(use-trait non-fungible-token .nft-trait.nft-trait)
;; the fee structure is defined by the calling client
;; this is to avoid duplication of the protocol just with adjusted fee structure
;; it is the responsibility of the client to adjust the post conditions accordingly
(define-trait fees-trait
((get-fees (uint) (response uint uint))
(hold-fees (uint) (response bool uint))
(release-fees (uint) (response bool uint))
(pay-fees (uint) (response bool uint))))
(define-constant expiry u100)
(define-map swaps uint {xbtc: uint, buyer: principal, nft-id: uint, nft-sender: (optional principal), when: uint, open: bool, nft: principal, fees: principal})
(define-data-var next-id uint u0)
;; helper function to transfer xbtc to a principal with memo
(define-private (xbtc-transfer-to (amount uint) (to principal) (memo (buff 34)))
(contract-call? 'SP3DX3H4FEYZJZ586MFBS25ZW3HZDMEW92260R2PR.Wrapped-Bitcoin
transfer amount tx-sender to (some memo)))
;; create a swap between btc and fungible token
(define-public (create-swap (xbtc uint) (nft-id uint) (nft-sender (optional principal)) (nft <non-fungible-token>) (fees <fees-trait>))
(let ((id (var-get next-id)))
(asserts! (map-insert swaps id
{xbtc: xbtc, buyer: tx-sender, nft-id: nft-id, nft-sender: nft-sender,
when: block-height, open: true, nft: (contract-of nft), fees: (contract-of fees)}) ERR_INVALID_ID)
(var-set next-id (+ id u1))
(try! (contract-call? fees hold-fees xbtc))
(match (xbtc-transfer-to xbtc (as-contract tx-sender) 0x636174616d6172616e2073776170)
success (ok id)
error (err (* error u100)))))
;; any user can cancle the swap after the expiry period
(define-public (cancel (id uint) (nft <non-fungible-token>) (fees <fees-trait>))
(let ((swap (unwrap! (map-get? swaps id) ERR_INVALID_ID))
(xbtc (get xbtc swap)))
(asserts! (is-eq (contract-of nft) (get nft swap)) ERR_INVALID_FUNGIBLE_TOKEN)
(asserts! (is-eq (contract-of fees) (get fees swap)) ERR_INVALID_FEES_TRAIT)
(asserts! (< (+ (get when swap) expiry) block-height) ERR_TOO_EARLY)
(asserts! (get open swap) ERR_ALREADY_DONE)
(asserts! (map-set swaps id (merge swap {open: false})) ERR_NATIVE_FAILURE)
(try! (contract-call? fees release-fees xbtc))
(match (as-contract (xbtc-transfer-to
xbtc (get buyer swap)
0x72657665727420636174616d6172616e2073776170))
success (ok success)
error (err (* error u100)))))
;; any user can submit a tx that contains the swap
(define-public (submit-swap
(id uint)
(nft <non-fungible-token>)
(fees <fees-trait>))
(let ((swap (unwrap! (map-get? swaps id) ERR_INVALID_ID))
(xbtc (get xbtc swap))
(receiver (default-to tx-sender (get nft-sender swap))))
(asserts! (get open swap) ERR_ALREADY_DONE)
(asserts! (is-eq (contract-of nft) (get nft swap)) ERR_INVALID_FUNGIBLE_TOKEN)
(asserts! (is-eq (contract-of fees) (get fees swap)) ERR_INVALID_FEES_TRAIT)
(asserts! (map-set swaps id (merge swap {open: false})) ERR_NATIVE_FAILURE)
(asserts! (is-eq tx-sender receiver) ERR_INVALID_RECEIVER)
(try! (contract-call? fees pay-fees xbtc))
(match (contract-call? nft transfer
(get nft-id swap) receiver (get buyer swap))
success-nft (begin
(asserts! success-nft ERR_NATIVE_FAILURE)
(match (as-contract (xbtc-transfer-to
(get xbtc swap) receiver
0x636174616d6172616e2073776170))
success (ok success)
error (err (* error u100))))
error-nft (err (* error-nft u1000)))))
(define-constant ERR_INVALID_ID (err u3))
(define-constant ERR_TOO_EARLY (err u4))
(define-constant ERR_ALREADY_DONE (err u7))
(define-constant ERR_INVALID_FUNGIBLE_TOKEN (err u8))
(define-constant ERR_INVALID_RECEIVER (err u9))
(define-constant ERR_INVALID_FEES (err u10))
(define-constant ERR_INVALID_FEES_TRAIT (err u11))
(define-constant ERR_NATIVE_FAILURE (err u99))