pragma solidity >=0.5.0;

contract WhitelistAdminRole {
    using Roles for Roles.Role;

    event WhitelistAdminAdded(address indexed account);
    event WhitelistAdminRemoved(address indexed account);

    Roles.Role private _whitelistAdmins;

    constructor () internal {
        _addWhitelistAdmin(msg.sender);
    }

    modifier onlyWhitelistAdmin() {
        require(isWhitelistAdmin(msg.sender));
        _;
    }

    function isWhitelistAdmin(address account) public view returns (bool) {
        return _whitelistAdmins.has(account);
    }

    function addWhitelistAdmin(address account) public onlyWhitelistAdmin {
        _addWhitelistAdmin(account);
    }

    function renounceWhitelistAdmin() public {
        _removeWhitelistAdmin(msg.sender);
    }

    function _addWhitelistAdmin(address account) internal {
        _whitelistAdmins.add(account);
        emit WhitelistAdminAdded(account);
    }

    function _removeWhitelistAdmin(address account) internal {
        _whitelistAdmins.remove(account);
        emit WhitelistAdminRemoved(account);
    }
}

interface IExchangeInteractor {
    function updatePrice() external;

    function getCurrentPrice() external view returns (uint256);

    event PriceUpdated(uint256 newPrice);
}

contract PauserRole {
    using Roles for Roles.Role;

    event PauserAdded(address indexed account);
    event PauserRemoved(address indexed account);

    Roles.Role private _pausers;

    constructor () internal {
        _addPauser(msg.sender);
    }

    modifier onlyPauser() {
        require(isPauser(msg.sender));
        _;
    }

    function isPauser(address account) public view returns (bool) {
        return _pausers.has(account);
    }

    function addPauser(address account) public onlyPauser {
        _addPauser(account);
    }

    function renouncePauser() public {
        _removePauser(msg.sender);
    }

    function _addPauser(address account) internal {
        _pausers.add(account);
        emit PauserAdded(account);
    }

    function _removePauser(address account) internal {
        _pausers.remove(account);
        emit PauserRemoved(account);
    }
}

library SafeERC20 {
    using SafeMath for uint256;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        require(token.transfer(to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        require(token.transferFrom(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'
        require((value == 0) || (token.allowance(msg.sender, spender) == 0));
        require(token.approve(spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        require(token.approve(spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value);
        require(token.approve(spender, newAllowance));
    }
}

contract Ownable {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev The Ownable constructor sets the original `owner` of the contract to the sender
     * account.
     */
    constructor () internal {
        _owner = msg.sender;
        emit OwnershipTransferred(address(0), _owner);
    }

    /**
     * @return the address of the owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner());
        _;
    }

    /**
     * @return true if `msg.sender` is the owner of the contract.
     */
    function isOwner() public view returns (bool) {
        return msg.sender == _owner;
    }

    /**
     * @dev Allows the current owner to relinquish control of the contract.
     * @notice Renouncing to ownership will leave the contract without an owner.
     * It will not be possible to call the functions with the `onlyOwner`
     * modifier anymore.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Allows the current owner to transfer control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0));
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

contract WhitelistedRole is WhitelistAdminRole {
    using Roles for Roles.Role;

    event WhitelistedAdded(address indexed account);
    event WhitelistedRemoved(address indexed account);

    Roles.Role private _whitelisteds;

    modifier onlyWhitelisted() {
        require(isWhitelisted(msg.sender));
        _;
    }

    function isWhitelisted(address account) public view returns (bool) {
        return _whitelisteds.has(account);
    }

    function addWhitelisted(address account) public onlyWhitelistAdmin {
        _addWhitelisted(account);
    }

    function removeWhitelisted(address account) public onlyWhitelistAdmin {
        _removeWhitelisted(account);
    }

    function renounceWhitelisted() public {
        _removeWhitelisted(msg.sender);
    }

    function _addWhitelisted(address account) internal {
        _whitelisteds.add(account);
        emit WhitelistedAdded(account);
    }

    function _removeWhitelisted(address account) internal {
        _whitelisteds.remove(account);
        emit WhitelistedRemoved(account);
    }
}

library Roles {
    struct Role {
        mapping (address => bool) bearer;
    }

    /**
     * @dev give an account access to this role
     */
    function add(Role storage role, address account) internal {
        require(account != address(0));
        require(!has(role, account));

        role.bearer[account] = true;
    }

    /**
     * @dev remove an account's access to this role
     */
    function remove(Role storage role, address account) internal {
        require(account != address(0));
        require(has(role, account));

        role.bearer[account] = false;
    }

    /**
     * @dev check if an account has this role
     * @return bool
     */
    function has(Role storage role, address account) internal view returns (bool) {
        require(account != address(0));
        return role.bearer[account];
    }
}

contract MinterRole {
    using Roles for Roles.Role;

    event MinterAdded(address indexed account);
    event MinterRemoved(address indexed account);

    Roles.Role private _minters;

    constructor () internal {
        _addMinter(msg.sender);
    }

    modifier onlyMinter() {
        require(isMinter(msg.sender));
        _;
    }

    function isMinter(address account) public view returns (bool) {
        return _minters.has(account);
    }

    function addMinter(address account) public onlyMinter {
        _addMinter(account);
    }

    function renounceMinter() public {
        _removeMinter(msg.sender);
    }

    function _addMinter(address account) internal {
        _minters.add(account);
        emit MinterAdded(account);
    }

    function _removeMinter(address account) internal {
        _minters.remove(account);
        emit MinterRemoved(account);
    }
}

contract ReentrancyGuard {
    /// @dev counter to allow mutex lock with only one SSTORE operation
    uint256 private _guardCounter;

    constructor () internal {
        // The counter starts at one to prevent changing it from zero to a non-zero
        // value, which is a more expensive operation.
        _guardCounter = 1;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _guardCounter += 1;
        uint256 localCounter = _guardCounter;
        _;
        require(localCounter == _guardCounter);
    }
}

contract Crowdsale is ReentrancyGuard {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;

    // The token being sold
    IERC20 private _token;

    // Address where funds are collected
    address payable private _wallet;

    // How many token units a buyer gets per wei.
    // The rate is the conversion between wei and the smallest and indivisible token unit.
    // So, if you are using a rate of 1 with a ERC20Detailed token with 3 decimals called TOK
    // 1 wei will give you 1 unit, or 0.001 TOK.
    uint256 private _rate;

    // Amount of wei raised
    uint256 private _weiRaised;

    /**
     * Event for token purchase logging
     * @param purchaser who paid for the tokens
     * @param beneficiary who got the tokens
     * @param value weis paid for purchase
     * @param amount amount of tokens purchased
     */
    event TokensPurchased(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);

    /**
     * @param rate Number of token units a buyer gets per wei
     * @dev The rate is the conversion between wei and the smallest and indivisible
     * token unit. So, if you are using a rate of 1 with a ERC20Detailed token
     * with 3 decimals called TOK, 1 wei will give you 1 unit, or 0.001 TOK.
     * @param wallet Address where collected funds will be forwarded to
     * @param token Address of the token being sold
     */
    constructor (uint256 rate, address payable wallet, IERC20 token) public {
        require(rate > 0);
        require(wallet != address(0));
        require(address(token) != address(0));

        _rate = rate;
        _wallet = wallet;
        _token = token;
    }

    /**
     * @dev fallback function ***DO NOT OVERRIDE***
     * Note that other contracts will transfer fund with a base gas stipend
     * of 2300, which is not enough to call buyTokens. Consider calling
     * buyTokens directly when purchasing tokens from a contract.
     */
    function () external payable {
        buyTokens(msg.sender);
    }

    /**
     * @return the token being sold.
     */
    function token() public view returns (IERC20) {
        return _token;
    }

    /**
     * @return the address where funds are collected.
     */
    function wallet() public view returns (address payable) {
        return _wallet;
    }

    /**
     * @return the number of token units a buyer gets per wei.
     */
    function rate() public view returns (uint256) {
        return _rate;
    }

    /**
     * @return the amount of wei raised.
     */
    function weiRaised() public view returns (uint256) {
        return _weiRaised;
    }

    /**
     * @dev low level token purchase ***DO NOT OVERRIDE***
     * This function has a non-reentrancy guard, so it shouldn't be called by
     * another `nonReentrant` function.
     * @param beneficiary Recipient of the token purchase
     */
    function buyTokens(address beneficiary) public nonReentrant payable {
        uint256 weiAmount = msg.value;
        _preValidatePurchase(beneficiary, weiAmount);

