pragma solidity 0.5.11;

/**
 * @title OUSD Vault Contract
 * @notice The Vault contract stores assets. On a deposit, OUSD will be minted
           and sent to the depositor. On a withdrawal, OUSD will be burned and
           assets will be sent to the withdrawer. The Vault accepts deposits of
           interest form yield bearing strategies which will modify the supply
           of OUSD.
 * @author Origin Protocol Inc
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

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

        return c;
    }

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

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     * - Subtraction cannot overflow.
     *
     * _Available since v2.4.0._
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

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

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

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

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
     *
     * _Available since v2.4.0._
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

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);
}

contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20};
     *
     * Requirements:
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for `sender`'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner`s tokens.
     *
     * This is internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`.`amount` is then deducted
     * from the caller's allowance.
     *
     * See {_burn} and {_approve}.
     */
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }
}

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));
    }

    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.

        // A Solidity high level call has three parts:
        //  1. The target address is checked to verify it contains contract code
        //  2. The call itself is made, and success asserted
        //  3. The return value is decoded, which in turn checks the size of the returned data.
        // solhint-disable-next-line max-line-length
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "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");
        }
    }
}

library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Converts an `address` into `address payable`. Note that this is
     * simply a type cast: the actual underlying value is not changed.
     *
     * _Available since v2.4.0._
     */
    function toPayable(address account) internal pure returns (address payable) {
        return address(uint160(account));
    }

    /**
     * @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].
     *
     * _Available since v2.4.0._
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

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

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 use in the initializer function of a contract.
   */
  modifier initializer() {
    require(initializing || isConstructor() || !initialized, "Contract instance has already been 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) {
    // extcodesize checks the size of the code stored in an address, and
    // address returns the current address. Since the code is still not
    // deployed when running a constructor, any checks on its code size will
    // yield zero, making it an effective way to detect if a contract is
    // under construction or not.
    address self = address(this);
    uint256 cs;
    assembly { cs := extcodesize(self) }
    return cs == 0;
  }

  // Reserved storage space to allow for layout changes in the future.
  uint256[50] private ______gap;
}

contract Governable {
    // Storage position of the owner and pendingOwner of the contract
    bytes32
        private constant governorPosition = 0x7bea13895fa79d2831e0a9e28edede30099005a50d652d8957cf8a607ee6ca4a;
    //keccak256("OUSD.governor");

    bytes32
        private constant pendingGovernorPosition = 0x44c4d30b2eaad5130ad70c3ba6972730566f3e6359ab83e800d905c61b1c51db;
    //keccak256("OUSD.pending.governor");

    event PendingGovernorshipTransfer(
        address indexed previousGovernor,
        address indexed newGovernor
    );

    event GovernorshipTransferred(
        address indexed previousGovernor,
        address indexed newGovernor
    );

    /**
     * @dev Initializes the contract setting the deployer as the initial Governor.
     */
    constructor() internal {
        _setGovernor(msg.sender);
        emit GovernorshipTransferred(address(0), _governor());
    }

    /**
     * @dev Returns the address of the current Governor.
     */
    function governor() public view returns (address) {
        return _governor();
    }

    function _governor() internal view returns (address governorOut) {
        bytes32 position = governorPosition;
        assembly {
            governorOut := sload(position)
        }
    }

    function _pendingGovernor()
        internal
        view
        returns (address pendingGovernor)
    {
        bytes32 position = pendingGovernorPosition;
        assembly {
            pendingGovernor := sload(position)
        }
    }

    /**
     * @dev Throws if called by any account other than the Governor.
     */
    modifier onlyGovernor() {
        require(isGovernor(), "Caller is not the Governor");
        _;
    }

    /**
     * @dev Returns true if the caller is the current Governor.
     */
    function isGovernor() public view returns (bool) {
        return msg.sender == _governor();
    }

    function _setGovernor(address newGovernor) internal {
        bytes32 position = governorPosition;
        assembly {
            sstore(position, newGovernor)
        }
    }

    function _setPendingGovernor(address newGovernor) internal {
        bytes32 position = pendingGovernorPosition;
        assembly {
            sstore(position, newGovernor)
        }
    }

    /**
     * @dev Transfers Governance of the contract to a new account (`newGovernor`).
     * Can only be called by the current Governor. Must be claimed for this to complete
     * @param _newGovernor Address of the new Governor
     */
    function transferGovernance(address _newGovernor) external onlyGovernor {
        _setPendingGovernor(_newGovernor);
        emit PendingGovernorshipTransfer(_governor(), _newGovernor);
    }

    /**
     * @dev Claim Governance of the contract to a new account (`newGovernor`).
     * Can only be called by the new Governor.
     */
    function claimGovernance() external {
        require(
            msg.sender == _pendingGovernor(),
            "Only the pending Governor can complete the claim"
        );
        _changeGovernor(msg.sender);
    }

    /**
     * @dev Change Governance of the contract to a new account (`newGovernor`).
     * @param _newGovernor Address of the new Governor
     */
    function _changeGovernor(address _newGovernor) internal {
        require(_newGovernor != address(0), "New Governor is address(0)");
        emit GovernorshipTransferred(_governor(), _newGovernor);
        _setGovernor(_newGovernor);
    }
}

interface IBasicToken {
    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);
}

interface IMinMaxOracle {
    //Assuming 8 decimals
    function priceMin(string calldata symbol) external returns (uint256);

    function priceMax(string calldata symbol) external returns (uint256);
}

interface IViewMinMaxOracle {
    function priceMin(string calldata symbol) external view returns (uint256);

    function priceMax(string calldata symbol) external view returns (uint256);
}

interface IStrategy {
    /**
     * @dev Deposit the given asset to Lending platform.
     * @param _asset asset address
     * @param _amount Amount to deposit
     */
    function deposit(address _asset, uint256 _amount)
        external
        returns (uint256 amountDeposited);

    /**
     * @dev Withdraw given asset from Lending platform
     */
    function withdraw(
        address _recipient,
        address _asset,
        uint256 _amount
    ) external returns (uint256 amountWithdrawn);

    /**
     * @dev Returns the current balance of the given asset.
     */
    function checkBalance(address _asset)
        external
        view
        returns (uint256 balance);

