Show native save dialogs in desktop app #50, #264

This commit introduces native operating system file dialogs in the
desktop application replacing the existing web-based dialogs.

It lays the foundation for future enhancements such as:

- Providing error messages when saving or executing files, addressing
  #264.
- Creating system restore points, addressing #50.

Documentation updates:

- Update `desktop-vs-web-features.md` with added functionality.
- Update `README.md` with security feature highlights.
- Update home page documentation to emphasize security features.

Other supporting changes include:

- Integrate IPC communication channels for secure Electron dialog API
  interactions.
- Refactor `IpcRegistration` for more type-safety and simplicity.
- Introduce a Vue hook to encapsulate dialog functionality.
- Improve errors during IPC registration for easier troubleshooting.
- Move `ClientLoggerFactory` for consistency in hooks organization and
  remove `LoggerFactory` interface for simplicity.
- Add tests for the save file dialog in the browser context.
- Add `Blob` polyfill in tests to compensate for the missing
  `blob.text()` function in `jsdom` (see jsdom/jsdom#2555).

Improve environment detection logic:

- Treat test environment as browser environments to correctly activate
  features based on the environment. This resolves issues where the
  environment is misidentified as desktop, but Electron preloader APIs
  are missing.
- Rename `isDesktop` environment identification variable to
  `isRunningAsDesktopApplication` for better clarity and to avoid
  confusion with desktop environments in web/browser/test environments.
- Simplify `BrowserRuntimeEnvironment` to consistently detect
  non-desktop application environments.
- Improve environment detection for Electron main process
  (electron/electron#2288).

src/infrastructure/Dialog/Browser/BrowserDialog.ts

@@ -0,0 +1,19 @@
+import { Dialog, FileType } from '@/presentation/common/Dialog';
+import { FileSaverDialog } from './FileSaverDialog';
+import { BrowserSaveFileDialog } from './BrowserSaveFileDialog';
+
+export class BrowserDialog implements Dialog {
+  constructor(private readonly saveFileDialog: BrowserSaveFileDialog = new FileSaverDialog()) {
+
+  }
+
+  public saveFile(
+    fileContents: string,
+    fileName: string,
+    type: FileType,
+  ): Promise<void> {
+    return Promise.resolve(
+      this.saveFileDialog.saveFile(fileContents, fileName, type),
+    );
+  }
+}

src/infrastructure/Dialog/Browser/BrowserSaveFileDialog.ts

@@ -0,0 +1,9 @@
+import { FileType } from '@/presentation/common/Dialog';
+
+export interface BrowserSaveFileDialog {
+  saveFile(
+    fileContents: string,
+    fileName: string,
+    fileType: FileType,
+  ): void;
+}

src/infrastructure/Dialog/Browser/FileSaverDialog.ts

@@ -0,0 +1,39 @@
+import fileSaver from 'file-saver';
+import { FileType } from '@/presentation/common/Dialog';
+import { BrowserSaveFileDialog } from './BrowserSaveFileDialog';
+
+export type SaveAsFunction = (data: Blob, filename?: string) => void;
+
+export type WindowOpenFunction = (url: string, target: string, features: string) => void;
+
+export class FileSaverDialog implements BrowserSaveFileDialog {
+  constructor(
+    private readonly fileSaverSaveAs: SaveAsFunction = fileSaver.saveAs,
+    private readonly windowOpen: WindowOpenFunction = window.open.bind(window),
+  ) { }
+
+  public saveFile(
+    fileContents: string,
+    fileName: string,
+    fileType: FileType,
+  ): void {
+    const mimeType = MimeTypes[fileType];
+    this.saveBlob(fileContents, mimeType, fileName);
+  }
+
+  private saveBlob(file: BlobPart, mimeType: string, fileName: string): void {
+    try {
+      const blob = new Blob([file], { type: mimeType });
+      this.fileSaverSaveAs(blob, fileName);
+    } catch (e) {
+      this.windowOpen(`data:${mimeType},${encodeURIComponent(file.toString())}`, '_blank', '');
+    }
+  }
+}
+
+const MimeTypes: Record<FileType, string> = {
+  // Some browsers (including firefox + IE) require right mime type
+  // otherwise they ignore extension and save the file as text.
+  [FileType.BatchFile]: 'application/bat', // https://en.wikipedia.org/wiki/Batch_file
+  [FileType.ShellScript]: 'text/x-shellscript', // https://de.wikipedia.org/wiki/Shellskript#MIME-Typ
+} as const;

