sources the tokens
     * @param dst The account which receives the tokens
     * @param transferTokens The number of pTokens to transfer
     */
    function transferVerify(
        address pToken,
        address src,
        address dst,
        uint transferTokens
    ) external;

    /*** Liquidity/Liquidation Calculations ***/

    /**
     * PIGGY-MODIFY:
    * @notice Calculate number of tokens of collateral asset to seize given an underlying amount
    * @dev Used in liquidation (called in cToken.liquidateBorrowFresh)
    * @param pTokenBorrowed The address of the borrowed cToken
    * @param pTokenCollateral The address of the collateral cToken
    * @param repayAmount The amount of cTokenBorrowed underlying to convert into cTokenCollateral tokens
    * @return (errorCode, number of cTokenCollateral tokens to be seized in a liquidation)
    */
    function liquidateCalculateSeizeTokens(
        address pTokenBorrowed,
        address pTokenCollateral,
        uint repayAmount
    ) external view returns (uint, uint);
}

// File: contracts/wepiggy/IInterestRateModel.sol

pragma solidity ^0.6.0;

/**
  * @title wepiggy's IInterestRateModel Interface
  * @author wepiggy
  */
interface IInterestRateModel {
    /**
      * @notice Calculates the current borrow interest rate per block
      * @param cash The total amount of cash the market has
      * @param borrows The total amount of borrows the market has outstanding
      * @param reserves The total amount of reserves the market has
      * @return The borrow rate per block (as a percentage, and scaled by 1e18)
      */
    function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint);

    /**
      * @notice Calculates the current supply interest rate per block
      * @param cash The total amount of cash the market has
      * @param borrows The total amount of borrows the market has outstanding
      * @param reserves The total amount of reserves the market has
      * @param reserveFactorMantissa The current reserve factor the market has
      * @return The supply rate per block (as a percentage, and scaled by 1e18)
      */
    function getSupplyRate(uint cash, uint borrows, uint reserves, uint reserveFactorMantissa) external view returns (uint);

}

// File: contracts/wepiggy/IPToken.sol

pragma solidity ^0.6.0;



contract PTokenStorage {
    /**
     * @notice Indicator that this is a PToken contract (for inspection)
     */
    bool public constant isPToken = true;

    /**
     * @dev Guard variable for re-entrancy checks
     */
    bool internal _notEntered;

    /**
     * @dev
     * @notice EIP-20 token name for this token
     */
    string public name;

    /**
     * @dev
     * @notice EIP-20 token symbol for this token
     */
    string public symbol;

    /**
     * @dev
     * @notice EIP-20 token decimals for this token
     */
    uint8 public decimals;

    /**
     * @dev
     * @notice Maximum borrow rate that can ever be applied (.0005% / block)
     */

    uint256 internal constant borrowRateMaxMantissa = 0.0005e16;

    /**
     * @dev
     * @notice Maximum fraction of interest that can be set aside for reserves
     */
    uint256 internal constant reserveFactorMaxMantissa = 1e18;

    /**
     * @dev
     * @notice Contract which oversees inter-pToken operations
     */
    IComptroller public comptroller;

    /**
     * @dev
     * @notice Model which tells what the current interest rate should be
     */
    IInterestRateModel public interestRateModel;

    /**
     * @dev
     * @notice Initial exchange rate used when minting the first PTokens (used when totalSupply = 0)
     */
    uint256 internal initialExchangeRateMantissa;

    /**
     * @dev
     * @notice Fraction of interest currently set aside for reserves
     */
    uint256 public reserveFactorMantissa;

    /**
     * @dev
     * @notice Block number that interest was last accrued at
     */
    uint256 public accrualBlockNumber;

    /**
     * @dev
     * @notice Accumulator of the total earned interest rate since the opening of the market
     */
    uint256 public borrowIndex;

    /**
     * @dev
     * @notice Total amount of outstanding borrows of the underlying in this market
     */
    uint256 public totalBorrows;

    /**
     * @dev
     * @notice Total amount of reserves of the underlying held in this market
     */
    uint256 public totalReserves;

    /**
     * @dev
     * @notice Total number of tokens in circulation
     */
    uint256 public totalSupply;

    /**
     * @dev
     * @notice Official record of token balances for each account
     */
    mapping(address => uint256) internal accountTokens;

    /**
     * @dev
     * @notice Approved token transfer amounts on behalf of others
     */
    mapping(address => mapping(address => uint256)) internal transferAllowances;

    /**
     * @notice Container for borrow balance information
     * @member principal Total balance (with accrued interest), after applying the most recent balance-changing action
     * @member interestIndex Global borrowIndex as of the most recent balance-changing action
     */
    struct BorrowSnapshot {
        uint256 principal;
        uint256 interestIndex;
    }