    /**
     * @dev Returns bool indicating whether strategy supports asset.
     */
    function supportsAsset(address _asset) external view returns (bool);

    /**
     * @dev Liquidate all assets in strategy and return them to Vault.
     */
    function liquidate() external;

    /**
     * @dev Get the APR for the Strategy.
     */
    function getAPR() external view returns (uint256);

    /**
     * @dev Collect reward tokens from the Strategy.
     */
    function collectRewardToken() external;
}

library Helpers {
    /**
     * @notice Fetch the `symbol()` from an ERC20 token
     * @dev Grabs the `symbol()` from a contract
     * @param _token Address of the ERC20 token
     * @return string Symbol of the ERC20 token
     */
    function getSymbol(address _token) internal view returns (string memory) {
        string memory symbol = IBasicToken(_token).symbol();
        return symbol;
    }

    /**
     * @notice Fetch the `decimals()` from an ERC20 token
     * @dev Grabs the `decimals()` from a contract and fails if
     *      the decimal value does not live within a certain range
     * @param _token Address of the ERC20 token
     * @return uint256 Decimals of the ERC20 token
     */
    function getDecimals(address _token) internal view returns (uint256) {
        uint256 decimals = IBasicToken(_token).decimals();
        require(
            decimals >= 4 && decimals <= 18,
            "Token must have sufficient decimal places"
        );

        return decimals;
    }
}

contract InitializableERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for `name`, `symbol`, and `decimals`. All three of
     * these values are immutable: they can only be set once during
     * construction.
     * @notice To avoid variable shadowing appended `Arg` after arguments name.
     */
    function _initialize(
        string memory nameArg,
        string memory symbolArg,
        uint8 decimalsArg
    ) internal {
        _name = nameArg;
        _symbol = symbolArg;
        _decimals = decimalsArg;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

contract InitializableToken is ERC20, InitializableERC20Detailed {
    /**
     * @dev Initialization function for implementing contract
     * @notice To avoid variable shadowing appended `Arg` after arguments name.
     */
    function _initialize(string memory _nameArg, string memory _symbolArg)
        internal
    {
        InitializableERC20Detailed._initialize(_nameArg, _symbolArg, 18);
    }
}

contract OUSD is Initializable, InitializableToken, Governable {
    using SafeMath for uint256;
    using StableMath for uint256;

    event TotalSupplyUpdated(
        uint256 totalSupply,
        uint256 totalCredits,
        uint256 creditsPerToken
    );

    uint256 private constant MAX_SUPPLY = ~uint128(0); // (2^128) - 1

    uint256 private _totalSupply;
    uint256 private totalCredits;
    // Exchange rate between internal credits and OUSD
    uint256 private creditsPerToken;

    mapping(address => uint256) private _creditBalances;

    // Allowances denominated in OUSD
    mapping(address => mapping(address => uint256)) private _allowances;

    address public vaultAddress = address(0);

    function initialize(
        string calldata _nameArg,
        string calldata _symbolArg,
        address _vaultAddress
    ) external onlyGovernor initializer {
        InitializableToken._initialize(_nameArg, _symbolArg);

        _totalSupply = 0;
        totalCredits = 0;
        creditsPerToken = 1e18;

        vaultAddress = _vaultAddress;
    }

    /**
     * @dev Verifies that the caller is the Savings Manager contract
     */
    modifier onlyVault() {
        require(vaultAddress == msg.sender, "Caller is not the Vault");
        _;
    }

    /**
     * @return The total supply of OUSD.
     */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev Gets the balance of the specified address.
     * @param _account The address to query the balance of.
     * @return A unit256 representing the _amount of base units owned by the
     *         specified address.
     */
    function balanceOf(address _account) public view returns (uint256) {
        if (creditsPerToken == 0) return 0;
        return _creditBalances[_account].divPrecisely(creditsPerToken);
    }

    /**
     * @dev Gets the credits balance of the specified address.
     * @param _account The address to query the balance of.
     * @return A uint256 representing the _amount of base units owned by the
     *         specified address.
     */
    function creditsBalanceOf(address _account) public view returns (uint256) {
        return _creditBalances[_account];
    }

    /**
     * @dev Transfer tokens to a specified address.
     * @param _to the address to transfer to.
     * @param _value the _amount to be transferred.
     * @return true on success.
     */
    function transfer(address _to, uint256 _value) public returns (bool) {
        uint256 creditValue = _removeCredits(msg.sender, _value);
        _creditBalances[_to] = _creditBalances[_to].add(creditValue);

        emit Transfer(msg.sender, _to, _value);

        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * @param _from The address you want to send tokens from.
     * @param _to The address you want to transfer to.
     * @param _value The _amount of tokens to be transferred.
     */
    function transferFrom(
        address _from,
        address _to,
        uint256 _value
    ) public returns (bool) {
        _allowances[_from][msg.sender] = _allowances[_from][msg.sender].sub(
            _value
        );

        uint256 creditValue = _removeCredits(_from, _value);
        _creditBalances[_to] = _creditBalances[_to].add(creditValue);

        emit Transfer(_from, _to, _value);

        return true;
    }

    /**
     * @dev Function to check the _amount of tokens that an owner has allowed to a _spender.
     * @param _owner The address which owns the funds.
     * @param _spender The address which will spend the funds.
     * @return The number of tokens still available for the _spender.
     */
    function allowance(address _owner, address _spender)
        public
        view
        returns (uint256)
    {
        return _allowances[_owner][_spender];
    }

    /**
     * @dev Approve the passed address to spend the specified _amount of tokens on behalf of
     * msg.sender. This method is included for ERC20 compatibility.
     * increaseAllowance and decreaseAllowance should be used instead.
     * Changing an allowance with this method brings the risk that someone may transfer both
     * the old and the new allowance - if they are both greater than zero - if a transfer
     * transaction is mined before the later approve() call is mined.
     *
     * @param _spender The address which will spend the funds.
     * @param _value The _amount of tokens to be spent.
     */
    function approve(address _spender, uint256 _value) public returns (bool) {
        _allowances[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * @dev Increase the _amount of tokens that an owner has allowed to a _spender.
     * This method should be used instead of approve() to avoid the double approval vulnerability
     * described above.
     * @param _spender The address which will spend the funds.
     * @param _addedValue The _amount of tokens to increase the allowance by.
     */
    function increaseAllowance(address _spender, uint256 _addedValue)
        public
        returns (bool)
    {
        _allowances[msg.sender][_spender] = _allowances[msg.sender][_spender]
            .add(_addedValue);
        emit Approval(msg.sender, _spender, _allowances[msg.sender][_spender]);
        return true;
    }