src/infrastructure/Dialog/Electron/ElectronDialog.ts

@@ -0,0 +1,17 @@
+import { Dialog, FileType } from '@/presentation/common/Dialog';
+import { NodeElectronSaveFileDialog } from './NodeElectronSaveFileDialog';
+import { ElectronSaveFileDialog } from './ElectronSaveFileDialog';
+
+export class ElectronDialog implements Dialog {
+  constructor(
+    private readonly fileSaveDialog: ElectronSaveFileDialog = new NodeElectronSaveFileDialog(),
+  ) { }
+
+  public async saveFile(
+    fileContents: string,
+    fileName: string,
+    type: FileType,
+  ): Promise<void> {
+    await this.fileSaveDialog.saveFile(fileContents, fileName, type);
+  }
+}

src/infrastructure/Dialog/Electron/ElectronSaveFileDialog.ts

@@ -0,0 +1,9 @@
+import { FileType } from '@/presentation/common/Dialog';
+
+export interface ElectronSaveFileDialog {
+  saveFile(
+    fileContents: string,
+    fileName: string,
+    type: FileType,
+  ): Promise<void>;
+}

src/infrastructure/Dialog/Electron/NodeElectronSaveFileDialog.ts

@@ -0,0 +1,98 @@
+import { join } from 'node:path';
+import { writeFile } from 'node:fs/promises';
+import { app, dialog } from 'electron/main';
+import { Logger } from '@/application/Common/Log/Logger';
+import { ElectronLogger } from '@/infrastructure/Log/ElectronLogger';
+import { FileType } from '@/presentation/common/Dialog';
+import { ElectronSaveFileDialog } from './ElectronSaveFileDialog';
+
+export interface ElectronFileDialogOperations {
+  getUserDownloadsPath(): string;
+  showSaveDialog(options: Electron.SaveDialogOptions): Promise<Electron.SaveDialogReturnValue>;
+}
+
+export interface NodeFileOperations {
+  readonly join: typeof join;
+  writeFile(file: string, data: string): Promise<void>;
+}
+
+export class NodeElectronSaveFileDialog implements ElectronSaveFileDialog {
+  constructor(
+    private readonly logger: Logger = ElectronLogger,
+    private readonly electron: ElectronFileDialogOperations = {
+      getUserDownloadsPath: () => app.getPath('downloads'),
+      showSaveDialog: dialog.showSaveDialog.bind(dialog),
+    },
+    private readonly node: NodeFileOperations = {
+      join,
+      writeFile,
+    },
+  ) { }
+
+  public async saveFile(
+    fileContents: string,
+    fileName: string,
+    type: FileType,
+  ): Promise<void> {
+    const userSelectedFilePath = await this.showSaveFileDialog(fileName, type);
+    if (!userSelectedFilePath) {
+      this.logger.info(`File save cancelled by user: ${fileName}`);
+      return;
+    }
+    await this.writeFile(userSelectedFilePath, fileContents);
+  }
+
+  private async writeFile(filePath: string, fileContents: string): Promise<void> {
+    try {
+      this.logger.info(`Saving file: ${filePath}`);
+      await this.node.writeFile(filePath, fileContents);
+      this.logger.info(`File saved: ${filePath}`);
+    } catch (error) {
+      this.logger.error(`Error saving file: ${error.message}`);
+    }
+  }
+
+  private async showSaveFileDialog(fileName: string, type: FileType): Promise<string | undefined> {
+    const downloadsFolder = this.electron.getUserDownloadsPath();
+    const defaultFilePath = this.node.join(downloadsFolder, fileName);
+    const dialogResult = await this.electron.showSaveDialog({
+      title: fileName,
+      defaultPath: defaultFilePath,
+      filters: getDialogFileFilters(type),
+      properties: [
+        'createDirectory', // Enables directory creation on macOS.
+        'showOverwriteConfirmation', // Shows overwrite confirmation on Linux.
+      ],
+    });
+    if (dialogResult.canceled) {
+      return undefined;
+    }
+    return dialogResult.filePath;
+  }
+}
+
+function getDialogFileFilters(fileType: FileType): Electron.FileFilter[] {
+  const filters = FileTypeSpecificFilters[fileType];
+  return [
+    ...filters,
+    {
+      name: 'All Files',
+      extensions: ['*'],
+    },
+  ];
+}
+
+const FileTypeSpecificFilters: Record<FileType, Electron.FileFilter[]> = {
+  [FileType.BatchFile]: [
+    {
+      name: 'Batch Files',
+      extensions: ['bat', 'cmd'],
+    },
+  ],
+  [FileType.ShellScript]: [
+    {
+      name: 'Shell Scripts',
+      extensions: ['sh', 'bash', 'zsh'],
+    },
+  ],
+};

