Shark-Stage: Investment & Crowdfunding Platform

Table of Contents

1. Project Overview
2. Features
3. Tech Stack
4. Architecture & Structure
5. Key Implementations
6. APIs & Integration
7. Challenges & Solutions
8. Performance & Optimization
9. Testing & Quality
10. Security Considerations
11. Deployment & Environment
12. What I Learned
13. Possible Improvements
14. Interview Notes

---

1. Project Overview

What Problem Does the Project Solve?

Shark-Stage is a comprehensive investment and crowdfunding platform that connects entrepreneurs with investors. The platform addresses several key challenges:

• Accessibility: Provides a unified platform for entrepreneurs to showcase their projects and for investors to discover opportunities
• Transparency: Enables clear communication between project owners and investors through real-time chat and structured offer systems
• Trust: Implements secure payment processing, project verification, and transaction tracking
• Efficiency: Streamlines the investment process from discovery to payment completion

Who Is It For?

• Entrepreneurs: Startups and business owners seeking funding for their projects
• Investors: Individuals and organizations looking to invest in promising ventures
• Administrators: Platform managers who oversee projects, users, and system operations

Key Goals

1. Multi-Platform Access: Provide seamless experience across web and mobile platforms
2. Secure Transactions: Implement robust payment processing with transaction tracking
3. Real-Time Communication: Enable instant messaging between users
4. User Experience: Deliver intuitive, responsive interfaces with modern design
5. Scalability: Build architecture that can handle growth in users and projects

---

2. Features

Core Features

Authentication & Authorization

• Email/Password Authentication: Secure signup and login with password validation
• Google OAuth Integration: One-click authentication via Google Sign-In
• JWT-based Session Management: Secure token-based authentication
• Role-based Access Control: Different permissions for users, investors, entrepreneurs, and admins
• Session Persistence: Cookie-based token storage with automatic refresh

Project Management

• Project Creation Wizard: Multi-step form for project submission (Basic Info, Details, Documents, Financial, Review)
• Project Browsing: Filterable and searchable project listings
• Project Details: Comprehensive project pages with images, descriptions, financial data
• Project Editing: Full CRUD operations for project owners
• Project Categories: Organized project categorization
• Progress Tracking: Visual progress indicators for funding goals

Investment System

• Investment Intent Creation: Secure payment intent generation
• Payment Processing: Mock payment gateway with support for real gateway integration
• Payment Methods Management: Save and manage multiple payment methods
• Transaction History: Complete transaction tracking and history
• Refund System: Automated refund processing with validation
• Offer Management: Create, accept, and manage investment offers
• Investment Dashboard: Track investments and returns

Real-Time Communication

• Socket.IO Chat: Real-time messaging between users
• Conversation Management: Organized chat threads
• Message History: Persistent message storage
• Online Status: User presence indicators
• Notifications: Real-time notifications for messages and updates

AI-Powered Features

• Chatbot Integration: AI assistant using Groq SDK for user support
• FAQ System: Automated FAQ responses
• Knowledge Base: Site-specific knowledge integration

Content Management

• Blog System: Create, edit, and manage blog posts
• Comments System: Interactive commenting on blog posts
• Image Upload: Cloudinary integration for image management
• Rich Content: Support for formatted text and media

Admin Dashboard

• User Management: View, edit, and manage user accounts
• Project Moderation: Approve, reject, or edit projects
• Blog Management: Content moderation and management
• FAQ Management: Create and edit FAQ entries
• Analytics: Dashboard with statistics and charts
• System Monitoring: Health checks and status monitoring

Optional / Advanced Features

• Dark Mode: Theme switching with persistence
• Responsive Design: Mobile-first, adaptive layouts
• Image Optimization: Automatic image compression and optimization
• Search & Filtering: Advanced search with multiple filter options
• Pagination: Efficient data loading with pagination
• Toast Notifications: User-friendly notification system
• Form Validation: Client and server-side validation
• Error Handling: Comprehensive error handling and user feedback

---

3. Tech Stack

Frontend

Web Application (Next.js)

• Framework: Next.js 16 (React 19)
• State Management: Redux Toolkit with React-Redux
• UI Library: Material-UI (MUI) v7
• Styling: Tailwind CSS 4, Emotion (CSS-in-JS)
• Forms: React Hook Form
• HTTP Client: Axios
• Real-Time: Socket.IO Client
• Charts: Recharts
• Animations: Framer Motion
• Image Upload: Cloudinary, Next-Cloudinary
• Authentication: React OAuth Google
• Notifications: React Hot Toast
• Icons: Lucide React, React Icons, MUI Icons

