package main

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"verstak/internal/core/activity"
	"verstak/internal/core/nodes"
	syncsvc "verstak/internal/core/sync"
	"verstak/internal/core/templates"
	"verstak/internal/core/util"
)

func (a *App) ListWorkspaceTree() ([]NodeDTO, error) {
	list, err := a.nodes.ListRoots(false)
	if err != nil {
		return nil, err
	}
	return toNodeDTOs(list), nil
}

func (a *App) ListChildren(parentID string) ([]NodeDTO, error) {
	list, err := a.nodes.ListChildren(parentID, false)
	if err != nil {
		return nil, err
	}
	return toNodeDTOs(list), nil
}

func (a *App) GetNodeDetail(nodeID string) (*NodeDTO, error) {
	n, err := a.nodes.GetActive(nodeID)
	if err != nil {
		return nil, err
	}
	dto := toNodeDTO(n)
	return &dto, nil
}

func (a *App) CreateNodeFromTemplate(parentID, title, templateID string) (*NodeDTO, error) {
	tmpl, ok := a.templates.Get(templateID)
	if !ok {
		return nil, fmt.Errorf("template %q not found", templateID)
	}

	seg := templates.SafeDisplayNameToPathSegment(title)
	if seg == "" {
		seg = "node"
	}

	var parent *nodes.Node
	var parentFsPath string
	if parentID != "" {
		var err error
		parent, err = a.nodes.GetActive(parentID)
		if err != nil {
			return nil, fmt.Errorf("parent not found: %w", err)
		}
		parentFsPath = parent.FsPath
	}

	fsPath := seg
	if parentFsPath != "" {
		fsPath = filepath.Join(parentFsPath, seg)
	}

	physPath := filepath.Join(a.vault, fsPath)
	physPath = templates.UniquePath(physPath)
	rel, _ := filepath.Rel(a.vault, physPath)
	fsPath = rel

	if _, err := syncsvc.SafeVaultPath(a.vault, fsPath); err != nil {
		return nil, fmt.Errorf("path safety: %w", err)
	}

	var pID *string
	if parentID != "" {
		pID = &parentID
	}

	sortOrder := 0
	n, err := a.nodes.Create(pID, tmpl.Type, title, sortOrder, tmpl.ID, fsPath)
	if err != nil {
		return nil, fmt.Errorf("create node: %w", err)
	}

	if err := os.MkdirAll(physPath, 0o755); err != nil {
		_ = a.nodes.SoftDelete(n.ID)
		return nil, fmt.Errorf("create folder: %w", err)
	}

	// Create child nodes for default files and folders with rollback on failure.
	nowRFC := time.Now().UTC().Format(time.RFC3339)
	type childInfo struct {
		id   string
		file bool
	}
	var created []childInfo
	rollbackChildren := func() {
		for i := len(created) - 1; i >= 0; i-- {
			_ = a.nodes.SoftDelete(created[i].id)
		}
	}

	for _, df := range tmpl.DefaultFiles {
		fpath := filepath.Join(physPath, df.Path)
		if err := os.MkdirAll(filepath.Dir(fpath), 0o755); err != nil {
			rollbackChildren()
			return nil, fmt.Errorf("create directory for %s: %w", df.Path, err)
		}
		fileTitle := strings.TrimSuffix(filepath.Base(df.Path), filepath.Ext(df.Path))
		if fileTitle == "" {
			fileTitle = "Overview"
		}
		childNode, childErr := a.nodes.Create(&n.ID, nodes.TypeNote, fileTitle, 0, "", "")
		if childErr != nil {
			rollbackChildren()
			return nil, fmt.Errorf("create child node for %s: %w", df.Path, childErr)
		}
		created = append(created, childInfo{id: childNode.ID, file: true})

