pragma solidity ^0.4.24;

// File: node_modules/zos-lib/contracts/upgradeability/Proxy.sol

/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  function () payable external {
    _fallback();
  }

  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal view returns (address);

  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize)

      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas, implementation, 0, calldatasize, 0, 0)

      // Copy the returned data.
      returndatacopy(0, 0, returndatasize)

      switch result
      // delegatecall returns 0 on error.
      case 0 { revert(0, returndatasize) }
      default { return(0, returndatasize) }
    }
  }

  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal {
  }

  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}

// File: openzeppelin-solidity/contracts/AddressUtils.sol

/**
 * Utility library of inline functions on addresses
 */
library AddressUtils {

  /**
   * Returns whether the target address is a contract
   * @dev This function will return false if invoked during the constructor of a contract,
   *  as the code is not actually created until after the constructor finishes.
   * @param addr address to check
   * @return whether the target address is a contract
   */
  function isContract(address addr) internal view returns (bool) {
    uint256 size;
    // XXX Currently there is no better way to check if there is a contract in an address
    // than to check the size of the code at that address.
    // See https://ethereum.stackexchange.com/a/14016/36603
    // for more details about how this works.
    // TODO Check this again before the Serenity release, because all addresses will be
    // contracts then.
    // solium-disable-next-line security/no-inline-assembly
    assembly { size := extcodesize(addr) }
    return size > 0;
  }

}

// File: node_modules/zos-lib/contracts/upgradeability/UpgradeabilityProxy.sol

/**
 * @title UpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract UpgradeabilityProxy is Proxy {
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address indexed implementation);

  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "org.zeppelinos.proxy.implementation", and is
   * validated in the constructor.
   */
  bytes32 private constant IMPLEMENTATION_SLOT = 0x7050c9e0f4ca769c69bd3a8ef740bc37934f8e2c036e5a723fd8ee048ed3f8c3;

  /**
   * @dev Contract constructor.
   * @param _implementation Address of the initial implementation.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  constructor(address _implementation, bytes _data) public payable {
    assert(IMPLEMENTATION_SLOT == keccak256("org.zeppelinos.proxy.implementation"));
    _setImplementation(_implementation);
    if(_data.length > 0) {
      require(_implementation.delegatecall(_data));
    }
  }

  /**
   * @dev Returns the current implementation.
   * @return Address of the current implementation
   */
  function _implementation() internal view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    assembly {
      impl := sload(slot)
    }
  }

  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }

  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) private {
    require(AddressUtils.isContract(newImplementation), "Cannot set a proxy implementation to a non-contract address");

    bytes32 slot = IMPLEMENTATION_SLOT;

    assembly {
      sstore(slot, newImplementation)
    }
  }
}

// File: node_modules\zos-lib\contracts\upgradeability\AdminUpgradeabilityProxy.sol

/**
 * @title AdminUpgradeabilityProxy
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks.
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract AdminUpgradeabilityProxy is UpgradeabilityProxy {
  /**
   * @dev Emitted when the administration has been transferred.
   * @param previousAdmin Address of the previous admin.
   * @param newAdmin Address of the new admin.
   */
  event AdminChanged(address previousAdmin, address newAdmin);

  /**
   * @dev Storage slot with the admin of the contract.
   * This is the keccak-256 hash of "org.zeppelinos.proxy.admin", and is
   * validated in the constructor.
   */
  bytes32 private constant ADMIN_SLOT = 0x10d6a54a4754c8869d6886b5f5d7fbfa5b4522237ea5c60d11bc4e7a1ff9390b;

  /**
   * @dev Modifier to check whether the `msg.sender` is the admin.
   * If it is, it will run the function. Otherwise, it will delegate the call
   * to the implementation.
   */
  modifier ifAdmin() {
    if (msg.sender == _admin()) {
      _;
    } else {
      _fallback();
    }
  }

  /**
   * Contract constructor.
   * It sets the `msg.sender` as the proxy administrator.
   * @param _implementation address of the initial implementation.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  constructor(address _implementation, bytes _data) UpgradeabilityProxy(_implementation, _data) public payable {
    assert(ADMIN_SLOT == keccak256("org.zeppelinos.proxy.admin"));

    _setAdmin(msg.sender);
  }

  /**
   * @return The address of the proxy admin.
   */
  function admin() external view ifAdmin returns (address) {
    return _admin();
  }

  /**
   * @return The address of the implementation.
   */
  function implementation() external view ifAdmin returns (address) {
    return _implementation();
  }

  /**
   * @dev Changes the admin of the proxy.
   * Only the current admin can call this function.
   * @param newAdmin Address to transfer proxy administration to.
   */
  function changeAdmin(address newAdmin) external ifAdmin {
    require(newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");
    emit AdminChanged(_admin(), newAdmin);
    _setAdmin(newAdmin);
  }