    /**
     * @dev Decrease the _amount of tokens that an owner has allowed to a _spender.
     * @param _spender The address which will spend the funds.
     * @param _subtractedValue The _amount of tokens to decrease the allowance by.
     */
    function decreaseAllowance(address _spender, uint256 _subtractedValue)
        public
        returns (bool)
    {
        uint256 oldValue = _allowances[msg.sender][_spender];
        if (_subtractedValue >= oldValue) {
            _allowances[msg.sender][_spender] = 0;
        } else {
            _allowances[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        emit Approval(msg.sender, _spender, _allowances[msg.sender][_spender]);
        return true;
    }

    /**
     * @notice Mints new tokens, increasing totalSupply.
     */
    function mint(address _account, uint256 _amount) external onlyVault {
        return _mint(_account, _amount);
    }

    /**
     * @dev Creates `_amount` tokens and assigns them to `_account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address _account, uint256 _amount) internal {
        require(_account != address(0), "Mint to the zero address");

        _totalSupply = _totalSupply.add(_amount);

        uint256 creditAmount = _amount.mulTruncate(creditsPerToken);
        _creditBalances[_account] = _creditBalances[_account].add(creditAmount);
        totalCredits = totalCredits.add(creditAmount);

        emit Transfer(address(0), _account, _amount);
    }

    /**
     * @notice Burns tokens, decreasing totalSupply.
     */
    function burn(address account, uint256 amount) external onlyVault {
        return _burn(account, amount);
    }

    /**
     * @dev Destroys `_amount` tokens from `_account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `_account` cannot be the zero address.
     * - `_account` must have at least `_amount` tokens.
     */
    function _burn(address _account, uint256 _amount) internal {
        require(_account != address(0), "Burn from the zero address");

        _totalSupply = _totalSupply.sub(_amount);
        uint256 creditAmount = _removeCredits(_account, _amount);
        totalCredits = totalCredits.sub(creditAmount);

        emit Transfer(_account, address(0), _amount);
    }

    /**
     * @dev Removes credits from a credit balance and burns rounding errors.
     * @param _account Account to remove credits from
     * @param _amount Amount in OUSD which will be converted to credits and
     *                removed
     */
    function _removeCredits(address _account, uint256 _amount)
        internal
        returns (uint256 creditAmount)
    {
        creditAmount = _amount.mulTruncate(creditsPerToken);
        uint256 currentCredits = _creditBalances[_account];
        if (
            currentCredits == creditAmount || currentCredits - 1 == creditAmount
        ) {
            _creditBalances[_account] = 0;
        } else if (currentCredits > creditAmount) {
            _creditBalances[_account] = currentCredits - creditAmount;
        } else {
            revert("Remove exceeds balance");
        }
    }

    /**
     * @dev Modify the supply without minting new tokens. This uses a change in
     *      the exchange rate between "credits" and OUSD tokens to change balances.
     * @param _newTotalSupply New total supply of OUSD.
     * @return uint256 representing the new total supply.
     */
    function changeSupply(uint256 _newTotalSupply)
        external
        onlyVault
        returns (uint256)
    {
        require(_totalSupply > 0, "Cannot increase 0 supply");

        if (_totalSupply == _newTotalSupply) {
            emit TotalSupplyUpdated(
                _totalSupply,
                totalCredits,
                creditsPerToken
            );
            return _totalSupply;
        }

        _totalSupply = _newTotalSupply;

        if (_totalSupply > MAX_SUPPLY) _totalSupply = MAX_SUPPLY;

        creditsPerToken = totalCredits.divPrecisely(_totalSupply);

        emit TotalSupplyUpdated(_totalSupply, totalCredits, creditsPerToken);
        return _totalSupply;
    }
}

library StableMath {
    using SafeMath for uint256;

    /**
     * @dev Scaling unit for use in specific calculations,
     * where 1 * 10**18, or 1e18 represents a unit '1'
     */
    uint256 private constant FULL_SCALE = 1e18;

    /***************************************
                    Helpers
    ****************************************/

    /**
     * @dev Adjust the scale of an integer
     * @param adjustment Amount to adjust by e.g. scaleBy(1e18, -1) == 1e17
     */
    function scaleBy(uint256 x, int8 adjustment)
        internal
        pure
        returns (uint256)
    {
        if (adjustment > 0) {
            x = x.mul(10**uint256(adjustment));
        } else if (adjustment < 0) {
            x = x.div(10**uint256(adjustment * -1));
        }
        return x;
    }

    /***************************************
               Precise Arithmetic
    ****************************************/

    /**
     * @dev Multiplies two precise units, and then truncates by the full scale
     * @param x Left hand input to multiplication
     * @param y Right hand input to multiplication
     * @return Result after multiplying the two inputs and then dividing by the shared
     *         scale unit
     */
    function mulTruncate(uint256 x, uint256 y) internal pure returns (uint256) {
        return mulTruncateScale(x, y, FULL_SCALE);
    }

    /**
     * @dev Multiplies two precise units, and then truncates by the given scale. For example,
     * when calculating 90% of 10e18, (10e18 * 9e17) / 1e18 = (9e36) / 1e18 = 9e18
     * @param x Left hand input to multiplication
     * @param y Right hand input to multiplication
     * @param scale Scale unit
     * @return Result after multiplying the two inputs and then dividing by the shared
     *         scale unit
     */
    function mulTruncateScale(
        uint256 x,
        uint256 y,
        uint256 scale
    ) internal pure returns (uint256) {
        // e.g. assume scale = fullScale
        // z = 10e18 * 9e17 = 9e36
        uint256 z = x.mul(y);
        // return 9e38 / 1e18 = 9e18
        return z.div(scale);
    }

