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SmartContract.txt
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SmartContract.txt
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pragma solidity ^0.4.11;
/**
* @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 {
address public owner;
/**
* @dev The Ownable constructor sets the original `owner` of the contract to the sender
* account.
*/
function Ownable() {
owner = msg.sender;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(msg.sender == owner);
_;
}
/**
* @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) onlyOwner {
if (newOwner != address(0)) {
owner = newOwner;
}
}
}
/// @title Interface for contracts conforming to ERC-721: Non-Fungible Tokens
/// @author Eric Rosas <Eric@empireappdesignz.com> (https://github.com/empireappdesignz)
contract ERC721 {
// Required methods
function totalSupply() public view returns (uint256 total);
function balanceOf(address _owner) public view returns (uint256 balance);
function ownerOf(uint256 _tokenId) external view returns (address owner);
function approve(address _to, uint256 _tokenId) external;
function transfer(address _to, uint256 _tokenId) external;
function transferFrom(address _from, address _to, uint256 _tokenId) external;
// Events
event Transfer(address from, address to, uint256 tokenId);
event Approval(address owner, address approved, uint256 tokenId);
// Optional
// function name() public view returns (string name);
// function symbol() public view returns (string symbol);
// function tokensOfOwner(address _owner) external view returns (uint256[] tokenIds);
// function tokenMetadata(uint256 _tokenId, string _preferredTransport) public view returns (string infoUrl);
// ERC-165 Compatibility (https://github.com/ethereum/EIPs/issues/165)
function supportsInterface(bytes4 _interfaceID) external view returns (bool);
}
/// @title Auction Core
/// @dev Contains models, variables, and internal methods for the auction.
/// @notice We omit a fallback function to prevent accidental sends to this contract.
contract ClockAuctionBase {
// Represents an auction on an NFT
struct Auction {
// Current owner of NFT
address seller;
// Price (in wei) at beginning of auction
uint128 startingPrice;
// Price (in wei) at end of auction
uint128 endingPrice;
// Duration (in seconds) of auction
uint64 duration;
// Time when auction started
// NOTE: 0 if this auction has been concluded
uint64 startedAt;
}
// Reference to contract tracking NFT ownership
ERC721 public nonFungibleContract;
// Cut owner takes on each auction, measured in basis points (1/100 of a percent).
// Values 0-10,000 map to 0%-100%
uint256 public ownerCut;
// Map from token ID to their corresponding auction.
mapping (uint256 => Auction) tokenIdToAuction;
event AuctionCreated(uint256 tokenId, uint256 startingPrice, uint256 endingPrice, uint256 duration);
event AuctionSuccessful(uint256 tokenId, uint256 totalPrice, address winner);
event AuctionCancelled(uint256 tokenId);
/// @dev Returns true if the claimant owns the token.
/// @param _claimant - Address claiming to own the token.
/// @param _tokenId - ID of token whose ownership to verify.
function _owns(address _claimant, uint256 _tokenId) internal view returns (bool) {
return (nonFungibleContract.ownerOf(_tokenId) == _claimant);
}
/// @dev Escrows the NFT, assigning ownership to this contract.
/// Throws if the escrow fails.
/// @param _owner - Current owner address of token to escrow.
/// @param _tokenId - ID of token whose approval to verify.
function _escrow(address _owner, uint256 _tokenId) internal {
// it will throw if transfer fails
nonFungibleContract.transferFrom(_owner, this, _tokenId);
}
/// @dev Transfers an NFT owned by this contract to another address.
/// Returns true if the transfer succeeds.
/// @param _receiver - Address to transfer NFT to.
/// @param _tokenId - ID of token to transfer.
function _transfer(address _receiver, uint256 _tokenId) internal {
// it will throw if transfer fails
nonFungibleContract.transfer(_receiver, _tokenId);
}
/// @dev Adds an auction to the list of open auctions. Also fires the
/// AuctionCreated event.
/// @param _tokenId The ID of the token to be put on auction.
/// @param _auction Auction to add.
function _addAuction(uint256 _tokenId, Auction _auction) internal {
// Require that all auctions have a duration of
// at least one minute. (Keeps our math from getting hairy!)
require(_auction.duration >= 1 minutes);
tokenIdToAuction[_tokenId] = _auction;
AuctionCreated(
uint256(_tokenId),
uint256(_auction.startingPrice),
uint256(_auction.endingPrice),
uint256(_auction.duration)
);
}
/// @dev Cancels an auction unconditionally.
function _cancelAuction(uint256 _tokenId, address _seller) internal {
_removeAuction(_tokenId);
_transfer(_seller, _tokenId);
AuctionCancelled(_tokenId);
}
/// @dev Computes the price and transfers winnings.