  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }

  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes data) payable external ifAdmin {
    _upgradeTo(newImplementation);
    require(newImplementation.delegatecall(data));
  }

  /**
   * @return The admin slot.
   */
  function _admin() internal view returns (address adm) {
    bytes32 slot = ADMIN_SLOT;
    assembly {
      adm := sload(slot)
    }
  }

  /**
   * @dev Sets the address of the proxy admin.
   * @param newAdmin Address of the new proxy admin.
   */
  function _setAdmin(address newAdmin) internal {
    bytes32 slot = ADMIN_SLOT;

    assembly {
      sstore(slot, newAdmin)
    }
  }

  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal {
    require(msg.sender != _admin(), "Cannot call fallback function from the proxy admin");
    super._willFallback();
  }
}

pragma solidity ^0.4.24;

// File: contracts/Gap.sol

/**
 * @title Gap
 *
 * @dev Reserved storage space to allow for layout changes in the future.
 */
contract Gap {    
    uint256[1000] private ______gap;
}

// File: zos-lib/contracts/Initializable.sol

/**
 * @title Initializable
 *
 * @dev Helper contract to support initializer functions. To use it, replace
 * the constructor with a function that has the `initializer` modifier.
 * WARNING: Unlike constructors, initializer functions must be manually
 * invoked. This applies both to deploying an Initializable contract, as well
 * as extending an Initializable contract via inheritance.
 * WARNING: When used with inheritance, manual care must be taken to not invoke
 * a parent initializer twice, or ensure that all initializers are idempotent,
 * because this is not dealt with automatically as with constructors.
 */
contract Initializable {

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

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

  /**
   * @dev Modifier to use in the initializer function of a contract.
   */
  modifier initializer() {
    require(initializing || isConstructor() || !initialized, "Contract instance has already been initialized");

    bool wasInitializing = initializing;
    initializing = true;
    initialized = true;

    _;

    initializing = wasInitializing;
  }

  /// @dev Returns true if and only if the function is running in the constructor
  function isConstructor() private view returns (bool) {
    // extcodesize checks the size of the code stored in an address, and
    // address returns the current address. Since the code is still not
    // deployed when running a constructor, any checks on its code size will
    // yield zero, making it an effective way to detect if a contract is
    // under construction or not.
    uint256 cs;
    assembly { cs := extcodesize(address) }
    return cs == 0;
  }

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

// File: openzeppelin-eth/contracts/ownership/Ownable.sol

/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable is Initializable {
  address private _owner;


  event OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );


  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  function initialize(address sender) public initializer {
    _owner = sender;
  }

  /**
   * @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 OwnershipRenounced(_owner);
    _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;
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/access/Roles.sol

/**
 * @title Roles
 * @dev Library for managing addresses assigned to a Role.
 */
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));
    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));
    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];
  }
}

// File: openzeppelin-eth/contracts/access/roles/SignerRole.sol

contract SignerRole is Initializable {
  using Roles for Roles.Role;

  event SignerAdded(address indexed account);
  event SignerRemoved(address indexed account);

  Roles.Role private signers;

  function initialize(address sender) public initializer {
    if (!isSigner(sender)) {
      _addSigner(sender);
    }
  }

  modifier onlySigner() {
    require(isSigner(msg.sender));
    _;
  }

  function isSigner(address account) public view returns (bool) {
    return signers.has(account);
  }

  function addSigner(address account) public onlySigner {
    _addSigner(account);
  }

  function renounceSigner() public {
    _removeSigner(msg.sender);
  }

  function _addSigner(address account) internal {
    signers.add(account);
    emit SignerAdded(account);
  }

  function _removeSigner(address account) internal {
    signers.remove(account);
    emit SignerRemoved(account);
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/introspection/IERC165.sol

/**
 * @title IERC165
 * @dev https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
 */
interface IERC165 {

  /**
   * @notice Query if a contract implements an interface
   * @param interfaceId The interface identifier, as specified in ERC-165
   * @dev Interface identification is specified in ERC-165. This function
   * uses less than 30,000 gas.
   */
  function supportsInterface(bytes4 interfaceId)
    external
    view
    returns (bool);
}