        // calculate token amount to be created
        uint256 tokens = _getTokenAmount(weiAmount);

        // update state
        _weiRaised = _weiRaised.add(weiAmount);

        _processPurchase(beneficiary, tokens);
        emit TokensPurchased(msg.sender, beneficiary, weiAmount, tokens);

        _updatePurchasingState(beneficiary, weiAmount);

        _forwardFunds();
        _postValidatePurchase(beneficiary, weiAmount);
    }

    /**
     * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met.
     * Use `super` in contracts that inherit from Crowdsale to extend their validations.
     * Example from CappedCrowdsale.sol's _preValidatePurchase method:
     *     super._preValidatePurchase(beneficiary, weiAmount);
     *     require(weiRaised().add(weiAmount) <= cap);
     * @param beneficiary Address performing the token purchase
     * @param weiAmount Value in wei involved in the purchase
     */
    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
        require(beneficiary != address(0));
        require(weiAmount != 0);
    }

    /**
     * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid
     * conditions are not met.
     * @param beneficiary Address performing the token purchase
     * @param weiAmount Value in wei involved in the purchase
     */
    function _postValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
        // solhint-disable-previous-line no-empty-blocks
    }

    /**
     * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends
     * its tokens.
     * @param beneficiary Address performing the token purchase
     * @param tokenAmount Number of tokens to be emitted
     */
    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
        _token.safeTransfer(beneficiary, tokenAmount);
    }

    /**
     * @dev Executed when a purchase has been validated and is ready to be executed. Doesn't necessarily emit/send
     * tokens.
     * @param beneficiary Address receiving the tokens
     * @param tokenAmount Number of tokens to be purchased
     */
    function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
        _deliverTokens(beneficiary, tokenAmount);
    }

    /**
     * @dev Override for extensions that require an internal state to check for validity (current user contributions,
     * etc.)
     * @param beneficiary Address receiving the tokens
     * @param weiAmount Value in wei involved in the purchase
     */
    function _updatePurchasingState(address beneficiary, uint256 weiAmount) internal {
        // solhint-disable-previous-line no-empty-blocks
    }

    /**
     * @dev Override to extend the way in which ether is converted to tokens.
     * @param weiAmount Value in wei to be converted into tokens
     * @return Number of tokens that can be purchased with the specified _weiAmount
     */
    function _getTokenAmount(uint256 weiAmount) internal view returns (uint256) {
        return weiAmount.mul(_rate);
    }

    /**
     * @dev Determines how ETH is stored/forwarded on purchases.
     */
    function _forwardFunds() internal {
        _wallet.transfer(msg.value);
    }
}

contract MintedCrowdsale is Crowdsale {
    /**
     * @dev Overrides delivery by minting tokens upon purchase.
     * @param beneficiary Token purchaser
     * @param tokenAmount Number of tokens to be minted
     */
    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
        // Potentially dangerous assumption about the type of the token.
        require(ERC20Mintable(address(token())).mint(beneficiary, tokenAmount));
    }
}

contract ThresholdWhitelistedCrowdsale is WhitelistedRole, Crowdsale {

    uint256 public threshold;

    constructor (uint256 _threshold) public {
        threshold = _threshold;
    }

    function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal view {
        if (_weiAmount >= threshold) {
            require(isWhitelisted(_beneficiary), "Investors with large sums must be whitelisted");
	}
        super._preValidatePurchase(_beneficiary, _weiAmount);
    }

}

contract TimedCrowdsale is Crowdsale {
    using SafeMath for uint256;

    uint256 private _openingTime;
    uint256 private _closingTime;

    /**
     * @dev Reverts if not in crowdsale time range.
     */
    modifier onlyWhileOpen {
        require(isOpen());
        _;
    }

    /**
     * @dev Constructor, takes crowdsale opening and closing times.
     * @param openingTime Crowdsale opening time
     * @param closingTime Crowdsale closing time
     */
    constructor (uint256 openingTime, uint256 closingTime) public {
        // solhint-disable-next-line not-rely-on-time
        require(openingTime >= block.timestamp);
        require(closingTime > openingTime);

        _openingTime = openingTime;
        _closingTime = closingTime;
    }

    /**
     * @return the crowdsale opening time.
     */
    function openingTime() public view returns (uint256) {
        return _openingTime;
    }

    /**
     * @return the crowdsale closing time.
     */
    function closingTime() public view returns (uint256) {
        return _closingTime;
    }

    /**
     * @return true if the crowdsale is open, false otherwise.
     */
    function isOpen() public view returns (bool) {
        // solhint-disable-next-line not-rely-on-time
        return block.timestamp >= _openingTime && block.timestamp <= _closingTime;
    }

    /**
     * @dev Checks whether the period in which the crowdsale is open has already elapsed.
     * @return Whether crowdsale period has elapsed
     */
    function hasClosed() public view returns (bool) {
        // solhint-disable-next-line not-rely-on-time
        return block.timestamp > _closingTime;
    }

    /**
     * @dev Extend parent behavior requiring to be within contributing period
     * @param beneficiary Token purchaser
     * @param weiAmount Amount of wei contributed
     */
    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal onlyWhileOpen view {
        super._preValidatePurchase(beneficiary, weiAmount);
    }
}

contract CappedCrowdsale is Crowdsale {
    using SafeMath for uint256;

    uint256 private _cap;

    /**
     * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
     * @param cap Max amount of wei to be contributed
     */
    constructor (uint256 cap) public {
        require(cap > 0);
        _cap = cap;
    }

    /**
     * @return the cap of the crowdsale.
     */
    function cap() public view returns (uint256) {
        return _cap;
    }

    /**
     * @dev Checks whether the cap has been reached.
     * @return Whether the cap was reached
     */
    function capReached() public view returns (bool) {
        return weiRaised() >= _cap;
    }

    /**
     * @dev Extend parent behavior requiring purchase to respect the funding cap.
     * @param beneficiary Token purchaser
     * @param weiAmount Amount of wei contributed
     */
    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
        super._preValidatePurchase(beneficiary, weiAmount);
        require(weiRaised().add(weiAmount) <= _cap);
    }
}

interface IERC20 {
    function transfer(address to, uint256 value) external returns (bool);

    function approve(address spender, uint256 value) external returns (bool);

    function transferFrom(address from, address to, uint256 value) external returns (bool);

    function totalSupply() external view returns (uint256);

    function balanceOf(address who) external view returns (uint256);

    function allowance(address owner, address spender) external view returns (uint256);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);
}

contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    constructor (string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    /**
     * @return the name of the token.
     */
    function name() public view returns (string memory) {
        return _name;
    }

    /**
     * @return the symbol of the token.
     */
    function symbol() public view returns (string memory) {
        return _symbol;
    }

    /**
     * @return the number of decimals of the token.
     */
    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

contract ERC20 is IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowed;

    uint256 private _totalSupply;

    /**
    * @dev Total number of tokens in existence
    */
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    /**
    * @dev Gets the balance of the specified address.
    * @param owner The address to query the balance of.
    * @return An uint256 representing the amount owned by the passed address.
    */
    function balanceOf(address owner) public view returns (uint256) {
        return _balances[owner];
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param owner address The address which owns the funds.
     * @param spender address The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowed[owner][spender];
    }

    /**
    * @dev Transfer token for a specified address
    * @param to The address to transfer to.
    * @param value The amount to be transferred.
    */
    function transfer(address to, uint256 value) public returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    /**
     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
     * 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
     * @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) {
        require(spender != address(0));

        _allowed[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    /**
     * @dev Transfer tokens from one address to another.
     * Note that while this function emits an Approval event, this is not required as per the specification,
     * and other compliant implementations may not emit the event.
     * @param from address The address which you want to send tokens from
     * @param to address The address which you want to transfer to
     * @param value uint256 the amount of tokens to be transferred
     */
    function transferFrom(address from, address to, uint256 value) public returns (bool) {
        _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
        _transfer(from, to, value);
        emit Approval(from, msg.sender, _allowed[from][msg.sender]);
        return true;
    }

    /**
     * @dev Increase the amount of tokens that an owner allowed to a spender.
     * approve should be called when allowed_[_spender] == 0. To increment
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @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) {
        require(spender != address(0));

