└── readme.md


/readme.md:
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  1 | # 1. Database Architecture Design
  2 | 
  3 | Designing a database for an e-commerce platform involves considering various aspects such as user profiles, product listings, categories, orders, and transaction history. The choice between a Relational Database Management System (RDBMS) or a NoSQL database depends on the specific requirements of the platform.
  4 | 
  5 | ### Database System Choice:
  6 | 
  7 | For an e-commerce platform with structured data and complex relationships (users, products, orders), an RDBMS like PostgreSQL, MySQL, or Microsoft SQL Server might be suitable. If there is a need for flexibility in data models or scalability, a NoSQL solution like MongoDB could be considered.
  8 | 
  9 | ### Database Architecture:
 10 | 
 11 | 1. **User Profiles:**
 12 |     - **Table/Collection:** `Users`
 13 |     - **Fields:**
 14 |         - UserID (Primary Key)
 15 |         - Username
 16 |         - Email
 17 |         - Password (Hashed)
 18 |         - Address
 19 |         - Phone Number
 20 |         - Other relevant user information
 21 | 2. **Product Listings:**
 22 |     - **Table/Collection:** `Products`
 23 |     - **Fields:**
 24 |         - ProductID (Primary Key)
 25 |         - SellerID (Foreign Key referencing Users)
 26 |         - Name
 27 |         - Description
 28 |         - Price
 29 |         - Quantity
 30 |         - CategoryID (Foreign Key referencing Categories)
 31 |         - Other product details
 32 | 3. **Product Categories:**
 33 |     - **Table/Collection:** `Categories`
 34 |     - **Fields:**
 35 |         - CategoryID (Primary Key)
 36 |         - CategoryName
 37 | 4. **Orders:**
 38 |     - **Table/Collection:** `Orders`
 39 |     - **Fields:**
 40 |         - OrderID (Primary Key)
 41 |         - UserID (Foreign Key referencing Users)
 42 |         - OrderDate
 43 |         - TotalAmount
 44 |         - Status (e.g., Pending, Shipped, Delivered)
 45 | 5. **Transaction History:**
 46 |     - **Table/Collection:** `Transactions`
 47 |     - **Fields:**
 48 |         - TransactionID (Primary Key)
 49 |         - OrderID (Foreign Key referencing Orders)
 50 |         - TransactionDate
 51 |         - PaymentMethod
 52 |         - Amount
 53 | 
 54 | ### Relationships:
 55 | 
 56 | - Users and Products: One-to-Many relationship (One user can have many products listed)
 57 | - Products and Categories: Many-to-One relationship (Many products can belong to one category)
 58 | - Users and Orders: One-to-Many relationship (One user can have many orders)
 59 | - Orders and Transactions: One-to-One relationship (One order has one transaction)
 60 | 
 61 | ### Scalability and Performance:
 62 | 
 63 | - Use indexing on key columns to speed up search and retrieval.
 64 | - Consider denormalization for frequently accessed data to reduce complex joins.
 65 | - Implement caching mechanisms to reduce database load.
 66 | - Scale vertically (upgrading hardware) or horizontally (sharding) based on performance needs.
 67 | 
 68 | ### Security Measures:
 69 | 
 70 | - **Encryption:** Use SSL/TLS for data in transit and encryption for sensitive fields.
 71 | - **Hashed Passwords:** Store passwords securely using strong cryptographic hashing algorithms.
 72 | - **Authentication and Authorization:** Implement secure authentication mechanisms, and ensure that users can only access data they are authorized to.
 73 | - **Parameterized Queries:** Use parameterized queries or prepared statements to prevent SQL injection attacks.
 74 | - **Regular Security Audits:** Regularly audit and update security protocols to address emerging threats.
