File System Operations

/**
 * Interface for file system operations used by AutoRest
 */
interface IFileSystem {
  /**
   * Enumerates all file URIs in a given folder
   * @param folderUri - URI of the folder to enumerate
   * @returns Promise resolving to array of file URIs
   */
  EnumerateFileUris(folderUri: string): Promise<Array<string>>;

  /**
   * Reads the content of a file
   * @param uri - URI of the file to read
   * @returns Promise resolving to file content as string
   */
  ReadFile(uri: string): Promise<string>;
}

/**
 * Real file system implementation for accessing actual files
 */
class RealFileSystem implements IFileSystem {
  /**
   * Creates a new RealFileSystem instance
   */
  constructor();

  /**
   * Enumerates file URIs in a folder, filtering for configuration files
   * @param folderUri - URI of the folder to enumerate
   * @returns Promise resolving to array of file URIs
   */
  EnumerateFileUris(folderUri: string): Promise<string[]>;

  /**
   * Reads content from a file URI
   * @param uri - URI of the file to read
   * @returns Promise resolving to file content
   */
  ReadFile(uri: string): Promise<string>;

  /**
   * Writes content to a file URI
   * @param uri - URI of the file to write
   * @param content - Content to write
   * @returns Promise that resolves when write completes
   */
  WriteFile(uri: string, content: string): Promise<void>;
}

import { RealFileSystem } from "@microsoft.azure/autorest-core/lib/file-system";

const fs = new RealFileSystem();

// Read a configuration file
const config = await fs.ReadFile("file:///path/to/autorest.json");
console.log("Config:", JSON.parse(config));

// List files in a directory
const files = await fs.EnumerateFileUris("file:///path/to/specs/");
console.log("Spec files:", files);

// Write generated output
await fs.WriteFile(
  "file:///output/generated-client.ts", 
  "// Generated client code here"
);

/**
 * In-memory file system implementation for testing and isolated operations
 */
class MemoryFileSystem implements IFileSystem {
  /** Default virtual root URI for memory file system */
  static readonly DefaultVirtualRootUri: string = "file:///";

  /**
   * Creates a new MemoryFileSystem with initial files
   * @param files - Map of relative paths to file contents
   */
  constructor(files: Map<string, string>);

  /**
   * Output files written during processing
   */
  readonly Outputs: Map<string, string>;

  /**
   * Reads content from a memory file
   * @param uri - URI of the file to read
   * @returns Promise resolving to file content
   * @throws Error if file doesn't exist
   */
  ReadFile(uri: string): Promise<string>;

  /**
   * Enumerates files in a virtual folder
   * @param folderUri - URI of the folder (defaults to root)
   * @returns Promise resolving to array of file URIs
   */
  EnumerateFileUris(folderUri?: string): Promise<Array<string>>;

  /**
   * Writes content to memory (stored in Outputs map)
   * @param uri - URI of the file to write
   * @param content - Content to write
   * @returns Promise that resolves when write completes
   */
  WriteFile(uri: string, content: string): Promise<void>;
}

import { MemoryFileSystem } from "@microsoft.azure/autorest-core/lib/file-system";

// Create with initial files
const initialFiles = new Map([
  ["swagger.json", JSON.stringify({ swagger: "2.0", info: { title: "Test API" } })],
  ["config.json", JSON.stringify({ "output-folder": "./generated" })]
]);

const memFs = new MemoryFileSystem(initialFiles);

// Read existing file
const swagger = await memFs.ReadFile("file:///swagger.json");
console.log("Swagger spec:", JSON.parse(swagger));

// List all files  
const files = await memFs.EnumerateFileUris();
console.log("Available files:", files);

// Write new file (goes to Outputs)
await memFs.WriteFile("file:///generated/client.ts", "export class ApiClient {}");

// Check outputs
console.log("Generated files:", Array.from(memFs.Outputs.keys()));
console.log("Client content:", memFs.Outputs.get("file:///generated/client.ts"));

/**
 * Enhanced file system with GitHub URI adjustment and authentication
 */
class EnhancedFileSystem implements IFileSystem {
  /**
   * Creates enhanced file system with optional GitHub authentication
   * @param githubAuthToken - Optional GitHub OAuth token for private repos
   */
  constructor(githubAuthToken?: string);

  /**
   * Enumerates file URIs in a folder, filtering for configuration files
   * @param folderUri - URI of the folder to enumerate
   * @returns Promise resolving to array of file URIs
   */
  EnumerateFileUris(folderUri: string): Promise<string[]>;

  /**
   * Reads content from URI with GitHub authentication support
   * @param uri - URI of the file to read (automatically converts GitHub URLs to raw format)
   * @returns Promise resolving to file content
   */
  ReadFile(uri: string): Promise<string>;

  /**
   * Writes content to a file URI
   * @param uri - URI of the file to write
   * @param content - Content to write
   * @returns Promise that resolves when write completes
   */  
  WriteFile(uri: string, content: string): Promise<void>;
}

import { EnhancedFileSystem } from "@microsoft.azure/autorest-core/lib/file-system";

// Create with GitHub token for private repositories
const enhancedFs = new EnhancedFileSystem("ghp_your_github_token_here");

// Read from GitHub (automatically converts to raw URL and adds auth)
const spec = await enhancedFs.ReadFile(
  "https://github.com/myorg/private-specs/blob/main/api.json"
);

// Read from public GitHub repo (no auth needed)
const publicSpec = await enhancedFs.ReadFile(
  "https://github.com/Azure/azure-rest-api-specs/blob/main/specification/cognitiveservices/data-plane/TextAnalytics/preview/v3.1/TextAnalytics.json"
);

// Enumerate files in a local folder
const localFiles = await enhancedFs.EnumerateFileUris("file:///specs/");