        _allowed[msg.sender][spender] = _allowed[msg.sender][spender].add(addedValue);
        emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
        return true;
    }

    /**
     * @dev Decrease the amount of tokens that an owner allowed to a spender.
     * approve should be called when allowed_[_spender] == 0. To decrement
     * allowed value is better to use this function to avoid 2 calls (and wait until
     * the first transaction is mined)
     * From MonolithDAO Token.sol
     * Emits an Approval event.
     * @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) {
        require(spender != address(0));

        _allowed[msg.sender][spender] = _allowed[msg.sender][spender].sub(subtractedValue);
        emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
        return true;
    }

    /**
    * @dev Transfer token for a specified addresses
    * @param from The address to transfer from.
    * @param to The address to transfer to.
    * @param value The amount to be transferred.
    */
    function _transfer(address from, address to, uint256 value) internal {
        require(to != address(0));

        _balances[from] = _balances[from].sub(value);
        _balances[to] = _balances[to].add(value);
        emit Transfer(from, to, value);
    }

    /**
     * @dev Internal function that mints an amount of the token and assigns it to
     * an account. This encapsulates the modification of balances such that the
     * proper events are emitted.
     * @param account The account that will receive the created tokens.
     * @param value The amount that will be created.
     */
    function _mint(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.add(value);
        _balances[account] = _balances[account].add(value);
        emit Transfer(address(0), account, value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account.
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burn(address account, uint256 value) internal {
        require(account != address(0));

        _totalSupply = _totalSupply.sub(value);
        _balances[account] = _balances[account].sub(value);
        emit Transfer(account, address(0), value);
    }

    /**
     * @dev Internal function that burns an amount of the token of a given
     * account, deducting from the sender's allowance for said account. Uses the
     * internal burn function.
     * Emits an Approval event (reflecting the reduced allowance).
     * @param account The account whose tokens will be burnt.
     * @param value The amount that will be burnt.
     */
    function _burnFrom(address account, uint256 value) internal {
        _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(value);
        _burn(account, value);
        emit Approval(account, msg.sender, _allowed[account][msg.sender]);
    }
}

contract ERC20Mintable is ERC20, MinterRole {
    /**
     * @dev Function to mint tokens
     * @param to The address that will receive the minted tokens.
     * @param value The amount of tokens to mint.
     * @return A boolean that indicates if the operation was successful.
     */
    function mint(address to, uint256 value) public onlyMinter returns (bool) {
        _mint(to, value);
        return true;
    }
}

contract ERC20Capped is ERC20Mintable {
    uint256 private _cap;

    constructor (uint256 cap) public {
        require(cap > 0);
        _cap = cap;
    }

    /**
     * @return the cap for the token minting.
     */
    function cap() public view returns (uint256) {
        return _cap;
    }

    function _mint(address account, uint256 value) internal {
        require(totalSupply().add(value) <= _cap);
        super._mint(account, value);
    }
}

contract VrParkToken is ERC20Mintable, ERC20Capped, ERC20Detailed, Ownable {

    uint8 internal constant DECIMALS = 18;

    constructor (uint256 _cap) public ERC20Detailed("VR", "VR", DECIMALS)
        ERC20Capped(_cap) {
        // empty block
    }

    function removeMinter(address account) public onlyOwner {
        _removeMinter(account);
    }

}

contract Pausable is PauserRole {
    event Paused(address account);
    event Unpaused(address account);

    bool private _paused;

    constructor () internal {
        _paused = false;
    }

    /**
     * @return true if the contract is paused, false otherwise.
     */
    function paused() public view returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     */
    modifier whenNotPaused() {
        require(!_paused);
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     */
    modifier whenPaused() {
        require(_paused);
        _;
    }

    /**
     * @dev called by the owner to pause, triggers stopped state
     */
    function pause() public onlyPauser whenNotPaused {
        _paused = true;
        emit Paused(msg.sender);
    }

    /**
     * @dev called by the owner to unpause, returns to normal state
     */
    function unpause() public onlyPauser whenPaused {
        _paused = false;
        emit Unpaused(msg.sender);
    }
}

contract PausableCrowdsale is Crowdsale, Pausable {
    /**
     * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met.
     * Use super to concatenate validations.
     * Adds the validation that the crowdsale must not be paused.
     * @param _beneficiary Address performing the token purchase
     * @param _weiAmount Value in wei involved in the purchase
     */
    function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal view whenNotPaused {
        return super._preValidatePurchase(_beneficiary, _weiAmount);
    }
}

contract VrParkIcoStep is TimedCrowdsale, PausableCrowdsale, MintedCrowdsale, CappedCrowdsale {

    using SafeMath for uint256;

    uint256 public bonusMultiplier;
    uint256 public constant ONE_HUNDRED_PERCENT = 100;
    
    IExchangeInteractor public interactor;

    constructor (uint256 _openTime, uint256 _closeTime, uint256 _rate, uint256 _cap, 
		 uint256 _bonusMultiplier, address payable _wallet, 
		 VrParkToken _token, IExchangeInteractor _interactor) public
        CappedCrowdsale(_cap)
        TimedCrowdsale(_openTime, _closeTime)
        Crowdsale(_rate, _wallet, _token) {
        require(_bonusMultiplier > 0, "Bonus multiplier must be greater than zero");

        bonusMultiplier = _bonusMultiplier;
        interactor = _interactor;
    }

    function _getTokenAmount(uint256 weiAmount) internal view returns(uint256) {
        uint256 usdEth = interactor.getCurrentPrice();
        uint256 rate = rate();
        return usdEth.mul(weiAmount).mul(bonusMultiplier).div(ONE_HUNDRED_PERCENT).div(rate);
    }
}


library SafeMath {
    /**
    * @dev Multiplies two unsigned integers, reverts on 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-solidity/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b);

        return c;
    }

    /**
    * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
    */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
    * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
    */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        uint256 c = a - b;

        return c;
    }

    /**
    * @dev Adds two unsigned integers, reverts on overflow.
    */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);

        return c;
    }

    /**
    * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
    * reverts when dividing by zero.
    */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b != 0);
        return a % b;
    }
}


/*

ORACLIZE_API

Copyright (c) 2015-2016 Oraclize SRL
Copyright (c) 2016 Oraclize LTD

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

*/
pragma solidity >= 0.5.0; // Incompatible compiler version - please select a compiler within the stated pragma range, or use a different version of the oraclizeAPI!

// Dummy contract only used to emit to end-user they are using wrong solc
contract solcChecker {
/* INCOMPATIBLE SOLC: import the following instead: "github.com/oraclize/ethereum-api/oraclizeAPI_0.4.sol" */ function f(bytes calldata x) external;
}

contract OraclizeI {

    address public cbAddress;

    function setProofType(byte _proofType) external;
    function setCustomGasPrice(uint _gasPrice) external;
    function getPrice(string memory _datasource) public returns (uint _dsprice);
    function randomDS_getSessionPubKeyHash() external view returns (bytes32 _sessionKeyHash);
    function getPrice(string memory _datasource, uint _gasLimit) public returns (uint _dsprice);
    function queryN(uint _timestamp, string memory _datasource, bytes memory _argN) public payable returns (bytes32 _id);
    function query(uint _timestamp, string calldata _datasource, string calldata _arg) external payable returns (bytes32 _id);
    function query2(uint _timestamp, string memory _datasource, string memory _arg1, string memory _arg2) public payable returns (bytes32 _id);
    function query_withGasLimit(uint _timestamp, string calldata _datasource, string calldata _arg, uint _gasLimit) external payable returns (bytes32 _id);
    function queryN_withGasLimit(uint _timestamp, string calldata _datasource, bytes calldata _argN, uint _gasLimit) external payable returns (bytes32 _id);
    function query2_withGasLimit(uint _timestamp, string calldata _datasource, string calldata _arg1, string calldata _arg2, uint _gasLimit) external payable returns (bytes32 _id);
}

contract OraclizeAddrResolverI {
    function getAddress() public returns (address _address);
}
/*

Begin solidity-cborutils

https://github.com/smartcontractkit/solidity-cborutils

MIT License

Copyright (c) 2018 SmartContract ChainLink, Ltd.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