    /**
     * @dev
     * @notice Mapping of account addresses to outstanding borrow balances
     */
    mapping(address => BorrowSnapshot) internal accountBorrows;

    address public migrator;

    uint256 public minInterestAccumulated;

}

abstract contract IPToken is PTokenStorage {

    /*** User Interface ***/

    function transfer(address dst, uint256 amount) external virtual returns (bool);

    function transferFrom(address src, address dst, uint256 amount) external virtual returns (bool);

    function approve(address spender, uint256 amount) external virtual returns (bool);

    function allowance(address owner, address spender) external virtual view returns (uint256);

    function balanceOf(address owner) external virtual view returns (uint256);

    function balanceOfUnderlying(address owner) external virtual returns (uint256);

    function getAccountSnapshot(address account) external virtual view returns (uint256, uint256, uint256, uint256);

    function borrowRatePerBlock() external virtual view returns (uint256);

    function supplyRatePerBlock() external virtual view returns (uint256);

    function totalBorrowsCurrent() external virtual returns (uint256);

    function borrowBalanceCurrent(address account) external virtual returns (uint256);

    function borrowBalanceStored(address account) public virtual view returns (uint256);

    function exchangeRateCurrent() public virtual returns (uint256);

    function exchangeRateStored() public virtual view returns (uint256);

    function getCash() external virtual view returns (uint256);

    function accrueInterest() public virtual returns (uint256);

    function seize(address liquidator, address borrower, uint256 seizeTokens) external virtual returns (uint256);

    /*** Admin Functions ***/

    function _setComptroller(IComptroller newComptroller) public virtual returns (uint256);

    function _setReserveFactor(uint256 newReserveFactorMantissa) external virtual returns (uint256);

    function _reduceReserves(uint256 reduceAmount) external virtual returns (uint256);

    function _setInterestRateModel(IInterestRateModel newInterestRateModel) public virtual returns (uint256);

    function _setMigrator(address newMigrator) public virtual returns (uint256);

    function _setMinInterestAccumulated(uint _minInterestAccumulated) public virtual returns (uint256);
}

// File: contracts/wepiggy/IPETH.sol

pragma solidity ^0.6.0;


abstract contract IPETH is IPToken {

    /*** User Interface ***/
    function mint() external payable virtual;

    function redeem(uint redeemTokens) external virtual returns (uint);

    function redeemUnderlying(uint redeemAmount) external virtual returns (uint);

    function borrow(uint borrowAmount) external virtual returns (uint);

    function repayBorrow() external payable virtual;

    function repayBorrowBehalf(address borrower) external virtual payable;

    function liquidateBorrow(address borrower, IPToken pTokenCollateral) external virtual payable;

}

// File: contracts/wepiggy/IPERC20.sol

pragma solidity ^0.6.0;


abstract contract IPERC20 is IPToken {

    address public underlying;

    /*** User Interface ***/

    function mint(uint256 mintAmount) external virtual returns (uint256);

    function redeem(uint256 redeemTokens) external virtual returns (uint256);

    function redeemUnderlying(uint256 redeemAmount) external virtual returns (uint256);

    function borrow(uint256 borrowAmount) external virtual returns (uint256);

    function repayBorrow(uint256 repayAmount) external virtual returns (uint256);

    function repayBorrowBehalf(address borrower, uint256 repayAmount) external virtual returns (uint256);

    function liquidateBorrow(address borrower, uint256 repayAmount, IPToken pTokenCollateral) external virtual returns (uint256);

    /*** Admin Functions ***/

    function _addReserves(uint256 addAmount) external virtual returns (uint256);
}

// File: contracts/uniswap/IUniswapV2Router01.sol

pragma solidity >=0.6.2;

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

// File: contracts/uniswap/IUniswapV2Router02.sol

pragma solidity >=0.6.2;


interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

// File: contracts/FlashLoanLiquidateWePiggy.sol

pragma solidity 0.6.12;













contract FlashLoanLiquidateWePiggy is FlashLoanReceiverBase {

    using SafeERC20 for IERC20;
    using SafeMath for uint256;

    IComptroller public comptroller;
    IUniswapV2Router02 public uniswapRouter;
    bool public transferAtOnce;

    constructor(address _addressProvider, address _addressComptroller, address _addressUniswapRouter) FlashLoanReceiverBase(_addressProvider) public {
        comptroller = IComptroller(_addressComptroller);
        uniswapRouter = IUniswapV2Router02(_addressUniswapRouter);
    }

