init

src/modules/cart/repositories/cart.repository.ts

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+import { Injectable } from '@nestjs/common';
+import { CacheService } from '../../utils/cache.service';
+import { Cart } from '../interfaces/cart.interface';
+
+@Injectable()
+export class CartRepository {
+  private readonly CART_TTL = 3600; // 1 hour in seconds
+  private readonly CART_KEY_PREFIX = 'cart';
+
+  constructor(private readonly cacheService: CacheService) {}
+
+  /**
+   * Get cart by user and restaurant
+   */
+  async findByUserAndRestaurant(userId: string, restaurantId: string): Promise<Cart | null> {
+    const cacheKey = this.getCacheKey(userId, restaurantId);
+    const cachedCart = await this.cacheService.get<string>(cacheKey);
+
+    if (cachedCart) {
+      try {
+        const parsed: unknown = JSON.parse(cachedCart);
+        if (this.isCart(parsed) && parsed.userId === userId && parsed.restaurantId === restaurantId) {
+          return parsed;
+        }
+      } catch {
+        // If parsing fails, return null
+      }
+    }
+
+    return null;
+  }
+
+  /**
+   * Save cart to cache
+   */
+  async save(cart: Cart): Promise<void> {
+    const cacheKey = this.getCacheKey(cart.userId, cart.restaurantId);
+    await this.cacheService.set(cacheKey, JSON.stringify(cart), this.CART_TTL);
+  }
+
+  /**
+   * Delete cart from cache
+   */
+  async delete(userId: string, restaurantId: string): Promise<void> {
+    const cacheKey = this.getCacheKey(userId, restaurantId);
+    await this.cacheService.del(cacheKey);
+  }
+
+  /**
+   * Generate cache key for cart
+   */
+  private getCacheKey(userId: string, restaurantId: string): string {
+    return `${this.CART_KEY_PREFIX}:${userId}:${restaurantId}`;
+  }
+
+  /**
+   * Type guard to check if an object is a Cart
+   */
+  private isCart(obj: unknown): obj is Cart {
+    if (typeof obj !== 'object' || obj === null) {
+      return false;
+    }
+    const cart = obj as Record<string, unknown>;
+    return (
+      typeof cart.userId === 'string' &&
+      typeof cart.restaurantId === 'string' &&
+      Array.isArray(cart.items) &&
+      typeof cart.subTotal === 'number' &&
+      typeof cart.itemsDiscount === 'number' &&
+      typeof cart.couponDiscount === 'number' &&
+      typeof cart.totalDiscount === 'number' &&
+      typeof cart.tax === 'number' &&
+      typeof cart.deliveryFee === 'number' &&
+      typeof cart.total === 'number' &&
+      typeof cart.totalItems === 'number' &&
+      typeof cart.createdAt === 'string' &&
+      typeof cart.updatedAt === 'string'
+    );
+  }
+}
+