/// Does NOT transfer ownership of token.
function _bid(uint256 _tokenId, uint256 _bidAmount)
internal
returns (uint256)
{
// Get a reference to the auction struct
Auction storage auction = tokenIdToAuction[_tokenId];
// Explicitly check that this auction is currently live.
// (Because of how Ethereum mappings work, we can't just count
// on the lookup above failing. An invalid _tokenId will just
// return an auction object that is all zeros.)
require(_isOnAuction(auction));
// Check that the bid is greater than or equal to the current price
uint256 price = _currentPrice(auction);
require(_bidAmount >= price);
// Grab a reference to the seller before the auction struct
// gets deleted.
address seller = auction.seller;
// The bid is good! Remove the auction before sending the fees
// to the sender so we can't have a reentrancy attack.
_removeAuction(_tokenId);
// Transfer proceeds to seller (if there are any!)
if (price > 0) {
// Calculate the auctioneer's cut.
// (NOTE: _computeCut() is guaranteed to return a
// value <= price, so this subtraction can't go negative.)
uint256 auctioneerCut = _computeCut(price);
uint256 sellerProceeds = price - auctioneerCut;
// NOTE: Doing a transfer() in the middle of a complex
// method like this is generally discouraged because of
// reentrancy attacks and DoS attacks if the seller is
// a contract with an invalid fallback function. We explicitly
// guard against reentrancy attacks by removing the auction
// before calling transfer(), and the only thing the seller
// can DoS is the sale of their own asset! (And if it's an
// accident, they can call cancelAuction(). )
seller.transfer(sellerProceeds);
}
// Calculate any excess funds included with the bid. If the excess
// is anything worth worrying about, transfer it back to bidder.
// NOTE: We checked above that the bid amount is greater than or
// equal to the price so this cannot underflow.
uint256 bidExcess = _bidAmount - price;
// Return the funds. Similar to the previous transfer, this is
// not susceptible to a re-entry attack because the auction is
// removed before any transfers occur.
msg.sender.transfer(bidExcess);
// Tell the world!
AuctionSuccessful(_tokenId, price, msg.sender);
return price;
}
/// @dev Removes an auction from the list of open auctions.
/// @param _tokenId - ID of NFT on auction.
function _removeAuction(uint256 _tokenId) internal {
delete tokenIdToAuction[_tokenId];
}
/// @dev Returns true if the NFT is on auction.
/// @param _auction - Auction to check.
function _isOnAuction(Auction storage _auction) internal view returns (bool) {
return (_auction.startedAt > 0);
}
/// @dev Returns current price of an NFT on auction. Broken into two
/// functions (this one, that computes the duration from the auction
/// structure, and the other that does the price computation) so we
/// can easily test that the price computation works correctly.
function _currentPrice(Auction storage _auction)
internal
view
returns (uint256)
{
uint256 secondsPassed = 0;
// A bit of insurance against negative values (or wraparound).
// Probably not necessary (since Ethereum guarnatees that the
// now variable doesn't ever go backwards).
if (now > _auction.startedAt) {
secondsPassed = now - _auction.startedAt;
}
return _computeCurrentPrice(
_auction.startingPrice,
_auction.endingPrice,
_auction.duration,
secondsPassed
);
}
/// @dev Computes the current price of an auction. Factored out
/// from _currentPrice so we can run extensive unit tests.
/// When testing, make this function public and turn on
/// `Current price computation` test suite.
function _computeCurrentPrice(
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration,
uint256 _secondsPassed
)
internal
pure
returns (uint256)
{
// NOTE: We don't use SafeMath (or similar) in this function because
// all of our public functions carefully cap the maximum values for
// time (at 64-bits) and currency (at 128-bits). _duration is
// also known to be non-zero (see the require() statement in
// _addAuction())
if (_secondsPassed >= _duration) {
// We've reached the end of the dynamic pricing portion
// of the auction, just return the end price.
return _endingPrice;
} else {
// Starting price can be higher than ending price (and often is!), so
// this delta can be negative.
int256 totalPriceChange = int256(_endingPrice) - int256(_startingPrice);
// This multiplication can't overflow, _secondsPassed will easily fit within
// 64-bits, and totalPriceChange will easily fit within 128-bits, their product
// will always fit within 256-bits.
int256 currentPriceChange = totalPriceChange * int256(_secondsPassed) / int256(_duration);
// currentPriceChange can be negative, but if so, will have a magnitude
// less that _startingPrice. Thus, this result will always end up positive.
int256 currentPrice = int256(_startingPrice) + currentPriceChange;
return uint256(currentPrice);
}
}
/// @dev Computes owner's cut of a sale.