    /**
        This function is called after your contract has received the flash loaned amount
     */
    function executeOperation(
        address _reserve,
        uint256 _amount,
        uint256 _fee,
        bytes calldata _params
    )
    external
    override
    {
        require(_amount <= getBalanceInternal(address(this), _reserve), "Invalid balance, was the flashLoan successful?");

        // pTokenBorrow 要被清算的pToken ; pTokenCollateral 抵押物pToken ; borrower 借款人 ; repayAmount 清算数量 ; path uniswap的交易路径
        (address _pTokenBorrow,address _pTokenCollateral,address borrower, uint repayAmount,address[] memory path) = abi.decode(_params, (address, address, address, uint, address[]));

        IPToken pTokenBorrow = IPToken(_pTokenBorrow);
        IPToken pTokenCollateral = IPToken(_pTokenCollateral);

        uint totalDebt = _amount.add(_fee);

        //enterMarket
        address[] memory pTokens = new address[](2);
        pTokens[0] = _pTokenBorrow;
        pTokens[1] = _pTokenCollateral;
        comptroller.enterMarkets(pTokens);

        if (_isEth(pTokenBorrow.symbol()) && _isEth(pTokenCollateral.symbol())) {

            _liquidateETHAndRepayETH(IPETH(_pTokenBorrow), IPETH(_pTokenCollateral), borrower, repayAmount, path, totalDebt);

        } else if (_isEth(pTokenBorrow.symbol()) && !_isEth(pTokenCollateral.symbol())) {

            _liquidateETHAndRepayERC20(IPETH(_pTokenBorrow), IPERC20(_pTokenCollateral), borrower, repayAmount, path, totalDebt);

        } else if (!_isEth(pTokenBorrow.symbol()) && _isEth(pTokenCollateral.symbol())) {

            _liquidateERC20AndRepayETH(IPERC20(_pTokenBorrow), IPETH(_pTokenCollateral), borrower, repayAmount, path, totalDebt);

        } else if (!_isEth(pTokenBorrow.symbol()) && !_isEth(pTokenCollateral.symbol())) {

            _liquidateERC20AndRepayERC20(IPERC20(_pTokenBorrow), IPERC20(_pTokenCollateral), borrower, repayAmount, path, totalDebt);
        }


        transferFundsBackToPoolInternal(_reserve, totalDebt);
    }

    /**
    *  _asset 需要借款的代币的合约地址，ETH为 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE
    *  amount 需要借款的金额
    */
    function liquidate(address _asset, uint amount, bytes memory data) public {
        ILendingPool lendingPool = ILendingPool(addressesProvider.getLendingPool());
        lendingPool.flashLoan(address(this), _asset, amount, data);

        if (transferAtOnce) {
            _transferInternal(_asset, msg.sender, getBalanceInternal(address(this), _asset));
        }
    }

    function transfer(address _asset, address payable _to, uint amount) public onlyOwner {
        _transferInternal(_asset, _to, amount);
    }

    function setTransferAtOnce(bool _transferAtOnce) public onlyOwner {
        transferAtOnce = _transferAtOnce;
    }

    function setComptroller(address _addressComptroller) public onlyOwner {
        comptroller = IComptroller(_addressComptroller);
    }


    // 清算ETH && 赎回ETH
    function _liquidateETHAndRepayETH(
        IPETH pTokenBorrow,
        IPETH pTokenCollateral,
        address borrower,
        uint repayAmount,
        address[] memory path,
        uint totalDebt
    )
    internal
    {

        address self = address(this);

        //计算清算的值
        (,uint seized) = comptroller.liquidateCalculateSeizeTokens(address(pTokenBorrow), address(pTokenCollateral), repayAmount);

        uint beforeBalance = pTokenCollateral.balanceOf(self);

        //调用清算方法
        pTokenBorrow.liquidateBorrow{value : repayAmount}(borrower, pTokenCollateral);

        uint afterBalance = pTokenCollateral.balanceOf(self);
        if (afterBalance.sub(beforeBalance) < seized) {
            seized = afterBalance.sub(beforeBalance);
        }

        //赎回ETH
        pTokenCollateral.redeem(seized);

    }

    // 清算ETH && 赎回ERC20 ， 得到 ETH
    function _liquidateETHAndRepayERC20(
        IPETH pTokenBorrow,
        IPERC20 pTokenCollateral,
        address borrower,
        uint repayAmount,
        address[] memory path,
        uint totalDebt
    )
    internal
    {

        address self = address(this);

        //计算清算的值
        (,uint seized) = comptroller.liquidateCalculateSeizeTokens(address(pTokenBorrow), address(pTokenCollateral), repayAmount);

        uint beforeBalance = pTokenCollateral.balanceOf(self);

