From efe02a69349115e2bf356a9934c05edae1475201 Mon Sep 17 00:00:00 2001
From: Maksim Pischulenok <pischule@outlook.com>
Date: Wed, 14 Jun 2023 00:01:16 +0300
Subject: [PATCH] Add automatic opt-in

---
 go.mod  |  9 ++++++---
 main.go | 21 ++++++++++++++++++---
 2 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/go.mod b/go.mod
index 050bb03..dca41e2 100644
--- a/go.mod
+++ b/go.mod
@@ -2,11 +2,14 @@ module pischule/mention-all-bot
 
 go 1.20
 
+require (
+	gopkg.in/telebot.v3 v3.1.3
+	gorm.io/driver/sqlite v1.5.2
+	gorm.io/gorm v1.25.2-0.20230530020048-26663ab9bf55
+)
+
 require (
 	github.com/jinzhu/inflection v1.0.0 // indirect
 	github.com/jinzhu/now v1.1.5 // indirect
 	github.com/mattn/go-sqlite3 v1.14.17 // indirect
-	gopkg.in/telebot.v3 v3.1.3 // indirect
-	gorm.io/driver/sqlite v1.5.2 // indirect
-	gorm.io/gorm v1.25.2-0.20230530020048-26663ab9bf55 // indirect
 )
diff --git a/main.go b/main.go
index e0d6b57..9c2c36c 100644
--- a/main.go
+++ b/main.go
@@ -135,9 +135,23 @@ func handleStats(c tele.Context) error {
 }
 
 func handleUserLeft(c tele.Context) error {
-	u := ChatUser{UserID: c.Message().UserLeft.ID, ChatID: c.Chat().ID}
-	log.Printf("user %d left chat %d", u.UserID, u.ChatID)
-	DB.Where(&u).Delete(&ChatUser{})
+	cu := ChatUser{UserID: c.Message().UserLeft.ID, ChatID: c.Chat().ID}
+	log.Printf("user %d left chat %d", cu.UserID, cu.ChatID)
+	DB.Where(&cu).Delete(&ChatUser{})
+	return nil
+}
+
+func handleUserJoined(c tele.Context) error {
+	u := c.Message().UserJoined
+	if u.IsBot {
+		return nil
+	}
+	cu := ChatUser{UserID: u.ID, ChatID: c.Chat().ID, Username: extractUsername(u)}
+	log.Printf("user %d joined chat %d", cu.UserID, cu.ChatID)
+	DB.Clauses(clause.OnConflict{
+		Columns:   []clause.Column{{Name: "chat_id"}, {Name: "user_id"}},
+		DoUpdates: clause.AssignmentColumns([]string{"username"}),
+	}).Create(&cu)
 	return nil
 }
 
@@ -151,5 +165,6 @@ func main() {
 	b.Handle("/all", handleAll)
 	b.Handle("/stats", handleStats)
 	b.Handle(tele.OnUserLeft, handleUserLeft)
+	b.Handle(tele.OnUserJoined, handleUserJoined)
 	b.Start()
 }