		content := fmt.Sprintf("# %s\n\n", title)
		if err := os.WriteFile(fpath, []byte(content), 0o640); err != nil {
			rollbackChildren()
			return nil, fmt.Errorf("write file %s: %w", df.Path, err)
		}
		relPath, _ := filepath.Rel(a.vault, fpath)
		fi, _ := os.Stat(fpath)
		size := int64(0)
		if fi != nil {
			size = fi.Size()
		}
		fileID := util.UUID7()
		_, _ = a.db.Exec(
			`INSERT INTO files (id,node_id,filename,path,storage_mode,size,sha256,mime,created_at,updated_at,missing)
			 VALUES (?,?,?,?,'vault',?,'','text/plain',?,?,0)`,
			fileID, childNode.ID, filepath.Base(fpath), relPath, size, nowRFC, nowRFC)
		_, _ = a.db.Exec(
			`INSERT OR IGNORE INTO notes (node_id, file_id, format) VALUES (?,?,?)`,
			childNode.ID, fileID, "markdown")
		_ = a.activity.Record(n.ID, activity.TargetNote, childNode.ID, "", activity.TypeNoteCreated, fileTitle, "")
		_ = a.sync.RecordOp(syncsvc.EntityNote, childNode.ID, syncsvc.OpCreate, map[string]interface{}{
			"node_id":    childNode.ID,
			"parent_id":  n.ID,
			"title":      fileTitle,
			"file_id":    fileID,
			"format":     "markdown",
			"content":    content,
			"filename":   filepath.Base(fpath),
			"path":       relPath,
			"created_at": nowRFC,
			"updated_at": nowRFC,
		})
	}

	for _, folderName := range tmpl.DefaultFolders {
		folderSeg := templates.SafeDisplayNameToPathSegment(folderName)
		if folderSeg == "" {
			folderSeg = "folder"
		}
		childNode, childErr := a.nodes.Create(&n.ID, nodes.TypeFolder, folderName, 0, "", "")
		if childErr != nil {
			rollbackChildren()
			return nil, fmt.Errorf("create child folder %s: %w", folderName, childErr)
		}
		created = append(created, childInfo{id: childNode.ID, file: false})

		childFsPath := folderSeg
		if fsPath != "" {
			childFsPath = filepath.Join(fsPath, folderSeg)
		}
		childPhysPath := filepath.Join(a.vault, childFsPath)
		childPhysPath = templates.UniquePath(childPhysPath)
		childRel, _ := filepath.Rel(a.vault, childPhysPath)
		childFsPath = childRel
		_ = a.nodes.UpdateFsPath(childNode.ID, childFsPath)
		if err := os.MkdirAll(childPhysPath, 0o755); err != nil {
			rollbackChildren()
			return nil, fmt.Errorf("create child folder directory %s: %w", folderName, err)
		}
		_ = a.activity.Record(n.ID, activity.TargetFolder, childNode.ID, "", activity.TypeNodeCreated, folderName, "")
		_ = a.sync.RecordOp(syncsvc.EntityFolder, childNode.ID, syncsvc.OpCreate, nodePayload(childNode))
	}

	pid := ""
	if parentID != "" {
		pid = parentID
	}
	_ = a.activity.Record(pid, activity.TargetNode, n.ID, "", activity.TypeNodeCreated, title, `{"template":"`+templateID+`"}`)
	_ = a.sync.RecordOp(syncsvc.EntityNode, n.ID, syncsvc.OpCreate, nodePayload(n))

	dto := toNodeDTO(n)
	return &dto, nil
}

func (a *App) DeleteNode(id string) error {
	n, err := a.nodes.GetActive(id)
	if err != nil {
		return a.nodes.SoftDelete(id)
	}
	pid := ""
	if n.ParentID != nil {
		pid = *n.ParentID
	}
	var entity string
	var targetType string
	var evType string
	switch n.Type {
	case nodes.TypeNote:
		entity = syncsvc.EntityNote
		targetType = activity.TargetNote
		evType = activity.TypeNoteDeleted
	case nodes.TypeFolder, nodes.TypeProject, nodes.TypeClient, nodes.TypeDocument, nodes.TypeRecipe, nodes.TypeSpace:
		entity = syncsvc.EntityFolder
		targetType = activity.TargetFolder
		evType = activity.TypeFolderDeleted
	case nodes.TypeFile:
		entity = syncsvc.EntityFile
		targetType = activity.TargetFile
		evType = activity.TypeFileDeleted
	default:
		entity = syncsvc.EntityNode
		targetType = activity.TargetNode
		evType = activity.TypeNodeDeleted
	}
	_ = a.activity.Record(pid, targetType, id, "", evType, n.Title, "")
	_ = a.sync.RecordOp(entity, id, syncsvc.OpDelete, nil)

