// File: contracts/treasury/LiquidationStrategyBase.sol



// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.7.6;

import {PermissionAdmin, PermissionOperators} from '@kyber.network/utils-sc/contracts/PermissionOperators.sol';
import {Utils} from '@kyber.network/utils-sc/contracts/Utils.sol';
import {IERC20Ext} from '@kyber.network/utils-sc/contracts/IERC20Ext.sol';
import {ReentrancyGuard} from '@openzeppelin/contracts/utils/ReentrancyGuard.sol';
import {SafeMath} from '@openzeppelin/contracts/math/SafeMath.sol';
import {SafeERC20} from '@openzeppelin/contracts/token/ERC20/SafeERC20.sol';
import {EnumerableSet} from '@openzeppelin/contracts/utils/EnumerableSet.sol';
import {ILiquidationCallback} from '../interfaces/liquidation/ILiquidationCallback.sol';
import {ILiquidationStrategyBase, ILiquidationPriceOracleBase} from '../interfaces/liquidation/ILiquidationStrategyBase.sol';
import {IPool} from '../interfaces/liquidation/IPool.sol';

contract LiquidationStrategyBase is ILiquidationStrategyBase, PermissionOperators,
  Utils, ReentrancyGuard {

  using SafeERC20 for IERC20Ext;
  using SafeMath for uint256;
  using EnumerableSet for EnumerableSet.AddressSet;

  // after repeatedPeriod since startTime, there will be duration (in seconds)
  // for liquidators to liquidate tokens in the treasury pool
  // for example: from deployed time, every 2 weeks liquidation is enabled for 4 days
  struct LiquidationSchedule {
    uint128 startTime;
    uint64 repeatedPeriod;
    uint64 duration;
  }

  // list of tokens that can be liquidate to
  EnumerableSet.AddressSet private _whitelistedLiquidators;
  EnumerableSet.AddressSet private _whitelistedPriceOracles;

  LiquidationSchedule private _liquidationSchedule;
  IPool private _treasuryPool;
  address payable private _rewardPool;

  bool public paused = false;
  event Pause(address caller, bool isPaused);

  event TreasuryPoolSet(address indexed treasuryPool);
  event RewardPoolSet(address indexed rewardPool);
  event LiquidationScheduleUpdated(uint128 startTime, uint64 repeatedPeriod, uint64 duration);
  event WhitelistedLiquidatorUpdated(address indexed liquidator, bool indexed isAdd);
  event WhitelistedPriceOracleUpdated(address indexed oracle, bool indexed isAdd);

  constructor(
    address admin,
    address treasuryPoolAddress,
    address payable rewardPoolAddress,
    uint128 startTime,
    uint64 repeatedPeriod,
    uint64 duration,
    address[] memory whitelistedLiquidators,
    address[] memory whitelistedOracles
  ) PermissionAdmin(admin) {
    _setTreasuryPool(treasuryPoolAddress);
    _setRewardPool(rewardPoolAddress);
    _setLiquidationSchedule(startTime, repeatedPeriod, duration);
    _updateWhitelistedLiquidators(whitelistedLiquidators, true);
    _updateWhitelistedPriceOracles(whitelistedOracles, true);
  }

  receive() external payable {}

  /**
   * @dev Update liquidation schedule
   *  to disable the liquidation: set repeatedPeriod to 0
   *  to always enable the liquidation: set duration >= repeatedPeriod
   * @param startTime: start time of the first liquidation schedule
   * @param repeatedPeriod period in seconds that the schedule will be repeated
   * @param duration duration of each schedule
   */
  function updateLiquidationSchedule(
    uint128 startTime,
    uint64 repeatedPeriod,
    uint64 duration
  )
    external onlyAdmin
  {
    _setLiquidationSchedule(startTime, repeatedPeriod, duration);
  }

  function updateTreasuryPool(address pool) external override onlyAdmin {
    _setTreasuryPool(pool);
  }

  function updateRewardPool(address payable pool) external override onlyAdmin {
    _setRewardPool(pool);
  }

  function updateWhitelistedLiquidators(address[] calldata liquidators, bool isAdd)
    external override onlyAdmin
  {
    _updateWhitelistedLiquidators(liquidators, isAdd);
  }

  function updateWhitelistedOracles(address[] calldata oracles, bool isAdd)
    external override onlyAdmin
  {
    _updateWhitelistedPriceOracles(oracles, isAdd);
  }

