;; A tiny NFT marketplace that allows users to list NFT for sale. They can specify the following:
;; - The NFT token to sell.
;; - Listing expiry in block height.
;; - The payment asset, either STX or a SIP010 fungible token.
;; - The NFT price in said payment asset.
;; - An optional intended taker. If set, only that principal will be able to fulfil the listing.
;;
;; Source: https://github.com/clarity-lang/book/tree/main/projects/tiny-market
;; (use-trait nft-trait 'STM6S3AESTK9NAYE3Z7RS00T11ER8JJCDNTKG711.nft-trait.nft-trait)
;; (use-trait ft-trait 'STM6S3AESTK9NAYE3Z7RS00T11ER8JJCDNTKG711.sip-010-trait.sip-010-trait)
(use-trait nft-trait 'SP2PABAF9FTAJYNFZH93XENAJ8FVY99RRM50D2JG9.nft-trait.nft-trait)
(use-trait ft-trait 'SP3FBR2AGK5H9QBDH3EEN6DF8EK8JY7RX8QJ5SVTE.sip-010-trait-ft-standard.sip-010-trait)
(define-constant contract-owner tx-sender)
;; listing errors
(define-constant ERR_EXPIRY_IN_PAST (err u1000))
(define-constant ERR_PRICE_ZERO (err u1001))
;; cancelling and fulfiling errors
(define-constant ERR_UNKNOWN_LISTING (err u2000))
(define-constant ERR_UNAUTHORISED (err u2001))
(define-constant ERR_LISTING_EXPIRED (err u2002))
(define-constant ERR_NFT_ASSET_MISMATCH (err u2003))
(define-constant ERR_PAYMENT_ASSET_MISMATCH (err u2004))
(define-constant ERR_MAKER_TAKER_EQUAL (err u2005))
(define-constant ERR_UNINTENDED_TAKER (err u2006))
(define-constant ERR_ASSET_CONTRACT_NOT_WHITELISTED (err u2007))
(define-constant ERR_PAYMENT_CONTRACT_NOT_WHITELISTED (err u2008))
;; Define a map data structure for the asset listings
(define-map listings
uint
{
maker: principal,
taker: (optional principal),
token-id: uint,
nft-asset-contract: principal,
expiry: uint,
price: uint,
payment-asset-contract: (optional principal)
}
)
;; Used for unique IDs for each listing
(define-data-var listing-nonce uint u0)
;; This marketplace requires any contracts used for assets or payments to be whitelisted
;; by the contract owner of this (marketplace) contract.
(define-map whitelisted-asset-contracts principal bool)
;; Function that checks if the given contract has been whitelisted.
(define-read-only (is-whitelisted (asset-contract principal))
(default-to true (map-get? whitelisted-asset-contracts asset-contract))
)
;; Only the contract owner of this (marketplace) contract can whitelist an asset contract.
(define-public (set-whitelisted (asset-contract principal) (whitelisted bool))
(begin
(asserts! (is-eq contract-owner tx-sender) ERR_UNAUTHORISED)
(ok (map-set whitelisted-asset-contracts asset-contract whitelisted))
)
)
;; Internal function to transfer an NFT asset from a sender to a given recipient.
(define-private (transfer-nft
(token-contract <nft-trait>)
(token-id uint)
(sender principal)
(recipient principal)
)
(contract-call? token-contract transfer token-id sender recipient)
)
;; Internal function to transfer fungible tokens from a sender to a given recipient.
(define-private (transfer-ft
(token-contract <ft-trait>)
(amount uint)
(sender principal)
(recipient principal)
)
(contract-call? token-contract transfer amount sender recipient none)
)
;; Public function to list an asset along with its contract
(define-public (list-asset
(nft-asset-contract <nft-trait>)
(nft-asset {
taker: (optional principal),
token-id: uint,
expiry: uint,
price: uint,
payment-asset-contract: (optional principal)
})
)
(let ((listing-id (var-get listing-nonce)))
;; Verify that the contract of this asset is whitelisted
(asserts! (is-whitelisted (contract-of nft-asset-contract)) ERR_ASSET_CONTRACT_NOT_WHITELISTED)
;; Verify that the asset is not expired
;; (asserts! (> (get expiry nft-asset) burn-block-height) ERR_EXPIRY_IN_PAST)
;; Verify that the asset price is greater than zero
(asserts! (> (get price nft-asset) u0) ERR_PRICE_ZERO)
;; Verify that the contract of the payment is whitelisted
(asserts! (match (get payment-asset-contract nft-asset)
payment-asset
(is-whitelisted payment-asset)
true
) ERR_PAYMENT_CONTRACT_NOT_WHITELISTED)
;; Transfer the NFT ownership to this contract's principal
(try! (transfer-nft
nft-asset-contract
(get token-id nft-asset)
tx-sender
(as-contract tx-sender)
))
;; List the NFT in the listings map
(map-set listings listing-id (merge
{ maker: tx-sender, nft-asset-contract: (contract-of nft-asset-contract) }
nft-asset
))
;; Increment the nonce to use for the next unique listing ID
(var-set listing-nonce (+ listing-id u1))
;; Return the created listing ID
(ok listing-id)
)
)
;; Public read-only function to retrieve a listing by its ID
(define-read-only (get-listing (listing-id uint))
(map-get? listings listing-id)
)
;; Public function to cancel a listing using an asset contract.