Mobile Application (Flutter)

• Framework: Flutter 3.10+
• State Management: Provider
• HTTP Client: Dio, HTTP
• Real-Time: Socket.IO Client
• Authentication: Firebase Auth, Google Sign-In
• Database: Cloud Firestore
• Storage: Firebase Storage
• Local Storage: Shared Preferences, SQFlite
• UI Components: Material Design, Custom Widgets
• Charts: FL Chart
• Image Handling: Image Picker, Cached Network Image
• Fonts: Google Fonts
• Utilities: Flutter SVG, URL Launcher, File Picker

Backend

• Runtime: Node.js
• Framework: Express.js 5
• Database: MongoDB with Mongoose ODM
• Authentication: JWT (JSON Web Tokens), Bcrypt
• Real-Time: Socket.IO
• File Upload: Multer
• Image Processing: Sharp
• AI Integration: Groq SDK, OpenAI SDK
• Payment Processing: Custom Payment Service Layer (Mock implementation)
• Rate Limiting: Express Rate Limit
• Logging: Morgan
• Environment: Dotenv

Database

• Primary Database: MongoDB Atlas (Cloud)
• Schema Design: Mongoose models with relationships
• Collections: Users, Projects, Payments, Offers, Messages, Conversations, Posts, Comments, FAQs, Notifications

Tools & Libraries

Development

• Version Control: Git
• Package Managers: npm, pub (Flutter)
• Build Tools: Next.js Build, Flutter Build
• Code Quality: ESLint, Flutter Lints

Deployment & Infrastructure

• Web Hosting: Netlify (Next.js)
• Backend Hosting: Railway / Render
• Mobile: Android APK, iOS App Store
• CDN: Cloudinary (images)

Why These Technologies Were Chosen

1. Next.js:

   • Server-side rendering for better SEO
   • Built-in API routes
   • Excellent developer experience
   • Automatic code splitting

2. Flutter:

   • Single codebase for iOS and Android
   • High performance with native compilation
   • Rich widget library
   • Strong community support

3. MongoDB:

   • Flexible schema for evolving project requirements
   • Excellent for document-based data (projects, users)
   • Easy horizontal scaling
   • Rich query capabilities

4. Socket.IO:

   • Real-time bidirectional communication
   • Automatic fallback to polling
   • Room-based messaging
   • Built-in authentication support

5. Redux Toolkit:

   • Predictable state management
   • DevTools integration
   • Middleware support for async operations
   • TypeScript-friendly

6. Firebase:

   • Quick authentication setup
   • Real-time database capabilities
   • Cloud storage for mobile apps
   • Cross-platform support

---

4. Architecture & Structure

Folder Structure Explanation

Backend (sharkserver/)

sharkserver/
├── config/              # Configuration files (payment, cloudinary)
├── controllers/         # Request handlers (auth, projects, payment, etc.)
│   ├── admin/          # Admin-specific controllers
│   ├── auth/           # Authentication controllers
│   ├── payment/        # Payment processing controllers
│   └── ...
├── middleware/         # Custom middleware (auth, admin)
├── models/            # Mongoose schemas
├── routers/           # Express route definitions
├── services/          # Business logic layer
│   └── payment/       # Payment service abstraction
├── utils/             # Utility functions (validators)
├── data/              # Seed data and knowledge base
└── index.js           # Application entry point

Web Frontend (sharkstage/)

sharkstage/
├── app/
│   ├── (auth)/        # Authentication routes
│   ├── (dashboard)/   # Protected dashboard routes
│   ├── (main)/        # Public routes
│   ├── components/    # Reusable React components
│   ├── hooks/         # Custom React hooks
│   └── layout.js      # Root layout
├── lib/               # Utility libraries (API, socket)
├── utils/             # Helper functions
└── public/            # Static assets

Mobile App (Shark-Stage/)

Shark-Stage/
├── lib/
│   ├── controllers/   # State controllers
│   ├── screens/       # Screen widgets
│   ├── services/      # API and business logic
│   ├── widgets/       # Reusable widgets
│   ├── theme/         # Theme configuration
│   └── utils/         # Utility functions
├── android/           # Android-specific code
├── ios/               # iOS-specific code
└── pubspec.yaml       # Dependencies