// File: openzeppelin-eth/contracts/token/ERC721/IERC721.sol

/**
 * @title ERC721 Non-Fungible Token Standard basic interface
 * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract IERC721 is Initializable, IERC165 {

  event Transfer(
    address indexed from,
    address indexed to,
    uint256 indexed tokenId
  );
  event Approval(
    address indexed owner,
    address indexed approved,
    uint256 indexed tokenId
  );
  event ApprovalForAll(
    address indexed owner,
    address indexed operator,
    bool approved
  );

  function balanceOf(address owner) public view returns (uint256 balance);
  function ownerOf(uint256 tokenId) public view returns (address owner);

  function approve(address to, uint256 tokenId) public;
  function getApproved(uint256 tokenId)
    public view returns (address operator);

  function setApprovalForAll(address operator, bool _approved) public;
  function isApprovedForAll(address owner, address operator)
    public view returns (bool);

  function transferFrom(address from, address to, uint256 tokenId) public;
  function safeTransferFrom(address from, address to, uint256 tokenId)
    public;

  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId,
    bytes data
  )
    public;
}

// File: openzeppelin-eth/contracts/token/ERC721/IERC721Receiver.sol

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
contract IERC721Receiver {
  /**
   * @notice Handle the receipt of an NFT
   * @dev The ERC721 smart contract calls this function on the recipient
   * after a `safeTransfer`. This function MUST return the function selector,
   * otherwise the caller will revert the transaction. The selector to be
   * returned can be obtained as `this.onERC721Received.selector`. This
   * function MAY throw to revert and reject the transfer.
   * Note: the ERC721 contract address is always the message sender.
   * @param operator The address which called `safeTransferFrom` function
   * @param from The address which previously owned the token
   * @param tokenId The NFT identifier which is being transferred
   * @param data Additional data with no specified format
   * @return `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
   */
  function onERC721Received(
    address operator,
    address from,
    uint256 tokenId,
    bytes data
  )
    public
    returns(bytes4);
}

// File: openzeppelin-eth/contracts/math/SafeMath.sol

/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, 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 numbers truncating the quotient, reverts on division by zero.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0); // Solidity only automatically asserts when dividing by 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 numbers, 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 numbers, 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 numbers 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;
  }
}

// File: openzeppelin-eth/contracts/utils/Address.sol

/**
 * Utility library of inline functions on addresses
 */
library Address {

  /**
   * Returns whether the target address is a contract
   * @dev This function will return false if invoked during the constructor of a contract,
   * as the code is not actually created until after the constructor finishes.
   * @param account address of the account to check
   * @return whether the target address is a contract
   */
  function isContract(address account) internal view returns (bool) {
    uint256 size;
    // XXX Currently there is no better way to check if there is a contract in an address
    // than to check the size of the code at that address.
    // See https://ethereum.stackexchange.com/a/14016/36603
    // for more details about how this works.
    // TODO Check this again before the Serenity release, because all addresses will be
    // contracts then.
    // solium-disable-next-line security/no-inline-assembly
    assembly { size := extcodesize(account) }
    return size > 0;
  }
}

// File: openzeppelin-eth/contracts/introspection/ERC165.sol

/**
 * @title ERC165
 * @author Matt Condon (@shrugs)
 * @dev Implements ERC165 using a lookup table.
 */
contract ERC165 is Initializable, IERC165 {

  bytes4 private constant _InterfaceId_ERC165 = 0x01ffc9a7;
  /**
   * 0x01ffc9a7 ===
   *   bytes4(keccak256('supportsInterface(bytes4)'))
   */

  /**
   * @dev a mapping of interface id to whether or not it's supported
   */
  mapping(bytes4 => bool) internal _supportedInterfaces;

  /**
   * @dev A contract implementing SupportsInterfaceWithLookup
   * implement ERC165 itself
   */
  function initialize()
    public
    initializer
  {
    _registerInterface(_InterfaceId_ERC165);
  }

  /**
   * @dev implement supportsInterface(bytes4) using a lookup table
   */
  function supportsInterface(bytes4 interfaceId)
    public
    view
    returns (bool)
  {
    return _supportedInterfaces[interfaceId];
  }

  /**
   * @dev private method for registering an interface
   */
  function _registerInterface(bytes4 interfaceId)
    internal
  {
    require(interfaceId != 0xffffffff);
    _supportedInterfaces[interfaceId] = true;
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/token/ERC721/ERC721.sol

/**
 * @title ERC721 Non-Fungible Token Standard basic implementation
 * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract ERC721 is Initializable, ERC165, IERC721 {

  using SafeMath for uint256;
  using Address for address;

  // Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
  // which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
  bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;

  // Mapping from token ID to owner
  mapping (uint256 => address) private _tokenOwner;

  // Mapping from token ID to approved address
  mapping (uint256 => address) private _tokenApprovals;

  // Mapping from owner to number of owned token
  mapping (address => uint256) private _ownedTokensCount;

