File Tree Widget System

/**
 * Tree implementation for file system with lazy loading
 */
@injectable()
class FileTree extends TreeImpl {
  /** Resolve child nodes for a parent node with lazy loading */
  resolveChildren(parent: CompositeTreeNode): Promise<TreeNode[]>;
  
  /** Resolve file statistics for a file stat node */
  protected resolveFileStat(node: FileStatNode): Promise<FileStat | undefined>;
  
  /** Convert file statistics to tree nodes */
  protected toNodes(fileStat: FileStat, parent: CompositeTreeNode): Promise<TreeNode[]>;
  
  /** Create individual tree node from file statistics */
  protected toNode(fileStat: FileStat, parent: CompositeTreeNode): FileNode | DirNode;
}

/**
 * Model managing tree state, navigation, and events
 */
@injectable()
interface FileTreeModel extends CompressedTreeModel, LocationService {
  /** Current root location of the file tree */
  location: URI | undefined;
  
  /** Get available drives/roots for navigation */
  drives(): Promise<URI[]>;
  
  /** Get currently selected file stat nodes */
  readonly selectedFileStatNodes: Readonly<FileStatNode>[];
  
  /** Find tree nodes by URI */
  getNodesByUri(uri: URI): IterableIterator<TreeNode>;
  
  /** Navigate to a specific location */
  navigateTo(uri: URI): Promise<TreeNode | undefined>;
  
  /** Copy file or directory to target location */
  copy(source: URI, target: Readonly<FileStatNode>): Promise<URI>;
  
  /** Move file or directory between locations */
  move(source: TreeNode, target: TreeNode): Promise<URI | undefined>;
  
  /** Handle file system change events */
  protected onFilesChanged(changes: FileChangesEvent): void;
  
  /** Check if root directory is affected by changes */
  protected isRootAffected(changes: FileChangesEvent): boolean;
  
  /** Get URIs affected by file system changes */
  protected getAffectedUris(changes: FileChangesEvent): URI[];
  
  /** Refresh nodes affected by file system changes */
  protected refreshAffectedNodes(uris: URI[]): boolean;
  
  /** Get tree nodes affected by URI changes */
  protected getAffectedNodes(uris: URI[]): Map<string, CompositeTreeNode>;
  
  /** Check if user should replace existing file */
  protected shouldReplace(fileName: string): Promise<boolean>;
  
  /** Refresh the tree or specific node */
  refresh(node?: CompositeTreeNode): Promise<void>;
  
  /** Paste from clipboard */
  paste(node?: TreeNode): Promise<void>;
}

/**
 * Tree widget component with drag/drop and context menu support
 */
@injectable()
interface FileTreeWidget extends TreeWidget {
  /** File tree model instance */
  override readonly model: FileTreeModel;
  
  /** Upload service for drag-and-drop file uploads */
  protected readonly uploadService: FileUploadService;
  
  /** Icon theme service for file icons */
  protected readonly iconThemeService: IconThemeService;
  
  /** Create custom node CSS class names */
  protected createNodeClassNames(node: TreeNode, props: NodeProps): string[];
  
  /** Render icon for tree node */
  protected renderIcon(node: TreeNode, props: NodeProps): React.ReactNode;
  
  /** Get tooltip text for node */
  protected getNodeTooltip(node: TreeNode): string | undefined;
  
  /** Handle drag start event for file operations */
  protected handleDragStartEvent(node: TreeNode, event: React.DragEvent): void;
  
  /** Handle drag over event for drop target validation */
  protected handleDragOverEvent(node: TreeNode | undefined, event: React.DragEvent): void;
  
  /** Handle drop event for file operations */
  protected handleDropEvent(node: TreeNode | undefined, event: React.DragEvent): Promise<void>;
  
  /** Get drop effect (copy or move) based on modifier keys */
  protected getDropEffect(event: React.DragEvent): 'copy' | 'move';
  
  /** Check if explorer arrows should be hidden */
  protected get hidesExplorerArrows(): boolean;
  
  /** Serialize node for storage */
  protected deflateForStorage(node: TreeNode): object;
  
  /** Deserialize node from storage */
  protected inflateFromStorage(node: any, parent?: TreeNode): TreeNode;
}

/**
 * Base tree node with file statistics
 */
interface FileStatNode extends SelectableTreeNode, Mutable<UriSelection>, FileSelection {
  /** File statistics for this node (added at runtime) */
  fileStat: FileStat;
}

/**
 * Tree node representing a file
 */
type FileNode = FileStatNode;

/**
 * Tree node representing a directory  
 */
type DirNode = FileStatNode & ExpandableTreeNode;

/**
 * Provides labels and icons for file tree nodes
 */
@injectable()
interface FileTreeLabelProvider extends LabelProvider {
  /** Get display name for file stat node */
  getName(element: FileStatNode): string;
  
