scoreboard/scoreboard.go: Add ability to set scoreboard sort order to descending (#1112)

Author: krivey

server/player/scoreboard/scoreboard.go

@@ -11,9 +11,10 @@ import (
 // Scoreboard implements the io.Writer and io.StringWriter interfaces. fmt.Fprintf and fmt.Fprint may be used
 // to write formatted text to the scoreboard.
 type Scoreboard struct {
-	name    string
-	lines   []string
-	padding bool
+	name       string
+	lines      []string
+	padding    bool
+	descending bool
 }
 
 // New returns a new scoreboard with the display name passed. Once returned, lines may be added to the
@@ -86,5 +87,19 @@ func (board *Scoreboard) Lines() []string {
 			lines[i] = " " + line + strings.Repeat(" ", len(board.name)-len(line)-2)
 		}
 	}
+	if board.descending {
+		slices.Reverse(lines)
+	}
 	return lines
 }
+
+// Descending returns whether the scoreboard is sorted in descending order.
+func (board *Scoreboard) Descending() bool {
+	return board.descending
+}
+
+// SetDescending sets the scoreboard sort order to descending.
+// When sending the scoreboard to the player, it will reverse the order of the lines to match when it's ascending.
+func (board *Scoreboard) SetDescending() {
+	board.descending = true
+}

server/session/text.go

@@ -77,12 +77,18 @@ func (s *Session) SendScoreboard(sb *scoreboard.Scoreboard) {
 
 	if currentName != sb.Name() {
 		s.RemoveScoreboard()
-		s.writePacket(&packet.SetDisplayObjective{
+		pk := &packet.SetDisplayObjective{
 			DisplaySlot:   "sidebar",
 			ObjectiveName: sb.Name(),
 			DisplayName:   sb.Name(),
 			CriteriaName:  "dummy",
-		})
+		}
+		if sb.Descending() {
+			pk.SortOrder = packet.ScoreboardSortOrderDescending
+		} else {
+			pk.SortOrder = packet.ScoreboardSortOrderAscending
+		}
+		s.writePacket(pk)
 		name, lines := sb.Name(), append([]string(nil), sb.Lines()...)
 		s.currentScoreboard.Store(&name)
 		s.currentLines.Store(&lines)