  // Mapping from owner to operator approvals
  mapping (address => mapping (address => bool)) private _operatorApprovals;

  bytes4 private constant _InterfaceId_ERC721 = 0x80ac58cd;
  /*
   * 0x80ac58cd ===
   *   bytes4(keccak256('balanceOf(address)')) ^
   *   bytes4(keccak256('ownerOf(uint256)')) ^
   *   bytes4(keccak256('approve(address,uint256)')) ^
   *   bytes4(keccak256('getApproved(uint256)')) ^
   *   bytes4(keccak256('setApprovalForAll(address,bool)')) ^
   *   bytes4(keccak256('isApprovedForAll(address,address)')) ^
   *   bytes4(keccak256('transferFrom(address,address,uint256)')) ^
   *   bytes4(keccak256('safeTransferFrom(address,address,uint256)')) ^
   *   bytes4(keccak256('safeTransferFrom(address,address,uint256,bytes)'))
   */

  function initialize()
    public
    initializer
  {
    ERC165.initialize();

    // register the supported interfaces to conform to ERC721 via ERC165
    _registerInterface(_InterfaceId_ERC721);
  }

  function _hasBeenInitialized() internal view returns (bool) {
    return supportsInterface(_InterfaceId_ERC721);
  }

  /**
   * @dev Gets the balance of the specified address
   * @param owner address to query the balance of
   * @return uint256 representing the amount owned by the passed address
   */
  function balanceOf(address owner) public view returns (uint256) {
    require(owner != address(0));
    return _ownedTokensCount[owner];
  }

  /**
   * @dev Gets the owner of the specified token ID
   * @param tokenId uint256 ID of the token to query the owner of
   * @return owner address currently marked as the owner of the given token ID
   */
  function ownerOf(uint256 tokenId) public view returns (address) {
    address owner = _tokenOwner[tokenId];
    require(owner != address(0));
    return owner;
  }

  /**
   * @dev Approves another address to transfer the given token ID
   * The zero address indicates there is no approved address.
   * There can only be one approved address per token at a given time.
   * Can only be called by the token owner or an approved operator.
   * @param to address to be approved for the given token ID
   * @param tokenId uint256 ID of the token to be approved
   */
  function approve(address to, uint256 tokenId) public {
    address owner = ownerOf(tokenId);
    require(to != owner);
    require(msg.sender == owner || isApprovedForAll(owner, msg.sender));

    _tokenApprovals[tokenId] = to;
    emit Approval(owner, to, tokenId);
  }

  /**
   * @dev Gets the approved address for a token ID, or zero if no address set
   * Reverts if the token ID does not exist.
   * @param tokenId uint256 ID of the token to query the approval of
   * @return address currently approved for the given token ID
   */
  function getApproved(uint256 tokenId) public view returns (address) {
    require(_exists(tokenId));
    return _tokenApprovals[tokenId];
  }

  /**
   * @dev Sets or unsets the approval of a given operator
   * An operator is allowed to transfer all tokens of the sender on their behalf
   * @param to operator address to set the approval
   * @param approved representing the status of the approval to be set
   */
  function setApprovalForAll(address to, bool approved) public {
    require(to != msg.sender);
    _operatorApprovals[msg.sender][to] = approved;
    emit ApprovalForAll(msg.sender, to, approved);
  }

  /**
   * @dev Tells whether an operator is approved by a given owner
   * @param owner owner address which you want to query the approval of
   * @param operator operator address which you want to query the approval of
   * @return bool whether the given operator is approved by the given owner
   */
  function isApprovedForAll(
    address owner,
    address operator
  )
    public
    view
    returns (bool)
  {
    return _operatorApprovals[owner][operator];
  }

  /**
   * @dev Transfers the ownership of a given token ID to another address
   * Usage of this method is discouraged, use `safeTransferFrom` whenever possible
   * Requires the msg sender to be the owner, approved, or operator
   * @param from current owner of the token
   * @param to address to receive the ownership of the given token ID
   * @param tokenId uint256 ID of the token to be transferred
  */
  function transferFrom(
    address from,
    address to,
    uint256 tokenId
  )
    public
  {
    require(_isApprovedOrOwner(msg.sender, tokenId));
    require(to != address(0));

    _clearApproval(from, tokenId);
    _removeTokenFrom(from, tokenId);
    _addTokenTo(to, tokenId);

    emit Transfer(from, to, tokenId);
  }

  /**
   * @dev Safely transfers the ownership of a given token ID to another address
   * If the target address is a contract, it must implement `onERC721Received`,
   * which is called upon a safe transfer, and return the magic value
   * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
   * the transfer is reverted.
   *
   * Requires the msg sender to be the owner, approved, or operator
   * @param from current owner of the token
   * @param to address to receive the ownership of the given token ID
   * @param tokenId uint256 ID of the token to be transferred
  */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId
  )
    public
  {
    // solium-disable-next-line arg-overflow
    safeTransferFrom(from, to, tokenId, "");
  }