Component Architecture

Web Frontend (React/Next.js)

• Component Hierarchy:

  • Layout components (Header, Sidebar, Footer)
  • Page components (route-specific)
  • Feature components (PaymentModal, ProjectCard)
  • UI components (InputField, Button, Spinner)

• State Management:

  • Redux Store for global state (auth, user data)
  • React Hook Form for form state
  • Local state (useState) for component-specific data

Mobile App (Flutter)

• Widget Tree:

  • Screens (full-page widgets)
  • Custom widgets (reusable UI components)
  • Providers (state management)

• State Management:

  • Provider pattern for app-wide state
  • Controllers for business logic
  • Local state for UI-only data

State Management Strategy

Web (Redux Toolkit)

// Store structure
{
  auth: {
    user: User | null,
    token: string | null,
    isAuthenticated: boolean
  },
  // Future slices can be added here
}

Benefits:

• Centralized state
• Time-travel debugging
• Predictable updates
• Middleware for async operations

Mobile (Provider)

• ThemeProvider: Manages dark/light mode
• AuthProvider: Handles authentication state
• API Service: Singleton service for API calls

Data Flow

Authentication Flow

1. User submits credentials → Frontend
2. Frontend sends request → Backend API
3. Backend validates → MongoDB
4. Backend generates JWT → Sets HTTP-only cookie
5. Frontend receives response → Updates Redux store
6. Subsequent requests include cookie → Automatic authentication

Payment Flow

1. User clicks "Invest" → Frontend
2. Frontend creates payment intent → Backend /payment/intent
3. Backend validates → Creates transaction record
4. Backend returns payment intent → Frontend
5. User enters payment details → Frontend
6. Frontend confirms payment → Backend /payment/confirm
7. Backend processes payment → Payment service
8. Backend updates project/investor → MongoDB
9. Backend sends notification → Socket.IO
10. Frontend receives confirmation → Updates UI

Real-Time Chat Flow

1. User sends message → Frontend Socket.IO client
2. Socket.IO emits message → Backend Socket.IO server
3. Backend validates user → JWT verification
4. Backend saves message → MongoDB
5. Backend emits to recipient → Socket.IO
6. Recipient receives message → Real-time update

---

5. Key Implementations

Complex Logic Implemented

1. Payment Service Abstraction Layer

Problem: Need to support multiple payment gateways (Mock, Stripe, Paymob) without code duplication.

Solution: Implemented Service Layer Pattern with Factory:

// Abstract interface
class IPaymentService {
  createPaymentIntent(amount, currency, metadata)
  confirmPayment(paymentIntentId, paymentMethod)
  refundPayment(transactionId, amount)
}

// Factory pattern
PaymentServiceFactory.getPaymentService() // Returns appropriate implementation

Benefits:

• Easy to switch payment providers
• Testable with mock service
• No changes to controller code when switching providers

2. Multi-Step Project Creation Wizard

Problem: Complex project creation form with validation at each step.

Solution:

• Step-based component architecture
• Form state persistence between steps
• Validation at each step before proceeding
• Review step showing all entered data
• Progress indicator

3. Real-Time Chat with Socket.IO

Problem: Implement real-time messaging with authentication and room management.

Solution:

• JWT authentication middleware for Socket.IO
• Room-based messaging (conversation-based)
• Message persistence in MongoDB
• Online/offline status tracking
• Automatic reconnection handling

4. Investment Offer System

Problem: Manage investment offers with automatic acceptance on payment completion.

Solution:

• Offer creation linked to payment intent
• Automatic offer acceptance on successful payment
• Project percentage calculation and validation
• Investor tracking in project model
• Transaction linking

Interesting UI/UX Solutions

1. Payment Modal with Saved Methods

• Problem: Users shouldn't re-enter payment details every time.

Solution:

• Display saved payment methods (last 4 digits, brand)
• Option to add new method
• Seamless switching between saved and new methods
• Visual feedback during payment processing

2. Responsive Navigation

• Problem: Navigation should work on all screen sizes.

Solution:

• Mobile: Hamburger menu with drawer
• Desktop: Horizontal navigation bar
• Adaptive sidebar for dashboard
• Touch-friendly interactions

3. Dark Mode Implementation

• Problem: Users prefer different themes.

Solution:

• Theme provider with persistence
• Smooth theme transitions
• Consistent color scheme across components
• System preference detection

4. Image Upload with Preview

• Problem: Users need to see images before uploading.