    /**
     * @dev Multiplies two precise units, and then truncates by the full scale, rounding up the result
     * @param x Left hand input to multiplication
     * @param y Right hand input to multiplication
     * @return Result after multiplying the two inputs and then dividing by the shared
     *          scale unit, rounded up to the closest base unit.
     */
    function mulTruncateCeil(uint256 x, uint256 y)
        internal
        pure
        returns (uint256)
    {
        // e.g. 8e17 * 17268172638 = 138145381104e17
        uint256 scaled = x.mul(y);
        // e.g. 138145381104e17 + 9.99...e17 = 138145381113.99...e17
        uint256 ceil = scaled.add(FULL_SCALE.sub(1));
        // e.g. 13814538111.399...e18 / 1e18 = 13814538111
        return ceil.div(FULL_SCALE);
    }

    /**
     * @dev Precisely divides two units, by first scaling the left hand operand. Useful
     *      for finding percentage weightings, i.e. 8e18/10e18 = 80% (or 8e17)
     * @param x Left hand input to division
     * @param y Right hand input to division
     * @return Result after multiplying the left operand by the scale, and
     *         executing the division on the right hand input.
     */
    function divPrecisely(uint256 x, uint256 y)
        internal
        pure
        returns (uint256)
    {
        // e.g. 8e18 * 1e18 = 8e36
        uint256 z = x.mul(FULL_SCALE);
        // e.g. 8e36 / 10e18 = 8e17
        return z.div(y);
    }
}

contract Vault is Initializable, Governable {
    using SafeMath for uint256;
    using StableMath for uint256;
    using SafeMath for int256;
    using SafeERC20 for IERC20;

    event AssetSupported(address _asset);
    event StrategyAdded(address _addr);
    event StrategyRemoved(address _addr);
    event Mint(address _addr, uint256 _value);
    event Redeem(address _addr, uint256 _value);
    event StrategyWeightsUpdated(
        address[] _strategyAddresses,
        uint256[] weights
    );
    event DepositsPaused();
    event DepositsUnpaused();

    // Assets supported by the Vault, i.e. Stablecoins
    struct Asset {
        bool isSupported;
    }
    mapping(address => Asset) assets;
    address[] allAssets;

    // Strategies supported by the Vault
    struct Strategy {
        bool isSupported;
        uint256 targetWeight; // 18 decimals. 100% = 1e18
    }
    mapping(address => Strategy) strategies;
    address[] allStrategies;

    // Address of the Oracle price provider contract
    address public priceProvider;
    // Pausing bools
    bool public rebasePaused = false;
    bool public depositPaused = true;
    // Redemption fee in basis points
    uint256 public redeemFeeBps;
    // Buffer of assets to keep in Vault to handle (most) withdrawals
    uint256 public vaultBuffer;
    // Mints over this amount automatically allocate funds. 18 decimals.
    uint256 public autoAllocateThreshold;
    // Mints over this amount automatically rebase. 18 decimals.
    uint256 public rebaseThreshold;

    OUSD oUSD;

    /**
     * @dev Verifies that the rebasing is not paused.
     */
    modifier whenNotRebasePaused() {
        require(!rebasePaused, "Rebasing paused");
        _;
    }

    /***************************************
                 Configuration
    ****************************************/

    /**
     * @dev Set address of price provider.
     * @param _priceProvider Address of price provider
     */
    function setPriceProvider(address _priceProvider) external onlyGovernor {
        priceProvider = _priceProvider;
    }

    /**
     * @dev Set a fee in basis points to be charged for a redeem.
     * @param _redeemFeeBps Basis point fee to be charged
     */
    function setRedeemFeeBps(uint256 _redeemFeeBps) external onlyGovernor {
        redeemFeeBps = _redeemFeeBps;
    }

    /**
     * @dev Set a buffer of assets to keep in the Vault to handle most
     * redemptions without needing to spend gas unwinding assets from a Strategy.
     * @param _vaultBuffer Percentage using 18 decimals. 100% = 1e18.
     */
    function setVaultBuffer(uint256 _vaultBuffer) external onlyGovernor {
        vaultBuffer = _vaultBuffer;
    }

    /**
     * @dev Sets the minimum amount of OUSD in a mint to trigger an
     * automatic allocation of funds afterwords.
     * @param _threshold OUSD amount with 18 fixed decimals.
     */
    function setAutoAllocateThreshold(uint256 _threshold)
        external
        onlyGovernor
    {
        autoAllocateThreshold = _threshold;
    }

    /**
     * @dev Set a minimum amount of OUSD in a mint or redeem that triggers a
     * rebase
     * @param _threshold OUSD amount with 18 fixed decimals.
     */
    function setRebaseThreshold(uint256 _threshold) external onlyGovernor {
        rebaseThreshold = _threshold;
    }

    /** @dev Add a supported asset to the contract, i.e. one that can be
     *         to mint OUSD.
     * @param _asset Address of asset
     */
    function supportAsset(address _asset) external onlyGovernor {
        require(!assets[_asset].isSupported, "Asset already supported");

        assets[_asset] = Asset({ isSupported: true });
        allAssets.push(_asset);

        emit AssetSupported(_asset);
    }

    /**
     * @dev Add a strategy to the Vault.
     * @param _addr Address of the strategy to add
     * @param _targetWeight Target percentage of asset allocation to strategy
     */
    function addStrategy(address _addr, uint256 _targetWeight)
        external
        onlyGovernor
    {
        require(!strategies[_addr].isSupported, "Strategy already added");

        strategies[_addr] = Strategy({
            isSupported: true,
            targetWeight: _targetWeight
        });
        allStrategies.push(_addr);

        emit StrategyAdded(_addr);
    }

    /**
     * @dev Remove a strategy from the Vault. Removes all invested assets and
     * returns them to the Vault.
     * @param _addr Address of the strategy to remove
     */

    function removeStrategy(address _addr) external onlyGovernor {
        require(strategies[_addr].isSupported, "Strategy not added");

        // Initialize strategyIndex with out of bounds result so function will
        // revert if no valid index found
        uint256 strategyIndex = allStrategies.length;
        for (uint256 i = 0; i < allStrategies.length; i++) {
            if (allStrategies[i] == _addr) {
                strategyIndex = i;
                break;
            }
        }

        assert(strategyIndex < allStrategies.length);

        allStrategies[strategyIndex] = allStrategies[allStrategies.length - 1];
        allStrategies.length--;

