Implement THREAD command

internal/backend/sqlite/sqlite.go

@@ -238,3 +238,9 @@ func (sb *SQLiteBackend) GetNewThreads(g *models.Group, perPage int, pageNum int
 
 	return numbers, sb.db.Select(&numbers, "SELECT atg.article_number FROM articles INNER JOIN articles_to_groups atg on atg.article_id = articles.id WHERE atg.group_id = ? AND articles.thread IS NULL ORDER BY articles.created_at DESC LIMIT ? OFFSET ?", g.ID, perPage, perPage*pageNum)
 }
+
+func (sb *SQLiteBackend) GetThread(g *models.Group, threadNum int) ([]int, error) {
+	var numbers []int
+
+	return numbers, sb.db.Select(&numbers, "SELECT atg.article_number FROM articles INNER JOIN articles_to_groups atg on atg.article_id = articles.id WHERE atg.group_id = ? AND articles.thread = json_extract((SELECT articles.header from articles INNER JOIN articles_to_groups a on articles.id = a.article_id WHERE a.group_id = ? AND a.article_number = ?), '$.Message-Id[0]') ORDER BY articles.created_at", g.ID, g.ID, threadNum)
+}

internal/backend/storage_backend.go

@@ -23,4 +23,5 @@ type StorageBackend interface {
 	GetNextArticleByNum(g *models.Group, a *models.Article) (models.Article, error)
 	GetArticlesByRange(g *models.Group, low, high int64) ([]models.Article, error)
 	GetNewThreads(g *models.Group, perPage int, pageNum int) ([]int, error)
+	GetThread(g *models.Group, threadNum int) ([]int, error)
 }

internal/server/handler.go

@@ -53,6 +53,7 @@ func NewHandler(b backend.StorageBackend, serverDomain, uploadPath string) *Hand
 
 		// project-specific extensions
 		"NEWTHREADS": h.handleNewThreads,
+		"THREAD":     h.handleThread,
 	}
 	h.serverDomain = serverDomain
 	h.uploadPath = uploadPath
@@ -905,6 +906,38 @@ func (h *Handler) handleNewThreads(s *Session, command string, arguments []strin
 	return dw.Close()
 }
 
+func (h *Handler) handleThread(s *Session, command string, arguments []string, id uint) error {
+	s.tconn.StartResponse(id)
+	defer s.tconn.EndResponse(id)
+
+	if s.currentGroup == nil {
+		return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 412, Message: "no newsgroup selected"}.String())
+	}
+
+	if len(arguments) == 0 {
+		return s.tconn.PrintfLine(protocol.ErrSyntaxError.String())
+	}
+
+	threadNumber, err := strconv.Atoi(arguments[0])
+	if err != nil {
+		return s.tconn.PrintfLine(protocol.ErrSyntaxError.String())
+	}
+
+	threadNums, err := h.backend.GetThread(s.currentGroup, threadNumber)
+	if err != nil {
+		if err != sql.ErrNoRows {
+			return err
+		}
+	}
+
+	dw := s.tconn.DotWriter()
+	dw.Write([]byte(protocol.NNTPResponse{Code: 226, Message: "Thread articles follows" + protocol.CRLF}.String()))
+	for _, v := range threadNums {
+		dw.Write([]byte(strconv.Itoa(v) + protocol.CRLF))
+	}
+	return dw.Close()
+}
+
 func (h *Handler) Handle(s *Session, message string, id uint) error {
 	splittedMessage := strings.Split(message, " ")
 	for i, v := range splittedMessage {