 75 | 
 76 | 
 77 | # 2. Coding Problem
 78 | 
 79 | Here's a PHP function named `filterProducts` that meets the requirements:
 80 | 
 81 | ```php
 82 | <?php
 83 | 
 84 | function filterProducts($products, $categoryName) {
 85 |     $filteredProducts = [];
 86 | 
 87 |     foreach ($products as $product) {
 88 |         $productCategory = strtolower($product['category']);
 89 |         $searchCategory = strtolower($categoryName);
 90 | 
 91 |         // Check if the category matches exactly or contains the specified category name
 92 |         if ($productCategory === $searchCategory || strpos($productCategory, $searchCategory) !== false) {
 93 |             $filteredProducts[] = $product;
 94 |         }
 95 |     }
 96 | 
 97 |     return $filteredProducts;
 98 | }
 99 | 
100 | // Sample products array
101 | $products = [
102 |     ['name' => 'Product 1', 'price' => 25.99, 'category' => 'Backend Development'],
103 |     ['name' => 'Product 2', 'price' => 49.99, 'category' => 'Frontend Development'],
104 |     ['name' => 'Product 3', 'price' => 12.99, 'category' => 'Full Stack Development'],
105 |     ['name' => 'Product 4', 'price' => 34.99, 'category' => 'Mobile App Development'],
106 | ];
107 | 
108 | // Sample cases
109 | $categoryName1 = 'backend';
110 | $categoryName2 = 'development';
111 | 
112 | $filteredProducts1 = filterProducts($products, $categoryName1);
113 | $filteredProducts2 = filterProducts($products, $categoryName2);
114 | 
115 | // Displaying the results
116 | echo "Products in the category '{$categoryName1}':\\n";
117 | print_r($filteredProducts1);
118 | 
119 | echo "\\nProducts in the category '{$categoryName2}':\\n";
120 | print_r($filteredProducts2);
121 | ?>
122 | 
123 | ```
124 | 
125 | This function takes an array of products and a category name as input, and it returns a new array containing only the products that match the specified category or contain the category name. The sample cases demonstrate how to use the function with different category names.
126 | 
127 | 
128 | # 3. Designing RESTful API for User Management
129 | 
130 | Designing a robust and scalable RESTful API for managing user profiles in a high-traffic application requires careful planning and consideration of various factors. Here's an approach addressing the key aspects:
131 | 
132 | ### URL Structure and HTTP Methods:
133 | 
134 | 1. **Create (POST):**
135 |     - Endpoint: `/api/user-profiles`
136 |     - Use POST method to create new user profiles.
137 | 2. **Read (GET):**
138 |     - Endpoint: `/api/user-profiles/{userID}`
139 |     - Use GET method to retrieve specific user profile by userID.
140 | 3. **Update (PUT/PATCH):**
141 |     - Endpoint: `/api/user-profiles/{userID}`
142 |     - Use PUT/PATCH method to update specific user profile by userID.
143 | 4. **Delete (DELETE):**
144 |     - Endpoint: `/api/user-profiles/{userID}`
145 |     - Use DELETE method to remove a specific user profile by userID.
146 | 
147 | ### Data Format for Requests and Responses:
148 | 
149 | - Use JSON as the data format for both requests and responses due to its simplicity and readability.
150 | 
151 | ### Authentication and Authorization:
152 | 
153 | - Implement token-based authentication (JWT) to secure endpoints.
154 | - Use OAuth 2.0 for handling authorization to restrict access to specific operations based on user roles.
155 | 
156 | ### Scalability and Security:
157 | 
158 | - Employ horizontal scaling by distributing load across multiple servers using load balancers.
159 | - Implement rate limiting to prevent abuse and ensure fair usage.
160 | - Use HTTPS to encrypt data transmission.
161 | - Employ security best practices like input validation, parameterized queries, and proper error handling.
162 | 
163 | ### Middleware/Frameworks:
164 | 
165 | - **Node.js with Express.js** can be used to build the API due to its scalability and performance.
166 | - Utilize middleware such as `body-parser` for parsing JSON, `helmet` for security headers, `cors` for cross-origin resource sharing, and `jsonwebtoken` for JWT authentication.
