trade.gno

 1package market
 2
 3import (
 4	"chain"
 5	"chain/banker"
 6	"chain/runtime/unsafe"
 7
 8	"gno.land/p/nt/grc721/v0"
 9)
10
11// List puts tid on sale for price ugnot. The token stays with the owner.
12// A dead listing (the recorded seller no longer owns it) is replaced.
13func List(cur realm, tid string, price int64) {
14	caller := requireUser(cur)
15	requireReady()
16	if price < 1 {
17		panic("market: price")
18	}
19	id := parseTid(tid)
20	if ownerOf(id) != caller {
21		panic("market: not owner")
22	}
23	listings.Set(string(id), listing{Seller: caller, Price: price})
24	chain.Emit("List", "tid", string(id), "seller", caller.String(), "price", i64(price))
25}
26
27// Cancel removes the caller's listing, or a listing whose seller no longer owns the token.
28func Cancel(cur realm, tid string) {
29	caller := requireUser(cur)
30	requireReady()
31	id := parseTid(tid)
32	lot := mustListing(id)
33	if caller != lot.Seller && caller != ownerOf(id) {
34		panic("market: cancel")
35	}
36	listings.Remove(string(id))
37	chain.Emit("Cancel", "tid", string(id), "caller", caller.String())
38}
39
40// Buy pays the listing price in ugnot and takes the token.
41// The attached send must be exactly the price, one ugnot coin.
42func Buy(cur realm, tid string) {
43	caller := requireUser(cur)
44	requireReady()
45	id := parseTid(tid)
46	lot := mustListing(id)
47	if caller == lot.Seller {
48		panic("market: self")
49	}
50	if ownerOf(id) != lot.Seller {
51		panic("market: stale")
52	}
53	paid := unsafe.OriginSend()
54	if len(paid) != 1 || paid[0].Denom != "ugnot" || paid[0].Amount != lot.Price {
55		panic("market: pay")
56	}
57	if err := ledger.TransferFrom(lot.Seller, lot.Seller, caller, id); err != nil {
58		panic("market: transfer")
59	}
60	coins := chain.NewCoins(chain.NewCoin("ugnot", lot.Price))
61	bank := banker.NewBanker(banker.BankerTypeOriginSend, cur)
62	bank.SendCoins(cur.Address(), lot.Seller, coins)
63	listings.Remove(string(id))
64	name, _ := metaNameImage(id)
65	pushSale(sale{Tid: string(id), Seller: lot.Seller, Buyer: caller, Price: lot.Price, Name: name})
66	chain.Emit(
67		"Buy",
68		"tid", string(id),
69		"seller", lot.Seller.String(),
70		"buyer", caller.String(),
71		"price", i64(lot.Price),
72	)
73}
74
75func mustListing(id grc721.TokenID) listing {
76	got := listings.Get(string(id))
77	if got == nil {
78		panic("market: no listing")
79	}
80	return got.(listing)
81}
82
83func pushSale(s sale) {
84	sales[saleN%saleCap] = s
85	saleN++
86}