Auction House

Auction House implements English auction with fixed step

For now there are two AuctionHouse contracts, the main difference between them is the type of sell asset:

• AuctionHouse721
  • sell asset = ERC721
  • buy asset = ETH or ERC20
• AuctionHouse1155
  • sell asset = ERC1155
  • buy asset = ETH or ERC20

There are two parameters of AuctionHouse that are the same for all autions and can be changed by AuctionHouse owner:

• minimalDuration
  • defines the minimal duration of auctions
• minimalStepBasePoint
  • is the minimal persentage increase between bids (in base points)
  • e.g. minimalStepBasePoint = 300 = 3%, first bid is 100 ETH, the second one should be not less than (100 + 100*3% =) 103

ERC721 Auction supports party bid

Features

Time frame

Auction time frame is decided by 2 parameters

• duration
  • mandatory parameter, that defines the duration of auction in seconds
  • it must be between minimalDuration(default value is 15 days) and 1000 days (constant)
• startTime
  • optional parameter that defines the start time an auction
  • unix timestamp, can't be less than the time of creation of the auction

So there are two cases of how the auction time frame can work:

• if startTime is 0, then then the auction starts at the first bid that satisfies minimalPrice. Then the endTime is calculated at the moment of the first bid as well (now + duration)
• if startTime is set, then the endTime is calculated at the creation of an auction (startTime + duration)

If a new bid is put when auction has less than minimalDuration left till endTime, then endTime = now + minimalDuration

Data model

Auction (ERC721):

• address sellToken - sell asset contract address
• uint sellTokenId - sell asset tokenId
• address buyAsset - buy asset contract address if ERC20 (address(0) if buy asset = ETH)
• uint96 endTime - auction end time in unix timestamp
• Bid lastBid - last successful Bid
• address payable seller - seller address
• uint96 minimalPrice - minimal amount of the first bid
• address payable buyer - last successful bidder
• uint64 protocolFee - protocolFee at the time of auction creation
• bytes4 dataType - version of data field
• bytes data - encoded additional data, V1 fields :
  • uint originFee - auction origin fee in one uint slot (first 12 bytes store value, last 20 bytes store recipient)
  • uint duration - auction duration
  • uint startTime - auction start time
  • uint buyOutPrice - auction buyOut price (if bid amout > buyout price, then auction finishes and all transfers are done )

Auction (ERC1155, the main difference from struct Auction ERC721 is the additional field uint96 sellTokenValue):

• address sellToken - sell asset contract address
• uint96 sellTokenValue - sell asset value
• uint sellTokenId - sell asset tokenId
• address buyAsset - buy asset contract address if ERC20 (address(0) if buy asset = ETH)
• uint96 endTime - auction end time in unix timestamp
• Bid lastBid - last successful Bid
• address payable seller - seller address
• uint96 minimalPrice - minimal amount of the first bid
• address payable buyer - last successful bidder
• uint64 protocolFee - protocolFee at the time of auction creation
• bytes4 dataType - version of data field
• bytes data - encoded additional data, V1 fields :
  • uint originFee - auction origin fee in one uint slot (first 12 bytes store value, last 20 bytes store recipient)
  • uint duration - auction duration
  • uint startTime - auction start time
  • uint buyOutPrice - auction buyOut price (if bid amout > buyout price, then auction finishes and all transfers are done )

Bid:

• amount - bid amount
• dataType - version of data field
• data - encoded additional data, V1 fields :
  • uint originFee - bid origin fee in one uint slot (first 12 bytes store value, last 20 bytes store recipient)

Main functions

startAuction -

• start new auction
• emits event AuctionCreated(uint indexed auctionId, address seller, uint128 endTime)
• can be called from anyone
• arguments for ERC721 Auction:
  • address _sellToken - sell token address
  • uint _sellTokenId - sell token Id
  • address _buyAsset - buy asset address (0 if ETH)
  • uint96 minimalPrice - minimal first bid price
  • bytes4 dataType - data field type
  • bytes memory data - additional Data
• arguments for ERC1155 Auction (1 additional field uint96 _sellTokenValue):
  • address _sellToken - sell token address
  • uint96 _sellTokenValue - sell token value
  • uint _sellTokenId - sell token Id
  • address _buyAsset - buy asset address (0 if ETH)
  • uint96 minimalPrice - minimal first bid price
  • bytes4 dataType - data field type
  • bytes memory data - additional Data

putBid -

• puts bid on specific auction
• emits event BidPlaced(uint indexed auctionId, address seller, uint128 endTime)
• can be called from anyone
• arguments:
  • _auctionId - auction Id
  • bid - bid struct

finishAuction -

• finishes auction if it's ended(now > endTime) and has at least 1 bid
• emits event AuctionFinished(_auctionId)
• can be called from anyone
• arguments:
  • _auctionId - auction Id

buyOut -

• buy out the sell item and finishes the auction
• emits event AuctionBuyOut(uint indexed auctionId, address buyer)
• emits event AuctionFinished(_auctionId)
• can be called from anyone
• arguments:
  • _auctionId - auction Id
  • bid - bid struct

finishAuction -

• finishes auction if it's not started and has no bids
• emits event AuctionCancelled(uint indexed auctionId)
• emits event AuctionFinished(_auctionId)
• can be called from auction creator
• arguments:
  • _auctionId - auction Id