	return a.files.DeleteNodeAndChildren(id)
}

func (a *App) RenameNode(nodeID, newTitle string) error {
	n, err := a.nodes.GetActive(nodeID)
	if err != nil {
		return err
	}

	seg := templates.SafeDisplayNameToPathSegment(newTitle)
	if seg == "" {
		seg = "node"
	}

	isFolderLike := n.Type != nodes.TypeNote && n.Type != nodes.TypeFile

	if isFolderLike {
		return a.renameFolderNode(nodeID, n, newTitle, seg)
	}
	return a.renameNoteFileNode(nodeID, n, newTitle, seg)
}

// renameFolderNode renames a folder-like node atomically: FS first, then DB transaction.
func (a *App) renameFolderNode(nodeID string, n *nodes.Node, newTitle, seg string) error {
	if n.FsPath == "" {
		return fmt.Errorf("cannot rename node %s (%s): fs_path is empty", n.ID, n.Title)
	}

	oldFsPath := n.FsPath
	oldPhysPath := filepath.Join(a.vault, oldFsPath)
	oldTitle := n.Title

	parentFsPath := ""
	if n.ParentID != nil {
		if p, err := a.nodes.GetActive(*n.ParentID); err == nil {
			parentFsPath = p.FsPath
		}
	}
	newFsPath := seg
	if parentFsPath != "" {
		newFsPath = filepath.Join(parentFsPath, seg)
	}
	newPhysPath := filepath.Join(a.vault, newFsPath)
	newPhysPath = templates.UniquePath(newPhysPath)
	rel, _ := filepath.Rel(a.vault, newPhysPath)
	newFsPath = rel

	if _, err := syncsvc.SafeVaultPath(a.vault, newFsPath); err != nil {
		return fmt.Errorf("path safety: %w", err)
	}

	// Pre-collect all descendant fs_path updates (before transaction, to avoid deadlock).
	type pathUp struct{ id, path string }
	var updates []pathUp
	var walk func(string, string)
	walk = func(id, p string) {
		updates = append(updates, pathUp{id, p})
		children, _ := a.nodes.ListChildren(id, false)
		for _, c := range children {
			cseg := templates.SafeDisplayNameToPathSegment(c.Title)
			walk(c.ID, filepath.Join(p, cseg))
		}
	}
	walk(nodeID, newFsPath)

	// Check source exists before filesystem rename
	if _, err := os.Stat(oldPhysPath); err != nil {
		return fmt.Errorf("source folder not found: %w", err)
	}
	if err := os.Rename(oldPhysPath, newPhysPath); err != nil {
		return fmt.Errorf("rename folder: %w", err)
	}

	// Atomic DB transaction: title + own fs_path + all descendant fs_paths
	nowT := time.Now().UTC().Format(time.RFC3339)
	slug := nodes.Slugify(newTitle)

	tx, err := a.db.Begin()
	if err != nil {
		_ = os.Rename(newPhysPath, oldPhysPath)
		return fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback()

	if _, err := tx.Exec(
		`UPDATE nodes SET title=?, slug=?, updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`,
		newTitle, slug, nowT, nodeID); err != nil {
		_ = os.Rename(newPhysPath, oldPhysPath)
		return err
	}
	for _, u := range updates {
		if _, err := tx.Exec(
			`UPDATE nodes SET fs_path=?, updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`,
			u.path, nowT, u.id); err != nil {
			_ = os.Rename(newPhysPath, oldPhysPath)
			return err
		}
	}

	if err := tx.Commit(); err != nil {
		_ = os.Rename(newPhysPath, oldPhysPath)
		return fmt.Errorf("commit tx: %w", err)
	}

	pid := ""
	if n.ParentID != nil {
		pid = *n.ParentID
	}
	_ = a.activity.Record(pid, activity.TargetFolder, nodeID, "", activity.TypeFolderRenamed, newTitle, `{"from":"`+oldTitle+`","to":"`+newTitle+`"}`)
	_ = a.sync.RecordOp(syncsvc.EntityFolder, nodeID, syncsvc.OpUpdate, map[string]interface{}{
		"title":      newTitle,
		"fs_path":    newFsPath,
		"updated_at": time.Now().UTC().Format(time.RFC3339),
	})
	return nil
}

