;; multiway-swap
;; Contract to facilitate a multiway NFT swap.
;; Each of the parties involved has to call confirm-and-escrow to ecrow their dues.
;; Once all parties confirmed, finalize has to be called to redistribute escrowed items.
;; At any point before the swap is finalized it can be canceled by a party involved,
;; regardles of whether they already called confirm-and-escrow or not.

;; traders
(define-constant TRADER-1 'ST1SJ3DTE5DN7X54YDH5D64R3BCB6A2AG2ZQ8YPD5)
(define-constant TRADER-2 'ST2CY5V39NHDPWSXMW9QDT3HC3GD6Q6XX4CFRK9AG)
(define-constant TRADER-3 'ST2JHG361ZXG51QTKY2NQCVBPPRRE2KZB1HR05NNC)

;; receivers
(define-constant RECEIVER-1 'STNHKEPYEPJ8ET55ZZ0M5A34J0R3N5FM2CMMMAZ6)


;; constants
(define-constant ERR_ESCROW_NOT_FILLED u401)
(define-constant ERR_SWAP_FINALIZED u402)
(define-constant ERR_RELEASING_ESCROW_FAILED u491)
(define-constant ERR_SWAP_CANCELED u499)

(define-constant ERR_IS_NOT_TRADER u410)
(define-constant ERR_CALLER_ALREADY_ESCROWED u411)
(define-constant ERR_FAILED_TO_ESCROW_STX u412)
(define-constant ERR_FAILED_TO_ESCROW_NFT u413)

(define-constant SWAP_STATE_ACTIVE u100)
(define-constant SWAP_STATE_READY_TO_FINALIZE u101)
(define-constant SWAP_STATE_FINALIZED u102)
(define-constant SWAP_STATE_CANCELED u109)

(define-constant TRADER_STATE_ACTIVE u110)
(define-constant TRADER_STATE_CONFIRMED u111)
(define-constant TRADER_STATE_CANCELED u119)

(define-constant NUM_TRADERS u3)

;; data maps and vars
(define-data-var swapState uint SWAP_STATE_ACTIVE)
(define-data-var confirmCount uint u0)

(define-map TraderState principal uint)

;; Set TraderState of each trader to TRADER_STATE_ACTIVE.
(map-set TraderState TRADER-1 TRADER_STATE_ACTIVE)
(map-set TraderState TRADER-2 TRADER_STATE_ACTIVE)
(map-set TraderState TRADER-3 TRADER_STATE_ACTIVE)

;; private functions
(define-private (deposit-escrow)
    (begin
        (if (is-eq tx-sender TRADER-1)
            (begin
                (unwrap! (stx-transfer? u1000000 tx-sender (as-contract tx-sender)) (err ERR_FAILED_TO_ESCROW_STX))
            )
            true
        )
        (if (is-eq tx-sender TRADER-2)
            (begin
                (unwrap! (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.punks transfer u4 tx-sender (as-contract tx-sender)) (err ERR_FAILED_TO_ESCROW_NFT))
            )
            true
        )
        (if (is-eq tx-sender TRADER-3)
            (begin
                (unwrap! (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.whales transfer u1 tx-sender (as-contract tx-sender)) (err ERR_FAILED_TO_ESCROW_NFT))
                (unwrap! (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.whales transfer u3 tx-sender (as-contract tx-sender)) (err ERR_FAILED_TO_ESCROW_NFT))
            )
            true
        )

        (map-set TraderState tx-sender TRADER_STATE_CONFIRMED)
        (unwrap-panic (update-swap-state))
        (ok true)
    )
)

(define-private (release-escrow)
    (begin
        (unwrap-panic (as-contract (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.whales transfer u1 tx-sender TRADER-1)))
        (unwrap-panic (as-contract (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.punks transfer u4 tx-sender TRADER-1)))
        (unwrap-panic (as-contract (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.whales transfer u3 tx-sender TRADER-2)))