        // Liquidate all assets
        IStrategy strategy = IStrategy(_addr);
        strategy.liquidate();

        emit StrategyRemoved(_addr);
    }

    /**
     * @notice Set the weights for multiple strategies.
     * @param _strategyAddresses Array of strategy addresses
     * @param _weights Array of corresponding weights, with 18 decimals.
     *                 For ex. 100%=1e18, 30%=3e17.
     */
    function setStrategyWeights(
        address[] calldata _strategyAddresses,
        uint256[] calldata _weights
    ) external onlyGovernor {
        require(
            _strategyAddresses.length == _weights.length,
            "Parameter length mismatch"
        );

        for (uint256 i = 0; i < _strategyAddresses.length; i++) {
            strategies[_strategyAddresses[i]].targetWeight = _weights[i];
        }

        emit StrategyWeightsUpdated(_strategyAddresses, _weights);
    }

    /***************************************
                      Core
    ****************************************/

    /**
     * @dev Deposit a supported asset and mint OUSD.
     * @param _asset Address of the asset being deposited
     * @param _amount Amount of the asset being deposited
     */
    function mint(address _asset, uint256 _amount) external {
        require(!depositPaused, "Deposits are paused");
        require(assets[_asset].isSupported, "Asset is not supported");
        require(_amount > 0, "Amount must be greater than 0");

        uint256[] memory assetPrices;
        // For now we have to live with the +1 oracle call because we need to
        // know the priceAdjustedDeposit before we decide wether or not to grab
        // assets. This will not effect small non-rebase/allocate mints
        uint256 priceAdjustedDeposit = _amount.mulTruncateScale(
            IMinMaxOracle(priceProvider)
                .priceMin(Helpers.getSymbol(_asset))
                .scaleBy(int8(10)), // 18-8 because oracles have 8 decimals precision
            10**Helpers.getDecimals(_asset)
        );
        if (
            (priceAdjustedDeposit > rebaseThreshold && !rebasePaused) ||
            (priceAdjustedDeposit >= autoAllocateThreshold)
        ) {
            assetPrices = _getAssetPrices(false);
        }

        // Rebase must happen before any transfers occur.
        if (priceAdjustedDeposit > rebaseThreshold && !rebasePaused) {
            rebase(assetPrices);
        }

        // Transfer the deposited coins to the vault
        IERC20 asset = IERC20(_asset);
        asset.safeTransferFrom(msg.sender, address(this), _amount);

        // Mint matching OUSD
        oUSD.mint(msg.sender, priceAdjustedDeposit);
        emit Mint(msg.sender, priceAdjustedDeposit);

        if (priceAdjustedDeposit >= autoAllocateThreshold) {
            allocate(assetPrices);
        }
    }

    /**
     * @dev Mint for multiple assets in the same call.
     * @param _assets Addresses of assets being deposited
     * @param _amounts Amount of each asset at the same index in the _assets
     *                 to deposit.
     */
    function mintMultiple(
        address[] calldata _assets,
        uint256[] calldata _amounts
    ) external {
        require(_assets.length == _amounts.length, "Parameter length mismatch");

        uint256 priceAdjustedTotal = 0;
        uint256[] memory assetPrices = _getAssetPrices(false);
        for (uint256 i = 0; i < allAssets.length; i++) {
            for (uint256 j = 0; j < _assets.length; j++) {
                if (_assets[j] == allAssets[i]) {
                    if (_amounts[j] > 0) {
                        uint256 assetDecimals = Helpers.getDecimals(
                            allAssets[i]
                        );
                        priceAdjustedTotal += _amounts[j].mulTruncateScale(
                            assetPrices[i],
                            10**assetDecimals
                        );
                    }
                }
            }
        }
        // Rebase must happen before any transfers occur.
        if (priceAdjustedTotal > rebaseThreshold && !rebasePaused) {
            rebase(assetPrices);
        }

        for (uint256 i = 0; i < _assets.length; i++) {
            IERC20 asset = IERC20(_assets[i]);
            asset.safeTransferFrom(msg.sender, address(this), _amounts[i]);
        }

        oUSD.mint(msg.sender, priceAdjustedTotal);
        emit Mint(msg.sender, priceAdjustedTotal);

        if (priceAdjustedTotal >= autoAllocateThreshold) {
            allocate(assetPrices);
        }
    }

    /**
     * @dev Withdraw a supported asset and burn OUSD.
     * @param _amount Amount of OUSD to burn
     */
    function redeem(uint256 _amount) public {
        uint256[] memory assetPrices = _getAssetPrices(false);
        if (_amount > rebaseThreshold && !rebasePaused) {
            rebase(assetPrices);
        }
        _redeem(_amount, assetPrices);
    }

    function _redeem(uint256 _amount, uint256[] memory assetPrices) internal {
        require(_amount > 0, "Amount must be greater than 0");

        uint256 feeAdjustedAmount;
        if (redeemFeeBps > 0) {
            uint256 redeemFee = _amount.mul(redeemFeeBps).div(10000);
            feeAdjustedAmount = _amount.sub(redeemFee);
        } else {
            feeAdjustedAmount = _amount;
        }

        // Calculate redemption outputs
        uint256[] memory outputs = _calculateRedeemOutputs(feeAdjustedAmount);
        // Send outputs
        for (uint256 i = 0; i < allAssets.length; i++) {
            if (outputs[i] == 0) continue;

            IERC20 asset = IERC20(allAssets[i]);

            if (asset.balanceOf(address(this)) >= outputs[i]) {
                // Use Vault funds first if sufficient
                asset.safeTransfer(msg.sender, outputs[i]);
            } else {
                address strategyAddr = _selectWithdrawStrategyAddr(
                    allAssets[i],
                    outputs[i],
                    assetPrices
                );

                if (strategyAddr != address(0)) {
                    // Nothing in Vault, but something in Strategy, send from there
                    IStrategy strategy = IStrategy(strategyAddr);
                    strategy.withdraw(msg.sender, allAssets[i], outputs[i]);
                } else {
                    // Cant find funds anywhere
                    revert("Liquidity error");
                }
            }
        }

        oUSD.burn(msg.sender, _amount);