/// @param _price - Sale price of NFT.
function _computeCut(uint256 _price) internal view returns (uint256) {
// NOTE: We don't use SafeMath (or similar) in this function because
// all of our entry functions carefully cap the maximum values for
// currency (at 128-bits), and ownerCut <= 10000 (see the require()
// statement in the ClockAuction constructor). The result of this
// function is always guaranteed to be <= _price.
return _price * ownerCut / 10000;
}
}
/**
* @title Pausable
* @dev Base contract which allows children to implement an emergency stop mechanism.
*/
contract Pausable is Ownable {
event Pause();
event Unpause();
bool public paused = false;
/**
* @dev modifier to allow actions only when the contract IS paused
*/
modifier whenNotPaused() {
require(!paused);
_;
}
/**
* @dev modifier to allow actions only when the contract IS NOT paused
*/
modifier whenPaused {
require(paused);
_;
}
/**
* @dev called by the owner to pause, triggers stopped state
*/
function pause() onlyOwner whenNotPaused returns (bool) {
paused = true;
Pause();
return true;
}
/**
* @dev called by the owner to unpause, returns to normal state
*/
function unpause() onlyOwner whenPaused returns (bool) {
paused = false;
Unpause();
return true;
}
}
/// @title Clock auction for non-fungible tokens.
/// @notice We omit a fallback function to prevent accidental sends to this contract.
contract ClockAuction is Pausable, ClockAuctionBase {
/// @dev The ERC-165 interface signature for ERC-721.
/// Ref: https://github.com/ethereum/EIPs/issues/165
/// Ref: https://github.com/ethereum/EIPs/issues/721
bytes4 constant InterfaceSignature_ERC721 = bytes4(0x9a20483d);
/// @dev Constructor creates a reference to the NFT ownership contract
/// and verifies the owner cut is in the valid range.
/// @param _nftAddress - address of a deployed contract implementing
/// the Nonfungible Interface.
/// @param _cut - percent cut the owner takes on each auction, must be
/// between 0-10,000.
function ClockAuction(address _nftAddress, uint256 _cut) public {
require(_cut <= 10000);
ownerCut = _cut;
ERC721 candidateContract = ERC721(_nftAddress);
require(candidateContract.supportsInterface(InterfaceSignature_ERC721));
nonFungibleContract = candidateContract;
}
/// @dev Remove all Ether from the contract, which is the owner's cuts
/// as well as any Ether sent directly to the contract address.
/// Always transfers to the NFT contract, but can be called either by
/// the owner or the NFT contract.
function withdrawBalance() external {
address nftAddress = address(nonFungibleContract);
require(
msg.sender == owner ||
msg.sender == nftAddress
);
// We are using this boolean method to make sure that even if one fails it will still work
bool res = nftAddress.send(this.balance);
}
/// @dev Creates and begins a new auction.
/// @param _tokenId - ID of token to auction, sender must be owner.
/// @param _startingPrice - Price of item (in wei) at beginning of auction.
/// @param _endingPrice - Price of item (in wei) at end of auction.
/// @param _duration - Length of time to move between starting
/// price and ending price (in seconds).
/// @param _seller - Seller, if not the message sender
function createAuction(
uint256 _tokenId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration,
address _seller
)
external
whenNotPaused
{
// Sanity check that no inputs overflow how many bits we've allocated
// to store them in the auction struct.
require(_startingPrice == uint256(uint128(_startingPrice)));
require(_endingPrice == uint256(uint128(_endingPrice)));
require(_duration == uint256(uint64(_duration)));
require(_owns(msg.sender, _tokenId));
_escrow(msg.sender, _tokenId);
Auction memory auction = Auction(
_seller,
uint128(_startingPrice),
uint128(_endingPrice),
uint64(_duration),
uint64(now)
);
_addAuction(_tokenId, auction);
}
/// @dev Bids on an open auction, completing the auction and transferring
/// ownership of the NFT if enough Ether is supplied.
