Changeset 0.15.0 (#71)

server/treepath/cursor.go

@@ -0,0 +1,39 @@
+package treepath
+
+import (
+	"database/sql"
+
+	"git.gobha.me/xcaliber/chat-switchboard/database"
+)
+
+// UpdateCursor upserts the channel_cursors row for a user.
+func UpdateCursor(channelID, userID, messageID string) error {
+	_, err := database.DB.Exec(`
+		INSERT INTO channel_cursors (channel_id, user_id, active_leaf_id)
+		VALUES ($1, $2, $3)
+		ON CONFLICT (channel_id, user_id) DO UPDATE SET
+			active_leaf_id = $3, updated_at = NOW()
+	`, channelID, userID, messageID)
+	return err
+}
+
+// NextSiblingIndex returns the next sibling_index for a new child of parentID.
+// For root messages (parentID is nil), counts existing roots in the channel.
+func NextSiblingIndex(channelID string, parentID *string) int {
+	var maxIdx sql.NullInt64
+	if parentID == nil {
+		database.DB.QueryRow(`
+			SELECT MAX(sibling_index) FROM messages
+			WHERE channel_id = $1 AND parent_id IS NULL AND deleted_at IS NULL
+		`, channelID).Scan(&maxIdx)
+	} else {
+		database.DB.QueryRow(`
+			SELECT MAX(sibling_index) FROM messages
+			WHERE parent_id = $1 AND deleted_at IS NULL
+		`, *parentID).Scan(&maxIdx)
+	}
+	if !maxIdx.Valid {
+		return 0
+	}
+	return int(maxIdx.Int64) + 1
+}