qmemory/index.js

A comprehensive production-ready Node.js utility library with MongoDB document operations, user ownership enforcement, Express.js HTTP utilities, environment-aware logging, and in-memory storage. Features 96%+ test coverage with comprehensive error handli

/**
 * My NPM Module
 * A simple Node.js module with database utilities
 * 
 * This serves as the main entry point for the NPM module, organizing and re-exporting
 * functionality from specialized modules in the /lib directory. This approach follows
 * the barrel pattern, providing a clean public API while maintaining internal code
 * organization.
 * 
 * Design rationale: By separating concerns into different modules and re-exporting
 * them here, we achieve better maintainability, testability, and allow consumers
 * to import everything from a single location while keeping the internal structure
 * flexible for future changes.
 */

// Import organized modules - each module handles a specific domain of functionality
// This separation allows for easier testing, maintenance, and selective importing
const {
  sendNotFound,
  sendConflict,
  sendInternalServerError,
  sendServiceUnavailable // helper for 503 responses
} = require('./lib/http-utils'); // Central location for HTTP helpers promotes consistency
const { ensureMongoDB, ensureUnique } = require('./lib/database-utils'); // Database helpers keep controllers clean
const {
  performUserDocOp,
  findUserDoc,
  deleteUserDoc,
  userDocActionOr404,
  fetchUserDocOr404,
  deleteUserDocOr404,
  listUserDocs,
  createUniqueDoc,
  updateUserDoc, // helper to update user documents safely
  validateDocumentUniqueness, // helper for uniqueness validation
  hasUniqueFieldChanges // helper for change detection
} = require('./lib/document-ops'); // Higher level document handling utilities
const { MemStorage, storage } = require('./lib/storage'); // in-memory storage class and singleton instance
const { greet, add, isEven } = require('./lib/utils'); // basic utility functions for common operations
const { logFunctionEntry, logFunctionExit, logFunctionError } = require('./lib/logging-utils'); // centralized logging patterns

// Export all functions for use as a module
// This barrel export pattern provides a single import point for consumers
// while maintaining internal organization. Each category is grouped logically
// to help consumers understand the available functionality at a glance.
module.exports = { // re-exposes modules so consumers import from one place
  // HTTP utilities - Express.js response helpers re-exposed from http-utils
  // Centralized HTTP response handling reduces duplication across controllers
  sendNotFound, // 404 response helper re-exported for convenience
  sendConflict, // 409 conflict helper re-exported for barrel pattern
  sendInternalServerError, // 500 response helper re-exported for consistency
  sendServiceUnavailable, // 503 response helper re-exported for unified API

  // Database utilities - MongoDB connection and validation helpers re-exposed from database-utils
  // These functions provide robust database interaction patterns with proper error handling
  ensureMongoDB, // initializes MongoDB connection for consumers
  ensureUnique, // duplicate check helper re-exported for unified API

  // Document operations - High-level document manipulation utilities re-exposed from document-ops
  // These encapsulate common CRUD patterns for user-owned documents,
  // reducing boilerplate in application controllers and ensuring consistent behavior
  performUserDocOp, // wrapper for generic document operations
  findUserDoc, // fetches a document scoped to the current user
  deleteUserDoc, // removes a user owned document safely
  userDocActionOr404, // triggers action or returns 404 if not found
  fetchUserDocOr404, // retrieves a document or fails with 404
  deleteUserDocOr404, // deletes a document or fails with 404
  listUserDocs, // lists documents for a specific user
  createUniqueDoc, // creates a document enforcing unique fields
  updateUserDoc, // update with uniqueness checks re-exported for convenience
  validateDocumentUniqueness, // helper for uniqueness validation re-exported
  hasUniqueFieldChanges, // helper for change detection re-exported

  // Storage - In-memory storage implementation and singleton instance re-exposed from storage module
  // Provides both the class for custom instantiation and a ready-to-use singleton
  MemStorage, // storage class allowing separate instances
  storage, // shared singleton instance re-exported for convenience

  // Basic utilities - Common helper functions for everyday operations re-exposed from utils
  // Simple, reusable functions for string formatting, math, and data validation
  greet, // generates a greeting string
  add, // performs simple integer addition
  isEven, // checks numeric parity

  // Logging utilities - Centralized logging patterns for consistent debugging re-exposed from logging-utils
  // Standardized logging functions for function entry, exit, and error tracking
  logFunctionEntry, // logs when a function begins execution
  logFunctionExit, // logs when a function completes execution
  logFunctionError // logs errors with context
};