Changeset 0.15.0 (#71)

server/treepath/siblings.go

@@ -0,0 +1,114 @@
+package treepath
+
+import (
+	"database/sql"
+	"fmt"
+
+	"git.gobha.me/xcaliber/chat-switchboard/database"
+)
+
+// GetSiblingCount returns how many live siblings share the same parent_id.
+// Root messages (parent_id IS NULL) count all roots in the same channel.
+func GetSiblingCount(channelID string, parentID *string) int {
+	var count int
+	if parentID == nil {
+		database.DB.QueryRow(`
+			SELECT COUNT(*) FROM messages
+			WHERE channel_id = $1 AND parent_id IS NULL AND deleted_at IS NULL
+		`, channelID).Scan(&count)
+	} else {
+		database.DB.QueryRow(`
+			SELECT COUNT(*) FROM messages
+			WHERE parent_id = $1 AND deleted_at IS NULL
+		`, *parentID).Scan(&count)
+	}
+	if count == 0 {
+		count = 1
+	}
+	return count
+}
+
+// GetSiblings returns all live siblings of a given message (including itself),
+// ordered by sibling_index.
+func GetSiblings(messageID string) ([]SiblingInfo, int, error) {
+	// First get the parent_id of the target message
+	var parentID *string
+	var channelID string
+	err := database.DB.QueryRow(`
+		SELECT parent_id, channel_id FROM messages
+		WHERE id = $1 AND deleted_at IS NULL
+	`, messageID).Scan(&parentID, &channelID)
+	if err != nil {
+		return nil, 0, fmt.Errorf("message not found: %w", err)
+	}
+
+	var rows *sql.Rows
+	if parentID == nil {
+		// Root messages: siblings are other roots in the same channel
+		rows, err = database.DB.Query(`
+			SELECT id, role, model, sibling_index, LEFT(content, 80), created_at
+			FROM messages
+			WHERE channel_id = $1 AND parent_id IS NULL AND deleted_at IS NULL
+			ORDER BY sibling_index, created_at
+		`, channelID)
+	} else {
+		rows, err = database.DB.Query(`
+			SELECT id, role, model, sibling_index, LEFT(content, 80), created_at
+			FROM messages
+			WHERE parent_id = $1 AND deleted_at IS NULL
+			ORDER BY sibling_index, created_at
+		`, *parentID)
+	}
+	if err != nil {
+		return nil, 0, err
+	}
+	defer rows.Close()
+
+	var siblings []SiblingInfo
+	currentIdx := 0
+	for i := 0; rows.Next(); i++ {
+		var s SiblingInfo
+		if err := rows.Scan(&s.ID, &s.Role, &s.Model, &s.SiblingIndex, &s.Preview, &s.CreatedAt); err != nil {
+			return nil, 0, err
+		}
+		if s.ID == messageID {
+			currentIdx = i
+		}
+		siblings = append(siblings, s)
+	}
+
+	return siblings, currentIdx, nil
+}
+
+// FindLeafFromMessage walks down from a message to find the deepest descendant.
+// Follows the first child (lowest sibling_index) at each level.
+// Used when switching branches: clicking a mid-tree sibling navigates to its leaf.
+func FindLeafFromMessage(messageID string) (string, error) {
+	var leafID string
+	err := database.DB.QueryRow(`
+		WITH RECURSIVE descendants AS (
+			SELECT id, 0 AS depth
+			FROM messages
+			WHERE id = $1 AND deleted_at IS NULL
+
+			UNION ALL
+
+			SELECT child.id, d.depth + 1
+			FROM messages child
+			JOIN descendants d ON child.parent_id = d.id
+			WHERE child.deleted_at IS NULL
+			  AND child.sibling_index = (
+			      SELECT MIN(sibling_index) FROM messages
+			      WHERE parent_id = d.id AND deleted_at IS NULL
+			  )
+		)
+		SELECT id FROM descendants
+		ORDER BY depth DESC
+		LIMIT 1
+	`, messageID).Scan(&leafID)
+
+	if err != nil {
+		return messageID, nil // if anything fails, just use the message itself
+	}
+	return leafID, nil
+}