  /**
   * @dev Safely transfers the ownership of a given token ID to another address
   * If the target address is a contract, it must implement `onERC721Received`,
   * which is called upon a safe transfer, and return the magic value
   * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
   * the transfer is reverted.
   * Requires the msg sender to be the owner, approved, or operator
   * @param from current owner of the token
   * @param to address to receive the ownership of the given token ID
   * @param tokenId uint256 ID of the token to be transferred
   * @param _data bytes data to send along with a safe transfer check
   */
  function safeTransferFrom(
    address from,
    address to,
    uint256 tokenId,
    bytes _data
  )
    public
  {
    transferFrom(from, to, tokenId);
    // solium-disable-next-line arg-overflow
    require(_checkAndCallSafeTransfer(from, to, tokenId, _data));
  }

  /**
   * @dev Returns whether the specified token exists
   * @param tokenId uint256 ID of the token to query the existence of
   * @return whether the token exists
   */
  function _exists(uint256 tokenId) internal view returns (bool) {
    address owner = _tokenOwner[tokenId];
    return owner != address(0);
  }

  /**
   * @dev Returns whether the given spender can transfer a given token ID
   * @param spender address of the spender to query
   * @param tokenId uint256 ID of the token to be transferred
   * @return bool whether the msg.sender is approved for the given token ID,
   *  is an operator of the owner, or is the owner of the token
   */
  function _isApprovedOrOwner(
    address spender,
    uint256 tokenId
  )
    internal
    view
    returns (bool)
  {
    address owner = ownerOf(tokenId);
    // Disable solium check because of
    // https://github.com/duaraghav8/Solium/issues/175
    // solium-disable-next-line operator-whitespace
    return (
      spender == owner ||
      getApproved(tokenId) == spender ||
      isApprovedForAll(owner, spender)
    );
  }

  /**
   * @dev Internal function to mint a new token
   * Reverts if the given token ID already exists
   * @param to The address that will own the minted token
   * @param tokenId uint256 ID of the token to be minted by the msg.sender
   */
  function _mint(address to, uint256 tokenId) internal {
    require(to != address(0));
    _addTokenTo(to, tokenId);
    emit Transfer(address(0), to, tokenId);
  }

  /**
   * @dev Internal function to burn a specific token
   * Reverts if the token does not exist
   * @param tokenId uint256 ID of the token being burned by the msg.sender
   */
  function _burn(address owner, uint256 tokenId) internal {
    _clearApproval(owner, tokenId);
    _removeTokenFrom(owner, tokenId);
    emit Transfer(owner, address(0), tokenId);
  }

  /**
   * @dev Internal function to clear current approval of a given token ID
   * Reverts if the given address is not indeed the owner of the token
   * @param owner owner of the token
   * @param tokenId uint256 ID of the token to be transferred
   */
  function _clearApproval(address owner, uint256 tokenId) internal {
    require(ownerOf(tokenId) == owner);
    if (_tokenApprovals[tokenId] != address(0)) {
      _tokenApprovals[tokenId] = address(0);
    }
  }

  /**
   * @dev Internal function to add a token ID to the list of a given address
   * @param to address representing the new owner of the given token ID
   * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
   */
  function _addTokenTo(address to, uint256 tokenId) internal {
    require(_tokenOwner[tokenId] == address(0));
    _tokenOwner[tokenId] = to;
    _ownedTokensCount[to] = _ownedTokensCount[to].add(1);
  }

  /**
   * @dev Internal function to remove a token ID from the list of a given address
   * @param from address representing the previous owner of the given token ID
   * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
   */
  function _removeTokenFrom(address from, uint256 tokenId) internal {
    require(ownerOf(tokenId) == from);
    _ownedTokensCount[from] = _ownedTokensCount[from].sub(1);
    _tokenOwner[tokenId] = address(0);
  }

  /**
   * @dev Internal function to invoke `onERC721Received` on a target address
   * The call is not executed if the target address is not a contract
   * @param from address representing the previous owner of the given token ID
   * @param to target address that will receive the tokens
   * @param tokenId uint256 ID of the token to be transferred
   * @param _data bytes optional data to send along with the call
   * @return whether the call correctly returned the expected magic value
   */
  function _checkAndCallSafeTransfer(
    address from,
    address to,
    uint256 tokenId,
    bytes _data
  )
    internal
    returns (bool)
  {
    if (!to.isContract()) {
      return true;
    }
    bytes4 retval = IERC721Receiver(to).onERC721Received(
      msg.sender, from, tokenId, _data);
    return (retval == _ERC721_RECEIVED);
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/token/ERC721/IERC721Enumerable.sol