// renameNoteFileNode renames a note or file node atomically: FS first, then DB transaction.
func (a *App) renameNoteFileNode(nodeID string, n *nodes.Node, newTitle, seg string) error {
	// Collect file records before any mutations (avoid deadlock with SetMaxOpenConns=1).
	type fileRec struct {
		id, path, filename string
	}
	var records []fileRec
	rows, err := a.db.Query(`SELECT id, path, filename FROM files WHERE node_id=?`, nodeID)
	if err == nil {
		for rows.Next() {
			var r fileRec
			if err := rows.Scan(&r.id, &r.path, &r.filename); err != nil {
				continue
			}
			records = append(records, r)
		}
		rows.Close()
	}

	// Compute new filenames and paths (no FS modifications yet).
	type renameOp struct {
		id          string
		oldAbs      string
		newAbs      string
		newFilename string
		newPath     string
	}
	var renameOps []renameOp
	for _, r := range records {
		if r.path == "" {
			continue
		}
		oldAbs := filepath.Join(a.vault, r.path)
		dir := filepath.Dir(r.path)
		var newFilename string
		if n.Type == nodes.TypeNote {
			ext := filepath.Ext(r.filename)
			if ext == "" {
				ext = ".md"
			}
			newFilename = seg + ext
		} else {
			newFilename = newTitle
		}
		newPath := filepath.Join(dir, newFilename)
		newAbs := filepath.Join(a.vault, newPath)

		// Check for collision
		if _, err := os.Stat(newAbs); err == nil {
			ext := filepath.Ext(newFilename)
			base := strings.TrimSuffix(newFilename, ext)
			baseSeg := templates.SafeDisplayNameToPathSegment(base)
			if baseSeg == "" {
				baseSeg = "renamed"
			}
			for i := 2; ; i++ {
				candidate := fmt.Sprintf("%s (%d)%s", baseSeg, i, ext)
				candidatePath := filepath.Join(dir, candidate)
				if _, err := os.Stat(filepath.Join(a.vault, candidatePath)); os.IsNotExist(err) {
					newFilename = candidate
					newPath = candidatePath
					newAbs = filepath.Join(a.vault, newPath)
					break
				}
			}
		}

		if _, err := os.Stat(oldAbs); err != nil {
			return fmt.Errorf("source file not found for rename: %w", err)
		}
		renameOps = append(renameOps, renameOp{
			id: r.id, oldAbs: oldAbs, newAbs: newAbs,
			newFilename: newFilename, newPath: newPath,
		})
	}

	// Perform all physical renames first
	successCount := 0
	for i, rop := range renameOps {
		if err := os.Rename(rop.oldAbs, rop.newAbs); err != nil {
			// Rollback completed FS renames
			for j := 0; j < i; j++ {
				_ = os.Rename(renameOps[j].newAbs, renameOps[j].oldAbs)
			}
			return fmt.Errorf("rename file: %w", err)
		}
		successCount++
	}

	// Atomic DB transaction: title + all file record updates
	nowT := time.Now().UTC().Format(time.RFC3339)
	slug := nodes.Slugify(newTitle)

	tx, err := a.db.Begin()
	if err != nil {
		for _, rop := range renameOps[:successCount] {
			_ = os.Rename(rop.newAbs, rop.oldAbs)
		}
		return fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback()

	if _, err := tx.Exec(
		`UPDATE nodes SET title=?, slug=?, updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`,
		newTitle, slug, nowT, nodeID); err != nil {
		for _, rop := range renameOps[:successCount] {
			_ = os.Rename(rop.newAbs, rop.oldAbs)
		}
		return err
	}
	for _, rop := range renameOps {
		if _, err := tx.Exec(
			`UPDATE files SET filename=?, path=? WHERE id=?`,
			rop.newFilename, rop.newPath, rop.id); err != nil {
			for _, rop2 := range renameOps[:successCount] {
				_ = os.Rename(rop2.newAbs, rop2.oldAbs)
			}
			return err
		}
	}

	if err := tx.Commit(); err != nil {
		for _, rop := range renameOps[:successCount] {
			_ = os.Rename(rop.newAbs, rop.oldAbs)
		}
		return fmt.Errorf("commit tx: %w", err)
	}

