state.gno

  1package shots
  2
  3import (
  4	"chain"
  5	"chain/banker"
  6	"strconv"
  7
  8	"gno.land/p/g1lnkytfqcjwllws63gvf0mv9yt04aswy4y9amhm/shootout/v0"
  9	"gno.land/p/nt/avl/v0"
 10)
 11
 12// The game state lives here, at the permanent path, so accepting a new
 13// implementation changes the rules engine without moving a single pot.
 14//
 15// Implementations never hold references into it. They read copies through
 16// StateRef and write whole values back, so every mutation is performed by
 17// code declared in this realm and persists here.
 18
 19var (
 20	games    = avl.NewTree() // gameKey(id) -> *shootout.Game
 21	sessions = avl.NewTree() // sessionKey(id, no) -> *shootout.Session
 22	lastID   uint64
 23)
 24
 25func gameKey(id uint64) string {
 26	s := strconv.FormatUint(id, 10)
 27	for len(s) < 20 {
 28		s = "0" + s
 29	}
 30	return s
 31}
 32
 33func sessionKey(id uint64, no int) string {
 34	s := strconv.Itoa(no)
 35	for len(s) < 10 {
 36		s = "0" + s
 37	}
 38	return gameKey(id) + "/" + s
 39}
 40
 41func getGame(id uint64) (shootout.Game, bool) {
 42	v := games.Get(gameKey(id))
 43	if v == nil {
 44		return shootout.Game{}, false
 45	}
 46	return *(v.(*shootout.Game)), true
 47}
 48
 49func getSession(id uint64, no int) (shootout.Session, bool) {
 50	v := sessions.Get(sessionKey(id, no))
 51	if v == nil {
 52		return shootout.Session{}, false
 53	}
 54	s := *(v.(*shootout.Session))
 55	s.Kicks = append([]shootout.Kick(nil), s.Kicks...)
 56	return s, true
 57}
 58
 59// StateRef is a permission to read and write the game state, handed to code
 60// running on this realm's cur. It carries the caller's realm value and
 61// re-checks it on every operation, so it cannot be stashed (the VM refuses to
 62// persist a realm value) or replayed after its frame returns.
 63type StateRef struct {
 64	rlm realm
 65}
 66
 67// Store hands a StateRef to the live implementation, or to a registered
 68// extension. Any other realm presents its own cur and is refused.
 69func Store(_ int, rlm realm) *StateRef {
 70	assertStateAccess(0, rlm)
 71	return &StateRef{rlm: rlm}
 72}
 73
 74// NewGameID allocates the next game id.
 75func (r *StateRef) NewGameID() uint64 {
 76	assertStateAccess(0, r.rlm)
 77	lastID++
 78	return lastID
 79}
 80
 81// Game returns a copy of game id.
 82func (r *StateRef) Game(id uint64) (shootout.Game, bool) {
 83	assertStateAccess(0, r.rlm)
 84	return getGame(id)
 85}
 86
 87// PutGame stores g (by value) under g.ID.
 88func (r *StateRef) PutGame(g shootout.Game) {
 89	assertStateAccess(0, r.rlm)
 90	if g.ID == 0 || g.ID > lastID {
 91		panic("shots: PutGame with an id that was never allocated")
 92	}
 93	c := g
 94	games.Set(gameKey(g.ID), &c)
 95}
 96
 97// Session returns a copy of session no of game id, kicks included.
 98func (r *StateRef) Session(id uint64, no int) (shootout.Session, bool) {
 99	assertStateAccess(0, r.rlm)
100	return getSession(id, no)
101}
102
103// PutSession stores s (by value, kicks copied).
104func (r *StateRef) PutSession(s shootout.Session) {
105	assertStateAccess(0, r.rlm)
106	if _, ok := getGame(s.GameID); !ok || s.No <= 0 {
107		panic("shots: PutSession for a game or session that does not exist")
108	}
109	c := s
110	c.Kicks = append([]shootout.Kick(nil), s.Kicks...)
111	sessions.Set(sessionKey(s.GameID, s.No), &c)
112}
113
114// Pay sends amount ugnot from this realm's balance to to.
115func (r *StateRef) Pay(to address, amount int64) {
116	assertStateAccess(0, r.rlm)
117	if amount <= 0 {
118		return
119	}
120	if !to.IsValid() {
121		panic("shots: invalid payee address")
122	}
123	bk := banker.NewBanker(banker.BankerTypeRealmSend, r.rlm)
124	bk.SendCoins(r.rlm.Address(), to, chain.NewCoins(chain.NewCoin(Denom, amount)))
125}
126
127// assertStateAccess panics unless rlm is a live cur belonging to this realm
128// or to a registered extension.
129func assertStateAccess(_ int, rlm realm) {
130	if !rlm.IsCurrent() {
131		panic("shots: realm value is not the caller's live cur")
132	}
133	if c := rlm.PkgPath(); c != selfPath && !proxy.IsExtension(c) {
134		panic("shots: state is reachable only through " + selfPath +
135			" or a registered extension, not from " + c)
136	}
137}