pingpong.gno

  1// Package pingpong is a two-player game where the only move is to pass the
  2// turn. It exists to demonstrate gnotif: every turn emits TurnPlayed, and
  3// the realm declares a verified gnotif trigger that tells the next player.
  4package pingpong
  5
  6import (
  7	"chain"
  8	"strconv"
  9	"strings"
 10
 11	"gno.land/p/nt/avl/v0"
 12	"gno.land/p/nt/seqid/v0"
 13
 14	"gno.land/r/g13rqvks880v0hmlfepcj0kkudq0js38d3pc5k6a/gnotif/v0"
 15)
 16
 17// Game is a match between First and Second. First plays turn 1. It is
 18// pending until Second accepts, and only then are players named in events
 19// that notify them.
 20type Game struct {
 21	ID                  string
 22	First, Second, Next address
 23	Turn                int
 24	Started             bool
 25}
 26
 27var (
 28	games    avl.Tree // id → *Game
 29	lastGame seqid.ID
 30	declared bool
 31)
 32
 33func load(id string) *Game {
 34	if !games.Has(id) {
 35		panic("unknown game")
 36	}
 37	return games.Get(id).(*Game)
 38}
 39
 40// NewGame invites opponent to a game and returns its id. The caller plays
 41// first once opponent accepts.
 42func NewGame(cur realm, opponent address) string {
 43	caller := cur.Previous().Address()
 44	// IsValid accepts all-uppercase bech32, but a caller's address is always
 45	// lowercase, so an uppercase opponent could never accept.
 46	if !opponent.IsValid() || opponent.String() != strings.ToLower(opponent.String()) {
 47		panic("invalid opponent")
 48	}
 49	if opponent == caller {
 50		panic("cannot play against yourself")
 51	}
 52	g := &Game{ID: lastGame.Next().String(), First: caller, Second: opponent, Next: caller}
 53	games.Set(g.ID, g)
 54	chain.Emit("GameInvited", "game", g.ID, "first", g.First.String(), "second", g.Second.String())
 55	return g.ID
 56}
 57
 58// Accept starts a pending game. Only the invited player may call it.
 59func Accept(cur realm, game string) {
 60	g := load(game)
 61	if g.Second != cur.Previous().Address() {
 62		panic("not invited")
 63	}
 64	if g.Started {
 65		panic("game already started")
 66	}
 67	g.Started = true
 68	chain.Emit("GameStarted", "game", g.ID, "first", g.First.String(), "second", g.Second.String())
 69}
 70
 71// Play takes the caller's turn in game and passes it to the other player.
 72func Play(cur realm, game string) {
 73	g := load(game)
 74	if !g.Started {
 75		panic("game not started")
 76	}
 77	if g.Next != cur.Previous().Address() {
 78		panic("not your turn")
 79	}
 80	if g.Next == g.First {
 81		g.Next = g.Second
 82	} else {
 83		g.Next = g.First
 84	}
 85	g.Turn++
 86	chain.Emit("TurnPlayed", "game", g.ID, "next", g.Next.String(), "turn", strconv.Itoa(g.Turn))
 87}
 88
 89// Leave cancels a pending game or ends a started one, and deletes it.
 90func Leave(cur realm, game string) {
 91	g := load(game)
 92	caller := cur.Previous().Address()
 93	if caller != g.First && caller != g.Second {
 94		panic("not a player")
 95	}
 96	games.Remove(game)
 97	chain.Emit("GameEnded", "game", g.ID, "by", caller.String())
 98}
 99
100// DeclareTriggers declares the "your turn" trigger in the gnotif registry.
101// The registry sees this realm as the caller, so the trigger is verified.
102func DeclareTriggers(cur realm) {
103	if declared {
104		panic("triggers already declared")
105	}
106	declared = true
107	gnotif.Declare(cross(cur), cur.PkgPath(), "TurnPlayed", "", "next", "Your turn", "Game {game}, turn {turn}", "/?game={game}")
108}