File Resource Management

/**
 * File resource implementation with encoding and version management
 */
class FileResource implements Resource {
  /** File URI */
  readonly uri: URI;
  
  /** Resource version information with encoding and timestamps */
  readonly version: FileResourceVersion | undefined;
  
  /** Detected or specified file encoding */
  readonly encoding: string | undefined;
  
  /** Whether file is read-only (boolean or MarkdownString with reason) */
  readonly readOnly: boolean | MarkdownString;
  
  /** Read entire file contents as string with encoding handling */
  readContents(options?: { encoding?: string }): Promise<string>;
  
  /** Read file contents as stream with encoding handling */
  readStream(options?: { encoding?: string }): Promise<ReadableStream<string>>;
  
  /** Detect file encoding using heuristics and BOM detection */
  guessEncoding(): Promise<string>;
  
  /** Save string content to file (available when not read-only) */
  saveContents?: (content: string, options?: SaveOptions) => Promise<void>;
  
  /** Save content stream to file (available when not read-only) */
  saveStream?: (content: ReadableStream<string>, options?: SaveOptions) => Promise<void>;
  
  /** Apply content changes to file (available when not read-only) */
  saveContentChanges?: (changes: TextDocumentContentChangeEvent[], options?: SaveOptions) => Promise<void>;
  
  /** Resource disposal for cleanup */
  dispose(): void;
}

/**
 * File resource version with encoding and timing information
 */
interface FileResourceVersion extends ResourceVersion {
  /** Character encoding of the file */
  readonly encoding: string;
  
  /** Last modification time (Unix timestamp) */
  readonly mtime: number;
  
  /** Entity tag for change detection */
  readonly etag: string;
}

interface ResourceVersion {
  /** Unique version identifier */
  readonly version: string;
}

/**
 * Resolver for creating FileResource instances from URIs
 */
@injectable()
class FileResourceResolver implements ResourceResolver {
  /** Priority for this resolver (lower numbers = higher priority) */
  readonly priority: number = -10;
  
  /** Check if this resolver can handle the given URI */
  canHandle(uri: URI): boolean;
  
  /** Resolve URI to FileResource instance */
  resolve(uri: URI): Promise<FileResource>;
  
  /** Event fired when resources are created or disposed */
  readonly onDidChangeContents: Event<URI>;
}

/**
 * Options for save operations
 */
interface SaveOptions {
  /** Override encoding for this save operation */
  encoding?: string;
  
  /** Create backup before saving */
  backup?: boolean;
  
  /** Format document before saving */
  format?: boolean;
  
  /** Trim trailing whitespace */
  trimTrailingWhitespace?: boolean;
  
  /** Insert final newline if missing */
  insertFinalNewline?: boolean;
  
  /** Force save even if file hasn't changed */
  force?: boolean;
}

/**
 * Incremental content change event
 */
interface TextDocumentContentChangeEvent {
  /** Range being replaced (undefined for full document changes) */
  range?: Range;
  
  /** Length of replaced text */
  rangeLength?: number;
  
  /** New text content */
  text: string;
}

interface Range {
  /** Starting position */
  start: Position;
  
  /** Ending position */
  end: Position;
}

interface Position {
  /** Line number (zero-based) */
  line: number;
  
  /** Character offset (zero-based) */
  character: number;
}

/**
 * Common character encodings supported by FileResource
 */
enum Encoding {
  UTF8 = 'utf8',
  UTF16BE = 'utf16be',
  UTF16LE = 'utf16le',
  UTF32BE = 'utf32be',
  UTF32LE = 'utf32le',
  ASCII = 'ascii',
  ISO88591 = 'iso88591',
  WINDOWS1252 = 'windows1252'
}

/**
 * Encoding detection result
 */
interface EncodingResult {
  /** Detected encoding */
  encoding: string;
  
  /** Confidence level (0-1) */
  confidence: number;
  
  /** Whether BOM was detected */
  hasBOM: boolean;
}

/**
 * Detect encoding from binary data
 */
function detectEncoding(buffer: Uint8Array): EncodingResult;