  /**
   * @dev Allow operator to pause the liquidation in case of emergency
   *  It's faster and more flexible than waiting for a proposal
   */
  function setPause(bool isPause) external onlyOperator {
    paused = isPause;
    emit Pause(msg.sender, isPause);
  }

  /** @dev Liquidate list of tokens to a single dest token,
  *   source token must not be a whitelisted token, dest must be a whitelisted token
  *   in case whitelisted liquidator is enabled, sender must be whitelisted
  *   funds need to be transferred back to the LiquidationStrategy before transferring to RewardPool
  * @param oracle the whitelisted oracle that will be used to get conversion data
  * @param sources list of source tokens to liquidate
  * @param amounts list of amounts corresponding to each source token
  * @param recipient receiver of source tokens
  * @param dest dest token to liquidate to
  * @param oracleHint hint for getting data from oracle
  * @param txData data to callback to recipient
  */
  function liquidate(
    ILiquidationPriceOracleBase oracle,
    IERC20Ext[] calldata sources,
    uint256[] calldata amounts,
    address payable recipient,
    IERC20Ext dest,
    bytes calldata oracleHint,
    bytes calldata txData
  )
    external virtual override nonReentrant
    returns (uint256 destAmount)
  {
    require(!paused, 'liquidate: only when not paused');
    require(isWhitelistedLiquidator(msg.sender), 'liquidate: only whitelisted liquidator');
    require(isWhitelistedOracle(address(oracle)), 'liquidate: only whitelisted oracle');
    require(isLiquidationEnabled(), 'liquidate: only when liquidation enabled');

    // request return data from oracle
    uint256 minReturn = oracle.getExpectedReturn(
      msg.sender, sources, amounts, dest, oracleHint
    );
    require(minReturn > 0, 'liquidate: minReturn == 0');

    uint256 destBalance = getBalance(dest, address(this));

    // request funds from treasury pool to recipient
    _treasuryPool.withdrawFunds(sources, amounts, recipient);
    // callback to recipient to transfer dest amount to reward
    // internal function to prevent stack too deep
    _liquidationCallback(sources, amounts, recipient, dest, minReturn, txData);

    destAmount = getBalance(dest, address(this)).sub(destBalance);
    require(destAmount >= minReturn, 'liquidate: low return amount');
    _transferToken(dest, rewardPool(), destAmount);
  }

  // Whitelisted liquidators
  function getWhitelistedLiquidatorsLength() external override view returns (uint256) {
    return _whitelistedLiquidators.length();
  }

  function getWhitelistedLiquidatorAt(uint256 index) external override view returns (address) {
    return _whitelistedLiquidators.at(index);
  }

  function getAllWhitelistedLiquidators()
    external view override returns (address[] memory liquidators)
  {
    uint256 length = _whitelistedLiquidators.length();
    liquidators = new address[](length);
    for(uint256 i = 0; i < length; i++) {
      liquidators[i] = _whitelistedLiquidators.at(i);
    }
  }

  // Whitelisted Price Orcales
  function getWhitelistedPriceOraclesLength() external override view returns (uint256) {
    return _whitelistedPriceOracles.length();
  }

  function getWhitelistedPriceOracleAt(uint256 index) external override view returns (address) {
    return _whitelistedPriceOracles.at(index);
  }

  function getAllWhitelistedPriceOracles()
    external view override returns (address[] memory oracles)
  {
    uint256 length = _whitelistedPriceOracles.length();
    oracles = new address[](length);
    for(uint256 i = 0; i < length; i++) {
      oracles[i] = _whitelistedPriceOracles.at(i);
    }
  }

  function getLiquidationSchedule()
    external override view
    returns(
      uint128 startTime,
      uint64 repeatedPeriod,
      uint64 duration
    )
  {
    (startTime, repeatedPeriod, duration) = (
      _liquidationSchedule.startTime,
      _liquidationSchedule.repeatedPeriod,
      _liquidationSchedule.duration
    );
  }

