From 68e74ad02ad5109cd3d14551f1fece209b5e547c Mon Sep 17 00:00:00 2001
From: Julian Yap <julianokyap@gmail.com>
Date: Fri, 7 Jul 2023 10:41:58 -0700
Subject: [PATCH] Add convertIDtoCreationTime

---
 main.go      | 13 +++++++++++++
 main_test.go | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 main_test.go

diff --git a/main.go b/main.go
index 08ffe76..ce690eb 100644
--- a/main.go
+++ b/main.go
@@ -769,6 +769,19 @@ func terminateMember(s *discordgo.Session, guildID string, userID string, reason
 	}
 }
 
+// Ported from https://github.com/hugonun/discordid2date/blob/master/main.js#L5
+func convertIDtoCreationTime(id string) time.Time {
+	idInt, _ := strconv.ParseInt(id, 10, 64)
+	bin := strconv.FormatInt(idInt, 2)
+	unixbin := ""
+	m := 64 - len(bin)
+	unixbin = bin[0 : 42-m]
+	unixInt, _ := strconv.ParseInt(unixbin, 2, 64)
+	unixCreationTime := unixInt + 1420070400000
+	creationTime := time.Unix(0, unixCreationTime*int64(time.Millisecond))
+	return creationTime
+}
+
 // This function is called on GuildMemberAdd event
 // Currently just performs Flood handling
 func guildMemberAdd(s *discordgo.Session, m *discordgo.GuildMemberAdd) {
diff --git a/main_test.go b/main_test.go
new file mode 100644
index 0000000..c767e16
--- /dev/null
+++ b/main_test.go
@@ -0,0 +1,35 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+	"time"
+)
+
+func Test_convertIDtoCreationTime(t *testing.T) {
+	timestamp := "2017-01-28 06:02:39.924 +0000 UTC"
+	timeObj, _ := time.Parse("2006-01-02 15:04:05.999 -0700 MST", timestamp)
+
+	type args struct {
+		id string
+	}
+	tests := []struct {
+		name string
+		args args
+		want time.Time
+	}{
+		{
+			name: "274781269861072896",
+			args: args{"274781269861072896"},
+			want: timeObj,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := convertIDtoCreationTime(tt.args.id).UTC() // Convert to UTC
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("convertIDtoCreationTime() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}