// SPDX-License-Identifier: MIT

pragma solidity 0.6.12;



// Part: HomoraCaster

contract HomoraCaster {
  /// @dev Call to the target using the given data.
  /// @param target The address target to call.
  /// @param data The data used in the call.
  function cast(address target, bytes calldata data) external payable {
    (bool ok, bytes memory returndata) = target.call{value: msg.value}(data);
    if (!ok) {
      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('bad cast call');
      }
    }
  }
}

// Part: IBank

interface IBank {
  /// The governor adds a new bank gets added to the system.
  event AddBank(address token, address cToken);
  /// The governor sets the address of the oracle smart contract.
  event SetOracle(address oracle);
  /// The governor sets the basis point fee of the bank.
  event SetFeeBps(uint feeBps);
  /// The governor withdraw tokens from the reserve of a bank.
  event WithdrawReserve(address user, address token, uint amount);
  /// Someone borrows tokens from a bank via a spell caller.
  event Borrow(uint positionId, address caller, address token, uint amount, uint share);
  /// Someone repays tokens to a bank via a spell caller.
  event Repay(uint positionId, address caller, address token, uint amount, uint share);
  /// Someone puts tokens as collateral via a spell caller.
  event PutCollateral(uint positionId, address caller, address token, uint id, uint amount);
  /// Someone takes tokens from collateral via a spell caller.
  event TakeCollateral(uint positionId, address caller, address token, uint id, uint amount);
  /// Someone calls liquidatation on a position, paying debt and taking collateral tokens.
  event Liquidate(
    uint positionId,
    address liquidator,
    address debtToken,
    uint amount,
    uint share,
    uint bounty
  );

  /// @dev Return the current position while under execution.
  function POSITION_ID() external view returns (uint);

  /// @dev Return the current target while under execution.
  function SPELL() external view returns (address);

  /// @dev Return the current executor (the owner of the current position).
  function EXECUTOR() external view returns (address);

  /// @dev Return bank information for the given token.
  function getBankInfo(address token)
    external
    view
    returns (
      bool isListed,
      address cToken,
      uint reserve,
      uint totalDebt,
      uint totalShare
    );

  /// @dev Return position information for the given position id.
  function getPositionInfo(uint positionId)
    external
    view
    returns (
      address owner,
      address collToken,
      uint collId,
      uint collateralSize
    );

  /// @dev Return the borrow balance for given positon and token without trigger interest accrual.
  function borrowBalanceStored(uint positionId, address token) external view returns (uint);

  /// @dev Trigger interest accrual and return the current borrow balance.
  function borrowBalanceCurrent(uint positionId, address token) external returns (uint);

  /// @dev Borrow tokens from the bank.
  function borrow(address token, uint amount) external;

  /// @dev Repays tokens to the bank.
  function repay(address token, uint amountCall) external;

  /// @dev Transmit user assets to the spell.
  function transmit(address token, uint amount) external;

  /// @dev Put more collateral for users.
  function putCollateral(
    address collToken,
    uint collId,
    uint amountCall
  ) external;

  /// @dev Take some collateral back.
  function takeCollateral(
    address collToken,
    uint collId,
    uint amount
  ) external;

  /// @dev Liquidate a position.
  function liquidate(
    uint positionId,
    address debtToken,
    uint amountCall
  ) external;

  function getBorrowETHValue(uint positionId) external view returns (uint);

  function accrue(address token) external;

  function nextPositionId() external view returns (uint);

  /// @dev Return current position information.
  function getCurrentPositionInfo()
    external
    view
    returns (
      address owner,
      address collToken,
      uint collId,
      uint collateralSize
    );

  function support(address token) external view returns (bool);

}

// Part: ICErc20

interface ICErc20 {
  function decimals() external returns (uint8);

  function underlying() external returns (address);

  function mint(uint mintAmount) external returns (uint);

  function redeem(uint redeemTokens) external returns (uint);

  function balanceOf(address user) external view returns (uint);

  function borrowBalanceCurrent(address account) external returns (uint);

  function borrowBalanceStored(address account) external view returns (uint);

  function borrow(uint borrowAmount) external returns (uint);

  function repayBorrow(uint repayAmount) external returns (uint);
}

// Part: IOracle

interface IOracle {
  /// @dev Return whether the oracle supports evaluating collateral value of the given address.
  /// @param token The ERC-1155 token to check the acceptence.
  /// @param id The token id to check the acceptance.
  function supportWrappedToken(address token, uint id) external view returns (bool);

  /// @dev Return the amount of token out as liquidation reward for liquidating token in.
  /// @param tokenIn The ERC-20 token that gets liquidated.
  /// @param tokenOut The ERC-1155 token to pay as reward.
  /// @param tokenOutId The id of the token to pay as reward.
  /// @param amountIn The amount of liquidating tokens.
  function convertForLiquidation(
    address tokenIn,
    address tokenOut,
    uint tokenOutId,
    uint amountIn
  ) external view returns (uint);

