Implement OVER/XOVER command

README.md

@@ -28,8 +28,8 @@
   - :heavy_check_mark: `HEAD`
   - :heavy_check_mark: `BODY`
   - :heavy_check_mark: `STAT`
-- :x: Articles overview
-  - :x: `OVER`
+- :construction: Articles overview
+  - :heavy_check_mark: `OVER`
   - :x: `LIST OVERVIEW.FMT`
   - :x: `HDR`
   - :x: `LIST HEADERS`

internal/backend/sqlite/sqlite.go

@@ -195,6 +195,24 @@ func (sb *SQLiteBackend) GetNextArticleByNum(g *models.Group, a *models.Article)
 	return nextArticle, json.Unmarshal([]byte(nextArticle.HeaderRaw), &nextArticle.Header)
 }
 
+func (sb *SQLiteBackend) GetArticlesByRange(g *models.Group, low, high int64) ([]models.Article, error) {
+	var articles []models.Article
+
+	if err := sb.db.Select(&articles, "SELECT articles.* FROM articles INNER JOIN articles_to_groups atg on atg.article_id = articles.id WHERE atg.article_number >= ? AND atg.article_number <= ? AND atg.group_id = ? ORDER BY atg.article_number", low, high, g.ID); err != nil {
+		return nil, err
+	}
+	for i := 0; i < len(articles); i++ {
+		if err := sb.db.Get(&articles[i].ArticleNumber, "SELECT article_number FROM articles_to_groups WHERE article_id = ?", articles[i].ID); err != nil {
+			return nil, err
+		}
+		if err := json.Unmarshal([]byte(articles[i].HeaderRaw), &articles[i].Header); err != nil {
+			return nil, err
+		}
+	}
+
+	return articles, nil
+}
+
 func (sb *SQLiteBackend) GetNewArticlesSince(timestamp int64) ([]string, error) {
 	var articleIds []string
 	return articleIds, sb.db.Select(&articleIds, "SELECT json_extract(articles.header, '$.Message-Id[0]') FROM articles WHERE created_at > datetime(?, 'unixepoch')", timestamp)

internal/backend/storage_backend.go

@@ -21,4 +21,5 @@ type StorageBackend interface {
 	GetNewArticlesSince(timestamp int64) ([]string, error)
 	GetLastArticleByNum(g *models.Group, a *models.Article) (models.Article, error)
 	GetNextArticleByNum(g *models.Group, a *models.Article) (models.Article, error)
+	GetArticlesByRange(g *models.Group, low, high int64) ([]models.Article, error)
 }

internal/protocol/constants.go

@@ -64,6 +64,8 @@ const (
 	CommandNewNews      = "NEWNEWS"
 	CommandLast         = "LAST"
 	CommandNext         = "NEXT"
+	CommandOver         = "OVER"
+	CommandXover        = "XOVER"
 )
 
 const (

internal/server/handler.go

@@ -44,6 +44,8 @@ func NewHandler(b backend.StorageBackend, serverDomain string) *Handler {
 		protocol.CommandNewNews:      h.handleNewNews,
 		protocol.CommandLast:         h.handleLast,
 		protocol.CommandNext:         h.handleNext,
+		protocol.CommandOver:         h.handleOver,
+		protocol.CommandXover:        h.handleOver,
 	}
 	h.serverDomain = serverDomain
 	return h
@@ -300,6 +302,11 @@ func (h *Handler) handlePost(s *Session, command string, arguments []string, id
 	// set path header
 	headers.Set("Path", fmt.Sprintf("%s!not-for-mail", h.serverDomain))
 
+	// set date header
+	if headers.Get("Date") == "" {
+		headers.Set("Date", time.Now().UTC().Format(time.RFC1123Z))
+	}
+
 	headerJson, err := json.Marshal(headers)
 	if err != nil {
 		return err
@@ -707,6 +714,99 @@ func (h *Handler) handleNext(s *Session, command string, arguments []string, id
 	return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 223, Message: fmt.Sprintf("%d %s retrieved", a.ArticleNumber, a.Header.Get("Message-Id"))}.String())
 }
 
+func (h *Handler) handleOver(s *Session, command string, arguments []string, id uint) error {
+	s.tconn.StartResponse(id)
+	defer s.tconn.EndResponse(id)
+
+	if len(arguments) == 0 && s.currentArticle == nil {
+		return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 420, Message: "No current article selected"}.String())
+	}
+
+	byRange := false
+	byNum := false
+	byMsgID := false
+	curArticle := false
+
+	if len(arguments) == 1 {
+		if _, _, err := utils.ParseRange(arguments[0]); err == nil {
+			byRange = true
+		} else if strings.ContainsAny(arguments[0], "<>") {
+			byMsgID = true
+		} else if _, err := strconv.Atoi(arguments[0]); err == nil {
+			byNum = true
+		}
+	} else if len(arguments) == 0 {
+		curArticle = true
+	} else {
+		return s.tconn.PrintfLine(protocol.ErrSyntaxError.String())
+	}
+
+	var articles []models.Article
+
+	if byRange {
+		if s.currentGroup == nil {
+			return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 412, Message: "No newsgroup selected"}.String())
+		}
+
+		low, high, err := utils.ParseRange(arguments[0])
+		if err != nil {
+			return err
+		}
+		if low > high {
+			return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 423, Message: "Empty range"}.String())
+		}
+		a, err := h.backend.GetArticlesByRange(s.currentGroup, low, high)
+		if err != nil {
+			if err == sql.ErrNoRows {
+				return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 423, Message: "No articles in that range"}.String())
+			}
+			return err
+		}
+		articles = append(articles, a...)
+	} else if byMsgID {
+		a, err := h.backend.GetArticle(arguments[0])
+		if err != nil {
+			if err == sql.ErrNoRows {
+				return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 430, Message: "No such article with that message-id"}.String())
+			}
+			return err
+		}
+		a.ArticleNumber = 0
+		articles = append(articles, a)
+	} else if byNum {
+		num, _ := strconv.Atoi(arguments[0])
+		a, err := h.backend.GetArticleByNumber(s.currentGroup, num)
+		if err != nil {
+			if err == sql.ErrNoRows {
+				return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 423, Message: "No such article in this group"}.String())
+			}
+			return err
+		}
+		articles = append(articles, a)
+	} else if curArticle {
+		articles = append(articles, *s.currentArticle)
+	}
+
+	dw := s.tconn.DotWriter()
+	dw.Write([]byte(protocol.NNTPResponse{Code: 224, Message: "Overview information follows" + protocol.CRLF}.String()))
+	for _, v := range articles {
+		dw.Write([]byte(strconv.Itoa(v.ArticleNumber) + "	"))
+		dw.Write([]byte(v.Header.Get("Subject") + "	"))
+		dw.Write([]byte(v.Header.Get("From") + "	"))
+		dw.Write([]byte(v.Header.Get("Date") + "	"))
+		dw.Write([]byte(v.Header.Get("Message-ID") + "	"))
+		dw.Write([]byte(v.Header.Get("References") + "	"))
+
+		bytesMetadata := len([]byte(v.Body))
+		linesMetadata := strings.Count(v.Body, "\n")
+
+		dw.Write([]byte(strconv.Itoa(bytesMetadata) + "	"))
+		dw.Write([]byte(strconv.Itoa(linesMetadata) + 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 {