Merge branch 'introduction-on-join' into 'main'

Send introduction text and help after the bot joins a room

See merge request etke.cc/postmoogle!16

bot/bot.go

@@ -19,14 +19,15 @@ import (
 
 // Bot represents matrix bot
 type Bot struct {
-	noowner    bool
-	federation bool
-	prefix     string
-	domain     string
-	rooms      map[string]id.RoomID
-	roomsmu    *sync.Mutex
-	log        *logger.Logger
-	lp         *linkpearl.Linkpearl
+	noowner           bool
+	federation        bool
+	prefix            string
+	domain            string
+	rooms             map[string]id.RoomID
+	roomsmu           *sync.Mutex
+	log               *logger.Logger
+	lp                *linkpearl.Linkpearl
+	handledJoinEvents sync.Map
 }
 
 // New creates a new matrix bot

bot/command.go

@@ -109,6 +109,26 @@ func (b *Bot) parseCommand(message string) []string {
 	return strings.Split(message, " ")
 }
 
+func (b *Bot) sendIntroduction(ctx context.Context, roomID id.RoomID) {
+	span := sentry.StartSpan(ctx, "http.server", sentry.TransactionName("sendIntroduction"))
+	defer span.Finish()
+
+	var msg strings.Builder
+	msg.WriteString("Hello!\n\n")
+	msg.WriteString("This is Postmoogle - a bot that bridges Email to Matrix.\n\n")
+	msg.WriteString(fmt.Sprintf(
+		"To get started, assign an email address to this room by sending a `%s %s SOME_INBOX` command.\n",
+		b.prefix,
+		optionMailbox,
+	))
+	msg.WriteString(fmt.Sprintf(
+		"You will then be able to send emails to `SOME_INBOX@%s` and have them appear in this room.",
+		b.domain,
+	))
+
+	b.Notice(ctx, roomID, msg.String())
+}
+
 func (b *Bot) sendHelp(ctx context.Context, roomID id.RoomID) {
 	span := sentry.StartSpan(ctx, "http.server", sentry.TransactionName("sendHelp"))
 	defer span.Finish()

bot/settings.go

@@ -39,8 +39,8 @@ func (s settings) Allowed(noowner bool, userID id.UserID) bool {
 func (s settings) Get(key string) string {
 	value := s[strings.ToLower(strings.TrimSpace(key))]
 
-	sanitizer, exists := sanitizers[key]
-	if exists {
+	sanitizer, ok := sanitizers[key]
+	if ok {
 		return sanitizer(value)
 	}
 	return value

bot/sync.go

@@ -9,6 +9,12 @@ import (
 )
 
 func (b *Bot) initSync() {
+	b.lp.OnEventType(
+		event.StateMember,
+		func(_ mautrix.EventSource, evt *event.Event) {
+			go b.onMembership(evt)
+		},
+	)
 	b.lp.OnEventType(
 		event.EventMessage,
 		func(_ mautrix.EventSource, evt *event.Event) {
@@ -21,6 +27,17 @@ func (b *Bot) initSync() {
 		})
 }
 
+func (b *Bot) onMembership(evt *event.Event) {
+	hub := sentry.CurrentHub().Clone()
+
+	if evt.Content.AsMember().Membership == event.MembershipJoin && evt.Sender == b.lp.GetClient().UserID {
+		b.onBotJoin(evt, hub)
+		return
+	}
+
+	// Potentially handle other membership events in the future
+}
+
 func (b *Bot) onMessage(evt *event.Event) {
 	// ignore own messages
 	if evt.Sender == b.lp.GetClient().UserID {
@@ -70,3 +87,19 @@ func (b *Bot) onEncryptedMessage(evt *event.Event) {
 
 	b.handle(span.Context(), decrypted)
 }
+
+// onBotJoin handles the "bot joined the room" event
+func (b *Bot) onBotJoin(evt *event.Event, hub *sentry.Hub) {
+	// Workaround for membership=join events which are delivered to us twice,
+	// as described in this bug report: https://github.com/matrix-org/synapse/issues/9768
+	_, ok := b.handledJoinEvents.LoadOrStore(evt.ID, true)
+	if ok {
+		b.log.Info("Suppressing already handled event %s", evt.ID)
+		return
+	}
+
+	ctx := sentry.SetHubOnContext(context.Background(), hub)
+
+	b.sendIntroduction(ctx, evt.RoomID)
+	b.sendHelp(ctx, evt.RoomID)
+}