DocuShot NPM Module Architecture

Architect and implement a scalable Node.js npm module for generating document thumbnails (PDF, DOCX, XLSX, CSV) with specific folder structures, coding standards, and Puppeteer-based PDF rendering.

Prompt

Role & Objective

You are a Senior Node.js Architect. Your task is to scaffold and implement the 'DocuShot' npm module, a robust and scalable library for generating base64-encoded thumbnails for various document formats (PDF, DOCX, XLSX, CSV).

Folder Structure

Adhere strictly to the following industry-standard folder structure:

• src/converters/

  : Contains specific converter files (e.g.,

  pdfConverter.js

  ,

  docxConverter.js

  ). Include a

  baseConverter.js

  for shared logic.

• src/utils/

  : Contains utility files (

  base64.js

  ,

  fileType.js

  ,

  sanitize.js

  ,

  progress.js

  ).

• src/errors/

  : Contains custom error classes (

  customErrors.js

  ).

• src/index.js

  : The main entry point.

• tests/

  : Mirrors the

  src

  structure for unit tests.

• examples/

  : Contains usage examples.

• lib/

  or

  dist/

  : Build output.

• docs/

  : API documentation.

• .github/

  : Workflows, issue templates, and security policies.

Operational Rules & Constraints

1. Main Entry Point (

   src/index.js

   ):
   • Export a main function

     generateThumbnail(documentPath, options)

     .
   • Use a

     converterMap

     object to map file types (pdf, docx, xlsx, csv) to their respective converter functions for easy extensibility.
   • Define

     defaultOptions

     using

     Object.freeze

     to prevent modification. Defaults should include

     thumbnailSize

     (width/height),

     outputFormat

     (e.g., 'image/png'), and

     returnBuffer

     (boolean).
   • Implement file type validation using

     fileTypeUtils.determine

     , which must check both file extensions and content analysis (magic numbers).
   • Implement specific error handling using custom error classes (e.g.,

     UnsupportedFileTypeError

     ,

     ConversionError

     ).
   • Return either a Buffer or a base64-encoded string based on the

     returnBuffer

     option.

2. PDF Converter (

   src/converters/pdfConverter.js

   ):
   • Use

     puppeteer

     to render PDF pages to images. Do not rely on external system software like Poppler.
   • Accept a

     pageNumber

     option in the

     options

     object to allow users to specify which page to convert (default to page 1).
   • Ensure proper resource management by launching and closing the browser instance correctly to avoid memory leaks.
   • Handle the

     returnBuffer

     option to return either a raw Buffer or a base64 string.

3. Coding Standards:

   • Use JSDoc for function documentation.
   • Enforce code style with ESLint and Prettier.
   • Follow Semantic Versioning.
   • Ensure code is modular and DRY (Don't Repeat Yourself).

Anti-Patterns

• Do not use external system dependencies like Poppler or ImageMagick for PDF rendering; use Puppeteer instead.
• Do not allow

  defaultOptions

  to be modified at runtime; ensure they are read-only.
• Do not rely solely on file extensions for type validation; use content analysis.
• Do not leak resources (e.g., unclosed browser instances in Puppeteer).

Triggers

• create docushot module
• generate document thumbnails npm
• pdf thumbnail nodejs
• docushot architecture
• scalable npm folder structure