        (unwrap-panic (as-contract (stx-transfer? u450000 tx-sender TRADER-2)))
        (unwrap-panic (as-contract (stx-transfer? u500000 tx-sender TRADER-3)))
        (unwrap-panic (as-contract (stx-transfer? u50000 tx-sender RECEIVER-1)))

        (var-set swapState SWAP_STATE_FINALIZED)
        (ok true)
    )
)

(define-private (return-escrow)
    (begin
        (if (is-eq (default-to ERR_IS_NOT_TRADER (map-get? TraderState TRADER-1)) TRADER_STATE_CONFIRMED)
            (begin
                (unwrap-panic (as-contract (stx-transfer? u1000000 tx-sender TRADER-1)))
            )
            true
        )
        (if (is-eq (default-to ERR_IS_NOT_TRADER (map-get? TraderState TRADER-2)) TRADER_STATE_CONFIRMED)
            (begin
                (unwrap-panic (as-contract (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.punks transfer u4 tx-sender TRADER-2)))
            )
            true
        )
        (if (is-eq (default-to ERR_IS_NOT_TRADER (map-get? TraderState TRADER-3)) TRADER_STATE_CONFIRMED)
            (begin
                (unwrap-panic (as-contract (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.whales transfer u1 tx-sender TRADER-3)))
                (unwrap-panic (as-contract (contract-call? 'ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.whales transfer u3 tx-sender TRADER-3)))
            )
            true
        )

        (map-set TraderState tx-sender TRADER_STATE_CANCELED)
        (var-set swapState SWAP_STATE_CANCELED)
        (ok true)
    )
)

(define-private (update-swap-state)
    (let
        ((cfCount (+ (var-get confirmCount) u1)))

        (var-set confirmCount cfCount)
        (if
            (is-eq cfCount NUM_TRADERS)
            (var-set swapState SWAP_STATE_READY_TO_FINALIZE)
            true
        )
        (ok true)
    )
)

;; public functions
(define-read-only (get-swap-state)
  (ok (var-get swapState))
)

(define-read-only (get-trader-state (trader principal))
  (unwrap! (map-get? TraderState trader) ERR_IS_NOT_TRADER)
)

(define-public (confirm-and-escrow)
    (let
        ((trState (unwrap! (map-get? TraderState tx-sender) (err ERR_IS_NOT_TRADER))))

        (asserts! (not (is-eq (var-get swapState) SWAP_STATE_FINALIZED)) (err ERR_SWAP_FINALIZED))
        (asserts! (not (is-eq (var-get swapState) SWAP_STATE_CANCELED)) (err ERR_SWAP_CANCELED))
        (asserts! (not (is-eq trState TRADER_STATE_CONFIRMED)) (err ERR_CALLER_ALREADY_ESCROWED))
        (try! (deposit-escrow))
        (ok true)
    )
)

(define-public (cancel)
    (begin
        (unwrap! (map-get? TraderState tx-sender) (err ERR_IS_NOT_TRADER))
        (asserts! (not (is-eq (var-get swapState) SWAP_STATE_FINALIZED)) (err ERR_SWAP_FINALIZED))
        (asserts! (not (is-eq (var-get swapState) SWAP_STATE_CANCELED)) (err ERR_SWAP_CANCELED))
        (unwrap! (return-escrow) (err ERR_RELEASING_ESCROW_FAILED))
        (ok true)
    )
)

(define-public (finalize)
    (begin
        (asserts! (not (is-eq (var-get swapState) SWAP_STATE_ACTIVE)) (err ERR_ESCROW_NOT_FILLED))
        (asserts! (not (is-eq (var-get swapState) SWAP_STATE_FINALIZED)) (err ERR_SWAP_FINALIZED))
        (asserts! (not (is-eq (var-get swapState) SWAP_STATE_CANCELED)) (err ERR_SWAP_CANCELED))
        (unwrap! (release-escrow) (err ERR_RELEASING_ESCROW_FAILED))
        (ok true)
    )
)