  /// @dev Return the value of the given input as ETH for collateral purpose.
  /// @param token The ERC-1155 token to check the value.
  /// @param id The id of the token to check the value.
  /// @param amount The amount of tokens to check the value.
  /// @param owner The owner of the token to check for collateral credit.
  function asETHCollateral(
    address token,
    uint id,
    uint amount,
    address owner
  ) external view returns (uint);

  /// @dev Return the value of the given input as ETH for borrow purpose.
  /// @param token The ERC-20 token to check the value.
  /// @param amount The amount of tokens to check the value.
  /// @param owner The owner of the token to check for borrow credit.
  function asETHBorrow(
    address token,
    uint amount,
    address owner
  ) external view returns (uint);

  /// @dev Return whether the ERC-20 token is supported
  /// @param token The ERC-20 token to check for support
  function support(address token) external view returns (bool);
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/Address

/**
 * @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);
            }
        }
    }
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/IERC165

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/IERC20

/**
 * @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);
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/Math

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/SafeMath

/**
 * @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;
    }
}

// Part: HomoraSafeMath

library HomoraSafeMath {
  using SafeMath for uint;

  /// @dev Computes round-up division.
  function ceilDiv(uint a, uint b) internal pure returns (uint) {
    return a.add(b).sub(1).div(b);
  }
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/ERC165

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts may inherit from this and call {_registerInterface} to declare
 * their support of an interface.
 */
abstract contract ERC165 is IERC165 {
    /*
     * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
     */
    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;

    /**
     * @dev Mapping of interface ids to whether or not it's supported.
     */
    mapping(bytes4 => bool) private _supportedInterfaces;

    constructor () internal {
        // Derived contracts need only register support for their own interfaces,
        // we register support for ERC165 itself here
        _registerInterface(_INTERFACE_ID_ERC165);
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     *
     * Time complexity O(1), guaranteed to always use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return _supportedInterfaces[interfaceId];
    }

    /**
     * @dev Registers the contract as an implementer of the interface defined by
     * `interfaceId`. Support of the actual ERC165 interface is automatic and
     * registering its interface id is not required.
     *
     * See {IERC165-supportsInterface}.
     *
     * Requirements:
     *
     * - `interfaceId` cannot be the ERC165 invalid interface (`0xffffffff`).
     */
    function _registerInterface(bytes4 interfaceId) internal virtual {
        require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
        _supportedInterfaces[interfaceId] = true;
    }
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/IERC1155

/**
 * @dev Required interface of an ERC1155 compliant contract, as defined in the
 * https://eips.ethereum.org/EIPS/eip-1155[EIP].
 *
 * _Available since v3.1._
 */
interface IERC1155 is IERC165 {
    /**
     * @dev Emitted when `value` tokens of token type `id` are transferred from `from` to `to` by `operator`.
     */
    event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);

    /**
     * @dev Equivalent to multiple {TransferSingle} events, where `operator`, `from` and `to` are the same for all
     * transfers.
     */
    event TransferBatch(address indexed operator, address indexed from, address indexed to, uint256[] ids, uint256[] values);

    /**
     * @dev Emitted when `account` grants or revokes permission to `operator` to transfer their tokens, according to
     * `approved`.
     */
    event ApprovalForAll(address indexed account, address indexed operator, bool approved);

    /**
     * @dev Emitted when the URI for token type `id` changes to `value`, if it is a non-programmatic URI.
     *
     * If an {URI} event was emitted for `id`, the standard
     * https://eips.ethereum.org/EIPS/eip-1155#metadata-extensions[guarantees] that `value` will equal the value
     * returned by {IERC1155MetadataURI-uri}.
     */
    event URI(string value, uint256 indexed id);

    /**
     * @dev Returns the amount of tokens of token type `id` owned by `account`.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function balanceOf(address account, uint256 id) external view returns (uint256);

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {balanceOf}.
     *
     * Requirements:
     *
     * - `accounts` and `ids` must have the same length.
     */
    function balanceOfBatch(address[] calldata accounts, uint256[] calldata ids) external view returns (uint256[] memory);

    /**
     * @dev Grants or revokes permission to `operator` to transfer the caller's tokens, according to `approved`,
     *
     * Emits an {ApprovalForAll} event.
     *
     * Requirements:
     *
     * - `operator` cannot be the caller.
     */
    function setApprovalForAll(address operator, bool approved) external;

    /**
     * @dev Returns true if `operator` is approved to transfer ``account``'s tokens.
     *
     * See {setApprovalForAll}.
     */
    function isApprovedForAll(address account, address operator) external view returns (bool);

    /**
     * @dev Transfers `amount` tokens of token type `id` from `from` to `to`.
     *
     * Emits a {TransferSingle} event.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - If the caller is not `from`, it must be have been approved to spend ``from``'s tokens via {setApprovalForAll}.
     * - `from` must have a balance of tokens of type `id` of at least `amount`.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155Received} and return the
     * acceptance magic value.
     */
    function safeTransferFrom(address from, address to, uint256 id, uint256 amount, bytes calldata data) external;