	pid := ""
	if n.ParentID != nil {
		pid = *n.ParentID
	}
	var evType string
	var targetType string
	var syncEntity string
	if n.Type == nodes.TypeNote {
		evType = activity.TypeNoteUpdated
		targetType = activity.TargetNote
		syncEntity = syncsvc.EntityNote
	} else {
		evType = activity.TypeFileRenamed
		targetType = activity.TargetFile
		syncEntity = syncsvc.EntityFile
	}
	_ = a.activity.Record(pid, targetType, nodeID, "", evType, newTitle, "")
	_ = a.sync.RecordOp(syncEntity, nodeID, syncsvc.OpUpdate, map[string]interface{}{
		"title":      newTitle,
		"updated_at": nowT,
	})
	return nil
}

func (a *App) isDescendant(ancestorID, nodeID string) error {
	if nodeID == "" || ancestorID == "" {
		return nil
	}
	current := nodeID
	depth := 0
	for current != "" && depth < 1000 {
		if current == ancestorID {
			return fmt.Errorf("cannot move a node into its own descendant")
		}
		n, err := a.nodes.Get(current)
		if err != nil || n.ParentID == nil {
			return nil
		}
		current = *n.ParentID
		depth++
	}
	return nil
}

func (a *App) MoveNode(nodeID, newParentID string) error {
	node, err := a.nodes.GetActive(nodeID)
	if err != nil {
		return err
	}

	// Prevent moving node into its own descendant
	if newParentID != "" {
		if err := a.isDescendant(newParentID, nodeID); err != nil {
			return err
		}
	}

	isFolderLike := node.Type != nodes.TypeNote && node.Type != nodes.TypeFile

	// Resolve new parent
	var parent *nodes.Node
	if newParentID != "" {
		parent, err = a.nodes.GetActive(newParentID)
		if err != nil {
			return fmt.Errorf("new parent not found: %w", err)
		}
	}

	// Compute new title (name conflict resolution) but don't commit yet.
	nodeTitle := node.Title
	titleChanged := false
	if parent != nil {
		destChildren, _ := a.nodes.ListChildren(newParentID, false)
		for i := range destChildren {
			if destChildren[i].Title == nodeTitle && destChildren[i].ID != nodeID {
				nodeTitle = fmt.Sprintf("%s (%d)", nodeTitle, 2)
				titleChanged = true
				break
			}
		}
	}

	if isFolderLike {
		return a.moveFolderNode(nodeID, node, parent, newParentID, nodeTitle, titleChanged)
	}
	return a.moveNoteFileNode(nodeID, node, parent, newParentID, nodeTitle, titleChanged)
}

// moveFolderNode moves a folder-like node atomically: FS first, then DB transaction.
func (a *App) moveFolderNode(nodeID string, node *nodes.Node, parent *nodes.Node, newParentID, nodeTitle string, titleChanged bool) error {
	if node.FsPath == "" {
		return fmt.Errorf("cannot move node %s (%s): fs_path is empty", node.ID, node.Title)
	}

	oldFsPath := node.FsPath
	oldPhysPath := filepath.Join(a.vault, oldFsPath)

	seg := templates.SafeDisplayNameToPathSegment(nodeTitle)
	newFsPath := seg
	if parent != nil && parent.FsPath != "" {
		newFsPath = filepath.Join(parent.FsPath, seg)
	}
	newPhysPath := filepath.Join(a.vault, newFsPath)
	newPhysPath = templates.UniquePath(newPhysPath)
	rel, _ := filepath.Rel(a.vault, newPhysPath)
	newFsPath = rel

	if _, err := syncsvc.SafeVaultPath(a.vault, newFsPath); err != nil {
		return fmt.Errorf("path safety: %w", err)
	}

	// Pre-collect all descendant fs_path updates (before transaction).
	type pathUp struct{ id, path string }
	var updates []pathUp
	var walk func(string, string)
	walk = func(id, p string) {
		updates = append(updates, pathUp{id, p})
		children, _ := a.nodes.ListChildren(id, false)
		for _, c := range children {
			cseg := templates.SafeDisplayNameToPathSegment(c.Title)
			walk(c.ID, filepath.Join(p, cseg))
		}
	}
	walk(nodeID, newFsPath)