  function treasuryPool() public override view returns (address) {
    return address(_treasuryPool);
  }

  function rewardPool() public override view returns (address payable) {
    return _rewardPool;
  }

  function isWhitelistedLiquidator(address liquidator)
    public view override returns (bool)
  {
    return _whitelistedLiquidators.contains(liquidator);
  }

  function isWhitelistedOracle(address oracle)
    public view override returns (bool)
  {
    return _whitelistedPriceOracles.contains(oracle);
  }

  function isLiquidationEnabled() public view override returns (bool) {
    LiquidationSchedule memory schedule = _liquidationSchedule;
    if (schedule.duration == 0) return false;
    if (block.timestamp < uint256(schedule.startTime)) return false;
    uint256 timeInPeriod = (block.timestamp - uint256(schedule.startTime)) % uint256(schedule.repeatedPeriod);
    return timeInPeriod < schedule.duration;
  }

  function _setTreasuryPool(address _pool) internal {
    require(_pool != address(0), 'invalid treasury pool');
    _treasuryPool = IPool(_pool);
    emit TreasuryPoolSet(_pool);
  }

  function _setRewardPool(address payable _pool) internal {
    require(_pool != address(0), 'invalid reward pool');
    _rewardPool = _pool;
    emit RewardPoolSet(_pool);
  }

  function _updateWhitelistedLiquidators(address[] memory _liquidators, bool _isAdd) internal {
    for(uint256 i = 0; i < _liquidators.length; i++) {
      if (_isAdd) {
        _whitelistedLiquidators.add(_liquidators[i]);
      } else {
        _whitelistedLiquidators.remove(_liquidators[i]);
      }
      emit WhitelistedLiquidatorUpdated(_liquidators[i], _isAdd);
    }
  }

  function _updateWhitelistedPriceOracles(address[] memory _oracles, bool _isAdd) internal {
    for(uint256 i = 0; i < _oracles.length; i++) {
      if (_isAdd) {
        _whitelistedPriceOracles.add(_oracles[i]);
      } else {
        _whitelistedPriceOracles.remove(_oracles[i]);
      }
      emit WhitelistedPriceOracleUpdated(_oracles[i], _isAdd);
    }
  }

  function _setLiquidationSchedule(
    uint128 _startTime,
    uint64 _repeatedPeriod,
    uint64 _duration
  ) internal {
    require(_repeatedPeriod > 0, 'repeated period is 0');
    _liquidationSchedule = LiquidationSchedule({
        startTime: _startTime,
        repeatedPeriod: _repeatedPeriod,
        duration: _duration
    });
    emit LiquidationScheduleUpdated(_startTime, _repeatedPeriod, _duration);
  }

  function _transferToken(IERC20Ext token, address payable recipient, uint256 amount) internal {
    if (token == ETH_TOKEN_ADDRESS) {
      (bool success, ) = recipient.call { value: amount }('');
      require(success, 'transfer eth failed');
    } else {
      token.safeTransfer(recipient, amount);
    }
  }

  function _liquidationCallback(
    IERC20Ext[] memory sources,
    uint256[] memory amounts,
    address payable recipient,
    IERC20Ext dest,
    uint256 minReturn,
    bytes calldata txData
  ) internal {
    ILiquidationCallback(recipient).liquidationCallback(
      msg.sender, sources, amounts, address(this), dest, minReturn, txData
    );
  }
}

// File: @kyber.network/utils-sc/contracts/PermissionOperators.sol



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

import "./PermissionAdmin.sol";


abstract contract PermissionOperators is PermissionAdmin {
    uint256 private constant MAX_GROUP_SIZE = 50;

    mapping(address => bool) internal operators;
    address[] internal operatorsGroup;

    event OperatorAdded(address newOperator, bool isAdd);

    modifier onlyOperator() {
        require(operators[msg.sender], "only operator");
        _;
    }

    function getOperators() external view returns (address[] memory) {
        return operatorsGroup;
    }

    function addOperator(address newOperator) public onlyAdmin {
        require(!operators[newOperator], "operator exists"); // prevent duplicates.
        require(operatorsGroup.length < MAX_GROUP_SIZE, "max operators");

        emit OperatorAdded(newOperator, true);
        operators[newOperator] = true;
        operatorsGroup.push(newOperator);
    }

    function removeOperator(address operator) public onlyAdmin {
        require(operators[operator], "not operator");
        operators[operator] = false;

        for (uint256 i = 0; i < operatorsGroup.length; ++i) {
            if (operatorsGroup[i] == operator) {
                operatorsGroup[i] = operatorsGroup[operatorsGroup.length - 1];
                operatorsGroup.pop();
                emit OperatorAdded(operator, false);
                break;
            }
        }
    }
}