  /** Get long name (full path) for file stat node */
  getLongName(element: FileStatNode): string;
  
  /** Get icon class for file stat node */
  getIcon(element: FileStatNode): string;
  
  /** Get CSS classes for file stat node */
  getClassNames(element: FileStatNode): string[];
  
  /** Check if element affects this node's label */
  affects(element: FileStatNode, event: DidChangeLabelEvent): boolean;
}

/**
 * Create configured file tree container
 */
function createFileTreeContainer(parent: interfaces.Container): interfaces.Container;

/**
 * Create configured file tree widget
 */
function createFileTreeWidget(parent: interfaces.Container): FileTreeWidget;

/**
 * Tree decorator for file-specific decorations
 */
@injectable()
interface FileTreeDecoratorAdapter extends TreeDecorator {
  /** Unique identifier for this decorator */
  readonly id: string;
  
  /** Event fired when decorations change */
  readonly onDidChangeDecorations: Event<(tree: Tree) => Map<string, TreeDecoration.Data>>;
  
  /** Get decorations for all nodes in tree */
  decorations(tree: Tree): MaybePromise<Map<string, TreeDecoration.Data>>;
  
  /** Merge node and bubbled decorations */
  protected mergeDecorations(ownDecoration?: TreeDecoration.Data, bubbledDecoration?: TreeDecoration.Data): TreeDecoration.Data | undefined;
  
  /** Convert decorations to Theia format */
  protected toTheiaDecoration(decorations: Decoration[], bubble?: boolean): TreeDecoration.Data;
  
  /** Get URI for tree node */
  protected getUriForNode(node: TreeNode): string | undefined;
  
  /** Trigger decoration change event */
  fireDidChangeDecorations(): void;
}

/** Main file tree CSS class */
const FILE_TREE_CLASS = 'theia-FileTree';

/** File stat node CSS class */
const FILE_STAT_NODE_CLASS = 'theia-FileStatNode';

/** Directory node CSS class */
const DIR_NODE_CLASS = 'theia-DirNode';

/** File stat icon CSS class */
const FILE_STAT_ICON_CLASS = 'theia-FileStatIcon';

/** File tree container factory with default props */
function createFileTreeContainer(
  parent: interfaces.Container, 
  overrides?: Partial<TreeContainerProps>
): Container;

import { FileTreeWidget, FileTreeModel } from "@theia/filesystem/lib/browser";
import { URI } from "@theia/core/lib/common/uri";

// Create and configure file tree widget
const container = createFileTreeContainer(parentContainer);
const fileTree = container.get(FileTreeWidget);

// Set root location
fileTree.model.location = URI.parse('file:///workspace');

// Handle selection changes
fileTree.model.onSelectionChanged(selection => {
  const selectedNodes = fileTree.model.selectedFileStatNodes;
  for (const node of selectedNodes) {
    console.log(`Selected: ${node.fileStat.resource.toString()}`);
  }
});

// Navigate programmatically
await fileTree.model.navigateTo(URI.parse('file:///workspace/src'));

// Reveal specific file
await fileTree.revealFile(URI.parse('file:///workspace/package.json'));

// Handle file operations
fileTree.model.onDidFileOperation(event => {
  console.log(`Operation: ${FileOperation[event.operation]} on ${event.target}`);
});

// Create files and folders
fileTree.createFile(); // Creates in current directory
fileTree.createFolder(); // Creates in current directory

// File upload
fileTree.model.onWillUpload(event => {
  console.log(`Uploading to: ${event.parent.fileStat.resource}`);
});

// Custom context menu
fileTree.registerMenuAction({
  commandId: 'custom.action',
  label: 'Custom Action',
  when: 'explorerResourceIsFile'
});

import { FileTree } from "@theia/filesystem/lib/browser";

// Custom tree with additional functionality
@injectable()
class CustomFileTree extends FileTree {
  
  // Override node creation for custom behavior
  protected toNode(fileStat: FileStat, parent: CompositeTreeNode): FileNode | DirNode {
    const node = super.toNode(fileStat, parent);
    
    // Add custom properties
    if (node.fileStat.isFile && node.fileStat.name.endsWith('.ts')) {
      (node as any).isTypeScript = true;
    }
    
    return node;
  }
  
  // Custom filtering
  protected async toNodes(fileStat: FileStat, parent: CompositeTreeNode): Promise<TreeNode[]> {
    const nodes = await super.toNodes(fileStat, parent);
    
    // Filter out hidden files
    return nodes.filter(node => 
      !node.name.startsWith('.') || this.showHiddenFiles
    );
  }
}

// Multi-selection operations
const selectedNodes = fileTree.model.selectedFileStatNodes;
if (selectedNodes.length > 1) {
  // Bulk operations
  await fileTree.delete(selectedNodes);
}