waitlist-mailer/lib/adapters/storage/MemoryStorage.ts

Modern, modular TypeScript library for managing waitlists with pluggable storage and mail providers. Supports MongoDB, SQL databases, and custom adapters with zero required dependencies for basic usage.

/**
 * In-memory storage adapter for waitlist-mailer.
 * Perfect for development, testing, and small-scale applications.
 * Data is lost when the process terminates.
 */

import { StorageProvider, WaitlistEntry, SearchOptions } from '../../types';

/**
 * Memory-based storage provider implementation.
 * No external dependencies required. Ideal for development and testing.
 * @template T - Optional metadata type
 */
export class MemoryStorage<T = any> implements StorageProvider<T> {
  private storage: Map<string, WaitlistEntry<T>> = new Map();

  /**
   * Add an email to memory storage.
   * @param email - The email to add
   * @param data - Optional metadata
   * @throws {Error} If the email already exists
   */
  async add(email: string, data?: T): Promise<void> {
    const normalized = email.toLowerCase();
    if (this.storage.has(normalized)) {
      throw new Error(`Email already exists: ${email}`);
    }

    this.storage.set(normalized, {
      email,
      metadata: data,
      createdAt: new Date(),
    });
  }

  /**
   * Remove an email from memory storage.
   * @param email - The email to remove
   * @returns true if the email was found and removed
   */
  async remove(email: string): Promise<boolean> {
    return this.storage.delete(email.toLowerCase());
  }

  /**
   * Check if an email exists in storage.
   * @param email - The email to check
   * @returns true if the email exists
   */
  async exists(email: string): Promise<boolean> {
    return this.storage.has(email.toLowerCase());
  }

  /**
   * Retrieve all entries from storage.
   * @returns Array of all WaitlistEntry objects
   */
  async getAll(): Promise<WaitlistEntry<T>[]> {
    return Array.from(this.storage.values());
  }

  /**
   * Count total entries in storage.
   * @returns Number of entries
   */
  async count(): Promise<number> {
    return this.storage.size;
  }

  /**
   * Clear all entries from storage.
   */
  async clear(): Promise<void> {
    this.storage.clear();
  }

  /**
   * Search entries by email pattern.
   * For MemoryStorage, this filters the in-memory Map.
   * @param pattern - The pattern to search for
   * @param options - Optional search options
   * @returns Matching entries
   */
  async search(pattern: string, options: SearchOptions = {}): Promise<WaitlistEntry<T>[]> {
    const { limit, offset = 0, caseInsensitive = true } = options;
    const searchPattern = caseInsensitive ? pattern.toLowerCase() : pattern;
    
    let results: WaitlistEntry<T>[] = [];
    
    for (const entry of this.storage.values()) {
      const emailToMatch = caseInsensitive ? entry.email.toLowerCase() : entry.email;
      if (emailToMatch.includes(searchPattern)) {
        results.push(entry);
      }
    }

    // Apply pagination
    if (offset > 0) {
      results = results.slice(offset);
    }
    if (limit !== undefined && limit > 0) {
      results = results.slice(0, limit);
    }

    return results;
  }

  /**
   * Iterate over entries in batches.
   * For MemoryStorage, yields entries from the in-memory Map.
   * @param batchSize - Number of entries per batch (default: 100)
   */
  async *iterate(batchSize: number = 100): AsyncIterableIterator<WaitlistEntry<T>> {
    const entries = Array.from(this.storage.values());
    for (let i = 0; i < entries.length; i += batchSize) {
      const batch = entries.slice(i, i + batchSize);
      for (const entry of batch) {
        yield entry;
      }
    }
  }
}