// File: @kyber.network/utils-sc/contracts/Utils.sol



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

import "./IERC20Ext.sol";


/**
 * @title Kyber utility file
 * mostly shared constants and rate calculation helpers
 * inherited by most of kyber contracts.
 * previous utils implementations are for previous solidity versions.
 */
abstract contract Utils {
    // Declared constants below to be used in tandem with
    // getDecimalsConstant(), for gas optimization purposes
    // which return decimals from a constant list of popular
    // tokens.
    IERC20Ext internal constant ETH_TOKEN_ADDRESS = IERC20Ext(
        0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE
    );
    IERC20Ext internal constant USDT_TOKEN_ADDRESS = IERC20Ext(
        0xdAC17F958D2ee523a2206206994597C13D831ec7
    );
    IERC20Ext internal constant DAI_TOKEN_ADDRESS = IERC20Ext(
        0x6B175474E89094C44Da98b954EedeAC495271d0F
    );
    IERC20Ext internal constant USDC_TOKEN_ADDRESS = IERC20Ext(
        0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48
    );
    IERC20Ext internal constant WBTC_TOKEN_ADDRESS = IERC20Ext(
        0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599
    );
    IERC20Ext internal constant KNC_TOKEN_ADDRESS = IERC20Ext(
        0xdd974D5C2e2928deA5F71b9825b8b646686BD200
    );
    uint256 public constant BPS = 10000; // Basic Price Steps. 1 step = 0.01%
    uint256 internal constant PRECISION = (10**18);
    uint256 internal constant MAX_QTY = (10**28); // 10B tokens
    uint256 internal constant MAX_RATE = (PRECISION * 10**7); // up to 10M tokens per eth
    uint256 internal constant MAX_DECIMALS = 18;
    uint256 internal constant ETH_DECIMALS = 18;
    uint256 internal constant MAX_ALLOWANCE = uint256(-1); // token.approve inifinite

    mapping(IERC20Ext => uint256) internal decimals;

    /// @dev Sets the decimals of a token to storage if not already set, and returns
    ///      the decimals value of the token. Prefer using this function over
    ///      getDecimals(), to avoid forgetting to set decimals in local storage.
    /// @param token The token type
    /// @return tokenDecimals The decimals of the token
    function getSetDecimals(IERC20Ext token) internal returns (uint256 tokenDecimals) {
        tokenDecimals = getDecimalsConstant(token);
        if (tokenDecimals > 0) return tokenDecimals;

        tokenDecimals = decimals[token];
        if (tokenDecimals == 0) {
            tokenDecimals = token.decimals();
            decimals[token] = tokenDecimals;
        }
    }

    /// @dev Get the balance of a user
    /// @param token The token type
    /// @param user The user's address
    /// @return The balance
    function getBalance(IERC20Ext token, address user) internal view returns (uint256) {
        if (token == ETH_TOKEN_ADDRESS) {
            return user.balance;
        } else {
            return token.balanceOf(user);
        }
    }

    /// @dev Get the decimals of a token, read from the constant list, storage,
    ///      or from token.decimals(). Prefer using getSetDecimals when possible.
    /// @param token The token type
    /// @return tokenDecimals The decimals of the token
    function getDecimals(IERC20Ext token) internal view returns (uint256 tokenDecimals) {
        // return token decimals if has constant value
        tokenDecimals = getDecimalsConstant(token);
        if (tokenDecimals > 0) return tokenDecimals;