/// @param _tokenId - ID of token to bid on.
function bid(uint256 _tokenId)
external
payable
whenNotPaused
{
// _bid will throw if the bid or funds transfer fails
_bid(_tokenId, msg.value);
_transfer(msg.sender, _tokenId);
}
/// @dev Cancels an auction that hasn't been won yet.
/// Returns the NFT to original owner.
/// @notice This is a state-modifying function that can
/// be called while the contract is paused.
/// @param _tokenId - ID of token on auction
function cancelAuction(uint256 _tokenId)
external
{
Auction storage auction = tokenIdToAuction[_tokenId];
require(_isOnAuction(auction));
address seller = auction.seller;
require(msg.sender == seller);
_cancelAuction(_tokenId, seller);
}
/// @dev Cancels an auction when the contract is paused.
/// Only the owner may do this, and NFTs are returned to
/// the seller. This should only be used in emergencies.
/// @param _tokenId - ID of the NFT on auction to cancel.
function cancelAuctionWhenPaused(uint256 _tokenId)
whenPaused
onlyOwner
external
{
Auction storage auction = tokenIdToAuction[_tokenId];
require(_isOnAuction(auction));
_cancelAuction(_tokenId, auction.seller);
}
/// @dev Returns auction info for an NFT on auction.
/// @param _tokenId - ID of NFT on auction.
function getAuction(uint256 _tokenId)
external
view
returns
(
address seller,
uint256 startingPrice,
uint256 endingPrice,
uint256 duration,
uint256 startedAt
) {
Auction storage auction = tokenIdToAuction[_tokenId];
require(_isOnAuction(auction));
return (
auction.seller,
auction.startingPrice,
auction.endingPrice,
auction.duration,
auction.startedAt
);
}
/// @dev Returns the current price of an auction.
/// @param _tokenId - ID of the token price we are checking.
function getCurrentPrice(uint256 _tokenId)
external
view
returns (uint256)
{
Auction storage auction = tokenIdToAuction[_tokenId];
require(_isOnAuction(auction));
return _currentPrice(auction);
}
}
/// @title Clock auction modified for sale of kitties
/// @notice We omit a fallback function to prevent accidental sends to this contract.
contract SaleClockAuction is ClockAuction {
// @dev Sanity check that allows us to ensure that we are pointing to the
// right auction in our setSaleAuctionAddress() call.
bool public isSaleClockAuction = true;
// Tracks last 5 sale price of gen0 kitty sales
uint256 public gen0SaleCount;
uint256[5] public lastGen0SalePrices;
// Delegate constructor
function SaleClockAuction(address _nftAddr, uint256 _cut) public
ClockAuction(_nftAddr, _cut) {}
/// @dev Creates and begins a new auction.
/// @param _tokenId - ID of token to auction, sender must be owner.
/// @param _startingPrice - Price of item (in wei) at beginning of auction.
/// @param _endingPrice - Price of item (in wei) at end of auction.
/// @param _duration - Length of auction (in seconds).
/// @param _seller - Seller, if not the message sender
function createAuction(
uint256 _tokenId,
uint256 _startingPrice,
uint256 _endingPrice,
uint256 _duration,
address _seller
)
external
{
// Sanity check that no inputs overflow how many bits we've allocated
// to store them in the auction struct.
require(_startingPrice == uint256(uint128(_startingPrice)));
require(_endingPrice == uint256(uint128(_endingPrice)));
require(_duration == uint256(uint64(_duration)));
require(msg.sender == address(nonFungibleContract));
_escrow(_seller, _tokenId);
Auction memory auction = Auction(
_seller,
uint128(_startingPrice),
uint128(_endingPrice),
uint64(_duration),
uint64(now)
);
_addAuction(_tokenId, auction);
}
/// @dev Updates lastSalePrice if seller is the nft contract
/// Otherwise, works the same as default bid method.
function bid(uint256 _tokenId)
external
payable
{
// _bid verifies token ID size
address seller = tokenIdToAuction[_tokenId].seller;
uint256 price = _bid(_tokenId, msg.value);
_transfer(msg.sender, _tokenId);
// If not a gen0 auction, exit
if (seller == address(nonFungibleContract)) {
// Track gen0 sale prices
lastGen0SalePrices[gen0SaleCount % 5] = price;
gen0SaleCount++;
}
}
function averageGen0SalePrice() external view returns (uint256) {
uint256 sum = 0;
for (uint256 i = 0; i < 5; i++) {
sum += lastGen0SalePrices[i];
}
return sum / 5;
}
}