        // Until we can prove that we won't affect the prices of our assets
        // by withdrawing them, this should be here.
        // It's possible that a strategy was off on its asset total, perhaps
        // a reward token sold for more or for less than anticipated.
        if (_amount > rebaseThreshold && !rebasePaused) {
            rebase(assetPrices);
        }

        emit Redeem(msg.sender, _amount);
    }

    /**
     * @notice Withdraw a supported asset and burn all OUSD.
     */
    function redeemAll() external {
        uint256[] memory assetPrices = _getAssetPrices(false);
        //unfortunately we have to do balanceOf twice
        if (oUSD.balanceOf(msg.sender) > rebaseThreshold && !rebasePaused) {
            rebase(assetPrices);
        }

        _redeem(oUSD.balanceOf(msg.sender), assetPrices);
    }

    /**
     * @notice Allocate unallocated funds on Vault to strategies.
     * @dev Allocate unallocated funds on Vault to strategies.
     **/
    function allocate() public {
        uint256[] memory assetPrices = _getAssetPrices(false);
        allocate(assetPrices);
    }

    /**
     * @notice Allocate unallocated funds on Vault to strategies.
     * @dev Allocate unallocated funds on Vault to strategies.
     **/
    function allocate(uint256[] memory assetPrices) internal {
        uint256 vaultValue = _totalValueInVault(assetPrices);
        // Nothing in vault to allocate
        if (vaultValue == 0) return;
        uint256 strategiesValue = _totalValueInStrategies(assetPrices);
        // We have a method that does the same as this, gas optimisation
        uint256 totalValue = vaultValue + strategiesValue;

        // We want to maintain a buffer on the Vault so calculate a percentage
        // modifier to multiply each amount being allocated by to enforce the
        // vault buffer
        uint256 vaultBufferModifier;
        if (strategiesValue == 0) {
            // Nothing in Strategies, allocate 100% minus the vault buffer to
            // strategies
            vaultBufferModifier = 1e18 - vaultBuffer;
        } else {
            vaultBufferModifier = vaultBuffer.mul(totalValue).div(vaultValue);
            if (1e18 > vaultBufferModifier) {
                // E.g. 1e18 - (1e17 * 10e18)/5e18 = 8e17
                // (5e18 * 8e17) / 1e18 = 4e18 allocated from Vault
                vaultBufferModifier = 1e18 - vaultBufferModifier;
            } else {
                // We need to let the buffer fill
                return;
            }
        }

        if (vaultBufferModifier == 0) return;

        // Iterate over all assets in the Vault and allocate the the appropriate
        // strategy
        for (uint256 i = 0; i < allAssets.length; i++) {
            IERC20 asset = IERC20(allAssets[i]);
            uint256 assetBalance = asset.balanceOf(address(this));
            // No balance, nothing to do here
            if (assetBalance == 0) continue;

            // Multiply the balance by the vault buffer modifier and truncate
            // to the scale of the asset decimals
            uint256 allocateAmount = assetBalance.mulTruncate(
                vaultBufferModifier
            );

            // Get the target Strategy to maintain weightings
            address depositStrategyAddr = _selectDepositStrategyAddr(
                address(asset),
                assetPrices
            );

            if (depositStrategyAddr != address(0) && allocateAmount > 0) {
                IStrategy strategy = IStrategy(depositStrategyAddr);
                // Transfer asset to Strategy and call deposit method to
                // mint or take required action
                asset.safeTransfer(address(strategy), allocateAmount);
                strategy.deposit(address(asset), allocateAmount);
            }
        }
    }

    /**
     * @dev Calculate the total value of assets held by the Vault and all
     *         strategies and update the supply of oUSD
     */
    function rebase() public whenNotRebasePaused returns (uint256) {
        uint256[] memory assetPrices = _getAssetPrices(false);
        rebase(assetPrices);
    }

    /**
     * @dev Calculate the total value of assets held by the Vault and all
     *         strategies and update the supply of oUSD
     */
    function rebase(uint256[] memory assetPrices)
        internal
        whenNotRebasePaused
        returns (uint256)
    {
        if (oUSD.totalSupply() == 0) return 0;
        return oUSD.changeSupply(_totalValue(assetPrices));
    }

    /**
     * @dev Determine the total value of assets held by the vault and its
     *         strategies.
     * @return uint256 value Total value in USD (1e18)
     */
    function totalValue() external returns (uint256 value) {
        uint256[] memory assetPrices = _getAssetPrices(false);
        value = _totalValue(assetPrices);
    }

    /**
     * @dev Internal Calculate the total value of the assets held by the
     *         vault and its strategies.
     * @return uint256 value Total value in USD (1e18)
     */
    function _totalValue(uint256[] memory assetPrices)
        internal
        view
        returns (uint256 value)
    {
        return
            _totalValueInVault(assetPrices) +
            _totalValueInStrategies(assetPrices);
    }

    /**
     * @dev Internal to calculate total value of all assets held in Vault.
     * @return uint256 Total value in ETH (1e18)
     */
    function _totalValueInVault(uint256[] memory assetPrices)
        internal
        view
        returns (uint256 value)
    {
        value = 0;
        for (uint256 y = 0; y < allAssets.length; y++) {
            IERC20 asset = IERC20(allAssets[y]);
            uint256 assetDecimals = Helpers.getDecimals(allAssets[y]);
            uint256 balance = asset.balanceOf(address(this));
            if (balance > 0) {
                value += balance.mulTruncateScale(
                    assetPrices[y],
                    10**assetDecimals
                );
            }
        }
    }

    /**
     * @dev Internal to calculate total value of all assets held in Strategies.
     * @return uint256 Total value in ETH (1e18)
     */
    function _totalValueInStrategies(uint256[] memory assetPrices)
        internal
        view
        returns (uint256 value)
    {
        value = 0;
        for (uint256 i = 0; i < allStrategies.length; i++) {
            value += _totalValueInStrategy(allStrategies[i], assetPrices);
        }
    }

    /**
     * @dev Internal to calculate total value of all assets held by strategy.
     * @param _strategyAddr Address of the strategy
     * @return uint256 Total value in ETH (1e18)
     */
    function _totalValueInStrategy(
        address _strategyAddr,
        uint256[] memory assetPrices
    ) internal view returns (uint256 value) {
        value = 0;
        IStrategy strategy = IStrategy(_strategyAddr);
        for (uint256 y = 0; y < allAssets.length; y++) {
            uint256 assetDecimals = Helpers.getDecimals(allAssets[y]);
            if (strategy.supportsAsset(allAssets[y])) {
                uint256 balance = strategy.checkBalance(allAssets[y]);
                if (balance > 0) {
                    value += balance.mulTruncateScale(
                        assetPrices[y],
                        10**assetDecimals
                    );
                }
            }
        }
    }