167 | 
168 | ### Integration with Frontend Framework:
169 | 
170 | - For integration with frontend frameworks like Angular or Vue.js:
171 |     - Use HTTP requests (GET, POST, PUT, DELETE) from frontend components to interact with API endpoints.
172 |     - Implement JWT authentication in frontend by storing tokens securely (e.g., in local storage) and sending them in headers for API requests.
173 |     - Handle responses and update the UI accordingly using components and state management libraries (e.g., Vuex for Vue.js or NgRx for Angular).
174 | 
175 | Bonus (Frontend Integration Example):
176 | 
177 | ```jsx
178 | // Vue.js Example - Using Axios for HTTP requests and Vuex for state management
179 | 
180 | // UserService.js - Manage API calls
181 | import axios from 'axios';
182 | 
183 | const API_BASE_URL = '<http://your-api-base-url/api/user-profiles>';
184 | 
185 | export default {
186 |   getUserProfile(userID) {
187 |     return axios.get(`${API_BASE_URL}/${userID}`);
188 |   },
189 |   createUserProfile(profileData) {
190 |     return axios.post(API_BASE_URL, profileData);
191 |   },
192 |   updateUserProfile(userID, updatedData) {
193 |     return axios.put(`${API_BASE_URL}/${userID}`, updatedData);
194 |   },
195 |   deleteUserProfile(userID) {
196 |     return axios.delete(`${API_BASE_URL}/${userID}`);
197 |   }
198 | };
199 | 
200 | // UserProfile.vue - Example component
201 | <template>
202 |   <div>
203 |     <!-- Display User Profile Data -->
204 |     <div v-if="userProfile">
205 |       <h2>{{ userProfile.name }}</h2>
206 |       <p>Email: {{ userProfile.email }}</p>
207 |       <!-- Other profile fields -->
208 |     </div>
209 |     <!-- Update Profile Form -->
210 |     <form v-if="editing" @submit.prevent="updateProfile">
211 |       <!-- Form fields for updating profile -->
212 |       <!-- Example: <input v-model="updatedProfile.name"> -->
213 |       <button type="submit">Update Profile</button>
214 |     </form>
215 |     <!-- Button to toggle edit mode -->
216 |     <button @click="toggleEditMode">{{ editing ? 'Cancel' : 'Edit' }}</button>
217 |   </div>
218 | </template>
219 | 
220 | <script>
221 | import UserService from './UserService';
222 | 
223 | export default {
224 |   data() {
225 |     return {
226 |       userProfile: null,
227 |       updatedProfile: {},
228 |       editing: false
229 |     };
230 |   },
231 |   created() {
232 |     this.fetchUserProfile();
233 |   },
234 |   methods: {
235 |     fetchUserProfile() {
236 |       const userID = 'user-id-to-fetch'; // Replace with actual user ID
237 |       UserService.getUserProfile(userID)
238 |         .then(response => {
239 |           this.userProfile = response.data;
240 |           this.updatedProfile = { ...this.userProfile }; // Clone for editing
241 |         })
242 |         .catch(error => {
243 |           console.error('Error fetching user profile:', error);
244 |         });
245 |     },
246 |     toggleEditMode() {
247 |       this.editing = !this.editing;
248 |     },
249 |     updateProfile() {
250 |       const userID = 'user-id-to-update'; // Replace with actual user ID
251 |       UserService.updateUserProfile(userID, this.updatedProfile)
252 |         .then(response => {
253 |           this.userProfile = response.data;
254 |           this.editing = false;
255 |         })
256 |         .catch(error => {
257 |           console.error('Error updating user profile:', error);
258 |         });
259 |     }
260 |   }
261 | };
262 | </script>
263 | 
264 | ```
265 | 
266 | This example demonstrates a Vue.js component for managing user profiles, utilizing Axios for API requests and Vuex for managing state related to user profiles.
267 | 


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