*/
library Buffer {

    struct buffer {
        bytes buf;
        uint capacity;
    }

    function init(buffer memory _buf, uint _capacity) internal pure {
        uint capacity = _capacity;
        if (capacity % 32 != 0) {
            capacity += 32 - (capacity % 32);
        }
        _buf.capacity = capacity; // Allocate space for the buffer data
        assembly {
            let ptr := mload(0x40)
            mstore(_buf, ptr)
            mstore(ptr, 0)
            mstore(0x40, add(ptr, capacity))
        }
    }

    function resize(buffer memory _buf, uint _capacity) private pure {
        bytes memory oldbuf = _buf.buf;
        init(_buf, _capacity);
        append(_buf, oldbuf);
    }

    function max(uint _a, uint _b) private pure returns (uint _max) {
        if (_a > _b) {
            return _a;
        }
        return _b;
    }
    /**
      * @dev Appends a byte array to the end of the buffer. Resizes if doing so
      *      would exceed the capacity of the buffer.
      * @param _buf The buffer to append to.
      * @param _data The data to append.
      * @return The original buffer.
      *
      */
    function append(buffer memory _buf, bytes memory _data) internal pure returns (buffer memory _buffer) {
        if (_data.length + _buf.buf.length > _buf.capacity) {
            resize(_buf, max(_buf.capacity, _data.length) * 2);
        }
        uint dest;
        uint src;
        uint len = _data.length;
        assembly {
            let bufptr := mload(_buf) // Memory address of the buffer data
            let buflen := mload(bufptr) // Length of existing buffer data
            dest := add(add(bufptr, buflen), 32) // Start address = buffer address + buffer length + sizeof(buffer length)
            mstore(bufptr, add(buflen, mload(_data))) // Update buffer length
            src := add(_data, 32)
        }
        for(; len >= 32; len -= 32) { // Copy word-length chunks while possible
            assembly {
                mstore(dest, mload(src))
            }
            dest += 32;
            src += 32;
        }
        uint mask = 256 ** (32 - len) - 1; // Copy remaining bytes
        assembly {
            let srcpart := and(mload(src), not(mask))
            let destpart := and(mload(dest), mask)
            mstore(dest, or(destpart, srcpart))
        }
        return _buf;
    }
    /**
      *
      * @dev Appends a byte to the end of the buffer. Resizes if doing so would
      * exceed the capacity of the buffer.
      * @param _buf The buffer to append to.
      * @param _data The data to append.
      * @return The original buffer.
      *
      */
    function append(buffer memory _buf, uint8 _data) internal pure {
        if (_buf.buf.length + 1 > _buf.capacity) {
            resize(_buf, _buf.capacity * 2);
        }
        assembly {
            let bufptr := mload(_buf) // Memory address of the buffer data
            let buflen := mload(bufptr) // Length of existing buffer data
            let dest := add(add(bufptr, buflen), 32) // Address = buffer address + buffer length + sizeof(buffer length)
            mstore8(dest, _data)
            mstore(bufptr, add(buflen, 1)) // Update buffer length
        }
    }
    /**
      *
      * @dev Appends a byte to the end of the buffer. Resizes if doing so would
      * exceed the capacity of the buffer.
      * @param _buf The buffer to append to.
      * @param _data The data to append.
      * @return The original buffer.
      *
      */
    function appendInt(buffer memory _buf, uint _data, uint _len) internal pure returns (buffer memory _buffer) {
        if (_len + _buf.buf.length > _buf.capacity) {
            resize(_buf, max(_buf.capacity, _len) * 2);
        }
        uint mask = 256 ** _len - 1;
        assembly {
            let bufptr := mload(_buf) // Memory address of the buffer data
            let buflen := mload(bufptr) // Length of existing buffer data
            let dest := add(add(bufptr, buflen), _len) // Address = buffer address + buffer length + sizeof(buffer length) + len
            mstore(dest, or(and(mload(dest), not(mask)), _data))
            mstore(bufptr, add(buflen, _len)) // Update buffer length
        }
        return _buf;
    }
}

library CBOR {

    using Buffer for Buffer.buffer;

    uint8 private constant MAJOR_TYPE_INT = 0;
    uint8 private constant MAJOR_TYPE_MAP = 5;
    uint8 private constant MAJOR_TYPE_BYTES = 2;
    uint8 private constant MAJOR_TYPE_ARRAY = 4;
    uint8 private constant MAJOR_TYPE_STRING = 3;
    uint8 private constant MAJOR_TYPE_NEGATIVE_INT = 1;
    uint8 private constant MAJOR_TYPE_CONTENT_FREE = 7;

    function encodeType(Buffer.buffer memory _buf, uint8 _major, uint _value) private pure {
        if (_value <= 23) {
            _buf.append(uint8((_major << 5) | _value));
        } else if (_value <= 0xFF) {
            _buf.append(uint8((_major << 5) | 24));
            _buf.appendInt(_value, 1);
        } else if (_value <= 0xFFFF) {
            _buf.append(uint8((_major << 5) | 25));
            _buf.appendInt(_value, 2);
        } else if (_value <= 0xFFFFFFFF) {
            _buf.append(uint8((_major << 5) | 26));
            _buf.appendInt(_value, 4);
        } else if (_value <= 0xFFFFFFFFFFFFFFFF) {
            _buf.append(uint8((_major << 5) | 27));
            _buf.appendInt(_value, 8);
        }
    }

    function encodeIndefiniteLengthType(Buffer.buffer memory _buf, uint8 _major) private pure {
        _buf.append(uint8((_major << 5) | 31));
    }

    function encodeUInt(Buffer.buffer memory _buf, uint _value) internal pure {
        encodeType(_buf, MAJOR_TYPE_INT, _value);
    }

    function encodeInt(Buffer.buffer memory _buf, int _value) internal pure {
        if (_value >= 0) {
            encodeType(_buf, MAJOR_TYPE_INT, uint(_value));
        } else {
            encodeType(_buf, MAJOR_TYPE_NEGATIVE_INT, uint(-1 - _value));
        }
    }

    function encodeBytes(Buffer.buffer memory _buf, bytes memory _value) internal pure {
        encodeType(_buf, MAJOR_TYPE_BYTES, _value.length);
        _buf.append(_value);
    }

    function encodeString(Buffer.buffer memory _buf, string memory _value) internal pure {
        encodeType(_buf, MAJOR_TYPE_STRING, bytes(_value).length);
        _buf.append(bytes(_value));
    }

    function startArray(Buffer.buffer memory _buf) internal pure {
        encodeIndefiniteLengthType(_buf, MAJOR_TYPE_ARRAY);
    }

    function startMap(Buffer.buffer memory _buf) internal pure {
        encodeIndefiniteLengthType(_buf, MAJOR_TYPE_MAP);
    }

    function endSequence(Buffer.buffer memory _buf) internal pure {
        encodeIndefiniteLengthType(_buf, MAJOR_TYPE_CONTENT_FREE);
    }
}
/*

End solidity-cborutils

*/
contract usingOraclize {

    using CBOR for Buffer.buffer;

    OraclizeI oraclize;
    OraclizeAddrResolverI OAR;

    uint constant day = 60 * 60 * 24;
    uint constant week = 60 * 60 * 24 * 7;
    uint constant month = 60 * 60 * 24 * 30;

    byte constant proofType_NONE = 0x00;
    byte constant proofType_Ledger = 0x30;
    byte constant proofType_Native = 0xF0;
    byte constant proofStorage_IPFS = 0x01;
    byte constant proofType_Android = 0x40;
    byte constant proofType_TLSNotary = 0x10;

    string oraclize_network_name;
    uint8 constant networkID_auto = 0;
    uint8 constant networkID_morden = 2;
    uint8 constant networkID_mainnet = 1;
    uint8 constant networkID_testnet = 2;
    uint8 constant networkID_consensys = 161;

    mapping(bytes32 => bytes32) oraclize_randomDS_args;
    mapping(bytes32 => bool) oraclize_randomDS_sessionKeysHashVerified;

    modifier oraclizeAPI {
        if ((address(OAR) == address(0)) || (getCodeSize(address(OAR)) == 0)) {
            oraclize_setNetwork(networkID_auto);
        }
        if (address(oraclize) != OAR.getAddress()) {
            oraclize = OraclizeI(OAR.getAddress());
        }
        _;
    }

    modifier oraclize_randomDS_proofVerify(bytes32 _queryId, string memory _result, bytes memory _proof) {
        // RandomDS Proof Step 1: The prefix has to match 'LP\x01' (Ledger Proof version 1)
        require((_proof[0] == "L") && (_proof[1] == "P") && (uint8(_proof[2]) == uint8(1)));
        bool proofVerified = oraclize_randomDS_proofVerify__main(_proof, _queryId, bytes(_result), oraclize_getNetworkName());
        require(proofVerified);
        _;
    }