	// Check source exists and do filesystem rename first
	if _, err := os.Stat(oldPhysPath); err != nil {
		return fmt.Errorf("source folder not found: %w", err)
	}
	if err := os.Rename(oldPhysPath, newPhysPath); err != nil {
		return fmt.Errorf("move folder: %w", err)
	}

	// Atomic DB transaction: title + parent_id + all fs_paths
	nowT := time.Now().UTC().Format(time.RFC3339)
	tx, err := a.db.Begin()
	if err != nil {
		_ = os.Rename(newPhysPath, oldPhysPath)
		return fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback()

	if titleChanged {
		slug := nodes.Slugify(nodeTitle)
		if _, err := tx.Exec(
			`UPDATE nodes SET title=?, slug=?, updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`,
			nodeTitle, slug, nowT, nodeID); err != nil {
			_ = os.Rename(newPhysPath, oldPhysPath)
			return err
		}
	}

	var parentVal interface{}
	if newParentID != "" {
		parentVal = newParentID
	}
	if _, err := tx.Exec(
		`UPDATE nodes SET parent_id=?, updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`,
		parentVal, nowT, nodeID); err != nil {
		_ = os.Rename(newPhysPath, oldPhysPath)
		return err
	}

	// Touch new parent
	if newParentID != "" {
		_, _ = tx.Exec(`UPDATE nodes SET updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`, nowT, newParentID)
	}

	// Touch old parent if different
	if node.ParentID != nil && *node.ParentID != newParentID {
		_, _ = tx.Exec(`UPDATE nodes SET updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`, nowT, *node.ParentID)
	}

	for _, u := range updates {
		if _, err := tx.Exec(
			`UPDATE nodes SET fs_path=?, updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`,
			u.path, nowT, u.id); err != nil {
			_ = os.Rename(newPhysPath, oldPhysPath)
			return err
		}
	}

	if err := tx.Commit(); err != nil {
		_ = os.Rename(newPhysPath, oldPhysPath)
		return fmt.Errorf("commit tx: %w", err)
	}

	// Update node.ParentID for activity/sync below
	if newParentID == "" {
		node.ParentID = nil
	} else {
		node.ParentID = &newParentID
	}
	node.FsPath = newFsPath

	pid := ""
	if node.ParentID != nil {
		pid = *node.ParentID
	}
	_ = a.activity.Record(pid, activity.TargetFolder, nodeID, "", activity.TypeFolderMoved, nodeTitle, `{"to":"`+newParentID+`"}`)
	_ = a.sync.RecordOp(syncsvc.EntityFolder, nodeID, syncsvc.OpMove, map[string]interface{}{
		"parent_id":  newParentID,
		"fs_path":    newFsPath,
		"updated_at": nowT,
	})
	return nil
}

// moveNoteFileNode moves a note/file atomically: FS first, then DB transaction.
func (a *App) moveNoteFileNode(nodeID string, node *nodes.Node, parent *nodes.Node, newParentID, nodeTitle string, titleChanged bool) error {
	// Collect file records before any mutations.
	type fileMove struct {
		id          string
		oldPath     string
		oldAbs      string
		newRelPath  string
		newAbs      string
	}
	var fileMoves []fileMove
	frows, ferr := a.db.Query(`SELECT id, path FROM files WHERE node_id=?`, nodeID)
	if ferr == nil {
		for frows.Next() {
			var fm fileMove
			if err := frows.Scan(&fm.id, &fm.oldPath); err != nil {
				continue
			}
			if fm.oldPath == "" {
				continue
			}
			fm.oldAbs = filepath.Join(a.vault, fm.oldPath)
			filename := filepath.Base(fm.oldPath)
			fm.newRelPath = filename
			if parent != nil && parent.FsPath != "" {
				fm.newRelPath = filepath.Join(parent.FsPath, filename)
			}
			fm.newAbs = filepath.Join(a.vault, fm.newRelPath)
			fileMoves = append(fileMoves, fm)
		}
		frows.Close()
	}

