userbook.gno

 1// Package userbook demonstrates a small userbook system working with gnoweb
 2package userbook
 3
 4import (
 5	"std"
 6	"time"
 7
 8	"gno.land/p/demo/avl"
 9	"gno.land/p/demo/seqid"
10	"gno.land/p/demo/ufmt"
11)
12
13type Signup struct {
14	address   std.Address
15	ordinal   int
16	timestamp time.Time
17}
18
19var (
20	signupsTree = avl.NewTree()
21	tracker     = avl.NewTree()
22	idCounter   seqid.ID
23)
24
25const signUpEvent = "SignUp"
26
27func init() {
28	cross(SignUp)() // Sign up the deployer
29}
30
31func SignUp() string {
32	crossing()
33
34	// Get transaction caller
35	caller := std.PreviousRealm().Address()
36
37	// Check if the user is already signed up
38	if _, exists := tracker.Get(caller.String()); exists {
39		panic(caller.String() + " is already signed up!")
40	}
41
42	now := time.Now()
43
44	// Sign up the user
45	signupsTree.Set(idCounter.Next().String(), &Signup{
46		caller,
47		signupsTree.Size(),
48		now,
49	})
50
51	tracker.Set(caller.String(), struct{}{})
52
53	std.Emit(signUpEvent, "account", caller.String())
54
55	return ufmt.Sprintf("%s added to userbook! Timestamp: %s", caller.String(), now.Format(time.RFC822Z))
56}