feat: add `FirstUnseenMessageID` API

protocol/message_persistence.go

@@ -620,6 +620,31 @@ func (db sqlitePersistence) MessageByChatID(chatID string, currCursor string, li
 	return result, newCursor, nil
 }
 
+func (db sqlitePersistence) FirstUnseenMessageID(chatID string) (string, error) {
+	var id string
+	err := db.db.QueryRow(
+		fmt.Sprintf(
+			`
+			SELECT
+				id
+			FROM
+				user_messages m1
+			WHERE
+				m1.local_chat_id = ? AND NOT(m1.seen) AND NOT(m1.hide) AND NOT(m1.deleted) AND NOT(m1.deleted_for_me)
+			ORDER BY %s ASC
+			LIMIT 1
+		`, cursor),
+		chatID).Scan(&id)
+
+	if err == sql.ErrNoRows {
+		return "", nil
+	}
+	if err != nil {
+		return "", err
+	}
+	return id, nil
+}
+
 // Get last chat message that is not hide or deleted or deleted_for_me
 func (db sqlitePersistence) LatestMessageByChatID(chatID string) ([]*common.Message, error) {
 	args := []interface{}{chatID}

protocol/messenger.go

@@ -4378,6 +4378,10 @@ func (m *Messenger) MessagesExist(ids []string) (map[string]bool, error) {
 	return m.persistence.MessagesExist(ids)
 }
 
+func (m *Messenger) FirstUnseenMessageID(chatID string) (string, error) {
+	return m.persistence.FirstUnseenMessageID(chatID)
+}
+
 func (m *Messenger) latestIncomingMessageClock(chatID string) (uint64, error) {
 	return m.persistence.latestIncomingMessageClock(chatID)
 }

protocol/persistence_test.go

@@ -247,6 +247,51 @@ func TestMessageByChatID(t *testing.T) {
 	)
 }
 
+func TestFirstUnseenMessageIDByChatID(t *testing.T) {
+	db, err := openTestDB()
+	require.NoError(t, err)
+	p := newSQLitePersistence(db)
+
+	messageID, err := p.FirstUnseenMessageID(testPublicChatID)
+	require.NoError(t, err)
+	require.Equal(t, "", messageID)
+
+	err = p.SaveMessages([]*common.Message{
+		{
+			ID:          "1",
+			LocalChatID: testPublicChatID,
+			ChatMessage: protobuf.ChatMessage{
+				Clock: 1,
+				Text:  "some-text"},
+			From: "me",
+			Seen: true,
+		},
+		{
+			ID:          "2",
+			LocalChatID: testPublicChatID,
+			ChatMessage: protobuf.ChatMessage{
+				Clock: 2,
+				Text:  "some-text"},
+			From: "me",
+			Seen: false,
+		},
+		{
+			ID:          "3",
+			LocalChatID: testPublicChatID,
+			ChatMessage: protobuf.ChatMessage{
+				Clock: 3,
+				Text:  "some-text"},
+			From: "me",
+			Seen: false,
+		},
+	})
+	require.NoError(t, err)
+
+	messageID, err = p.FirstUnseenMessageID(testPublicChatID)
+	require.NoError(t, err)
+	require.Equal(t, "2", messageID)
+}
+
 func TestLatestMessageByChatID(t *testing.T) {
 	db, err := openTestDB()
 	require.NoError(t, err)

services/ext/api.go

@@ -589,6 +589,10 @@ func (api *PublicAPI) MessageByMessageID(messageID string) (*common.Message, err
 	return api.service.messenger.MessageByID(messageID)
 }
 
+func (api *PublicAPI) FirstUnseenMessageID(chatID string) (string, error) {
+	return api.service.messenger.FirstUnseenMessageID(chatID)
+}
+
 func (api *PublicAPI) AllMessagesFromChatWhichMatchTerm(chatID, searchTerm string, caseSensitive bool) (*ApplicationMessagesResponse, error) {
 	messages, err := api.service.messenger.AllMessageByChatIDWhichMatchTerm(chatID, searchTerm, caseSensitive)
 	if err != nil {