    function oraclize_setNetwork(uint8 _networkID) internal returns (bool _networkSet) {
      return oraclize_setNetwork();
      _networkID; // silence the warning and remain backwards compatible
    }

    function oraclize_setNetworkName(string memory _network_name) internal {
        oraclize_network_name = _network_name;
    }

    function oraclize_getNetworkName() internal view returns (string memory _networkName) {
        return oraclize_network_name;
    }

    function oraclize_setNetwork() internal returns (bool _networkSet) {
        if (getCodeSize(0x1d3B2638a7cC9f2CB3D298A3DA7a90B67E5506ed) > 0) { //mainnet
            OAR = OraclizeAddrResolverI(0x1d3B2638a7cC9f2CB3D298A3DA7a90B67E5506ed);
            oraclize_setNetworkName("eth_mainnet");
            return true;
        }
        if (getCodeSize(0xc03A2615D5efaf5F49F60B7BB6583eaec212fdf1) > 0) { //ropsten testnet
            OAR = OraclizeAddrResolverI(0xc03A2615D5efaf5F49F60B7BB6583eaec212fdf1);
            oraclize_setNetworkName("eth_ropsten3");
            return true;
        }
        if (getCodeSize(0xB7A07BcF2Ba2f2703b24C0691b5278999C59AC7e) > 0) { //kovan testnet
            OAR = OraclizeAddrResolverI(0xB7A07BcF2Ba2f2703b24C0691b5278999C59AC7e);
            oraclize_setNetworkName("eth_kovan");
            return true;
        }
        if (getCodeSize(0x146500cfd35B22E4A392Fe0aDc06De1a1368Ed48) > 0) { //rinkeby testnet
            OAR = OraclizeAddrResolverI(0x146500cfd35B22E4A392Fe0aDc06De1a1368Ed48);
            oraclize_setNetworkName("eth_rinkeby");
            return true;
        }
        if (getCodeSize(0x6f485C8BF6fc43eA212E93BBF8ce046C7f1cb475) > 0) { //ethereum-bridge
            OAR = OraclizeAddrResolverI(0x6f485C8BF6fc43eA212E93BBF8ce046C7f1cb475);
            return true;
        }
        if (getCodeSize(0x20e12A1F859B3FeaE5Fb2A0A32C18F5a65555bBF) > 0) { //ether.camp ide
            OAR = OraclizeAddrResolverI(0x20e12A1F859B3FeaE5Fb2A0A32C18F5a65555bBF);
            return true;
        }
        if (getCodeSize(0x51efaF4c8B3C9AfBD5aB9F4bbC82784Ab6ef8fAA) > 0) { //browser-solidity
            OAR = OraclizeAddrResolverI(0x51efaF4c8B3C9AfBD5aB9F4bbC82784Ab6ef8fAA);
            return true;
        }
        return false;
    }

    function __callback(bytes32 _myid, string memory _result) public {
        __callback(_myid, _result, new bytes(0));
    }

    function __callback(bytes32 _myid, string memory _result, bytes memory _proof) public {
      return;
      _myid; _result; _proof; // Silence compiler warnings
    }

    function oraclize_getPrice(string memory _datasource) oraclizeAPI internal returns (uint _queryPrice) {
        return oraclize.getPrice(_datasource);
    }

    function oraclize_getPrice(string memory _datasource, uint _gasLimit) oraclizeAPI internal returns (uint _queryPrice) {
        return oraclize.getPrice(_datasource, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string memory _arg) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource);
        if (price > 1 ether + tx.gasprice * 200000) {
            return 0; // Unexpectedly high price
        }
        return oraclize.query.value(price)(0, _datasource, _arg);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string memory _arg) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource);
        if (price > 1 ether + tx.gasprice * 200000) {
            return 0; // Unexpectedly high price
        }
        return oraclize.query.value(price)(_timestamp, _datasource, _arg);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string memory _arg, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource,_gasLimit);
        if (price > 1 ether + tx.gasprice * _gasLimit) {
            return 0; // Unexpectedly high price
        }
        return oraclize.query_withGasLimit.value(price)(_timestamp, _datasource, _arg, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string memory _arg, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource, _gasLimit);
        if (price > 1 ether + tx.gasprice * _gasLimit) {
           return 0; // Unexpectedly high price
        }
        return oraclize.query_withGasLimit.value(price)(0, _datasource, _arg, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string memory _arg1, string memory _arg2) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource);
        if (price > 1 ether + tx.gasprice * 200000) {
            return 0; // Unexpectedly high price
        }
        return oraclize.query2.value(price)(0, _datasource, _arg1, _arg2);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string memory _arg1, string memory _arg2) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource);
        if (price > 1 ether + tx.gasprice * 200000) {
            return 0; // Unexpectedly high price
        }
        return oraclize.query2.value(price)(_timestamp, _datasource, _arg1, _arg2);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string memory _arg1, string memory _arg2, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource, _gasLimit);
        if (price > 1 ether + tx.gasprice * _gasLimit) {
            return 0; // Unexpectedly high price
        }
        return oraclize.query2_withGasLimit.value(price)(_timestamp, _datasource, _arg1, _arg2, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string memory _arg1, string memory _arg2, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource, _gasLimit);
        if (price > 1 ether + tx.gasprice * _gasLimit) {
            return 0; // Unexpectedly high price
        }
        return oraclize.query2_withGasLimit.value(price)(0, _datasource, _arg1, _arg2, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[] memory _argN) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource);
        if (price > 1 ether + tx.gasprice * 200000) {
            return 0; // Unexpectedly high price
        }
        bytes memory args = stra2cbor(_argN);
        return oraclize.queryN.value(price)(0, _datasource, args);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[] memory _argN) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource);
        if (price > 1 ether + tx.gasprice * 200000) {
            return 0; // Unexpectedly high price
        }
        bytes memory args = stra2cbor(_argN);
        return oraclize.queryN.value(price)(_timestamp, _datasource, args);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[] memory _argN, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource, _gasLimit);
        if (price > 1 ether + tx.gasprice * _gasLimit) {
            return 0; // Unexpectedly high price
        }
        bytes memory args = stra2cbor(_argN);
        return oraclize.queryN_withGasLimit.value(price)(_timestamp, _datasource, args, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[] memory _argN, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource, _gasLimit);
        if (price > 1 ether + tx.gasprice * _gasLimit) {
            return 0; // Unexpectedly high price
        }
        bytes memory args = stra2cbor(_argN);
        return oraclize.queryN_withGasLimit.value(price)(0, _datasource, args, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[1] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](1);
        dynargs[0] = _args[0];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[1] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](1);
        dynargs[0] = _args[0];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[1] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](1);
        dynargs[0] = _args[0];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[1] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](1);
        dynargs[0] = _args[0];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[2] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](2);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[2] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](2);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[2] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](2);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[2] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](2);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[3] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](3);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[3] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](3);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[3] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](3);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[3] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](3);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[4] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](4);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[4] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](4);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[4] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](4);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[4] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](4);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[5] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](5);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        dynargs[4] = _args[4];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[5] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](5);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        dynargs[4] = _args[4];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, string[5] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](5);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        dynargs[4] = _args[4];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, string[5] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        string[] memory dynargs = new string[](5);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        dynargs[4] = _args[4];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[] memory _argN) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource);
        if (price > 1 ether + tx.gasprice * 200000) {
            return 0; // Unexpectedly high price
        }
        bytes memory args = ba2cbor(_argN);
        return oraclize.queryN.value(price)(0, _datasource, args);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[] memory _argN) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource);
        if (price > 1 ether + tx.gasprice * 200000) {
            return 0; // Unexpectedly high price
        }
        bytes memory args = ba2cbor(_argN);
        return oraclize.queryN.value(price)(_timestamp, _datasource, args);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[] memory _argN, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource, _gasLimit);
        if (price > 1 ether + tx.gasprice * _gasLimit) {
            return 0; // Unexpectedly high price
        }
        bytes memory args = ba2cbor(_argN);
        return oraclize.queryN_withGasLimit.value(price)(_timestamp, _datasource, args, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[] memory _argN, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        uint price = oraclize.getPrice(_datasource, _gasLimit);
        if (price > 1 ether + tx.gasprice * _gasLimit) {
            return 0; // Unexpectedly high price
        }
        bytes memory args = ba2cbor(_argN);
        return oraclize.queryN_withGasLimit.value(price)(0, _datasource, args, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[1] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](1);
        dynargs[0] = _args[0];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[1] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](1);
        dynargs[0] = _args[0];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[1] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](1);
        dynargs[0] = _args[0];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[1] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](1);
        dynargs[0] = _args[0];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[2] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](2);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[2] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](2);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[2] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](2);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[2] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](2);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[3] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](3);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[3] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](3);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[3] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](3);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[3] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](3);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[4] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](4);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[4] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](4);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[4] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](4);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[4] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](4);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[5] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](5);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        dynargs[4] = _args[4];
        return oraclize_query(_datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[5] memory _args) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](5);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        dynargs[4] = _args[4];
        return oraclize_query(_timestamp, _datasource, dynargs);
    }