        //调用清算方法
        pTokenBorrow.liquidateBorrow{value : repayAmount}(borrower, pTokenCollateral);

        uint afterBalance = pTokenCollateral.balanceOf(self);
        if (afterBalance.sub(beforeBalance) < seized) {
            seized = afterBalance.sub(beforeBalance);
        }

        //赎回ERC20
        pTokenCollateral.redeem(seized);

        //去 uniSwap等交易所进行交易，获得 ETH
        IERC20 erc20 = IERC20(pTokenCollateral.underlying());
        uint amountIn = erc20.balanceOf(self);
        _approveMax(address(erc20), address(uniswapRouter), amountIn);

        uniswapRouter.swapExactTokensForETH(amountIn, totalDebt, path, self, block.timestamp);

    }

    // 清算ERC20 && 赎回ETH ， 得到 ERC20  --> OK
    function _liquidateERC20AndRepayETH(
        IPERC20 pTokenBorrow,
        IPETH pTokenCollateral,
        address borrower,
        uint repayAmount,
        address[] memory path,
        uint totalDebt
    )
    internal
    {
        address self = address(this);

        //计算清算的值
        (,uint seized) = comptroller.liquidateCalculateSeizeTokens(address(pTokenBorrow), address(pTokenCollateral), repayAmount);

        uint beforeBalance = pTokenCollateral.balanceOf(self);

        //调用清算方法
        IERC20 erc20 = IERC20(pTokenBorrow.underlying());
        _approveMax(address(erc20), address(pTokenBorrow), repayAmount);
        pTokenBorrow.liquidateBorrow(borrower, repayAmount, pTokenCollateral);

        uint afterBalance = pTokenCollateral.balanceOf(self);
        if (afterBalance.sub(beforeBalance) < seized) {
            seized = afterBalance.sub(beforeBalance);
        }

        //赎回ETH
        pTokenCollateral.redeem(seized);

        //去 uniSwap等交易所进行交易，获得 对应的token
        uint amountIn = self.balance;
        uniswapRouter.swapExactETHForTokens{value : amountIn}(totalDebt, path, self, block.timestamp);

    }

    // 清算ERC20 && 赎回ERC20  --> OK
    function _liquidateERC20AndRepayERC20(
        IPERC20 pTokenBorrow,
        IPERC20 pTokenCollateral,
        address borrower,
        uint repayAmount,
        address[] memory path,
        uint totalDebt
    )
    internal
    {

        address self = address(this);

        //计算清算的值
        (,uint seized) = comptroller.liquidateCalculateSeizeTokens(address(pTokenBorrow), address(pTokenCollateral), repayAmount);

        uint beforeBalance = pTokenCollateral.balanceOf(self);

        //调用清算方法
        IERC20 erc20 = IERC20(pTokenBorrow.underlying());
        _approveMax(address(erc20), address(pTokenBorrow), repayAmount);
        pTokenBorrow.liquidateBorrow(borrower, repayAmount, pTokenCollateral);

        uint afterBalance = pTokenCollateral.balanceOf(self);
        if (afterBalance.sub(beforeBalance) < seized) {
            seized = afterBalance.sub(beforeBalance);
        }

        //赎回ERC20
        pTokenCollateral.redeem(seized);

        //去 uniSwap等交易所进行交易，获得 ERC20。（不相同的时候进行交易）
        if (pTokenBorrow.underlying() != pTokenCollateral.underlying()) {
            IERC20 erc20 = IERC20(pTokenCollateral.underlying());
            uint amountIn = erc20.balanceOf(self);
            _approveMax(address(erc20), address(uniswapRouter), amountIn);
            uniswapRouter.swapExactTokensForTokens(amountIn, totalDebt, path, self, block.timestamp);
        }

    }

    function _transferInternal(address _asset, address payable _to, uint amount) internal {
        address self = address(this);

        uint balance = getBalanceInternal(self, _asset);
        if (balance < amount) {
            amount = balance;
        }

        transferInternal(_to, _asset, amount);
    }

    function _isEth(string memory symbol) internal pure returns (bool){
        return _compareStrings(symbol, "pETH");
    }

    function _approveMax(address _asset, address _spender, uint amount) internal {
        IERC20 erc20 = IERC20(_asset);

        uint allowance = erc20.allowance(address(this), _spender);
        if (allowance < amount) {
            uint MAX_INT = 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff;
            erc20.safeApprove(_spender, MAX_INT);
        }
    }

    function _compareStrings(string memory a, string memory b) internal pure returns (bool) {
        return (keccak256(abi.encodePacked((a))) == keccak256(abi.encodePacked((b))));
    }


}