src/infrastructure/RuntimeEnvironment/Browser/BrowserOs/BrowserConditions.ts

@@ -84,4 +84,23 @@ export const BrowserConditions: readonly BrowserCondition[] = [
     notExistingPartsInUserAgent: ['like Mac OS X'], // Eliminate iOS and iPadOS for Safari
     touchSupport: TouchSupportExpectation.MustNotExist, // Distinguish from iPadOS for Safari
   },
+  ...generateJsdomBrowserConditions(),
 ] as const;
+
+function generateJsdomBrowserConditions(): readonly BrowserCondition[] {
+  // jsdom user agent format: `Mozilla/5.0 (${process.platform || "unknown OS"}) ...` (https://archive.ph/2023.02.14-193200/https://github.com/jsdom/jsdom#advanced-configuration)
+  const operatingSystemPlatformMap: Partial<Record<
+  OperatingSystem,
+  NodeJS.Platform> // Enforce right platform constants at compile time
+  > = {
+    [OperatingSystem.Linux]: 'linux',
+    [OperatingSystem.Windows]: 'win32',
+    [OperatingSystem.macOS]: 'darwin',
+  } as const;
+  return Object
+    .entries(operatingSystemPlatformMap)
+    .map(([operatingSystemKey, platformString]): BrowserCondition => ({
+      operatingSystem: Number(operatingSystemKey),
+      existingPartsInSameUserAgent: ['jsdom', platformString],
+    }));
+}

src/infrastructure/RuntimeEnvironment/Browser/BrowserRuntimeEnvironment.ts

@@ -1,5 +1,4 @@
 import { OperatingSystem } from '@/domain/OperatingSystem';
-import { WindowVariables } from '@/infrastructure/WindowVariables/WindowVariables';
 import { IEnvironmentVariables } from '@/infrastructure/EnvironmentVariables/IEnvironmentVariables';
 import { EnvironmentVariablesFactory } from '@/infrastructure/EnvironmentVariables/EnvironmentVariablesFactory';
 import { RuntimeEnvironment } from '../RuntimeEnvironment';
@@ -8,7 +7,7 @@ import { BrowserEnvironment, BrowserOsDetector } from './BrowserOs/BrowserOsDete
 import { isTouchEnabledDevice } from './TouchSupportDetection';
 
 export class BrowserRuntimeEnvironment implements RuntimeEnvironment {
-  public readonly isDesktop: boolean;
+  public readonly isRunningAsDesktopApplication: boolean;
 
   public readonly os: OperatingSystem | undefined;
 
@@ -18,31 +17,34 @@ export class BrowserRuntimeEnvironment implements RuntimeEnvironment {
     window: Partial<Window>,
     environmentVariables: IEnvironmentVariables = EnvironmentVariablesFactory.Current.instance,
     browserOsDetector: BrowserOsDetector = new ConditionBasedOsDetector(),
-    touchDetector = isTouchEnabledDevice,
+    touchDetector: TouchDetector = isTouchEnabledDevice,
   ) {
     if (!window) { throw new Error('missing window'); } // do not trust strictNullChecks for global objects
     this.isNonProduction = environmentVariables.isNonProduction;
-    this.isDesktop = isDesktop(window);
-    if (this.isDesktop) {
-      this.os = window?.os;
-    } else {
-      this.os = undefined;
-      const userAgent = getUserAgent(window);
-      if (userAgent) {
-        const browserEnvironment: BrowserEnvironment = {
-          userAgent,
-          isTouchSupported: touchDetector(),
-        };
-        this.os = browserOsDetector.detect(browserEnvironment);
-      }
-    }
+    this.isRunningAsDesktopApplication = isElectronRendererProcess(window);
+    this.os = determineOperatingSystem(window, touchDetector, browserOsDetector);
   }
 }
 
-function getUserAgent(window: Partial<Window>): string | undefined {
-  return window?.navigator?.userAgent;
+function isElectronRendererProcess(globalWindow: Partial<Window>): boolean {
+  return globalWindow.isRunningAsDesktopApplication === true; // Preloader injects this
+  // We could also do `globalWindow?.navigator?.userAgent?.includes('Electron') === true;`
 }
 