    /**
     * @dev xref:ROOT:erc1155.adoc#batch-operations[Batched] version of {safeTransferFrom}.
     *
     * Emits a {TransferBatch} event.
     *
     * Requirements:
     *
     * - `ids` and `amounts` must have the same length.
     * - If `to` refers to a smart contract, it must implement {IERC1155Receiver-onERC1155BatchReceived} and return the
     * acceptance magic value.
     */
    function safeBatchTransferFrom(address from, address to, uint256[] calldata ids, uint256[] calldata amounts, bytes calldata data) external;
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/IERC1155Receiver

/**
 * _Available since v3.1._
 */
interface IERC1155Receiver is IERC165 {

    /**
        @dev Handles the receipt of a single ERC1155 token type. This function is
        called at the end of a `safeTransferFrom` after the balance has been updated.
        To accept the transfer, this must return
        `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
        (i.e. 0xf23a6e61, or its own function selector).
        @param operator The address which initiated the transfer (i.e. msg.sender)
        @param from The address which previously owned the token
        @param id The ID of the token being transferred
        @param value The amount of tokens being transferred
        @param data Additional data with no specified format
        @return `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))` if transfer is allowed
    */
    function onERC1155Received(
        address operator,
        address from,
        uint256 id,
        uint256 value,
        bytes calldata data
    )
        external
        returns(bytes4);

    /**
        @dev Handles the receipt of a multiple ERC1155 token types. This function
        is called at the end of a `safeBatchTransferFrom` after the balances have
        been updated. To accept the transfer(s), this must return
        `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
        (i.e. 0xbc197c81, or its own function selector).
        @param operator The address which initiated the batch transfer (i.e. msg.sender)
        @param from The address which previously owned the token
        @param ids An array containing ids of each token being transferred (order and length must match values array)
        @param values An array containing amounts of each token being transferred (order and length must match ids array)
        @param data Additional data with no specified format
        @return `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))` if transfer is allowed
    */
    function onERC1155BatchReceived(
        address operator,
        address from,
        uint256[] calldata ids,
        uint256[] calldata values,
        bytes calldata data
    )
        external
        returns(bytes4);
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/Initializable

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {

    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        return !Address.isContract(address(this));
    }
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/SafeERC20

/**
 * @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");
        }
    }
}

// Part: Governable

contract Governable is Initializable {
  event SetGovernor(address governor);
  event SetPendingGovernor(address pendingGovernor);
  event AcceptGovernor(address governor);

  address public governor; // The current governor.
  address public pendingGovernor; // The address pending to become the governor once accepted.

  bytes32[64] _gap; // reserve space for upgrade

  modifier onlyGov() {
    require(msg.sender == governor, 'not the governor');
    _;
  }

  /// @dev Initialize using msg.sender as the first governor.
  function __Governable__init() internal initializer {
    governor = msg.sender;
    pendingGovernor = address(0);
    emit SetGovernor(msg.sender);
  }

  /// @dev Set the pending governor, which will be the governor once accepted.
  /// @param _pendingGovernor The address to become the pending governor.
  function setPendingGovernor(address _pendingGovernor) external onlyGov {
    pendingGovernor = _pendingGovernor;
    emit SetPendingGovernor(_pendingGovernor);
  }

  /// @dev Accept to become the new governor. Must be called by the pending governor.
  function acceptGovernor() external {
    require(msg.sender == pendingGovernor, 'not the pending governor');
    pendingGovernor = address(0);
    governor = msg.sender;
    emit AcceptGovernor(msg.sender);
  }
}

// Part: OpenZeppelin/openzeppelin-contracts@3.4.0/ERC1155Receiver

/**
 * @dev _Available since v3.1._
 */
abstract contract ERC1155Receiver is ERC165, IERC1155Receiver {
    constructor() internal {
        _registerInterface(
            ERC1155Receiver(address(0)).onERC1155Received.selector ^
            ERC1155Receiver(address(0)).onERC1155BatchReceived.selector
        );
    }
}

// Part: ERC1155NaiveReceiver

contract ERC1155NaiveReceiver is ERC1155Receiver {
  bytes32[64] __gap; // reserve space for upgrade

  function onERC1155Received(
    address, /* operator */
    address, /* from */
    uint, /* id */
    uint, /* value */
    bytes calldata /* data */
  ) external override returns (bytes4) {
    return this.onERC1155Received.selector;
  }

  function onERC1155BatchReceived(
    address, /* operator */
    address, /* from */
    uint[] calldata, /* ids */
    uint[] calldata, /* values */
    bytes calldata /* data */
  ) external override returns (bytes4) {
    return this.onERC1155BatchReceived.selector;
  }
}