;; This function can only be called by the NFT's creator, and must use the same asset contract that
;; the NFT uses.
(define-public (cancel-listing (listing-id uint) (nft-asset-contract <nft-trait>))
(let (
(listing (unwrap! (map-get? listings listing-id) ERR_UNKNOWN_LISTING))
(maker (get maker listing))
)
;; Verify that the caller of the function is the creator of the NFT to be cancelled
(asserts! (is-eq maker tx-sender) ERR_UNAUTHORISED)
;; Verify that the asset contract to use is the same one that the NFT uses
(asserts! (is-eq
(get nft-asset-contract listing)
(contract-of nft-asset-contract)
) ERR_NFT_ASSET_MISMATCH)
;; Delete the listing
(map-delete listings listing-id)
;; Transfer the NFT from this contract's principal back to the creator's principal
(as-contract (transfer-nft nft-asset-contract (get token-id listing) tx-sender maker))
)
)
;; Private function to validate that a purchase can be fulfilled
(define-private (assert-can-fulfil
(nft-asset-contract principal)
(payment-asset-contract (optional principal))
(listing {
maker: principal,
taker: (optional principal),
token-id: uint,
nft-asset-contract: principal,
expiry: uint,
price: uint,
payment-asset-contract: (optional principal)
})
)
(begin
;; Verify that the buyer is not the same as the NFT creator
(asserts! (not (is-eq (get maker listing) tx-sender)) ERR_MAKER_TAKER_EQUAL)
;; Verify the buyer has been set in the listing metadata as its `taker`
(asserts!
(match (get taker listing) intended-taker (is-eq intended-taker tx-sender) true)
ERR_UNINTENDED_TAKER
)
;; Verify the listing for purchase is not expired
(asserts! (< burn-block-height (get expiry listing)) ERR_LISTING_EXPIRED)
;; Verify the asset contract used to purchase the NFT is the same as the one set on the NFT
(asserts! (is-eq (get nft-asset-contract listing) nft-asset-contract) ERR_NFT_ASSET_MISMATCH)
;; Verify the payment contract used to purchase the NFT is the same as the one set on the NFT
(asserts!
(is-eq (get payment-asset-contract listing) payment-asset-contract)
ERR_PAYMENT_ASSET_MISMATCH
)
(ok true)
)
)
;; Public function to purchase a listing using STX as payment
(define-public (fulfil-listing-stx (listing-id uint) (nft-asset-contract <nft-trait>))
(let (
;; Verify the given listing ID exists
(listing (unwrap! (map-get? listings listing-id) ERR_UNKNOWN_LISTING))
;; Set the NFT's taker to the purchaser (caller of the_function)
(taker tx-sender)
)
;; Validate that the purchase can be fulfilled
(try! (assert-can-fulfil (contract-of nft-asset-contract) none listing))
;; Transfer the NFT to the purchaser (caller of the function)
(try! (as-contract (transfer-nft nft-asset-contract (get token-id listing) tx-sender taker)))
;; Transfer the STX payment from the purchaser to the creator of the NFT
(try! (stx-transfer? (get price listing) taker (get maker listing)))
;; Remove the NFT from the marketplace listings
(map-delete listings listing-id)
;; Return the listing ID that was just purchased
(ok listing-id)
)
)
;; Public function to purchase a listing using another fungible token as payment
(define-public (fulfil-listing-ft
(listing-id uint)
(nft-asset-contract <nft-trait>)
(payment-asset-contract <ft-trait>)
)
(let (
;; Verify the given listing ID exists
(listing (unwrap! (map-get? listings listing-id) ERR_UNKNOWN_LISTING))
;; Set the NFT's taker to the purchaser (caller of the_function)
(taker tx-sender)
)
;; Validate that the purchase can be fulfilled
(try! (assert-can-fulfil
(contract-of nft-asset-contract)
(some (contract-of payment-asset-contract))
listing
))
;; Transfer the NFT to the purchaser (caller of the function)
(try! (as-contract (transfer-nft nft-asset-contract (get token-id listing) tx-sender taker)))
;; Transfer the tokens as payment from the purchaser to the creator of the NFT
(try! (transfer-ft payment-asset-contract (get price listing) taker (get maker listing)))
;; Remove the NFT from the marketplace listings
(map-delete listings listing-id)
;; Return the listing ID that was just purchased
(ok listing-id)
)
)