/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract IERC721Enumerable is Initializable, IERC721 {
  function totalSupply() public view returns (uint256);
  function tokenOfOwnerByIndex(
    address owner,
    uint256 index
  )
    public
    view
    returns (uint256 tokenId);

  function tokenByIndex(uint256 index) public view returns (uint256);
}

// File: openzeppelin-eth/contracts/token/ERC721/ERC721Enumerable.sol

contract ERC721Enumerable is Initializable, ERC165, ERC721, IERC721Enumerable {
  // Mapping from owner to list of owned token IDs
  mapping(address => uint256[]) private _ownedTokens;

  // Mapping from token ID to index of the owner tokens list
  mapping(uint256 => uint256) private _ownedTokensIndex;

  // Array with all token ids, used for enumeration
  uint256[] private _allTokens;

  // Mapping from token id to position in the allTokens array
  mapping(uint256 => uint256) private _allTokensIndex;

  bytes4 private constant _InterfaceId_ERC721Enumerable = 0x780e9d63;
  /**
   * 0x780e9d63 ===
   *   bytes4(keccak256('totalSupply()')) ^
   *   bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) ^
   *   bytes4(keccak256('tokenByIndex(uint256)'))
   */

  /**
   * @dev Constructor function
   */
  function initialize() public initializer {
    require(ERC721._hasBeenInitialized());

    // register the supported interface to conform to ERC721 via ERC165
    _registerInterface(_InterfaceId_ERC721Enumerable);
  }

  function _hasBeenInitialized() internal view returns (bool) {
    return supportsInterface(_InterfaceId_ERC721Enumerable);
  }

  /**
   * @dev Gets the token ID at a given index of the tokens list of the requested owner
   * @param owner address owning the tokens list to be accessed
   * @param index uint256 representing the index to be accessed of the requested tokens list
   * @return uint256 token ID at the given index of the tokens list owned by the requested address
   */
  function tokenOfOwnerByIndex(
    address owner,
    uint256 index
  )
    public
    view
    returns (uint256)
  {
    require(index < balanceOf(owner));
    return _ownedTokens[owner][index];
  }

  /**
   * @dev Gets the total amount of tokens stored by the contract
   * @return uint256 representing the total amount of tokens
   */
  function totalSupply() public view returns (uint256) {
    return _allTokens.length;
  }

  /**
   * @dev Gets the token ID at a given index of all the tokens in this contract
   * Reverts if the index is greater or equal to the total number of tokens
   * @param index uint256 representing the index to be accessed of the tokens list
   * @return uint256 token ID at the given index of the tokens list
   */
  function tokenByIndex(uint256 index) public view returns (uint256) {
    require(index < totalSupply());
    return _allTokens[index];
  }

  /**
   * @dev Internal function to add a token ID to the list of a given address
   * @param to address representing the new owner of the given token ID
   * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
   */
  function _addTokenTo(address to, uint256 tokenId) internal {
    super._addTokenTo(to, tokenId);
    uint256 length = _ownedTokens[to].length;
    _ownedTokens[to].push(tokenId);
    _ownedTokensIndex[tokenId] = length;
  }

  /**
   * @dev Internal function to remove a token ID from the list of a given address
   * @param from address representing the previous owner of the given token ID
   * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
   */
  function _removeTokenFrom(address from, uint256 tokenId) internal {
    super._removeTokenFrom(from, tokenId);

    // To prevent a gap in the array, we store the last token in the index of the token to delete, and
    // then delete the last slot.
    uint256 tokenIndex = _ownedTokensIndex[tokenId];
    uint256 lastTokenIndex = _ownedTokens[from].length.sub(1);
    uint256 lastToken = _ownedTokens[from][lastTokenIndex];

    _ownedTokens[from][tokenIndex] = lastToken;
    // This also deletes the contents at the last position of the array
    _ownedTokens[from].length--;

    // Note that this will handle single-element arrays. In that case, both tokenIndex and lastTokenIndex are going to
    // be zero. Then we can make sure that we will remove tokenId from the ownedTokens list since we are first swapping
    // the lastToken to the first position, and then dropping the element placed in the last position of the list

    _ownedTokensIndex[tokenId] = 0;
    _ownedTokensIndex[lastToken] = tokenIndex;
  }

  /**
   * @dev Internal function to mint a new token
   * Reverts if the given token ID already exists
   * @param to address the beneficiary that will own the minted token
   * @param tokenId uint256 ID of the token to be minted by the msg.sender
   */
  function _mint(address to, uint256 tokenId) internal {
    super._mint(to, tokenId);