-function isDesktop(window: Partial<WindowVariables>): boolean {
-  return window?.isDesktop === true;
+function determineOperatingSystem(
+  globalWindow: Partial<Window>,
+  touchDetector: TouchDetector,
+  browserOsDetector: BrowserOsDetector,
+): OperatingSystem | undefined {
+  const userAgent = globalWindow?.navigator?.userAgent;
+  if (!userAgent) {
+    return undefined;
+  }
+  const browserEnvironment: BrowserEnvironment = {
+    userAgent,
+    isTouchSupported: touchDetector(),
+  };
+  return browserOsDetector.detect(browserEnvironment);
 }
+
+type TouchDetector = () => boolean;

src/infrastructure/RuntimeEnvironment/Node/NodeRuntimeEnvironment.ts

@@ -3,7 +3,7 @@ import { RuntimeEnvironment } from '../RuntimeEnvironment';
 import { convertPlatformToOs } from './NodeOsMapper';
 
 export class NodeRuntimeEnvironment implements RuntimeEnvironment {
-  public readonly isDesktop: boolean;
+  public readonly isRunningAsDesktopApplication: boolean;
 
   public readonly os: OperatingSystem | undefined;
 
@@ -14,7 +14,7 @@ export class NodeRuntimeEnvironment implements RuntimeEnvironment {
     convertToOs: PlatformToOperatingSystemConverter = convertPlatformToOs,
   ) {
     if (!nodeProcess) { throw new Error('missing process'); } // do not trust strictNullChecks for global objects
-    this.isDesktop = true;
+    this.isRunningAsDesktopApplication = true;
     this.os = convertToOs(nodeProcess.platform);
     this.isNonProduction = nodeProcess.env.NODE_ENV !== 'production'; // populated by Vite
   }

src/infrastructure/RuntimeEnvironment/RuntimeEnvironment.ts

@@ -1,7 +1,7 @@
 import { OperatingSystem } from '@/domain/OperatingSystem';
 
 export interface RuntimeEnvironment {
-  readonly isDesktop: boolean;
+  readonly isRunningAsDesktopApplication: boolean;
   readonly os: OperatingSystem | undefined;
   readonly isNonProduction: boolean;
 }

src/infrastructure/RuntimeEnvironment/RuntimeEnvironmentFactory.ts

@@ -3,32 +3,47 @@ import { NodeRuntimeEnvironment } from './Node/NodeRuntimeEnvironment';
 import { RuntimeEnvironment } from './RuntimeEnvironment';
 
 export const CurrentEnvironment = determineAndCreateRuntimeEnvironment({
-  getGlobalWindow: () => globalThis.window,
-  getGlobalProcess: () => globalThis.process,
+  window: globalThis.window,
+  process: globalThis.process,
 });
 
 export function determineAndCreateRuntimeEnvironment(
-  globalAccessor: GlobalAccessor,
+  globalAccessor: GlobalPropertiesAccessor,
   browserEnvironmentFactory: BrowserRuntimeEnvironmentFactory = (
     window,
   ) => new BrowserRuntimeEnvironment(window),
-  nodeEnvironmentFactory: NodeRuntimeEnvironmentFactory = () => new NodeRuntimeEnvironment(),
+  nodeEnvironmentFactory: NodeRuntimeEnvironmentFactory = (
+    process: NodeJS.Process,
+  ) => new NodeRuntimeEnvironment(process),
 ): RuntimeEnvironment {
-  if (globalAccessor.getGlobalProcess()) {
-    return nodeEnvironmentFactory();
+  if (isElectronMainProcess(globalAccessor.process)) {
+    return nodeEnvironmentFactory(globalAccessor.process);
   }
-  const window = globalAccessor.getGlobalWindow();
-  if (window) {
-    return browserEnvironmentFactory(window);
+  const { window } = globalAccessor;
+  if (!window) {
+    throw new Error('Unsupported runtime environment: The current context is neither a recognized browser nor a desktop environment.');
   }
-  throw new Error('Unsupported runtime environment: The current context is neither a recognized browser nor a Node.js environment.');
+  return browserEnvironmentFactory(window);
+}
+
+function isElectronMainProcess(
+  nodeProcess: NodeJS.Process | undefined,
+): nodeProcess is NodeJS.Process {
+  // Electron populates `nodeProcess.versions.electron` with its version, see https://web.archive.org/web/20240113162837/https://www.electronjs.org/docs/latest/api/process#processversionselectron-readonly.
+  if (!nodeProcess) {
+    return false;
+  }
+  if (nodeProcess.versions.electron) {
+    return true;
+  }
+  return false;
 }
 
 export type BrowserRuntimeEnvironmentFactory = (window: Window) => RuntimeEnvironment;
 
-export type NodeRuntimeEnvironmentFactory = () => NodeRuntimeEnvironment;
+export type NodeRuntimeEnvironmentFactory = (process: NodeJS.Process) => NodeRuntimeEnvironment;
 
