Function validateFileType

apps/sim/lib/uploads/utils/validation.ts:256–285

(fileName: string, mimeType: string)

 * Validate if a file type is supported for document processing
 */
export function validateFileType(fileName: string, mimeType: string): FileValidationError | null {
  const raw = extractExtension(fileName)
  const extension = (isAlphanumericExtension(raw) ? raw : '') as SupportedDocumentExtension

  if (!SUPPORTED_DOCUMENT_EXTENSIONS.includes(extension)) {
    return {
      code: 'UNSUPPORTED_FILE_TYPE',
      message: `Unsupported file type${extension ? `: ${extension}` : ` for "${fileName}"`}. Supported types are: ${SUPPORTED_DOCUMENT_EXTENSIONS.join(', ')}`,
      supportedTypes: [...SUPPORTED_DOCUMENT_EXTENSIONS],
    }
  }

  const baseMimeType = mimeType.split(';')[0].trim()

  // Allow empty MIME types if the extension is supported (browsers often don't recognize certain file types)
  if (!baseMimeType) {
    return null
  }

  const allowedMimeTypes = SUPPORTED_MIME_TYPES[extension]
  if (!allowedMimeTypes.includes(baseMimeType)) {
    return {
      code: 'MIME_TYPE_MISMATCH',
      message: `MIME type ${baseMimeType} does not match file extension ${extension}. Expected: ${allowedMimeTypes.join(', ')}`,
      supportedTypes: allowedMimeTypes,
    }
  }

  return null
}

/**
 * Check if file extension is supported