        // handle case where token decimals is not a declared decimal constant
        tokenDecimals = decimals[token];
        // moreover, very possible that old tokens have decimals 0
        // these tokens will just have higher gas fees.
        return (tokenDecimals > 0) ? tokenDecimals : token.decimals();
    }

    function calcDestAmount(
        IERC20Ext src,
        IERC20Ext dest,
        uint256 srcAmount,
        uint256 rate
    ) internal view returns (uint256) {
        return calcDstQty(srcAmount, getDecimals(src), getDecimals(dest), rate);
    }

    function calcSrcAmount(
        IERC20Ext src,
        IERC20Ext dest,
        uint256 destAmount,
        uint256 rate
    ) internal view returns (uint256) {
        return calcSrcQty(destAmount, getDecimals(src), getDecimals(dest), rate);
    }

    function calcDstQty(
        uint256 srcQty,
        uint256 srcDecimals,
        uint256 dstDecimals,
        uint256 rate
    ) internal pure returns (uint256) {
        require(srcQty <= MAX_QTY, "srcQty > MAX_QTY");
        require(rate <= MAX_RATE, "rate > MAX_RATE");

        if (dstDecimals >= srcDecimals) {
            require((dstDecimals - srcDecimals) <= MAX_DECIMALS, "dst - src > MAX_DECIMALS");
            return (srcQty * rate * (10**(dstDecimals - srcDecimals))) / PRECISION;
        } else {
            require((srcDecimals - dstDecimals) <= MAX_DECIMALS, "src - dst > MAX_DECIMALS");
            return (srcQty * rate) / (PRECISION * (10**(srcDecimals - dstDecimals)));
        }
    }

    function calcSrcQty(
        uint256 dstQty,
        uint256 srcDecimals,
        uint256 dstDecimals,
        uint256 rate
    ) internal pure returns (uint256) {
        require(dstQty <= MAX_QTY, "dstQty > MAX_QTY");
        require(rate <= MAX_RATE, "rate > MAX_RATE");

        //source quantity is rounded up. to avoid dest quantity being too low.
        uint256 numerator;
        uint256 denominator;
        if (srcDecimals >= dstDecimals) {
            require((srcDecimals - dstDecimals) <= MAX_DECIMALS, "src - dst > MAX_DECIMALS");
            numerator = (PRECISION * dstQty * (10**(srcDecimals - dstDecimals)));
            denominator = rate;
        } else {
            require((dstDecimals - srcDecimals) <= MAX_DECIMALS, "dst - src > MAX_DECIMALS");
            numerator = (PRECISION * dstQty);
            denominator = (rate * (10**(dstDecimals - srcDecimals)));
        }
        return (numerator + denominator - 1) / denominator; //avoid rounding down errors
    }

    function calcRateFromQty(
        uint256 srcAmount,
        uint256 destAmount,
        uint256 srcDecimals,
        uint256 dstDecimals
    ) internal pure returns (uint256) {
        require(srcAmount <= MAX_QTY, "srcAmount > MAX_QTY");
        require(destAmount <= MAX_QTY, "destAmount > MAX_QTY");

        if (dstDecimals >= srcDecimals) {
            require((dstDecimals - srcDecimals) <= MAX_DECIMALS, "dst - src > MAX_DECIMALS");
            return ((destAmount * PRECISION) / ((10**(dstDecimals - srcDecimals)) * srcAmount));
        } else {
            require((srcDecimals - dstDecimals) <= MAX_DECIMALS, "src - dst > MAX_DECIMALS");
            return ((destAmount * PRECISION * (10**(srcDecimals - dstDecimals))) / srcAmount);
        }
    }

    /// @dev save storage access by declaring token decimal constants
    /// @param token The token type
    /// @return token decimals
    function getDecimalsConstant(IERC20Ext token) internal pure returns (uint256) {
        if (token == ETH_TOKEN_ADDRESS) {
            return ETH_DECIMALS;
        } else if (token == USDT_TOKEN_ADDRESS) {
            return 6;
        } else if (token == DAI_TOKEN_ADDRESS) {
            return 18;
        } else if (token == USDC_TOKEN_ADDRESS) {
            return 6;
        } else if (token == WBTC_TOKEN_ADDRESS) {
            return 8;
        } else if (token == KNC_TOKEN_ADDRESS) {
            return 18;
        } else {
            return 0;
        }
    }

    function minOf(uint256 x, uint256 y) internal pure returns (uint256) {
        return x > y ? y : x;
    }
}