    /**
     * @dev Calculate difference in percent of asset allocation for a
               strategy.
     * @param _strategyAddr Address of the strategy
     * @return int256 Difference between current and target. 18 decimals. For ex. 10%=1e17.
     */
    function _strategyWeightDifference(
        address _strategyAddr,
        uint256[] memory assetPrices
    ) internal view returns (int256 difference) {
        difference =
            int256(strategies[_strategyAddr].targetWeight) -
            int256(
                _totalValueInStrategy(_strategyAddr, assetPrices).divPrecisely(
                    _totalValue(assetPrices)
                )
            );
    }

    /**
     * @dev Select a strategy for allocating an asset to.
     * @param _asset Address of asset
     * @return address Address of the target strategy
     */
    function _selectDepositStrategyAddr(
        address _asset,
        uint256[] memory assetPrices
    ) internal view returns (address depositStrategyAddr) {
        depositStrategyAddr = address(0);
        int256 maxDifference = 0;

        for (uint256 i = 0; i < allStrategies.length; i++) {
            IStrategy strategy = IStrategy(allStrategies[i]);
            if (strategy.supportsAsset(_asset)) {
                int256 diff = _strategyWeightDifference(
                    allStrategies[i],
                    assetPrices
                );
                if (diff >= maxDifference) {
                    maxDifference = diff;
                    depositStrategyAddr = allStrategies[i];
                }
            }
        }
    }

    /**
     * @dev Select a strategy for withdrawing an asset from.
     * @param _asset Address of asset
     * @return address Address of the target strategy for withdrawal
     */
    function _selectWithdrawStrategyAddr(
        address _asset,
        uint256 _amount,
        uint256[] memory assetPrices
    ) internal view returns (address withdrawStrategyAddr) {
        withdrawStrategyAddr = address(0);
        int256 minDifference = 1e18;

        for (uint256 i = 0; i < allStrategies.length; i++) {
            IStrategy strategy = IStrategy(allStrategies[i]);
            if (
                strategy.supportsAsset(_asset) &&
                strategy.checkBalance(_asset) > _amount
            ) {
                int256 diff = _strategyWeightDifference(
                    allStrategies[i],
                    assetPrices
                );
                if (diff <= minDifference) {
                    minDifference = diff;
                    withdrawStrategyAddr = allStrategies[i];
                }
            }
        }
    }

    /**
     * @notice Get the balance of an asset held in Vault and all strategies.
     * @param _asset Address of asset
     * @return uint256 Balance of asset in decimals of asset
     */
    function checkBalance(address _asset) external view returns (uint256) {
        return _checkBalance(_asset);
    }

    /**
     * @notice Get the balance of an asset held in Vault and all strategies.
     * @param _asset Address of asset
     * @return uint256 Balance of asset in decimals of asset
     */
    function _checkBalance(address _asset)
        internal
        view
        returns (uint256 balance)
    {
        IERC20 asset = IERC20(_asset);
        balance = asset.balanceOf(address(this));
        for (uint256 i = 0; i < allStrategies.length; i++) {
            IStrategy strategy = IStrategy(allStrategies[i]);
            if (strategy.supportsAsset(_asset)) {
                balance += strategy.checkBalance(_asset);
            }
        }
    }

    /**
     * @notice Get the balance of all assets held in Vault and all strategies.
     * @return uint256 Balance of all assets (1e18)
     */
    function _checkBalance() internal view returns (uint256 balance) {
        balance = 0;
        for (uint256 i = 0; i < allAssets.length; i++) {
            uint256 assetDecimals = Helpers.getDecimals(allAssets[i]);
            balance += _checkBalance(allAssets[i]).scaleBy(
                int8(18 - assetDecimals)
            );
        }
    }

    /**
     * @notice Calculate the outputs for a redeem function, i.e. the mix of
     * coins that will be returned
     */
    function calculateRedeemOutputs(uint256 _amount)
        external
        returns (uint256[] memory)
    {
        return _calculateRedeemOutputs(_amount);
    }

    /**
     * @notice Calculate the outputs for a redeem function, i.e. the mix of
     * coins that will be returned.
     * @return Array of amounts respective to the supported assets
     */
    function _calculateRedeemOutputs(uint256 _amount)
        internal
        returns (uint256[] memory outputs)
    {
        uint256[] memory assetPrices = _getAssetPrices(true);

        uint256 totalBalance = _checkBalance();
        uint256 totalOutputValue = 0; // Running total of USD value of assets
        uint256 assetCount = getAssetCount();

        // Initialise arrays
        // Price of each asset in USD in 1e18
        outputs = new uint256[](assetCount);

        for (uint256 i = 0; i < allAssets.length; i++) {
            uint256 assetDecimals = Helpers.getDecimals(allAssets[i]);

            // Get the proportional amount of this token for the redeem in 1e18
            uint256 proportionalAmount = _checkBalance(allAssets[i])
                .scaleBy(int8(18 - assetDecimals))
                .mul(_amount)
                .div(totalBalance);

            if (proportionalAmount > 0) {
                // Running USD total of all coins in the redeem outputs in 1e18
                totalOutputValue += proportionalAmount.mulTruncate(
                    assetPrices[i]
                );
                // Save the output amount in the decimals of the asset
                outputs[i] = proportionalAmount.scaleBy(
                    int8(assetDecimals - 18)
                );
            }
        }

        // USD difference in amount of coins calculated due to variations in
        // price in 1e18
        int256 outputValueDiff = int256(_amount - totalOutputValue);
        // Make up the difference by adding/removing an equal proportion of
        // each coin according to its USD value
        for (uint256 i = 0; i < outputs.length; i++) {
            if (outputs[i] == 0) continue;
            if (outputValueDiff < 0) {
                outputs[i] -= uint256(-outputValueDiff).mul(outputs[i]).div(
                    totalOutputValue
                );
            } else if (outputValueDiff > 0) {
                outputs[i] += uint256(outputValueDiff).mul(outputs[i]).div(
                    totalOutputValue
                );
            }
        }
    }