// File: HomoraBank.sol

contract HomoraBank is Governable, ERC1155NaiveReceiver, IBank {
  using SafeMath for uint;
  using HomoraSafeMath for uint;
  using SafeERC20 for IERC20;

  uint private constant _NOT_ENTERED = 1;
  uint private constant _ENTERED = 2;
  uint private constant _NO_ID = uint(-1);
  address private constant _NO_ADDRESS = address(1);

  struct Bank {
    bool isListed; // Whether this market exists.
    uint8 index; // Reverse look up index for this bank.
    address cToken; // The CToken to draw liquidity from.
    uint reserve; // The reserve portion allocated to Homora protocol.
    uint totalDebt; // The last recorded total debt since last action.
    uint totalShare; // The total debt share count across all open positions.
  }

  struct Position {
    address owner; // The owner of this position.
    address collToken; // The ERC1155 token used as collateral for this position.
    uint collId; // The token id used as collateral.
    uint collateralSize; // The size of collateral token for this position.
    uint debtMap; // Bitmap of nonzero debt. i^th bit is set iff debt share of i^th bank is nonzero.
    mapping(address => uint) debtShareOf; // The debt share for each token.
  }

  uint public _GENERAL_LOCK; // TEMPORARY: re-entrancy lock guard.
  uint public _IN_EXEC_LOCK; // TEMPORARY: exec lock guard.
  uint public override POSITION_ID; // TEMPORARY: position ID currently under execution.
  address public override SPELL; // TEMPORARY: spell currently under execution.

  address public caster; // The caster address for untrusted execution.
  IOracle public oracle; // The oracle address for determining prices.
  uint public feeBps; // The fee collected as protocol reserve in basis points from interest.
  uint public override nextPositionId; // Next available position ID, starting from 1 (see initialize).

  address[] public allBanks; // The list of all listed banks.
  mapping(address => Bank) public banks; // Mapping from token to bank data.
  mapping(address => bool) public cTokenInBank; // Mapping from cToken to its existence in bank.
  mapping(uint => Position) public positions; // Mapping from position ID to position data.

  bool public allowContractCalls; // The boolean status whether to allow call from contract (false = onlyEOA)
  mapping(address => bool) public whitelistedTokens; // Mapping from token to whitelist status
  mapping(address => bool) public whitelistedSpells; // Mapping from spell to whitelist status
  mapping(address => bool) public whitelistedUsers; // Mapping from user to whitelist status

  uint public bankStatus; // Each bit stores certain bank status, e.g. borrow allowed, repay allowed

  /// @dev Ensure that the function is called from EOA when allowContractCalls is set to false and caller is not whitelisted
  modifier onlyEOAEx() {
    if (!allowContractCalls && !whitelistedUsers[msg.sender]) {
      require(msg.sender == tx.origin, 'not eoa');
    }
    _;
  }

  /// @dev Reentrancy lock guard.
  modifier lock() {
    require(_GENERAL_LOCK == _NOT_ENTERED, 'general lock');
    _GENERAL_LOCK = _ENTERED;
    _;
    _GENERAL_LOCK = _NOT_ENTERED;
  }

  /// @dev Ensure that the function is called from within the execution scope.
  modifier inExec() {
    require(POSITION_ID != _NO_ID, 'not within execution');
    require(SPELL == msg.sender, 'not from spell');
    require(_IN_EXEC_LOCK == _NOT_ENTERED, 'in exec lock');
    _IN_EXEC_LOCK = _ENTERED;
    _;
    _IN_EXEC_LOCK = _NOT_ENTERED;
  }

  /// @dev Ensure that the interest rate of the given token is accrued.
  modifier poke(address token) {
    accrue(token);
    _;
  }

  /// @dev Initialize the bank smart contract, using msg.sender as the first governor.
  /// @param _oracle The oracle smart contract address.
  /// @param _feeBps The fee collected to Homora bank.
  function initialize(IOracle _oracle, uint _feeBps) external initializer {
    __Governable__init();
    _GENERAL_LOCK = _NOT_ENTERED;
    _IN_EXEC_LOCK = _NOT_ENTERED;
    POSITION_ID = _NO_ID;
    SPELL = _NO_ADDRESS;
    caster = address(new HomoraCaster());
    oracle = _oracle;
    require(address(_oracle) != address(0), 'bad oracle address');
    feeBps = _feeBps;
    nextPositionId = 1;
    bankStatus = 3; // allow both borrow and repay
    emit SetOracle(address(_oracle));
    emit SetFeeBps(_feeBps);
  }

  /// @dev Return the current executor (the owner of the current position).
  function EXECUTOR() external view override returns (address) {
    uint positionId = POSITION_ID;
    require(positionId != _NO_ID, 'not under execution');
    return positions[positionId].owner;
  }

  /// @dev Set allowContractCalls
  /// @param ok The status to set allowContractCalls to (false = onlyEOA)
  function setAllowContractCalls(bool ok) external onlyGov {
    allowContractCalls = ok;
  }