/**
 * Check if encoding is valid/supported
 */
function isValidEncoding(encoding: string): boolean;

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

// Get resource resolver
const resolver = container.get(FileResourceResolver);

// Resolve file to resource
const fileUri = URI.parse('file:///workspace/src/main.ts');
const resource = await resolver.resolve(fileUri);

// Read file contents
const content = await resource.readContents();
console.log(`File content: ${content}`);

// Read with specific encoding
const contentUtf16 = await resource.readContents({ encoding: 'utf16le' });

// Check if file is read-only
if (typeof resource.readOnly === 'boolean' && !resource.readOnly) {
  // File is writable
  await resource.saveContents?.('console.log("Hello, World!");');
} else {
  console.log('File is read-only');
  if (typeof resource.readOnly !== 'boolean') {
    console.log(`Reason: ${resource.readOnly.value}`);
  }
}

// Stream reading for large files
const stream = await resource.readStream();
const reader = stream.getReader();

try {
  while (true) {
    const { done, value } = await reader.read();
    if (done) break;
    console.log('Chunk:', value);
  }
} finally {
  reader.releaseLock();
}

// Encoding detection
const encoding = await resource.guessEncoding();
console.log(`Detected encoding: ${encoding}`);

// Version information
if (resource.version) {
  console.log(`Version: ${resource.version.version}`);
  console.log(`Encoding: ${resource.version.encoding}`);
  console.log(`Modified: ${new Date(resource.version.mtime)}`);
  console.log(`ETag: ${resource.version.etag}`);
}

// Incremental updates
if (resource.saveContentChanges) {
  await resource.saveContentChanges([{
    range: { start: { line: 0, character: 0 }, end: { line: 0, character: 0 } },
    text: '// Added comment\n'
  }]);
}

// Save with options
await resource.saveContents?.('new content', {
  encoding: 'utf8',
  trimTrailingWhitespace: true,
  insertFinalNewline: true,
  format: true
});

// Resource cleanup
resource.dispose();

import { ResourceProvider, Resource } from "@theia/core/lib/common/resource";

// Working with resource provider
const resourceProvider = container.get(ResourceProvider);

// Get or create resource
const resource = await resourceProvider.get(fileUri);

// Listen for content changes
resource.onDidChangeContents(uri => {
  console.log(`Resource changed: ${uri.toString()}`);
});

// Batch operations with multiple resources
const resources = await Promise.all([
  resourceProvider.get(URI.parse('file:///file1.txt')),
  resourceProvider.get(URI.parse('file:///file2.txt')),
  resourceProvider.get(URI.parse('file:///file3.txt'))
]);

// Read all contents in parallel
const contents = await Promise.all(
  resources.map(resource => resource.readContents())
);

// Save all with same options
const saveOptions = { trimTrailingWhitespace: true, insertFinalNewline: true };
await Promise.all(
  resources.map((resource, index) => 
    resource.saveContents?.(contents[index].toUpperCase(), saveOptions)
  )
);

// Binary file handling
const binaryResource = await resourceProvider.get(URI.parse('file:///image.png'));
const binaryContent = await binaryResource.readContents({ encoding: 'binary' });

// Custom resource with additional functionality
class CustomFileResource extends FileResource {
  
  // Add custom metadata
  async getCustomMetadata(): Promise<any> {
    // Custom implementation
    return {};
  }
  
  // Override encoding detection with custom logic
  async guessEncoding(): Promise<string> {
    // Custom encoding detection logic
    const detected = await super.guessEncoding();
    
    // Apply custom rules
    if (this.uri.path.endsWith('.log')) {
      return 'ascii';  // Force ASCII for log files
    }
    
    return detected;
  }
  
  // Add validation before save
  async saveContents(content: string, options?: SaveOptions): Promise<void> {
    // Validate content before saving
    if (!this.validateContent(content)) {
      throw new Error('Invalid content format');
    }
    
    return super.saveContents!(content, options);
  }
  
  private validateContent(content: string): boolean {
    // Custom validation logic
    return content.length > 0;
  }
}