Solution:

• Client-side image preview
• Drag-and-drop support
• Multiple image selection
• Progress indicators
• Cloudinary integration for optimization

Performance Optimizations

1. Image Optimization

• Cloudinary Integration: Automatic image compression and format conversion
• Lazy Loading: Images load only when visible
• Responsive Images: Different sizes for different devices
• Caching: Browser caching for static assets

2. Code Splitting

• Next.js Automatic Splitting: Route-based code splitting
• Dynamic Imports: Lazy load heavy components
• Flutter: Tree shaking and deferred loading

3. API Optimization

• Pagination: Limit data transfer with paginated responses
• Selective Field Loading: Only fetch required fields
• Caching: Client-side caching for frequently accessed data
• Debouncing: Debounce search and filter inputs

4. State Management Optimization

• Memoization: React.memo for expensive components
• Selective Redux Updates: Only update changed slices
• Provider Optimization: Minimize provider rebuilds

Reusability Patterns

1. Component Composition

• Base Components: Reusable UI primitives (Button, Input, Card)
• Feature Components: Composed from base components
• Layout Components: Consistent page structures

2. Custom Hooks

• useAuth: Authentication logic reuse
• useSocket: Socket.IO connection management
• useTheme: Theme switching logic

3. Utility Functions

• Validators: Reusable validation functions
• Formatters: Date, currency, number formatting
• API Helpers: Consistent API call patterns

4. Service Layer Pattern

• API Service: Centralized HTTP client
• Payment Service: Abstracted payment logic
• Socket Service: Real-time communication abstraction

---

6. APIs & Integration

API Structure

RESTful API Design

Base URL: https://api.sharkstage.com

Authentication:
  POST   /auth/signup
  POST   /auth/signin
  POST   /auth/google
  GET    /auth/me
  POST   /auth/logout

Projects:
  GET    /projects              # List projects (with filters)
  GET    /projects/:id         # Get project details
  POST   /projects              # Create project (authenticated)
  PUT    /projects/:id          # Update project (owner only)
  DELETE /projects/:id          # Delete project (owner only)

Payments:
  POST   /payment/intent        # Create payment intent
  POST   /payment/confirm       # Confirm payment
  GET    /payment/status/:id    # Get payment status
  POST   /payment/refund        # Process refund
  GET    /payment/methods       # Get saved payment methods
  POST   /payment/methods       # Save payment method

Chat:
  GET    /chat/conversations    # Get user conversations
  GET    /chat/messages/:id     # Get conversation messages
  POST   /chat/messages         # Send message (also via Socket.IO)

Blog:
  GET    /blog                  # List blog posts
  GET    /blog/:id              # Get blog post
  POST   /blog                  # Create post (authenticated)
  PUT    /blog/:id              # Update post
  DELETE /blog/:id              # Delete post

Admin:
  GET    /admin/users           # List all users
  GET    /admin/projects        # List all projects
  GET    /admin/analytics       # Get analytics data

Data Fetching Strategy

Web Frontend

• Server-Side Rendering (SSR): Initial page load with data
• Client-Side Fetching: Subsequent data updates via Axios
• Redux Integration: Cache API responses in Redux store
• Optimistic Updates: Update UI before server confirmation

Mobile App

• Dio HTTP Client: Configured with interceptors
• Error Handling: Centralized error handling
• Loading States: Consistent loading indicators
• Offline Support: Cached data with SharedPreferences

Error Handling

Backend

• Try-Catch Blocks: Comprehensive error catching
• Custom Error Classes: Structured error responses
• HTTP Status Codes: Appropriate status codes (400, 401, 403, 404, 500)
• Error Logging: Morgan for request logging

Frontend

• Axios Interceptors: Global error handling
• User-Friendly Messages: Translated error messages
• Toast Notifications: Visual error feedback
• Fallback UI: Error boundaries and fallback components

Authentication / Authorization

Authentication Flow

1. Signup/Login:

   • User provides credentials
   • Backend validates and creates JWT
   • JWT stored in HTTP-only cookie
   • Frontend receives user data

2. Token Refresh:

   • Automatic token validation on each request
   • Token expiration handling
   • Automatic logout on invalid token

3. Google OAuth:

   • Frontend redirects to Google
   • Google returns authorization code
   • Backend exchanges code for user info
   • Backend creates/updates user and returns JWT