    /**
     * @notice Get an array of the supported asset prices in USD.
     * @return uint256[] Array of asset prices in USD (1e18)
     */
    function _getAssetPrices(bool useMax)
        internal
        returns (uint256[] memory assetPrices)
    {
        assetPrices = new uint256[](getAssetCount());

        IMinMaxOracle oracle = IMinMaxOracle(priceProvider);
        // Price from Oracle is returned with 8 decimals
        // _amount is in assetDecimals

        for (uint256 i = 0; i < allAssets.length; i++) {
            string memory symbol = Helpers.getSymbol(allAssets[i]);
            // Get all the USD prices of the asset in 1e18
            if (useMax) {
                assetPrices[i] = oracle.priceMax(symbol).scaleBy(int8(18 - 8));
            } else {
                assetPrices[i] = oracle.priceMin(symbol).scaleBy(int8(18 - 8));
            }
        }
    }

    /***************************************
                    Pause
    ****************************************/

    /**
     * @dev Set the deposit paused flag to true to prevent rebasing.
     */
    function pauseRebase() external onlyGovernor {
        rebasePaused = true;
    }

    /**
     * @dev Set the deposit paused flag to true to allow rebasing.
     */
    function unpauseRebase() external onlyGovernor {
        rebasePaused = false;
    }

    /**
     * @dev Set the deposit paused flag to true to prevent deposits.
     */
    function pauseDeposits() external onlyGovernor {
        depositPaused = true;

        emit DepositsPaused();
    }

    /**
     * @dev Set the deposit paused flag to false to enable deposits.
     */
    function unpauseDeposits() external onlyGovernor {
        depositPaused = false;

        emit DepositsUnpaused();
    }

    /***************************************
                    Utils
    ****************************************/

    /**
     * @dev Return the number of assets suppported by the Vault.
     */
    function getAssetCount() public view returns (uint256) {
        return allAssets.length;
    }

    /**
     * @dev Return all asset addresses in order
     */
    function getAllAssets() external view returns (address[] memory) {
        return allAssets;
    }

    /**
     * @dev Return the number of strategies active on the Vault.
     */
    function getStrategyCount() public view returns (uint256) {
        return allStrategies.length;
    }

    /**
     * @dev Get the total APR of the Vault and all Strategies.
     */
    function getAPR() external returns (uint256) {
        if (getStrategyCount() == 0) return 0;

        uint256[] memory assetPrices = _getAssetPrices(true);

        uint256 totalAPR = 0;
        // Get the value from strategies
        for (uint256 i = 0; i < allStrategies.length; i++) {
            IStrategy strategy = IStrategy(allStrategies[i]);
            if (strategy.getAPR() > 0) {
                totalAPR += _totalValueInStrategy(allStrategies[i], assetPrices)
                    .divPrecisely(_totalValue(assetPrices))
                    .mulTruncate(strategy.getAPR());
            }
        }
        return totalAPR;
    }

    /**
     * @dev Transfer token to governor. Intended for recovering tokens stuck in
     *      contract, i.e. mistaken sends.
     * @param _asset Address for the asset
     * @param _amount Amount of the asset to transfer
     */
    function transferToken(address _asset, uint256 _amount)
        external
        onlyGovernor
    {
        IERC20(_asset).transfer(governor(), _amount);
    }

    /**
     * @dev Collect reward tokens from all strategies.
     */
    function collectRewardTokens() external onlyGovernor {
        for (uint256 i = 0; i < allStrategies.length; i++) {
            collectRewardTokens(allStrategies[i]);
        }
    }

    /**
     * @dev Collect reward tokens from a single strategy and transfer them to
            Vault.
     * @param _strategyAddr Address of the strategy to collect rewards from
     */
    function collectRewardTokens(address _strategyAddr) public onlyGovernor {
        IStrategy strategy = IStrategy(_strategyAddr);
        strategy.collectRewardToken();
    }

    /**
     * @dev Determines if an asset is supported by the vault.
     * @param _asset Address of the asset
     */
    function isSupportedAsset(address _asset) external view returns (bool) {
        return assets[_asset].isSupported;
    }

    function _priceUSDMint(string memory symbol) internal returns (uint256) {
        // Price from Oracle is returned with 8 decimals
        // scale to 18 so 18-8=10
        return IMinMaxOracle(priceProvider).priceMin(symbol).scaleBy(10);
    }

    /**
     * @dev Returns the total price in 18 digit USD for a given asset.
     *      Using Min since min is what we use for mint pricing
     * @param symbol String symbol of the asset
     * @return uint256 USD price of 1 of the asset
     */
    function priceUSDMint(string calldata symbol) external returns (uint256) {
        return _priceUSDMint(symbol);
    }

    /**
     * @dev Returns the total price in 18 digit USD for a given asset.
     *      Using Max since max is what we use for redeem pricing
     * @param symbol String symbol of the asset
     * @return uint256 USD price of 1 of the asset
     */
    function _priceUSDRedeem(string memory symbol) internal returns (uint256) {
        // Price from Oracle is returned with 8 decimals
        // scale to 18 so 18-8=10
        return IMinMaxOracle(priceProvider).priceMax(symbol).scaleBy(10);
    }

    /**
     * @dev Returns the total price in 18 digit USD for a given asset.
     *      Using Max since max is what we use for redeem pricing
     * @param symbol String symbol of the asset
     * @return uint256 USD price of 1 of the asset
     */
    function priceUSDRedeem(string calldata symbol) external returns (uint256) {
        // Price from Oracle is returned with 8 decimals
        // scale to 18 so 18-8=10
        return _priceUSDRedeem(symbol);
    }
}
{"success": true, "error": null, "results": {"detectors": [{"check": "uninitialized-state", "impact": "High", "confidence": "High"}, {"check": "shadowing-state", "impact": "High", "confidence": "High"}, {"check": "incorrect-equality", "impact": "Medium", "confidence": "High"}, {"check": "uninitialized-local", "impact": "Medium", "confidence": "Medium"}, {"check": "unchecked-transfer", "impact": "High", "confidence": "Medium"}, {"check": "unused-return", "impact": "Medium", "confidence": "Medium"}]}}