// File: @kyber.network/utils-sc/contracts/IERC20Ext.sol



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

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";


/**
 * @dev Interface extending ERC20 standard to include decimals() as
 *      it is optional in the OpenZeppelin IERC20 interface.
 */
interface IERC20Ext is IERC20 {
    /**
     * @dev This function is required as Kyber requires to interact
     *      with token.decimals() with many of its operations.
     */
    function decimals() external view returns (uint8 digits);
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor () {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

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

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

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

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

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

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

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

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

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

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

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

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

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

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

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

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

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

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

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

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

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

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

            bytes32 lastvalue = set._values[lastIndex];

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

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

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

            return true;
        } else {
            return false;
        }
    }

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

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

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

    // Bytes32Set

    struct Bytes32Set {
        Set _inner;
    }

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

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

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

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

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

    // AddressSet

    struct AddressSet {
        Set _inner;
    }

    /**
     * @dev Add a value to a set. O(1).
     *
     * Returns true if the value was added to the set, that is if it was not
     * already present.
     */
    function add(AddressSet storage set, address value) internal returns (bool) {
        return _add(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Removes a value from a set. O(1).
     *
     * Returns true if the value was removed from the set, that is if it was
     * present.
     */
    function remove(AddressSet storage set, address value) internal returns (bool) {
        return _remove(set._inner, bytes32(uint256(uint160(value))));
    }

    /**
     * @dev Returns true if the value is in the set. O(1).
     */
    function contains(AddressSet storage set, address value) internal view returns (bool) {
        return _contains(set._inner, bytes32(uint256(uint160(value))));
    }

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

   /**
    * @dev Returns the value stored at position `index` in the set. O(1).
    *
    * Note that there are no guarantees on the ordering of values inside the
    * array, and it may change when more values are added or removed.
    *
    * Requirements:
    *
    * - `index` must be strictly less than {length}.
    */
    function at(AddressSet storage set, uint256 index) internal view returns (address) {
        return address(uint160(uint256(_at(set._inner, index))));
    }


    // UintSet

    struct UintSet {
        Set _inner;
    }

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

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

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

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

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

// File: contracts/interfaces/liquidation/ILiquidationCallback.sol



// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.7.6;


import {IERC20Ext} from '@kyber.network/utils-sc/contracts/IERC20Ext.sol';

interface ILiquidationCallback {
  function liquidationCallback(
    address caller,
    IERC20Ext[] calldata sources,
    uint256[] calldata amounts,
    address payable recipient,
    IERC20Ext dest,
    uint256 minReturn,
    bytes calldata txData
  ) external;
}

// File: contracts/interfaces/liquidation/ILiquidationStrategyBase.sol



// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.7.6;


import {IERC20Ext} from '@kyber.network/utils-sc/contracts/IERC20Ext.sol';
import {ILiquidationPriceOracleBase} from './ILiquidationPriceOracleBase.sol';

/**
* Use different logics to compute price oracle
* If token is not supported, it should return 0 as conversion rate
*/
interface ILiquidationStrategyBase {

  function updateTreasuryPool(address pool) external;
  function updateRewardPool(address payable pool) external;
  function updateWhitelistedLiquidators(
    address[] calldata liquidators,
    bool isAdd
  ) external;
  function updateWhitelistedOracles(
    address[] calldata oracles,
    bool isAdd
  ) external;

  function liquidate(
    ILiquidationPriceOracleBase oracle,
    IERC20Ext[] calldata sources,
    uint256[] calldata amounts,
    address payable recipient,
    IERC20Ext dest,
    bytes calldata oracleHint,
    bytes calldata txData
  ) external returns (uint256 destAmount);

  function isLiquidationEnabled() external view returns (bool);
  function getLiquidationSchedule()
    external view
    returns(
      uint128 startTime,
      uint64 repeatedPeriod,
      uint64 duration
    );

  function isWhitelistedLiquidator(address liquidator)
    external view returns (bool);
  function getWhitelistedLiquidatorsLength() external view returns (uint256);
  function getWhitelistedLiquidatorAt(uint256 index) external view returns (address);
  function getAllWhitelistedLiquidators()
    external view returns (address[] memory liquidators);

  function isWhitelistedOracle(address oracle)
    external view returns (bool);
  function getWhitelistedPriceOraclesLength() external view returns (uint256);
  function getWhitelistedPriceOracleAt(uint256 index) external view returns (address);
  function getAllWhitelistedPriceOracles()
    external view returns (address[] memory oracles);
  function treasuryPool() external view returns (address);
  function rewardPool() external view returns (address payable);
}

