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

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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

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- 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 )

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- 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)

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#### 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