# Decentralized Order

## Order Schema

```js
    struct Order {
        address exchange;
        address maker;
        address taker;
        address makerRelayerFeeRecipient;
        address takerRelayerFeeRecipient;
        uint8 side;
        uint8 saleKind;
        address nftAddress;
        uint256 tokenId;
        bytes calldata;
        bytes replacementPattern;
        address staticTarget;
        bytes staticExtradata;
        address paymentToken;
        uint256 basePrice;
        uint256 extra;
        uint256 listingTime;
        uint256 expirationTime;
        uint256 salt;
    }
```

All of the following fields must be present in an order. Some have special sentinel values.

### exchange

Address of the *NiftyConnectExchange* contract. This is a versioning mechanism, ensuring that all signed orders are only valid for a particular deployed version of the Wyvern Protocol on a particular Ethereum chain.

### maker

Order maker (who may be buying or selling the contract call — the maker/taker differentiation is strictly a matter of fees).

### taker

Order taker, a specific address must take the order, otherwise the zero-address is a sentinel value to indicate that the order can be taken by anyone.

### makerRelayerFeeRecipient

Maker relayer fee will be paid to `makerRelayerFeeRecipient`. These tools can facilitate users to make buy/sell orders, this address can be specified.

### takerProtocolFeeRecipient

Taker relayer fee will be paid to `takerProtocolFeeRecipient`. These tools can facilitate users to take buy/sell orders, this address can be specified.

### side

Side (`0` buy/`1` sell). Sell-side orders execute contract calls and receive tokens, buy-side orders purchase contract calls and pay tokens.

### saleKind

Kind of sale, `0` for `FixedPrice` and `1` for `DutchAuction`.

### nftAddress;

The nft asset contract address

### tokenId;

The token id of a NFT asset

### calldata

Order calldata is the abi encoding contract calldata to [MerkleValidator](https://github.com/NiftyConnect/NiftyConnect-Contracts/blob/main/contracts/MerkleValidator.sol) which specifies how the nft assets will be transferred. `MerkleValidator` has implemented three methods to handle transferring `ERC721` and `ERC1155` assets: `matchERC721UsingCriteria`, `matchERC721WithSafeTransferUsingCriteria` and `matchERC1155UsingCriteria`.

### replacementPattern

Mask specifies which parts of the calldata can be changed, or an empty array for no replacement. Please refer to [replacement pattern guide](https://docs.niftyconnect.org/niftyconnect-protocol-document/docs/replacement-pattern-guide)

### staticTarget

Target for `STATICCALL`, or zero-address as a sentinel value to indicate no `STATICCALL`.

### staticExtradata

Extra data for `STATICCALL` (bytes).

### paymentToken

Token used to pay for call, or the zero-address as a sentinel value for special-case unwrapped Ether.

### basePrice

Base price of the order, in units of the specified `paymentToken`.

### extra

Extra parameter for price calculation, specifying starting/ending price difference for Dutch auctions. Could be used to specify minimum bid for English auctions in the future should those be implemented.

### listingTime

Order listing Unix timestamp.

### expirationTime

Order expiration Unix timestamp or `0` as a sentinel value for no expiry.

### salt

Order salt to distinguish otherwise-identical orders.

## Event

```
event OrderApprovedPartOne(
                            bytes32 indexed hash, 
                            address exchange, 
                            address indexed maker, 
                            address taker, 
                            address indexed makerRelayerFeeRecipient, 
                            uint8 side, 
                            uint8 saleKind, 
                            address nftAddress, 
                            uint256 tokenId, 
                            bytes32 ipfsHash);
                            
event OrderApprovedPartTwo(
                            bytes32 indexed hash, 
                            bytes calldata, 
                            bytes replacementPattern, 
                            address staticTarget, 
                            bytes staticExtradata, 
                            address paymentToken, 
                            uint basePrice, 
                            uint extra, 
                            uint listingTime, 
                            uint expirationTime, 
                            uint salt);
```

In this protocol, only decentralized orders are supported. All order data can be parsed from the above two events: `OrderApprovedPartOne` and `OrderApprovedPartTwo`. Users can write an extra order message (such as personal contact information or the merkle proof of metadata for trait-based order) to IPFS and write the IPFS hash to `ipfsHash` in the event `OrderApprovedPartOne`.