    _allTokensIndex[tokenId] = _allTokens.length;
    _allTokens.push(tokenId);
  }

  /**
   * @dev Internal function to burn a specific token
   * Reverts if the token does not exist
   * @param owner owner of the token to burn
   * @param tokenId uint256 ID of the token being burned by the msg.sender
   */
  function _burn(address owner, uint256 tokenId) internal {
    super._burn(owner, tokenId);

    // Reorg all tokens array
    uint256 tokenIndex = _allTokensIndex[tokenId];
    uint256 lastTokenIndex = _allTokens.length.sub(1);
    uint256 lastToken = _allTokens[lastTokenIndex];

    _allTokens[tokenIndex] = lastToken;
    _allTokens[lastTokenIndex] = 0;

    _allTokens.length--;
    _allTokensIndex[tokenId] = 0;
    _allTokensIndex[lastToken] = tokenIndex;
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/token/ERC721/IERC721Metadata.sol

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract IERC721Metadata is Initializable, IERC721 {
  function name() external view returns (string);
  function symbol() external view returns (string);
  function tokenURI(uint256 tokenId) public view returns (string);
}

// File: openzeppelin-eth/contracts/token/ERC721/ERC721Metadata.sol

contract ERC721Metadata is Initializable, ERC165, ERC721, IERC721Metadata {
  // Token name
  string internal _name;

  // Token symbol
  string internal _symbol;

  // Optional mapping for token URIs
  mapping(uint256 => string) private _tokenURIs;

  bytes4 private constant InterfaceId_ERC721Metadata = 0x5b5e139f;
  /**
   * 0x5b5e139f ===
   *   bytes4(keccak256('name()')) ^
   *   bytes4(keccak256('symbol()')) ^
   *   bytes4(keccak256('tokenURI(uint256)'))
   */

  /**
   * @dev Constructor function
   */
  function initialize(string name, string symbol) public initializer {
    require(ERC721._hasBeenInitialized());

    _name = name;
    _symbol = symbol;

    // register the supported interfaces to conform to ERC721 via ERC165
    _registerInterface(InterfaceId_ERC721Metadata);
  }

  function _hasBeenInitialized() internal view returns (bool) {
    return supportsInterface(InterfaceId_ERC721Metadata);
  }

  /**
   * @dev Gets the token name
   * @return string representing the token name
   */
  function name() external view returns (string) {
    return _name;
  }

  /**
   * @dev Gets the token symbol
   * @return string representing the token symbol
   */
  function symbol() external view returns (string) {
    return _symbol;
  }

  /**
   * @dev Returns an URI for a given token ID
   * Throws if the token ID does not exist. May return an empty string.
   * @param tokenId uint256 ID of the token to query
   */
  function tokenURI(uint256 tokenId) public view returns (string) {
    require(_exists(tokenId));
    return _tokenURIs[tokenId];
  }

  /**
   * @dev Internal function to set the token URI for a given token
   * Reverts if the token ID does not exist
   * @param tokenId uint256 ID of the token to set its URI
   * @param uri string URI to assign
   */
  function _setTokenURI(uint256 tokenId, string uri) internal {
    require(_exists(tokenId));
    _tokenURIs[tokenId] = uri;
  }

  /**
   * @dev Internal function to burn a specific token
   * Reverts if the token does not exist
   * @param owner owner of the token to burn
   * @param tokenId uint256 ID of the token being burned by the msg.sender
   */
  function _burn(address owner, uint256 tokenId) internal {
    super._burn(owner, tokenId);

    // Clear metadata (if any)
    if (bytes(_tokenURIs[tokenId]).length != 0) {
      delete _tokenURIs[tokenId];
    }
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/token/ERC721/ERC721Full.sol

/**
 * @title Full ERC721 Token
 * This implementation includes all the required and some optional functionality of the ERC721 standard
 * Moreover, it includes approve all functionality using operator terminology
 * @dev see https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md
 */
contract ERC721Full is Initializable, ERC721, ERC721Enumerable, ERC721Metadata {
  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/access/roles/MinterRole.sol

contract MinterRole is Initializable {
  using Roles for Roles.Role;

  event MinterAdded(address indexed account);
  event MinterRemoved(address indexed account);

  Roles.Role private minters;

  function initialize(address sender) public initializer {
    if (!isMinter(sender)) {
      _addMinter(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);
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/token/ERC721/ERC721Mintable.sol

/**
 * @title ERC721Mintable
 * @dev ERC721 minting logic
 */
contract ERC721Mintable is Initializable, ERC721, MinterRole {
  function initialize(address sender) public initializer {
    require(ERC721._hasBeenInitialized());
    MinterRole.initialize(sender);
  }

  /**
   * @dev Function to mint tokens
   * @param to The address that will receive the minted tokens.
   * @param tokenId The token id to mint.
   * @return A boolean that indicates if the operation was successful.
   */
  function mint(
    address to,
    uint256 tokenId
  )
    public
    onlyMinter
    returns (bool)
  {
    _mint(to, tokenId);
    return true;
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/token/ERC721/ERC721MetadataMintable.sol