Authorization Middleware

// Protected routes
const authMiddleware = (req, res, next) => {
  const token = req.cookies.token || req.headers.authorization;
  if (!token) return res.status(401).json({ error: 'Unauthorized' });
  
  const decoded = jwt.verify(token, process.env.JWT_SECRET);
  req.user = decoded;
  next();
};

// Admin routes
const adminMiddleware = (req, res, next) => {
  if (req.user.role !== 'admin') {
    return res.status(403).json({ error: 'Forbidden' });
  }
  next();
};

Role-Based Access Control

• User Roles: user, investor, entrepreneur, admin
• Route Protection: Middleware-based protection
• Component-Level: Conditional rendering based on role
• API-Level: Backend validation of user permissions

---

7. Challenges & Solutions

Technical Challenges

Challenge 1: Cross-Platform State Synchronization

Problem: Keeping user state consistent across web and mobile apps.

Solution:

• Centralized backend API as single source of truth
• JWT tokens for stateless authentication
• Real-time updates via Socket.IO for critical state changes
• Optimistic UI updates with server reconciliation

Challenge 2: Payment Gateway Abstraction

Problem: Need to support multiple payment providers without code changes.

Solution:

• Implemented Service Layer Pattern with abstract interface
• Factory pattern for provider selection
• Configuration-based provider switching
• Mock service for development and testing

Trade-off: Slight overhead from abstraction layer, but provides flexibility and testability.

Challenge 3: Real-Time Chat Scalability

Problem: Socket.IO connections and message delivery at scale.

Solution:

• Room-based messaging (one room per conversation)
• Message persistence in MongoDB
• Connection pooling and reconnection handling
• Rate limiting on message sending

Trade-off: Increased database writes, but ensures message delivery and history.

Challenge 4: Image Upload and Storage

Problem: Handling large image uploads and storage costs.

Solution:

• Cloudinary integration for automatic optimization
• Client-side image compression before upload
• Lazy loading and responsive images
• CDN delivery for fast loading

Trade-off: Dependency on third-party service, but reduces server load and storage costs.

Challenge 5: Form Validation Complexity

Problem: Complex multi-step forms with interdependent validation.

Solution:

• React Hook Form for form state management
• Custom validation functions
• Step-by-step validation
• Server-side validation as final check

Trade-off: More code for validation, but ensures data integrity and better UX.

How They Were Solved

1. Incremental Development: Built features incrementally, testing at each step
2. Design Patterns: Applied proven patterns (Factory, Service Layer, Provider)
3. Third-Party Services: Leveraged specialized services (Cloudinary, Firebase)
4. Error Handling: Comprehensive error handling at every layer
5. Documentation: Maintained documentation for complex flows

Trade-offs Made

1. MongoDB vs SQL:

   • Chose: MongoDB for flexibility
   • Trade-off: Less strict data relationships, but faster development

2. Redux vs Context API:

   • Chose: Redux for web, Provider for mobile
   • Trade-off: More boilerplate, but better tooling and scalability

3. Mock Payment vs Real Gateway:

   • Chose: Mock for development
   • Trade-off: Not production-ready, but allows testing without costs

4. Server-Side vs Client-Side Rendering:

   • Chose: Hybrid approach (SSR for initial load, CSR for updates)
   • Trade-off: More complex setup, but better performance and SEO

---

8. Performance & Optimization

Rendering Optimization

Web (Next.js)

• Server-Side Rendering: Initial HTML from server
• Static Generation: Pre-rendered pages where possible
• Incremental Static Regeneration: Update static pages on demand
• React.memo: Prevent unnecessary re-renders
• useMemo/useCallback: Memoize expensive computations

Mobile (Flutter)

• Widget Optimization: Const widgets where possible
• ListView.builder: Lazy loading for lists
• Image Caching: Cached network images
• State Management: Minimize provider rebuilds

Code Splitting

Web

• Route-Based Splitting: Automatic with Next.js
• Dynamic Imports: Lazy load heavy components
• Chunk Optimization: Webpack optimization

Mobile

• Tree Shaking: Remove unused code
• Deferred Loading: Load features on demand

Caching

Client-Side

• Redux Store: Cache API responses
• Browser Cache: Static assets caching
• Service Workers: (Future) Offline support

Server-Side

• MongoDB Indexes: Optimized queries
• Response Caching: Cache frequently accessed data
• CDN: Cloudinary CDN for images

SEO (Web Application)

