V2: Convert Tool (#3828)

🔄 Dynamic Processing Strategies

- Adaptive routing: Same tool uses different backend endpoints based on
file analysis
- Combined vs separate processing: Intelligently chooses between merge
operations and individual file processing
- Cross-format workflows: Enable complex conversions like "mixed files →
PDF" that other tools can't handle

  ⚙️ Format-Specific Intelligence

  Each conversion type gets tailored options:
  - HTML/ZIP → PDF: Zoom controls (0.1-3.0 increments) with live preview
  - Email → PDF: Attachment handling, size limits, recipient control
  - PDF → PDF/A: Digital signature detection with warnings
  - Images → PDF: Smart combining vs individual file options

 File Architecture

  Core Implementation:
  ├── Convert.tsx                     # Main stepped workflow UI
├── ConvertSettings.tsx # Centralized settings with smart detection
├── GroupedFormatDropdown.tsx # Enhanced format selector with grouping
├── useConvertParameters.ts # Smart detection & parameter management
  ├── useConvertOperation.ts         # Multi-strategy processing logic
  └── Settings Components:
      ├── ConvertFromWebSettings.tsx      # HTML zoom controls
      ├── ConvertFromEmailSettings.tsx    # Email attachment options
├── ConvertToPdfaSettings.tsx # PDF/A with signature detection
      ├── ConvertFromImageSettings.tsx    # Image PDF options
      └── ConvertToImageSettings.tsx      # PDF to image options

 Utility Layer

  Utils & Services:
├── convertUtils.ts # Format detection & endpoint routing
  ├── fileResponseUtils.ts          # Generic API response handling
└── setupTests.ts # Enhanced test environment with crypto mocks

  Testing & Quality

  Comprehensive Test Coverage

  Test Suite:
├── useConvertParameters.test.ts # Parameter logic & smart detection
  ├── useConvertParametersAutoDetection.test.ts  # File type analysis
├── ConvertIntegration.test.tsx # End-to-end conversion workflows
  ├── ConvertSmartDetectionIntegration.test.tsx  # Mixed file scenarios
  ├── ConvertE2E.spec.ts                     # Playwright browser tests
├── convertUtils.test.ts # Utility function validation
  └── fileResponseUtils.test.ts              # API response handling

  Advanced Test Features

  - Crypto API mocking: Proper test environment for file hashing
  - File.arrayBuffer() polyfills: Complete browser API simulation
  - Multi-file scenario testing: Complex batch processing validation
- CI/CD integration: Vitest runs in GitHub Actions with proper artifacts

---------

Co-authored-by: Connor Yoh <connor@stirlingpdf.com>
Co-authored-by: Anthony Stirling <77850077+Frooodle@users.noreply.github.com>

frontend/src/utils/fileUtils.ts

@@ -125,4 +125,51 @@ export function cleanupFileUrls(files: FileWithUrl[]): void {
 export function shouldUseDirectIndexedDBAccess(file: FileWithUrl): boolean {
   const FILE_SIZE_LIMIT = 100 * 1024 * 1024; // 100MB
   return file.size > FILE_SIZE_LIMIT;
+}
+
+/**
+ * Detects and normalizes file extension from filename
+ * @param filename - The filename to extract extension from
+ * @returns Normalized file extension in lowercase, empty string if no extension
+ */
+export function detectFileExtension(filename: string): string {
+  if (!filename || typeof filename !== 'string') return '';
+  
+  const parts = filename.split('.');
+  // If there's no extension (no dots or only one part), return empty string
+  if (parts.length <= 1) return '';
+  
+  // Get the last part (extension) in lowercase
+  let extension = parts[parts.length - 1].toLowerCase();
+  
+  // Normalize common extension variants
+  if (extension === 'jpeg') extension = 'jpg';
+  
+  return extension;
+}
+
+/**
+ * Gets the filename without extension
+ * @param filename - The filename to process
+ * @returns Filename without extension
+ */
+export function getFilenameWithoutExtension(filename: string): string {
+  if (!filename || typeof filename !== 'string') return '';
+  
+  const parts = filename.split('.');
+  if (parts.length <= 1) return filename;
+  
+  // Return all parts except the last one (extension)
+  return parts.slice(0, -1).join('.');
+}
+
+/**
+ * Creates a new filename with a different extension
+ * @param filename - Original filename
+ * @param newExtension - New extension (without dot)
+ * @returns New filename with the specified extension
+ */
+export function changeFileExtension(filename: string, newExtension: string): string {
+  const nameWithoutExt = getFilenameWithoutExtension(filename);
+  return `${nameWithoutExt}.${newExtension}`;
 }