-export interface GlobalAccessor {
-  getGlobalWindow(): Window | undefined;
-  getGlobalProcess(): NodeJS.Process | undefined;
+export interface GlobalPropertiesAccessor {
+  readonly window: Window | undefined;
+  readonly process: NodeJS.Process | undefined;
 }

src/infrastructure/SaveFileDialog.ts

@@ -1,33 +0,0 @@
-import fileSaver from 'file-saver';
-
-export enum FileType {
-  BatchFile,
-  ShellScript,
-}
-
-export class SaveFileDialog {
-  public static saveFile(
-    text: string,
-    fileName: string,
-    type: FileType,
-  ): void {
-    const mimeType = this.mimeTypes[type];
-    this.saveBlob(text, mimeType, fileName);
-  }
-
-  private static readonly mimeTypes: Record<FileType, string> = {
-    // Some browsers (including firefox + IE) require right mime type
-    // otherwise they ignore extension and save the file as text.
-    [FileType.BatchFile]: 'application/bat', // https://en.wikipedia.org/wiki/Batch_file
-    [FileType.ShellScript]: 'text/x-shellscript', // https://de.wikipedia.org/wiki/Shellskript#MIME-Typ
-  };
-
-  private static saveBlob(file: BlobPart, fileType: string, fileName: string): void {
-    try {
-      const blob = new Blob([file], { type: fileType });
-      fileSaver.saveAs(blob, fileName);
-    } catch (e) {
-      window.open(`data:${fileType},${encodeURIComponent(file.toString())}`, '_blank', '');
-    }
-  }
-}

src/infrastructure/WindowVariables/WindowVariables.ts

@@ -1,11 +1,13 @@
 import { OperatingSystem } from '@/domain/OperatingSystem';
 import { Logger } from '@/application/Common/Log/Logger';
 import { CodeRunner } from '@/application/CodeRunner/CodeRunner';
+import { Dialog } from '@/presentation/common/Dialog';
 
 /* Primary entry point for platform-specific injections */
 export interface WindowVariables {
-  readonly isDesktop: boolean;
+  readonly isRunningAsDesktopApplication?: true;
   readonly codeRunner?: CodeRunner;
   readonly os?: OperatingSystem;
-  readonly log: Logger;
+  readonly log?: Logger;
+  readonly dialog?: Dialog;
 }

src/infrastructure/WindowVariables/WindowVariablesValidator.ts

@@ -18,13 +18,14 @@ export function validateWindowVariables(variables: Partial<WindowVariables>) {
 }
 
 function* testEveryProperty(variables: Partial<WindowVariables>): Iterable<string> {
-  const tests: {
-    [K in PropertyKeys<Required<WindowVariables>>]: boolean;
-  } = {
+  const tests: Record<PropertyKeys<Required<WindowVariables>>, boolean> = {
     os: testOperatingSystem(variables.os),
-    isDesktop: testIsDesktop(variables.isDesktop),
+    isRunningAsDesktopApplication: testIsRunningAsDesktopApplication(
+      variables.isRunningAsDesktopApplication,
+    ),
     codeRunner: testCodeRunner(variables),
     log: testLogger(variables),
+    dialog: testDialog(variables),
   };
 
   for (const [propertyName, testResult] of Object.entries(tests)) {
@@ -48,23 +49,30 @@ function testOperatingSystem(os: unknown): boolean {
 }
 
 function testLogger(variables: Partial<WindowVariables>): boolean {
-  if (!variables.isDesktop) {
+  if (!variables.isRunningAsDesktopApplication) {
     return true;
   }
   return isPlainObject(variables.log);
 }
 
 function testCodeRunner(variables: Partial<WindowVariables>): boolean {
-  if (!variables.isDesktop) {
+  if (!variables.isRunningAsDesktopApplication) {
     return true;
   }
   return isPlainObject(variables.codeRunner)
     && isFunction(variables.codeRunner.runCode);
 }
 
-function testIsDesktop(isDesktop: unknown): boolean {
-  if (isDesktop === undefined) {
+function testIsRunningAsDesktopApplication(isRunningAsDesktopApplication: unknown): boolean {
+  if (isRunningAsDesktopApplication === undefined) {
     return true;
   }
-  return isBoolean(isDesktop);
+  return isBoolean(isRunningAsDesktopApplication);
+}
+
+function testDialog(variables: Partial<WindowVariables>): boolean {
+  if (!variables.isRunningAsDesktopApplication) {
+    return true;
+  }
+  return isPlainObject(variables.dialog);
 }