    function oraclize_query(uint _timestamp, string memory _datasource, bytes[5] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](5);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        dynargs[4] = _args[4];
        return oraclize_query(_timestamp, _datasource, dynargs, _gasLimit);
    }

    function oraclize_query(string memory _datasource, bytes[5] memory _args, uint _gasLimit) oraclizeAPI internal returns (bytes32 _id) {
        bytes[] memory dynargs = new bytes[](5);
        dynargs[0] = _args[0];
        dynargs[1] = _args[1];
        dynargs[2] = _args[2];
        dynargs[3] = _args[3];
        dynargs[4] = _args[4];
        return oraclize_query(_datasource, dynargs, _gasLimit);
    }

    function oraclize_setProof(byte _proofP) oraclizeAPI internal {
        return oraclize.setProofType(_proofP);
    }


    function oraclize_cbAddress() oraclizeAPI internal returns (address _callbackAddress) {
        return oraclize.cbAddress();
    }

    function getCodeSize(address _addr) view internal returns (uint _size) {
        assembly {
            _size := extcodesize(_addr)
        }
    }

    function oraclize_setCustomGasPrice(uint _gasPrice) oraclizeAPI internal {
        return oraclize.setCustomGasPrice(_gasPrice);
    }

    function oraclize_randomDS_getSessionPubKeyHash() oraclizeAPI internal returns (bytes32 _sessionKeyHash) {
        return oraclize.randomDS_getSessionPubKeyHash();
    }

    function parseAddr(string memory _a) internal pure returns (address _parsedAddress) {
        bytes memory tmp = bytes(_a);
        uint160 iaddr = 0;
        uint160 b1;
        uint160 b2;
        for (uint i = 2; i < 2 + 2 * 20; i += 2) {
            iaddr *= 256;
            b1 = uint160(uint8(tmp[i]));
            b2 = uint160(uint8(tmp[i + 1]));
            if ((b1 >= 97) && (b1 <= 102)) {
                b1 -= 87;
            } else if ((b1 >= 65) && (b1 <= 70)) {
                b1 -= 55;
            } else if ((b1 >= 48) && (b1 <= 57)) {
                b1 -= 48;
            }
            if ((b2 >= 97) && (b2 <= 102)) {
                b2 -= 87;
            } else if ((b2 >= 65) && (b2 <= 70)) {
                b2 -= 55;
            } else if ((b2 >= 48) && (b2 <= 57)) {
                b2 -= 48;
            }
            iaddr += (b1 * 16 + b2);
        }
        return address(iaddr);
    }

    function strCompare(string memory _a, string memory _b) internal pure returns (int _returnCode) {
        bytes memory a = bytes(_a);
        bytes memory b = bytes(_b);
        uint minLength = a.length;
        if (b.length < minLength) {
            minLength = b.length;
        }
        for (uint i = 0; i < minLength; i ++) {
            if (a[i] < b[i]) {
                return -1;
            } else if (a[i] > b[i]) {
                return 1;
            }
        }
        if (a.length < b.length) {
            return -1;
        } else if (a.length > b.length) {
            return 1;
        } else {
            return 0;
        }
    }

    function indexOf(string memory _haystack, string memory _needle) internal pure returns (int _returnCode) {
        bytes memory h = bytes(_haystack);
        bytes memory n = bytes(_needle);
        if (h.length < 1 || n.length < 1 || (n.length > h.length)) {
            return -1;
        } else if (h.length > (2 ** 128 - 1)) {
            return -1;
        } else {
            uint subindex = 0;
            for (uint i = 0; i < h.length; i++) {
                if (h[i] == n[0]) {
                    subindex = 1;
                    while(subindex < n.length && (i + subindex) < h.length && h[i + subindex] == n[subindex]) {
                        subindex++;
                    }
                    if (subindex == n.length) {
                        return int(i);
                    }
                }
            }
            return -1;
        }
    }

    function strConcat(string memory _a, string memory _b) internal pure returns (string memory _concatenatedString) {
        return strConcat(_a, _b, "", "", "");
    }

    function strConcat(string memory _a, string memory _b, string memory _c) internal pure returns (string memory _concatenatedString) {
        return strConcat(_a, _b, _c, "", "");
    }

    function strConcat(string memory _a, string memory _b, string memory _c, string memory _d) internal pure returns (string memory _concatenatedString) {
        return strConcat(_a, _b, _c, _d, "");
    }

    function strConcat(string memory _a, string memory _b, string memory _c, string memory _d, string memory _e) internal pure returns (string memory _concatenatedString) {
        bytes memory _ba = bytes(_a);
        bytes memory _bb = bytes(_b);
        bytes memory _bc = bytes(_c);
        bytes memory _bd = bytes(_d);
        bytes memory _be = bytes(_e);
        string memory abcde = new string(_ba.length + _bb.length + _bc.length + _bd.length + _be.length);
        bytes memory babcde = bytes(abcde);
        uint k = 0;
        uint i = 0;
        for (i = 0; i < _ba.length; i++) {
            babcde[k++] = _ba[i];
        }
        for (i = 0; i < _bb.length; i++) {
            babcde[k++] = _bb[i];
        }
        for (i = 0; i < _bc.length; i++) {
            babcde[k++] = _bc[i];
        }
        for (i = 0; i < _bd.length; i++) {
            babcde[k++] = _bd[i];
        }
        for (i = 0; i < _be.length; i++) {
            babcde[k++] = _be[i];
        }
        return string(babcde);
    }

    function safeParseInt(string memory _a) internal pure returns (uint _parsedInt) {
        return safeParseInt(_a, 0);
    }

    function safeParseInt(string memory _a, uint _b) internal pure returns (uint _parsedInt) {
        bytes memory bresult = bytes(_a);
        uint mint = 0;
        bool decimals = false;
        for (uint i = 0; i < bresult.length; i++) {
            if ((uint(uint8(bresult[i])) >= 48) && (uint(uint8(bresult[i])) <= 57)) {
                if (decimals) {
                   if (_b == 0) break;
                    else _b--;
                }
                mint *= 10;
                mint += uint(uint8(bresult[i])) - 48;
            } else if (uint(uint8(bresult[i])) == 46) {
                require(!decimals, 'More than one decimal encountered in string!');
                decimals = true;
            } else {
                revert("Non-numeral character encountered in string!");
            }
        }
        if (_b > 0) {
            mint *= 10 ** _b;
        }
        return mint;
    }

    function parseInt(string memory _a) internal pure returns (uint _parsedInt) {
        return parseInt(_a, 0);
    }

    function parseInt(string memory _a, uint _b) internal pure returns (uint _parsedInt) {
        bytes memory bresult = bytes(_a);
        uint mint = 0;
        bool decimals = false;
        for (uint i = 0; i < bresult.length; i++) {
            if ((uint(uint8(bresult[i])) >= 48) && (uint(uint8(bresult[i])) <= 57)) {
                if (decimals) {
                   if (_b == 0) {
                       break;
                   } else {
                       _b--;
                   }
                }
                mint *= 10;
                mint += uint(uint8(bresult[i])) - 48;
            } else if (uint(uint8(bresult[i])) == 46) {
                decimals = true;
            }
        }
        if (_b > 0) {
            mint *= 10 ** _b;
        }
        return mint;
    }

    function uint2str(uint _i) internal pure returns (string memory _uintAsString) {
        if (_i == 0) {
            return "0";
        }
        uint j = _i;
        uint len;
        while (j != 0) {
            len++;
            j /= 10;
        }
        bytes memory bstr = new bytes(len);
        uint k = len - 1;
        while (_i != 0) {
            bstr[k--] = byte(uint8(48 + _i % 10));
            _i /= 10;
        }
        return string(bstr);
    }