  /// @dev Set whitelist spell status
  /// @param spells list of spells to change status
  /// @param statuses list of statuses to change to
  function setWhitelistSpells(address[] calldata spells, bool[] calldata statuses)
    external
    onlyGov
  {
    require(spells.length == statuses.length, 'spells & statuses length mismatched');
    for (uint idx = 0; idx < spells.length; idx++) {
      whitelistedSpells[spells[idx]] = statuses[idx];
    }
  }

  /// @dev Set whitelist token status
  /// @param tokens list of tokens to change status
  /// @param statuses list of statuses to change to
  function setWhitelistTokens(address[] calldata tokens, bool[] calldata statuses)
    external
    onlyGov
  {
    require(tokens.length == statuses.length, 'tokens & statuses length mismatched');
    for (uint idx = 0; idx < tokens.length; idx++) {
      if (statuses[idx]) {
        // check oracle suppport
        require(support(tokens[idx]), 'oracle not support token');
      }
      whitelistedTokens[tokens[idx]] = statuses[idx];
    }
  }

  /// @dev Set whitelist user status
  /// @param users list of users to change status
  /// @param statuses list of statuses to change to
  function setWhitelistUsers(address[] calldata users, bool[] calldata statuses) external onlyGov {
    require(users.length == statuses.length, 'users & statuses length mismatched');
    for (uint idx = 0; idx < users.length; idx++) {
      whitelistedUsers[users[idx]] = statuses[idx];
    }
  }

  /// @dev Check whether the oracle supports the token
  /// @param token ERC-20 token to check for support
  function support(address token) public view override returns (bool) {
    return oracle.support(token);
  }

  /// @dev Set bank status
  /// @param _bankStatus new bank status to change to
  function setBankStatus(uint _bankStatus) external onlyGov {
    bankStatus = _bankStatus;
  }

  /// @dev Bank borrow status allowed or not
  /// @notice check last bit of bankStatus
  function allowBorrowStatus() public view returns (bool) {
    return (bankStatus & 0x01) > 0;
  }

  /// @dev Bank repay status allowed or not
  /// @notice Check second-to-last bit of bankStatus
  function allowRepayStatus() public view returns (bool) {
    return (bankStatus & 0x02) > 0;
  }

  /// @dev Trigger interest accrual for the given bank.
  /// @param token The underlying token to trigger the interest accrual.
  function accrue(address token) public override {
    Bank storage bank = banks[token];
    require(bank.isListed, 'bank not exist');
    uint totalDebt = bank.totalDebt;
    uint debt = ICErc20(bank.cToken).borrowBalanceCurrent(address(this));
    if (debt > totalDebt) {
      uint fee = debt.sub(totalDebt).mul(feeBps).div(10000);
      bank.totalDebt = debt;
      bank.reserve = bank.reserve.add(doBorrow(token, fee));
    } else if (totalDebt != debt) {
      // We should never reach here because CREAMv2 does not support *repayBorrowBehalf*
      // functionality. We set bank.totalDebt = debt nonetheless to ensure consistency. But do
      // note that if *repayBorrowBehalf* exists, an attacker can maliciously deflate debt
      // share value and potentially make this contract stop working due to math overflow.
      bank.totalDebt = debt;
    }
  }

  /// @dev Convenient function to trigger interest accrual for a list of banks.
  /// @param tokens The list of banks to trigger interest accrual.
  function accrueAll(address[] memory tokens) external {
    for (uint idx = 0; idx < tokens.length; idx++) {
      accrue(tokens[idx]);
    }
  }

  /// @dev Return the borrow balance for given position and token without triggering interest accrual.
  /// @param positionId The position to query for borrow balance.
  /// @param token The token to query for borrow balance.
  function borrowBalanceStored(uint positionId, address token) public view override returns (uint) {
    uint totalDebt = banks[token].totalDebt;
    uint totalShare = banks[token].totalShare;
    uint share = positions[positionId].debtShareOf[token];
    if (share == 0 || totalDebt == 0) {
      return 0;
    } else {
      return share.mul(totalDebt).ceilDiv(totalShare);
    }
  }

  /// @dev Trigger interest accrual and return the current borrow balance.
  /// @param positionId The position to query for borrow balance.
  /// @param token The token to query for borrow balance.
  function borrowBalanceCurrent(uint positionId, address token) external override returns (uint) {
    accrue(token);
    return borrowBalanceStored(positionId, token);
  }

  /// @dev Return bank information for the given token.
  /// @param token The token address to query for bank information.
  function getBankInfo(address token)
    external
    view
    override
    returns (
      bool isListed,
      address cToken,
      uint reserve,
      uint totalDebt,
      uint totalShare
    )
  {
    Bank storage bank = banks[token];
    return (bank.isListed, bank.cToken, bank.reserve, bank.totalDebt, bank.totalShare);
  }

  /// @dev Return position information for the given position id.
  /// @param positionId The position id to query for position information.
  function getPositionInfo(uint positionId)
    public
    view
    override
    returns (
      address owner,
      address collToken,
      uint collId,
      uint collateralSize
    )
  {
    Position storage pos = positions[positionId];
    return (pos.owner, pos.collToken, pos.collId, pos.collateralSize);
  }