/**
 * @title ERC721MetadataMintable
 * @dev ERC721 minting logic with metadata
 */
contract ERC721MetadataMintable is Initializable, ERC721, ERC721Metadata, MinterRole {
  function initialize(address sender) public initializer {
    require(ERC721._hasBeenInitialized());
    require(ERC721Metadata._hasBeenInitialized());
    MinterRole.initialize(sender);
  }

  /**
   * @dev Function to mint tokens
   * @param to The address that will receive the minted tokens.
   * @param tokenId The token id to mint.
   * @param tokenURI The token URI of the minted token.
   * @return A boolean that indicates if the operation was successful.
   */
  function mintWithTokenURI(
    address to,
    uint256 tokenId,
    string tokenURI
  )
    public
    onlyMinter
    returns (bool)
  {
    _mint(to, tokenId);
    _setTokenURI(tokenId, tokenURI);
    return true;
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/access/roles/PauserRole.sol

contract PauserRole is Initializable {
  using Roles for Roles.Role;

  event PauserAdded(address indexed account);
  event PauserRemoved(address indexed account);

  Roles.Role private pausers;

  function initialize(address sender) public initializer {
    if (!isPauser(sender)) {
      _addPauser(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);
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/lifecycle/Pausable.sol

/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 */
contract Pausable is Initializable, PauserRole {
  event Paused();
  event Unpaused();

  bool private _paused = false;

  function initialize(address sender) public initializer {
    PauserRole.initialize(sender);
  }

  /**
   * @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();
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() public onlyPauser whenPaused {
    _paused = false;
    emit Unpaused();
  }

  uint256[50] private ______gap;
}

// File: openzeppelin-eth/contracts/token/ERC721/ERC721Pausable.sol

/**
 * @title ERC721 Non-Fungible Pausable token
 * @dev ERC721 modified with pausable transfers.
 **/
contract ERC721Pausable is Initializable, ERC721, Pausable {
  function initialize(address sender) public initializer {
    require(ERC721._hasBeenInitialized());
    Pausable.initialize(sender);
  }

  function approve(
    address to,
    uint256 tokenId
  )
    public
    whenNotPaused
  {
    super.approve(to, tokenId);
  }

  function setApprovalForAll(
    address to,
    bool approved
  )
    public
    whenNotPaused
  {
    super.setApprovalForAll(to, approved);
  }

  function transferFrom(
    address from,
    address to,
    uint256 tokenId
  )
    public
    whenNotPaused
  {
    super.transferFrom(from, to, tokenId);
  }

  uint256[50] private ______gap;
}

// File: contracts\Space.sol

contract Space is Gap, Initializable, Ownable, SignerRole, ERC721Full, ERC721Mintable, ERC721MetadataMintable, ERC721Pausable {    

    function initialize(address owner) public initializer {

        Ownable.initialize(owner);
        ERC721.initialize();        
        ERC721Metadata.initialize("Spheroid SPACE", "SPACE");
        ERC721Enumerable.initialize();
        ERC721Mintable.initialize(owner);
        ERC721MetadataMintable.initialize(owner);
        ERC721Pausable.initialize(owner);
    }

    function mint(address to, uint256 tokenId) public whenNotPaused returns (bool)
    {
        return super.mint(to, tokenId);
    }

    function mintWithTokenURI(address to, uint256 tokenId, string tokenURI) public whenNotPaused returns (bool)
    {
        return super.mintWithTokenURI(to, tokenId, tokenURI);
    }

    function withdraw(uint256 tokenId, uint256 expires, uint8 v, bytes32 r, bytes32 s) public whenNotPaused returns (bool) {
        // Temporarily disable expiration because of a lot of pending transactions
        // require(expires > now);
        bytes32 h = keccak256(abi.encodePacked(msg.sender, tokenId, expires));
        address signer = ecrecover(h, v, r, s);        
        require(isSigner(signer));
        _mint(msg.sender, tokenId);
        return true;
    }

    function unpause() public onlyOwner {
        super.unpause();
    }

    function addMinter(address account) public onlyOwner {
        super._addMinter(account);
    }

    function removeMinter(address account) public onlyOwner {
        super._removeMinter(account);        
    }

    function addPauser(address account) public onlyOwner {
        super._addPauser(account);
    }

    function removePauser(address account) public onlyOwner {
        super._removePauser(account);        
    }

    function addSigner(address account) public onlyOwner {
        super._addSigner(account);
    }

    function removeSigner(address account) public onlyOwner {
        super._removeSigner(account);        
    }
}