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/g1sl6fyq6mrc3wydt8xluhxx4aqsudpp9vhv6g2a/gnotif"
15)
16
17// Game is a match between First and Second. First plays turn 1.
18type Game struct {
19	ID                  string
20	First, Second, Next address
21	Turn                int
22}
23
24var (
25	games    avl.Tree // id → *Game
26	lastGame seqid.ID
27	declared bool
28)
29
30// NewGame opens a game against opponent and returns its id. The caller plays first.
31func NewGame(cur realm, opponent address) string {
32	caller := cur.Previous().Address()
33	if opponent == caller {
34		panic("cannot play against yourself")
35	}
36	g := &Game{ID: lastGame.Next().String(), First: caller, Second: opponent, Next: caller}
37	games.Set(g.ID, g)
38	chain.Emit("GameCreated", "game", g.ID, "first", g.First.String(), "second", g.Second.String())
39	return g.ID
40}
41
42// Play takes the caller's turn in game and passes it to the other player.
43func Play(cur realm, game string) {
44	v := games.Get(game)
45	if v == nil {
46		panic("unknown game")
47	}
48	g := v.(*Game)
49	if g.Next != cur.Previous().Address() {
50		panic("not your turn")
51	}
52	if g.Next == g.First {
53		g.Next = g.Second
54	} else {
55		g.Next = g.First
56	}
57	g.Turn++
58	chain.Emit("TurnPlayed", "game", g.ID, "next", g.Next.String(), "turn", strconv.Itoa(g.Turn))
59}
60
61// DeclareTriggers declares the "your turn" trigger in the gnotif registry.
62// The registry sees this realm as the caller, so the trigger is verified.
63func DeclareTriggers(cur realm) {
64	if declared {
65		panic("triggers already declared")
66	}
67	declared = true
68	gnotif.Declare(cross(cur), cur.PkgPath(), "TurnPlayed", "", "next", "Your turn", "Game {game}, turn {turn}", "/?game={game}")
69}
70
71// Render lists the games with their players, turn and next player.
72func Render(path string) string {
73	var b strings.Builder
74	b.WriteString("# pingpong\n\n")
75	games.Iterate("", "", func(_ string, v any) bool {
76		g := v.(*Game)
77		b.WriteString("- **" + g.ID + "** " + g.First.String() + " vs " + g.Second.String() +
78			" · turn " + strconv.Itoa(g.Turn) + " · next " + g.Next.String() + "\n")
79		return false
80	})
81	return b.String()
82}