  /// @dev Return current position information
  function getCurrentPositionInfo()
    external
    view
    override
    returns (
      address owner,
      address collToken,
      uint collId,
      uint collateralSize
    )
  {
    require(POSITION_ID != _NO_ID, 'no id');
    return getPositionInfo(POSITION_ID);
  }

  /// @dev Return the debt share of the given bank token for the given position id.
  /// @param positionId position id to get debt of
  /// @param token ERC20 debt token to query
  function getPositionDebtShareOf(uint positionId, address token) external view returns (uint) {
    return positions[positionId].debtShareOf[token];
  }

  /// @dev Return the list of all debts for the given position id.
  /// @param positionId position id to get debts of
  function getPositionDebts(uint positionId)
    external
    view
    returns (address[] memory tokens, uint[] memory debts)
  {
    Position storage pos = positions[positionId];
    uint count = 0;
    uint bitMap = pos.debtMap;
    while (bitMap > 0) {
      if ((bitMap & 1) != 0) {
        count++;
      }
      bitMap >>= 1;
    }
    tokens = new address[](count);
    debts = new uint[](count);
    bitMap = pos.debtMap;
    count = 0;
    uint idx = 0;
    while (bitMap > 0) {
      if ((bitMap & 1) != 0) {
        address token = allBanks[idx];
        Bank storage bank = banks[token];
        tokens[count] = token;
        debts[count] = pos.debtShareOf[token].mul(bank.totalDebt).ceilDiv(bank.totalShare);
        count++;
      }
      idx++;
      bitMap >>= 1;
    }
  }

  /// @dev Return the total collateral value of the given position in ETH.
  /// @param positionId The position ID to query for the collateral value.
  function getCollateralETHValue(uint positionId) public view returns (uint) {
    Position storage pos = positions[positionId];
    uint size = pos.collateralSize;
    if (size == 0) {
      return 0;
    } else {
      require(pos.collToken != address(0), 'bad collateral token');
      return oracle.asETHCollateral(pos.collToken, pos.collId, size, pos.owner);
    }
  }

  /// @dev Return the total borrow value of the given position in ETH.
  /// @param positionId The position ID to query for the borrow value.
  function getBorrowETHValue(uint positionId) public view override returns (uint) {
    uint value = 0;
    Position storage pos = positions[positionId];
    address owner = pos.owner;
    uint bitMap = pos.debtMap;
    uint idx = 0;
    while (bitMap > 0) {
      if ((bitMap & 1) != 0) {
        address token = allBanks[idx];
        uint share = pos.debtShareOf[token];
        Bank storage bank = banks[token];
        uint debt = share.mul(bank.totalDebt).ceilDiv(bank.totalShare);
        value = value.add(oracle.asETHBorrow(token, debt, owner));
      }
      idx++;
      bitMap >>= 1;
    }
    return value;
  }

  /// @dev Add a new bank to the ecosystem.
  /// @param token The underlying token for the bank.
  /// @param cToken The address of the cToken smart contract.
  function addBank(address token, address cToken) external onlyGov {
    Bank storage bank = banks[token];
    require(!cTokenInBank[cToken], 'cToken already exists');
    require(!bank.isListed, 'bank already exists');
    cTokenInBank[cToken] = true;
    bank.isListed = true;
    require(allBanks.length < 256, 'reach bank limit');
    bank.index = uint8(allBanks.length);
    bank.cToken = cToken;
    IERC20(token).safeApprove(cToken, 0);
    IERC20(token).safeApprove(cToken, uint(-1));
    allBanks.push(token);
    emit AddBank(token, cToken);
  }

  /// @dev Set the oracle smart contract address.
  /// @param _oracle The new oracle smart contract address.
  function setOracle(IOracle _oracle) external onlyGov {
    require(address(_oracle) != address(0), 'cannot set zero address oracle');
    oracle = _oracle;
    emit SetOracle(address(_oracle));
  }

  /// @dev Set the fee bps value that Homora bank charges.
  /// @param _feeBps The new fee bps value.
  function setFeeBps(uint _feeBps) external onlyGov {
    require(_feeBps <= 10000, 'fee too high');
    feeBps = _feeBps;
    emit SetFeeBps(_feeBps);
  }

  /// @dev Withdraw the reserve portion of the bank.
  /// @param amount The amount of tokens to withdraw.
  function withdrawReserve(address token, uint amount) external onlyGov lock {
    Bank storage bank = banks[token];
    require(bank.isListed, 'bank not exist');
    bank.reserve = bank.reserve.sub(amount);
    IERC20(token).safeTransfer(msg.sender, amount);
    emit WithdrawReserve(msg.sender, token, amount);
  }