    function stra2cbor(string[] memory _arr) internal pure returns (bytes memory _cborEncoding) {
        safeMemoryCleaner();
        Buffer.buffer memory buf;
        Buffer.init(buf, 1024);
        buf.startArray();
        for (uint i = 0; i < _arr.length; i++) {
            buf.encodeString(_arr[i]);
        }
        buf.endSequence();
        return buf.buf;
    }

    function ba2cbor(bytes[] memory _arr) internal pure returns (bytes memory _cborEncoding) {
        safeMemoryCleaner();
        Buffer.buffer memory buf;
        Buffer.init(buf, 1024);
        buf.startArray();
        for (uint i = 0; i < _arr.length; i++) {
            buf.encodeBytes(_arr[i]);
        }
        buf.endSequence();
        return buf.buf;
    }

    function oraclize_newRandomDSQuery(uint _delay, uint _nbytes, uint _customGasLimit) internal returns (bytes32 _queryId) {
        require((_nbytes > 0) && (_nbytes <= 32));
        _delay *= 10; // Convert from seconds to ledger timer ticks
        bytes memory nbytes = new bytes(1);
        nbytes[0] = byte(uint8(_nbytes));
        bytes memory unonce = new bytes(32);
        bytes memory sessionKeyHash = new bytes(32);
        bytes32 sessionKeyHash_bytes32 = oraclize_randomDS_getSessionPubKeyHash();
        assembly {
            mstore(unonce, 0x20)
            /*
             The following variables can be relaxed.
             Check the relaxed random contract at https://github.com/oraclize/ethereum-examples
             for an idea on how to override and replace commit hash variables.
            */
            mstore(add(unonce, 0x20), xor(blockhash(sub(number, 1)), xor(coinbase, timestamp)))
            mstore(sessionKeyHash, 0x20)
            mstore(add(sessionKeyHash, 0x20), sessionKeyHash_bytes32)
        }
        bytes memory delay = new bytes(32);
        assembly {
            mstore(add(delay, 0x20), _delay)
        }
        bytes memory delay_bytes8 = new bytes(8);
        copyBytes(delay, 24, 8, delay_bytes8, 0);
        bytes[4] memory args = [unonce, nbytes, sessionKeyHash, delay];
        bytes32 queryId = oraclize_query("random", args, _customGasLimit);
        bytes memory delay_bytes8_left = new bytes(8);
        assembly {
            let x := mload(add(delay_bytes8, 0x20))
            mstore8(add(delay_bytes8_left, 0x27), div(x, 0x100000000000000000000000000000000000000000000000000000000000000))
            mstore8(add(delay_bytes8_left, 0x26), div(x, 0x1000000000000000000000000000000000000000000000000000000000000))
            mstore8(add(delay_bytes8_left, 0x25), div(x, 0x10000000000000000000000000000000000000000000000000000000000))
            mstore8(add(delay_bytes8_left, 0x24), div(x, 0x100000000000000000000000000000000000000000000000000000000))
            mstore8(add(delay_bytes8_left, 0x23), div(x, 0x1000000000000000000000000000000000000000000000000000000))
            mstore8(add(delay_bytes8_left, 0x22), div(x, 0x10000000000000000000000000000000000000000000000000000))
            mstore8(add(delay_bytes8_left, 0x21), div(x, 0x100000000000000000000000000000000000000000000000000))
            mstore8(add(delay_bytes8_left, 0x20), div(x, 0x1000000000000000000000000000000000000000000000000))
        }
        oraclize_randomDS_setCommitment(queryId, keccak256(abi.encodePacked(delay_bytes8_left, args[1], sha256(args[0]), args[2])));
        return queryId;
    }

    function oraclize_randomDS_setCommitment(bytes32 _queryId, bytes32 _commitment) internal {
        oraclize_randomDS_args[_queryId] = _commitment;
    }

    function verifySig(bytes32 _tosignh, bytes memory _dersig, bytes memory _pubkey) internal returns (bool _sigVerified) {
        bool sigok;
        address signer;
        bytes32 sigr;
        bytes32 sigs;
        bytes memory sigr_ = new bytes(32);
        uint offset = 4 + (uint(uint8(_dersig[3])) - 0x20);
        sigr_ = copyBytes(_dersig, offset, 32, sigr_, 0);
        bytes memory sigs_ = new bytes(32);
        offset += 32 + 2;
        sigs_ = copyBytes(_dersig, offset + (uint(uint8(_dersig[offset - 1])) - 0x20), 32, sigs_, 0);
        assembly {
            sigr := mload(add(sigr_, 32))
            sigs := mload(add(sigs_, 32))
        }
        (sigok, signer) = safer_ecrecover(_tosignh, 27, sigr, sigs);
        if (address(uint160(uint256(keccak256(_pubkey)))) == signer) {
            return true;
        } else {
            (sigok, signer) = safer_ecrecover(_tosignh, 28, sigr, sigs);
            return (address(uint160(uint256(keccak256(_pubkey)))) == signer);
        }
    }

    function oraclize_randomDS_proofVerify__sessionKeyValidity(bytes memory _proof, uint _sig2offset) internal returns (bool _proofVerified) {
        bool sigok;
        // Random DS Proof Step 6: Verify the attestation signature, APPKEY1 must sign the sessionKey from the correct ledger app (CODEHASH)
        bytes memory sig2 = new bytes(uint(uint8(_proof[_sig2offset + 1])) + 2);
        copyBytes(_proof, _sig2offset, sig2.length, sig2, 0);
        bytes memory appkey1_pubkey = new bytes(64);
        copyBytes(_proof, 3 + 1, 64, appkey1_pubkey, 0);
        bytes memory tosign2 = new bytes(1 + 65 + 32);
        tosign2[0] = byte(uint8(1)); //role
        copyBytes(_proof, _sig2offset - 65, 65, tosign2, 1);
        bytes memory CODEHASH = hex"fd94fa71bc0ba10d39d464d0d8f465efeef0a2764e3887fcc9df41ded20f505c";
        copyBytes(CODEHASH, 0, 32, tosign2, 1 + 65);
        sigok = verifySig(sha256(tosign2), sig2, appkey1_pubkey);
        if (!sigok) {
            return false;
        }
        // Random DS Proof Step 7: Verify the APPKEY1 provenance (must be signed by Ledger)
        bytes memory LEDGERKEY = hex"7fb956469c5c9b89840d55b43537e66a98dd4811ea0a27224272c2e5622911e8537a2f8e86a46baec82864e98dd01e9ccc2f8bc5dfc9cbe5a91a290498dd96e4";
        bytes memory tosign3 = new bytes(1 + 65);
        tosign3[0] = 0xFE;
        copyBytes(_proof, 3, 65, tosign3, 1);
        bytes memory sig3 = new bytes(uint(uint8(_proof[3 + 65 + 1])) + 2);
        copyBytes(_proof, 3 + 65, sig3.length, sig3, 0);
        sigok = verifySig(sha256(tosign3), sig3, LEDGERKEY);
        return sigok;
    }

    function oraclize_randomDS_proofVerify__returnCode(bytes32 _queryId, string memory _result, bytes memory _proof) internal returns (uint8 _returnCode) {
        // Random DS Proof Step 1: The prefix has to match 'LP\x01' (Ledger Proof version 1)
        if ((_proof[0] != "L") || (_proof[1] != "P") || (uint8(_proof[2]) != uint8(1))) {
            return 1;
        }
        bool proofVerified = oraclize_randomDS_proofVerify__main(_proof, _queryId, bytes(_result), oraclize_getNetworkName());
        if (!proofVerified) {
            return 2;
        }
        return 0;
    }

    function matchBytes32Prefix(bytes32 _content, bytes memory _prefix, uint _nRandomBytes) internal pure returns (bool _matchesPrefix) {
        bool match_ = true;
        require(_prefix.length == _nRandomBytes);
        for (uint256 i = 0; i< _nRandomBytes; i++) {
            if (_content[i] != _prefix[i]) {
                match_ = false;
            }
        }
        return match_;
    }

