refactor fstree to separate package

fstree.go

@@ -1,117 +0,0 @@
-/*
-This file contains the implementation of an in-memory tree of files and folders that the app used.
-It is initialised at startup and used for state changes in UI and later persisted to disk.
-
-- ruinivist, 30Dec25
-*/
-
-package main
-
-import (
-	"errors"
-	"path/filepath"
-)
-
-// enums for node types
-type FsNodeType int
-
-const (
-	FileNode FsNodeType = iota
-	FolderNode
-)
-
-// ==================== FsNode definition ====================
-// a single node, Fs => deals with file system related info mostly
-// a name for example can be content derived as well
-type FsNode struct {
-	nodeType FsNodeType
-	path     string
-	children []*FsNode
-	parent   *FsNode // for fast traversal up the tree
-	// for view layer
-	expanded bool
-}
-
-func (n *FsNode) FileName() string {
-	return filepath.Base(n.path)
-}
-
-// ==================== FsNode definition ====================
-
-// ==================== FsTree definition ====================
-type FsTree interface {
-	CreateNode(parent *FsNode, name string, nodeType FsNodeType) error
-	DeleteNode(node *FsNode) error
-	ToggleExpand(node *FsNode) error
-}
-
-// reminder: a bit redundant but I this above shows what funcs are there at a glace
-// so I still like to use this pattern ( 30Dec25)
-type FsTreeImpl struct {
-	root *FsNode
-}
-
-func NewFsTree(rootPath string) *FsTreeImpl {
-	root := &FsNode{
-		nodeType: FolderNode,
-		path:     rootPath,
-		children: make([]*FsNode, 0),
-		expanded: true,
-	}
-	walkFileSystemAndBuildTree(rootPath, root)
-
-	return &FsTreeImpl{
-		root: root,
-	}
-}
-
-func (t *FsTreeImpl) CreateNode(parent *FsNode, name string, nodeType FsNodeType) error {
-	if parent == nil {
-		return errors.New("parent node cannot be nil")
-	}
-	if parent.nodeType != FolderNode {
-		return errors.New("can only add nodes to folder nodes")
-	}
-	if name == "" {
-		return errors.New("node name cannot be empty")
-	}
-
-	newNode := &FsNode{
-		nodeType: nodeType,
-		path:     filepath.Join(parent.path, name),
-		children: make([]*FsNode, 0),
-		parent:   parent,
-		expanded: false,
-	}
-
-	parent.children = append(parent.children, newNode)
-	return nil
-}
-
-func (t *FsTreeImpl) DeleteNode(node *FsNode) error {
-	if node == nil {
-		return errors.New("node to delete cannot be nil")
-	}
-	parent := node.parent
-	if parent == nil {
-		return errors.New("node to delete must have a parent")
-	}
-
-	parent.children = RemoveFromSlice(parent.children, node)
-	return nil
-}
-
-// ToggleExpand toggles the expanded state of a node
-func (t *FsTreeImpl) ToggleExpand(node *FsNode) error {
-	if node == nil {
-		return errors.New("node cannot be nil")
-	}
-	if node.nodeType != FolderNode {
-		return errors.New("only folder nodes can be expanded or collapsed")
-	}
-
-	node.expanded = !node.expanded
-	return nil
-}
-
-// ==================== FsTree definition ====================