  /// @dev Liquidate a position. Pay debt for its owner and take the collateral.
  /// @param positionId The position ID to liquidate.
  /// @param debtToken The debt token to repay.
  /// @param amountCall The amount to repay when doing transferFrom call.
  function liquidate(
    uint positionId,
    address debtToken,
    uint amountCall
  ) external override lock poke(debtToken) {
    uint collateralValue = getCollateralETHValue(positionId);
    uint borrowValue = getBorrowETHValue(positionId);
    require(collateralValue < borrowValue, 'position still healthy');
    Position storage pos = positions[positionId];
    (uint amountPaid, uint share) = repayInternal(positionId, debtToken, amountCall);
    require(pos.collToken != address(0), 'bad collateral token');
    uint bounty =
      Math.min(
        oracle.convertForLiquidation(debtToken, pos.collToken, pos.collId, amountPaid),
        pos.collateralSize
      );
    pos.collateralSize = pos.collateralSize.sub(bounty);
    IERC1155(pos.collToken).safeTransferFrom(address(this), msg.sender, pos.collId, bounty, '');
    emit Liquidate(positionId, msg.sender, debtToken, amountPaid, share, bounty);
  }

  /// @dev Execute the action via HomoraCaster, calling its function with the supplied data.
  /// @param positionId The position ID to execute the action, or zero for new position.
  /// @param spell The target spell to invoke the execution via HomoraCaster.
  /// @param data Extra data to pass to the target for the execution.
  function execute(
    uint positionId,
    address spell,
    bytes memory data
  ) external payable lock onlyEOAEx returns (uint) {
    require(whitelistedSpells[spell], 'spell not whitelisted');
    if (positionId == 0) {
      positionId = nextPositionId++;
      positions[positionId].owner = msg.sender;
    } else {
      require(positionId < nextPositionId, 'position id not exists');
      require(msg.sender == positions[positionId].owner, 'not position owner');
    }
    POSITION_ID = positionId;
    SPELL = spell;
    HomoraCaster(caster).cast{value: msg.value}(spell, data);
    uint collateralValue = getCollateralETHValue(positionId);
    uint borrowValue = getBorrowETHValue(positionId);
    require(collateralValue >= borrowValue, 'insufficient collateral');
    POSITION_ID = _NO_ID;
    SPELL = _NO_ADDRESS;
    return positionId;
  }

  /// @dev Borrow tokens from that bank. Must only be called while under execution.
  /// @param token The token to borrow from the bank.
  /// @param amount The amount of tokens to borrow.
  function borrow(address token, uint amount) external override inExec poke(token) {
    require(allowBorrowStatus(), 'borrow not allowed');
    require(whitelistedTokens[token], 'token not whitelisted');
    Bank storage bank = banks[token];
    Position storage pos = positions[POSITION_ID];
    uint totalShare = bank.totalShare;
    uint totalDebt = bank.totalDebt;
    uint share = totalShare == 0 ? amount : amount.mul(totalShare).ceilDiv(totalDebt);
    bank.totalShare = bank.totalShare.add(share);
    uint newShare = pos.debtShareOf[token].add(share);
    pos.debtShareOf[token] = newShare;
    if (newShare > 0) {
      pos.debtMap |= (1 << uint(bank.index));
    }
    IERC20(token).safeTransfer(msg.sender, doBorrow(token, amount));
    emit Borrow(POSITION_ID, msg.sender, token, amount, share);
  }

  /// @dev Repay tokens to the bank. Must only be called while under execution.
  /// @param token The token to repay to the bank.
  /// @param amountCall The amount of tokens to repay via transferFrom.
  function repay(address token, uint amountCall) external override inExec poke(token) {
    require(allowRepayStatus(), 'repay not allowed');
    require(whitelistedTokens[token], 'token not whitelisted');
    (uint amount, uint share) = repayInternal(POSITION_ID, token, amountCall);
    emit Repay(POSITION_ID, msg.sender, token, amount, share);
  }

  /// @dev Perform repay action. Return the amount actually taken and the debt share reduced.
  /// @param positionId The position ID to repay the debt.
  /// @param token The bank token to pay the debt.
  /// @param amountCall The amount to repay by calling transferFrom, or -1 for debt size.
  function repayInternal(
    uint positionId,
    address token,
    uint amountCall
  ) internal returns (uint, uint) {
    Bank storage bank = banks[token];
    Position storage pos = positions[positionId];
    uint totalShare = bank.totalShare;
    uint totalDebt = bank.totalDebt;
    uint oldShare = pos.debtShareOf[token];
    uint oldDebt = oldShare.mul(totalDebt).ceilDiv(totalShare);
    if (amountCall == uint(-1)) {
      amountCall = oldDebt;
    }
    uint paid = doRepay(token, doERC20TransferIn(token, amountCall));
    require(paid <= oldDebt, 'paid exceeds debt'); // prevent share overflow attack
    uint lessShare = paid == oldDebt ? oldShare : paid.mul(totalShare).div(totalDebt);
    bank.totalShare = totalShare.sub(lessShare);
    uint newShare = oldShare.sub(lessShare);
    pos.debtShareOf[token] = newShare;
    if (newShare == 0) {
      pos.debtMap &= ~(1 << uint(bank.index));
    }
    return (paid, lessShare);
  }