    function oraclize_randomDS_proofVerify__main(bytes memory _proof, bytes32 _queryId, bytes memory _result, string memory _contextName) internal returns (bool _proofVerified) {
        // Random DS Proof Step 2: The unique keyhash has to match with the sha256 of (context name + _queryId)
        uint ledgerProofLength = 3 + 65 + (uint(uint8(_proof[3 + 65 + 1])) + 2) + 32;
        bytes memory keyhash = new bytes(32);
        copyBytes(_proof, ledgerProofLength, 32, keyhash, 0);
        if (!(keccak256(keyhash) == keccak256(abi.encodePacked(sha256(abi.encodePacked(_contextName, _queryId)))))) {
            return false;
        }
        bytes memory sig1 = new bytes(uint(uint8(_proof[ledgerProofLength + (32 + 8 + 1 + 32) + 1])) + 2);
        copyBytes(_proof, ledgerProofLength + (32 + 8 + 1 + 32), sig1.length, sig1, 0);
        // Random DS Proof Step 3: We assume sig1 is valid (it will be verified during step 5) and we verify if '_result' is the _prefix of sha256(sig1)
        if (!matchBytes32Prefix(sha256(sig1), _result, uint(uint8(_proof[ledgerProofLength + 32 + 8])))) {
            return false;
        }
        // Random DS Proof Step 4: Commitment match verification, keccak256(delay, nbytes, unonce, sessionKeyHash) == commitment in storage.
        // This is to verify that the computed args match with the ones specified in the query.
        bytes memory commitmentSlice1 = new bytes(8 + 1 + 32);
        copyBytes(_proof, ledgerProofLength + 32, 8 + 1 + 32, commitmentSlice1, 0);
        bytes memory sessionPubkey = new bytes(64);
        uint sig2offset = ledgerProofLength + 32 + (8 + 1 + 32) + sig1.length + 65;
        copyBytes(_proof, sig2offset - 64, 64, sessionPubkey, 0);
        bytes32 sessionPubkeyHash = sha256(sessionPubkey);
        if (oraclize_randomDS_args[_queryId] == keccak256(abi.encodePacked(commitmentSlice1, sessionPubkeyHash))) { //unonce, nbytes and sessionKeyHash match
            delete oraclize_randomDS_args[_queryId];
        } else return false;
        // Random DS Proof Step 5: Validity verification for sig1 (keyhash and args signed with the sessionKey)
        bytes memory tosign1 = new bytes(32 + 8 + 1 + 32);
        copyBytes(_proof, ledgerProofLength, 32 + 8 + 1 + 32, tosign1, 0);
        if (!verifySig(sha256(tosign1), sig1, sessionPubkey)) {
            return false;
        }
        // Verify if sessionPubkeyHash was verified already, if not.. let's do it!
        if (!oraclize_randomDS_sessionKeysHashVerified[sessionPubkeyHash]) {
            oraclize_randomDS_sessionKeysHashVerified[sessionPubkeyHash] = oraclize_randomDS_proofVerify__sessionKeyValidity(_proof, sig2offset);
        }
        return oraclize_randomDS_sessionKeysHashVerified[sessionPubkeyHash];
    }
    /*
     The following function has been written by Alex Beregszaszi (@axic), use it under the terms of the MIT license
    */
    function copyBytes(bytes memory _from, uint _fromOffset, uint _length, bytes memory _to, uint _toOffset) internal pure returns (bytes memory _copiedBytes) {
        uint minLength = _length + _toOffset;
        require(_to.length >= minLength); // Buffer too small. Should be a better way?
        uint i = 32 + _fromOffset; // NOTE: the offset 32 is added to skip the `size` field of both bytes variables
        uint j = 32 + _toOffset;
        while (i < (32 + _fromOffset + _length)) {
            assembly {
                let tmp := mload(add(_from, i))
                mstore(add(_to, j), tmp)
            }
            i += 32;
            j += 32;
        }
        return _to;
    }
    /*
     The following function has been written by Alex Beregszaszi (@axic), use it under the terms of the MIT license
     Duplicate Solidity's ecrecover, but catching the CALL return value
    */
    function safer_ecrecover(bytes32 _hash, uint8 _v, bytes32 _r, bytes32 _s) internal returns (bool _success, address _recoveredAddress) {
        /*
         We do our own memory management here. Solidity uses memory offset
         0x40 to store the current end of memory. We write past it (as
         writes are memory extensions), but don't update the offset so
         Solidity will reuse it. The memory used here is only needed for
         this context.
         FIXME: inline assembly can't access return values
        */
        bool ret;
        address addr;
        assembly {
            let size := mload(0x40)
            mstore(size, _hash)
            mstore(add(size, 32), _v)
            mstore(add(size, 64), _r)
            mstore(add(size, 96), _s)
            ret := call(3000, 1, 0, size, 128, size, 32) // NOTE: we can reuse the request memory because we deal with the return code.
            addr := mload(size)
        }
        return (ret, addr);
    }
    /*
     The following function has been written by Alex Beregszaszi (@axic), use it under the terms of the MIT license
    */
    function ecrecovery(bytes32 _hash, bytes memory _sig) internal returns (bool _success, address _recoveredAddress) {
        bytes32 r;
        bytes32 s;
        uint8 v;
        if (_sig.length != 65) {
            return (false, address(0));
        }
        /*
         The signature format is a compact form of:
           {bytes32 r}{bytes32 s}{uint8 v}
         Compact means, uint8 is not padded to 32 bytes.
        */
        assembly {
            r := mload(add(_sig, 32))
            s := mload(add(_sig, 64))
            /*
             Here we are loading the last 32 bytes. We exploit the fact that
             'mload' will pad with zeroes if we overread.
             There is no 'mload8' to do this, but that would be nicer.
            */
            v := byte(0, mload(add(_sig, 96)))
            /*
              Alternative solution:
              'byte' is not working due to the Solidity parser, so lets
              use the second best option, 'and'
              v := and(mload(add(_sig, 65)), 255)
            */
        }
        /*
         albeit non-transactional signatures are not specified by the YP, one would expect it
         to match the YP range of [27, 28]
         geth uses [0, 1] and some clients have followed. This might change, see:
         https://github.com/ethereum/go-ethereum/issues/2053
        */
        if (v < 27) {
            v += 27;
        }
        if (v != 27 && v != 28) {
            return (false, address(0));
        }
        return safer_ecrecover(_hash, v, r, s);
    }

    function safeMemoryCleaner() internal pure {
        assembly {
            let fmem := mload(0x40)
            codecopy(fmem, codesize, sub(msize, fmem))
        }
    }
}
/*

END ORACLIZE_API

*/


/**
 * @title Exchange interactor for Monoreto ICO.
 * 
 */
contract ExchangeInteractor is usingOraclize, IExchangeInteractor, Ownable {

    using SafeMath for uint256;

    // 4 hours
    uint256 public constant QUERY_TIME_PERIOD = 14400;

    uint256 public usdEthRate;
    string public jsonPath = "json(json(https://api.kraken.com/0/public/Ticker?pair=ETHUSD).result.XETHZUSD.c.0)";

    event NewUsdEthRate(uint256 rate);
    event NewQuery(string comment);
    event EthReceived(uint256 eth);

    constructor (uint256 _initialUsdEthRate) public {
        require(_initialUsdEthRate > 0, "Initial USDETH rate must be greater than zero!");

        usdEthRate = _initialUsdEthRate;

        oraclize_setProof(proofType_TLSNotary | proofStorage_IPFS);
        updatePrice();
    }

    /**
     * @dev when using oraclize, ETH are withdrawed from contract address
     * so it should be able to receive ETH.
     */
    function () external payable {
        emit EthReceived(msg.value);
    }

    function setJsonPath(string calldata _jsonPath) external onlyOwner {
        jsonPath = _jsonPath;
    }

    function __callback(bytes32 myid, string memory result, bytes memory proof) public {
        require(msg.sender == oraclize_cbAddress(), "Invoked not by oraclize address!");
        usdEthRate = parseInt(result, 5).div(100000);
        emit NewUsdEthRate(usdEthRate);
        updatePrice();
    }

    function updatePrice() public onlyOwner {
        if (oraclize.getPrice("URL") > address(this).balance) {
            emit NewQuery("Insufficient funds");
        } else {
            oraclize_query(QUERY_TIME_PERIOD, "URL", jsonPath);
        }
    }

    function getCurrentPrice() public view returns (uint256) {
        return usdEthRate;
    }

    function close() public onlyOwner {
        msg.sender.transfer(address(this).balance);
    }

}