	// Perform filesystem moves first (with rollback on partial failure).
	for i, fm := range fileMoves {
		if _, err := os.Stat(fm.oldAbs); err != nil {
			for j := 0; j < i; j++ {
				_ = os.Rename(fileMoves[j].newAbs, fileMoves[j].oldAbs)
			}
			return fmt.Errorf("source file not found for move: %w", err)
		}
		_ = os.MkdirAll(filepath.Dir(fm.newAbs), 0o750)
		if err := os.Rename(fm.oldAbs, fm.newAbs); err != nil {
			for j := 0; j < i; j++ {
				_ = os.Rename(fileMoves[j].newAbs, fileMoves[j].oldAbs)
			}
			return fmt.Errorf("move file: %w", err)
		}
	}

	// Atomic DB transaction: title + parent_id + file paths
	nowT := time.Now().UTC().Format(time.RFC3339)
	tx, err := a.db.Begin()
	if err != nil {
		for _, fm := range fileMoves {
			_ = os.Rename(fm.newAbs, fm.oldAbs)
		}
		return fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback()

	if titleChanged {
		slug := nodes.Slugify(nodeTitle)
		if _, err := tx.Exec(
			`UPDATE nodes SET title=?, slug=?, updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`,
			nodeTitle, slug, nowT, nodeID); err != nil {
			for _, fm := range fileMoves {
				_ = os.Rename(fm.newAbs, fm.oldAbs)
			}
			return err
		}
	}

	var parentVal interface{}
	if newParentID != "" {
		parentVal = newParentID
	}
	if _, err := tx.Exec(
		`UPDATE nodes SET parent_id=?, updated_at=?, revision=revision+1 WHERE id=? AND deleted_at IS NULL`,
		parentVal, nowT, nodeID); err != nil {
		for _, fm := range fileMoves {
			_ = os.Rename(fm.newAbs, fm.oldAbs)
		}
		return err
	}

	for _, fm := range fileMoves {
		if _, err := tx.Exec(`UPDATE files SET path=? WHERE id=?`,
			fm.newRelPath, fm.id); err != nil {
			for _, fm2 := range fileMoves {
				_ = os.Rename(fm2.newAbs, fm2.oldAbs)
			}
			return err
		}
	}

	if err := tx.Commit(); err != nil {
		for _, fm := range fileMoves {
			_ = os.Rename(fm.newAbs, fm.oldAbs)
		}
		return fmt.Errorf("commit tx: %w", err)
	}

	if newParentID == "" {
		node.ParentID = nil
	} else {
		node.ParentID = &newParentID
	}

	pid := ""
	if node.ParentID != nil {
		pid = *node.ParentID
	}
	var targetType string
	var evType string
	var syncEntity string
	if node.Type == nodes.TypeNote {
		targetType = activity.TargetNote
		evType = activity.TypeNoteUpdated
		syncEntity = syncsvc.EntityNote
	} else {
		targetType = activity.TargetFile
		evType = activity.TypeFileMoved
		syncEntity = syncsvc.EntityFile
	}
	_ = a.activity.Record(pid, targetType, nodeID, "", evType, nodeTitle, `{"to":"`+newParentID+`"}`)
	_ = a.sync.RecordOp(syncEntity, nodeID, syncsvc.OpMove, map[string]interface{}{
		"parent_id":  newParentID,
		"updated_at": nowT,
	})
	return nil
}

func (a *App) ListEnabledTemplates() ([]TemplateDTO, error) {
	list := a.templates.Enabled()
	result := make([]TemplateDTO, len(list))
	for i, t := range list {
		result[i] = TemplateDTO{
			ID:    t.ID,
			Title: t.Title,
			Type:  t.Type,
			Icon:  t.Icon,
		}
	}
	return result, nil
}

type fileMoveInfo struct {
	id, oldPath, newRelPath string
}

func (a *App) rollbackFileMoves(moves []fileMoveInfo) error {
	for _, fm := range moves {
		oldAbs := filepath.Join(a.vault, fm.oldPath)
		newAbs := filepath.Join(a.vault, fm.newRelPath)
		_ = os.Rename(newAbs, oldAbs)
	}
	return nil
}

func (a *App) OpenNodeFolder(nodeID string) (string, error) {
	n, err := a.nodes.GetActive(nodeID)
	if err != nil {
		return "", err
	}
	if n.FsPath == "" {
		return "", fmt.Errorf("node %s has no physical path", nodeID)
	}
	physPath := filepath.Join(a.vault, n.FsPath)
	return physPath, nil
}