  /// @dev Transmit user assets to the caller, so users only need to approve Bank for spending.
  /// @param token The token to transfer from user to the caller.
  /// @param amount The amount to transfer.
  function transmit(address token, uint amount) external override inExec {
    Position storage pos = positions[POSITION_ID];
    IERC20(token).safeTransferFrom(pos.owner, msg.sender, amount);
  }

  /// @dev Put more collateral for users. Must only be called during execution.
  /// @param collToken The ERC1155 token to collateral.
  /// @param collId The token id to collateral.
  /// @param amountCall The amount of tokens to put via transferFrom.
  function putCollateral(
    address collToken,
    uint collId,
    uint amountCall
  ) external override inExec {
    Position storage pos = positions[POSITION_ID];
    if (pos.collToken != collToken || pos.collId != collId) {
      require(oracle.supportWrappedToken(collToken, collId), 'collateral not supported');
      require(pos.collateralSize == 0, 'another type of collateral already exists');
      pos.collToken = collToken;
      pos.collId = collId;
    }
    uint amount = doERC1155TransferIn(collToken, collId, amountCall);
    pos.collateralSize = pos.collateralSize.add(amount);
    emit PutCollateral(POSITION_ID, msg.sender, collToken, collId, amount);
  }

  /// @dev Take some collateral back. Must only be called during execution.
  /// @param collToken The ERC1155 token to take back.
  /// @param collId The token id to take back.
  /// @param amount The amount of tokens to take back via transfer.
  function takeCollateral(
    address collToken,
    uint collId,
    uint amount
  ) external override inExec {
    Position storage pos = positions[POSITION_ID];
    require(collToken == pos.collToken, 'invalid collateral token');
    require(collId == pos.collId, 'invalid collateral token');
    if (amount == uint(-1)) {
      amount = pos.collateralSize;
    }
    pos.collateralSize = pos.collateralSize.sub(amount);
    IERC1155(collToken).safeTransferFrom(address(this), msg.sender, collId, amount, '');
    emit TakeCollateral(POSITION_ID, msg.sender, collToken, collId, amount);
  }

  /// @dev Internal function to perform borrow from the bank and return the amount received.
  /// @param token The token to perform borrow action.
  /// @param amountCall The amount use in the transferFrom call.
  /// NOTE: Caller must ensure that cToken interest was already accrued up to this block.
  function doBorrow(address token, uint amountCall) internal returns (uint) {
    Bank storage bank = banks[token]; // assume the input is already sanity checked.
    uint balanceBefore = IERC20(token).balanceOf(address(this));
    require(ICErc20(bank.cToken).borrow(amountCall) == 0, 'bad borrow');
    uint balanceAfter = IERC20(token).balanceOf(address(this));
    bank.totalDebt = bank.totalDebt.add(amountCall);
    return balanceAfter.sub(balanceBefore);
  }

  /// @dev Internal function to perform repay to the bank and return the amount actually repaid.
  /// @param token The token to perform repay action.
  /// @param amountCall The amount to use in the repay call.
  /// NOTE: Caller must ensure that cToken interest was already accrued up to this block.
  function doRepay(address token, uint amountCall) internal returns (uint) {
    Bank storage bank = banks[token]; // assume the input is already sanity checked.
    ICErc20 cToken = ICErc20(bank.cToken);
    uint oldDebt = bank.totalDebt;
    require(cToken.repayBorrow(amountCall) == 0, 'bad repay');
    uint newDebt = cToken.borrowBalanceStored(address(this));
    bank.totalDebt = newDebt;
    return oldDebt.sub(newDebt);
  }

  /// @dev Internal function to perform ERC20 transfer in and return amount actually received.
  /// @param token The token to perform transferFrom action.
  /// @param amountCall The amount use in the transferFrom call.
  function doERC20TransferIn(address token, uint amountCall) internal returns (uint) {
    uint balanceBefore = IERC20(token).balanceOf(address(this));
    IERC20(token).safeTransferFrom(msg.sender, address(this), amountCall);
    uint balanceAfter = IERC20(token).balanceOf(address(this));
    return balanceAfter.sub(balanceBefore);
  }

  /// @dev Internal function to perform ERC1155 transfer in and return amount actually received.
  /// @param token The token to perform transferFrom action.
  /// @param id The id to perform transferFrom action.
  /// @param amountCall The amount use in the transferFrom call.
  function doERC1155TransferIn(
    address token,
    uint id,
    uint amountCall
  ) internal returns (uint) {
    uint balanceBefore = IERC1155(token).balanceOf(address(this), id);
    IERC1155(token).safeTransferFrom(msg.sender, address(this), id, amountCall, '');
    uint balanceAfter = IERC1155(token).balanceOf(address(this), id);
    return balanceAfter.sub(balanceBefore);
  }
}