// File: contracts/interfaces/liquidation/IPool.sol



// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.7.6;


import {IERC20Ext} from '@kyber.network/utils-sc/contracts/IERC20Ext.sol';

interface IPool {

  event AuthorizedStrategy(address indexed strategy);
  event UnauthorizedStrategy(address indexed strategy);
  event Paused(address indexed sender);
  event Unpaused(address indexed sender);
  event WithdrawToken(
    IERC20Ext indexed token,
    address indexed sender,
    address indexed recipient,
    uint256 amount
  );

  function pause() external;
  function unpause() external;
  function authorizeStrategies(address[] calldata strategies) external;
  function unauthorizeStrategies(address[] calldata strategies) external;
  function withdrawFunds(
    IERC20Ext[] calldata tokens,
    uint256[] calldata amounts,
    address payable recipient
  ) external;
  function isPaused() external view returns (bool);
  function isAuthorizedStrategy(address strategy) external view returns (bool);
  function getAuthorizedStrategiesLength() external view returns (uint256);
  function getAuthorizedStrategyAt(uint256 index) external view returns (address);
  function getAllAuthorizedStrategies()
    external view returns (address[] memory strategies);
}

// File: @kyber.network/utils-sc/contracts/PermissionAdmin.sol



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


abstract contract PermissionAdmin {
    address public admin;
    address public pendingAdmin;

    event AdminClaimed(address newAdmin, address previousAdmin);

    event TransferAdminPending(address pendingAdmin);

    constructor(address _admin) {
        require(_admin != address(0), "admin 0");
        admin = _admin;
    }

    modifier onlyAdmin() {
        require(msg.sender == admin, "only admin");
        _;
    }

    /**
     * @dev Allows the current admin to set the pendingAdmin address.
     * @param newAdmin The address to transfer ownership to.
     */
    function transferAdmin(address newAdmin) public onlyAdmin {
        require(newAdmin != address(0), "new admin 0");
        emit TransferAdminPending(newAdmin);
        pendingAdmin = newAdmin;
    }

    /**
     * @dev Allows the current admin to set the admin in one tx. Useful initial deployment.
     * @param newAdmin The address to transfer ownership to.
     */
    function transferAdminQuickly(address newAdmin) public onlyAdmin {
        require(newAdmin != address(0), "admin 0");
        emit TransferAdminPending(newAdmin);
        emit AdminClaimed(newAdmin, admin);
        admin = newAdmin;
    }

    /**
     * @dev Allows the pendingAdmin address to finalize the change admin process.
     */
    function claimAdmin() public {
        require(pendingAdmin == msg.sender, "not pending");
        emit AdminClaimed(pendingAdmin, admin);
        admin = pendingAdmin;
        pendingAdmin = address(0);
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @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



// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

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

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: contracts/interfaces/liquidation/ILiquidationPriceOracleBase.sol



// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.7.6;


import {IERC20Ext} from '@kyber.network/utils-sc/contracts/IERC20Ext.sol';

/**
* Use different logics to compute price oracle
* If token is not supported, it should return 0 as conversion rate
*/
interface ILiquidationPriceOracleBase {

  /**
   * @dev Return list of min amounts that expected to get in return
   *  when liquidating corresponding list of src tokens
   * @param liquidator address of the liquidator
   * @param tokenIns list of src tokens
   * @param amountIns list of src amounts
   * @param tokenOut dest token
   * @param hint hint for getting conversion rates
   * @return minAmountOut min expected amount for the token out
   */
  function getExpectedReturn(
    address liquidator,
    IERC20Ext[] calldata tokenIns,
    uint256[] calldata amountIns,
    IERC20Ext tokenOut,
    bytes calldata hint
  ) external view returns (uint256 minAmountOut);
}