ticket.gno

  1package arena
  2
  3import (
  4	"chain"
  5	"math/overflow"
  6	"strconv"
  7)
  8
  9// QuoteBuy is the exact ugnot a buyer must attach to mint amount tickets.
 10// due = curve + creator fee + protocol fee + referral fee.
 11// curve is what stays in the reserve. Fees are paid on top and forwarded.
 12func QuoteBuy(handle string, amount int) (due, curve, creatorFee, protocolFee, referralFee int64) {
 13	p := lookup(handle)
 14	if p == nil {
 15		panic("unknown handle")
 16	}
 17	curve = curveCost(bookOf(p.Addr).Supply, amount)
 18	creatorFee, protocolFee, referralFee = splitFees(curve, p.Referrer.IsValid())
 19	due = overflow.Add64p(curve, overflow.Add64p(creatorFee, overflow.Add64p(protocolFee, referralFee)))
 20	return
 21}
 22
 23// QuoteSell is what a seller receives, and the fees taken out of the curve refund.
 24// The reserve drops by the full curve amount, so later sells stay solvent.
 25func QuoteSell(handle string, amount int) (proceeds, curve, creatorFee, protocolFee, referralFee int64) {
 26	p := lookup(handle)
 27	if p == nil {
 28		panic("unknown handle")
 29	}
 30	b := bookOf(p.Addr)
 31	if amount < 1 || amount > MaxTrade {
 32		panic("amount")
 33	}
 34	if amount > b.Supply {
 35		panic("not enough tickets")
 36	}
 37	curve = curveCost(b.Supply-amount, amount)
 38	creatorFee, protocolFee, referralFee = splitFees(curve, p.Referrer.IsValid())
 39	proceeds = curve - creatorFee - protocolFee - referralFee
 40	if proceeds <= 0 {
 41		panic("proceeds")
 42	}
 43	return
 44}
 45
 46// Buy mints amount tickets of handle. Attach exactly QuoteBuy's due in ugnot.
 47func Buy(cur realm, handle string, amount int) {
 48	who := caller(cur)
 49	if state.paused {
 50		panic("paused")
 51	}
 52	mustMember(who)
 53	due, curve, creatorFee, protocolFee, referralFee := QuoteBuy(handle, amount)
 54	sent := takeUgnot(cur)
 55	if sent != due {
 56		panic("send exactly " + strconv.FormatInt(due, 10) + "ugnot")
 57	}
 58	p := lookup(handle)
 59	b := bookOf(p.Addr)
 60	b.Supply += amount
 61	b.Reserve = overflow.Add64p(b.Reserve, curve)
 62	state.totalReserve = overflow.Add64p(state.totalReserve, curve)
 63	addShares(who, p.Addr, amount)
 64	forwardFees(cur, p, creatorFee, protocolFee, referralFee)
 65	chain.Emit(
 66		"ArenaBuy",
 67		"buyer", who.String(),
 68		"creator", p.Addr.String(),
 69		"handle", p.Handle,
 70		"amount", strconv.Itoa(amount),
 71		"curve", strconv.FormatInt(curve, 10),
 72		"due", strconv.FormatInt(due, 10),
 73	)
 74}
 75
 76// Sell burns amount tickets and pays the caller from the reserve, minus fees.
 77// Sells stay available while the realm is paused.
 78func Sell(cur realm, handle string, amount int) {
 79	who := caller(cur)
 80	mustNoPay()
 81	mustMember(who)
 82	proceeds, curve, creatorFee, protocolFee, referralFee := QuoteSell(handle, amount)
 83	if getShares(who, lookup(handle).Addr) < amount {
 84		panic("not enough tickets")
 85	}
 86	p := lookup(handle)
 87	b := bookOf(p.Addr)
 88	if b.Reserve < curve || state.totalReserve < curve {
 89		panic("insolvent")
 90	}
 91	b.Supply -= amount
 92	b.Reserve = overflow.Sub64p(b.Reserve, curve)
 93	state.totalReserve = overflow.Sub64p(state.totalReserve, curve)
 94	subShares(who, p.Addr, amount)
 95	payout(cur, who, proceeds, "seller")
 96	forwardFees(cur, p, creatorFee, protocolFee, referralFee)
 97	chain.Emit(
 98		"ArenaSell",
 99		"seller", who.String(),
100		"creator", p.Addr.String(),
101		"handle", p.Handle,
102		"amount", strconv.Itoa(amount),
103		"curve", strconv.FormatInt(curve, 10),
104		"proceeds", strconv.FormatInt(proceeds, 10),
105	)
106}
107
108func forwardFees(cur realm, creator *Profile, creatorFee, protocolFee, referralFee int64) {
109	if protocolFee > 0 && !state.treasury.IsValid() {
110		panic("treasury not set")
111	}
112	payout(cur, creator.Addr, creatorFee, "creator")
113	payout(cur, state.treasury, protocolFee, "treasury")
114	if referralFee > 0 {
115		payout(cur, creator.Referrer, referralFee, "referrer")
116	}
117}
118
119func addShares(holder, creator address, n int) {
120	if n < 1 {
121		panic("amount")
122	}
123	had := getShares(holder, creator)
124	setShares(holder, creator, had+n)
125	if had == 0 {
126		bookOf(creator).Holders++
127	}
128}
129
130func subShares(holder, creator address, n int) {
131	had := getShares(holder, creator)
132	if n < 1 || had < n {
133		panic("not enough tickets")
134	}
135	setShares(holder, creator, had-n)
136	if had == n {
137		b := bookOf(creator)
138		if b.Holders > 0 {
139			b.Holders--
140		}
141	}
142}
143
144func splitFees(curve int64, referred bool) (creator, protocol, referral int64) {
145	creator = bps(curve, CreatorFeeBps)
146	protocol = bps(curve, ProtocolFeeBps)
147	if referred {
148		referral = bps(curve, ReferralFeeBps)
149	}
150	return
151}
152
153func bps(amount, points int64) int64 {
154	if amount == 0 || points == 0 {
155		return 0
156	}
157	if amount < 0 || points < 0 {
158		panic("fee")
159	}
160	return overflow.Mul64p(amount, points) / 10_000
161}
162
163// curveCost is the ugnot reserve needed to move `amount` tickets starting at supply.
164// Ticket i (1-based) is priced i² * TicketUnit. The sum of squares is exact.
165func curveCost(supply, amount int) int64 {
166	if amount < 1 || amount > MaxTrade {
167		panic("amount")
168	}
169	if supply < 0 {
170		panic("supply")
171	}
172	from := int64(supply)
173	to := from + int64(amount)
174	if to > int64(MaxSupply) {
175		panic("supply cap")
176	}
177	return overflow.Mul64p(sumSq(to)-sumSq(from), TicketUnit)
178}
179
180func sumSq(n int64) int64 {
181	if n <= 0 {
182		return 0
183	}
184	if n > int64(MaxSupply) {
185		panic("supply cap")
186	}
187	// n*(n+1)*(2n+1)/6, dividing 2 and 3 out before multiplying.
188	a := n
189	b := n + 1
190	if a%2 == 0 {
191		a /= 2
192	} else {
193		b /= 2
194	}
195	c := 2*n + 1
196	if a%3 == 0 {
197		a /= 3
198	} else if b%3 == 0 {
199		b /= 3
200	} else if c%3 == 0 {
201		c /= 3
202	} else {
203		panic("sumSq")
204	}
205	return overflow.Mul64p(overflow.Mul64p(a, b), c)
206}