• Server-Side Rendering: Search engines can crawl content
• Meta Tags: Dynamic meta tags per page
• Structured Data: (Future) Schema.org markup
• Sitemap: (Future) XML sitemap generation
• Robots.txt: Proper crawler directives

---

9. Testing & Quality

Testing Approach

Current State

• Manual Testing: Comprehensive manual testing of all features
• User Acceptance Testing: Testing with real user scenarios
• Integration Testing: Testing API endpoints with Postman/Thunder Client

Planned Testing

• Unit Tests: Jest for backend, Flutter test for mobile
• Integration Tests: API endpoint testing
• E2E Tests: Cypress/Playwright for web, Flutter integration tests for mobile
• Component Tests: React Testing Library for React components

Tools Used

• Postman/Thunder Client: API testing
• Browser DevTools: Performance profiling
• Flutter DevTools: Mobile app debugging
• Redux DevTools: State inspection
• MongoDB Compass: Database inspection

Code Quality Practices

Backend

• ESLint: Code linting
• Consistent Naming: Clear, descriptive names
• Error Handling: Comprehensive try-catch blocks
• Code Comments: Documentation for complex logic
• Modular Structure: Separation of concerns

Frontend

• ESLint: Code linting
• Prettier: Code formatting (planned)
• Component Documentation: JSDoc comments
• TypeScript: (Future) Type safety
• Accessibility: Semantic HTML, ARIA labels

Mobile

• Flutter Lints: Built-in linting rules
• Widget Documentation: Clear widget descriptions
• State Management: Consistent provider usage

---

10. Security Considerations

Auth Security

Password Security

• Bcrypt Hashing: Passwords hashed with bcrypt (salt rounds: 10)
• Password Requirements: Minimum 8 characters, uppercase, number
• No Plain Text Storage: Passwords never stored in plain text

JWT Security

• HTTP-Only Cookies: Tokens stored in HTTP-only cookies (prevents XSS)
• Secure Flag: Cookies only sent over HTTPS in production
• Token Expiration: Tokens expire after set time
• Secret Key: Strong JWT secret stored in environment variables

OAuth Security

• Google OAuth: Secure OAuth 2.0 flow
• State Parameter: CSRF protection
• Token Validation: Server-side token verification

Data Validation

Input Validation

• Client-Side: Immediate feedback with React Hook Form
• Server-Side: Comprehensive validation with custom validators
• Sanitization: Input sanitization to prevent injection attacks
• Type Checking: Validation of data types

File Upload Security

• File Type Validation: Only allowed image types
• File Size Limits: Maximum file size restrictions
• Virus Scanning: (Future) Server-side scanning
• Secure Storage: Files stored in Cloudinary (not on server)

Common Vulnerabilities Handled

1. SQL/NoSQL Injection

• Mongoose: Parameterized queries prevent injection
• Input Sanitization: All inputs sanitized
• Validation: Strict schema validation

2. XSS (Cross-Site Scripting)

• React Escaping: React automatically escapes content
• Content Security Policy: (Future) CSP headers
• Sanitization: User-generated content sanitized

3. CSRF (Cross-Site Request Forgery)

• SameSite Cookies: Cookies with SameSite attribute
• Origin Validation: CORS configuration
• State Parameter: OAuth state validation

4. Rate Limiting

• Express Rate Limit: Rate limiting on auth endpoints
• IP-Based Limiting: Prevent brute force attacks
• Request Throttling: Limit requests per IP

5. Authentication Bypass

• Middleware Protection: All protected routes use auth middleware
• Role Verification: Admin routes verify admin role
• Token Validation: Every request validates token

6. Sensitive Data Exposure

• Environment Variables: Secrets in .env files
• No Logging: Passwords and tokens never logged
• HTTPS: All production traffic over HTTPS
• Payment Data: Only last 4 digits of cards stored

---

11. Deployment & Environment

Deployment Platform

Web Frontend

• Platform: Netlify
• Build Command: npm run build
• Publish Directory: .next
• Environment Variables: Configured in Netlify dashboard
• Custom Domain: (Future) Custom domain setup

Backend API

• Platform: Railway / Render
• Runtime: Node.js
• Process Manager: PM2 (or platform-managed)
• Database: MongoDB Atlas (cloud)
• Environment Variables: Configured in platform dashboard

Mobile App

• Android: APK build, Google Play Store (planned)
• iOS: App Store (planned)
• Build Process: Flutter build commands
• Signing: Keystore for Android, certificates for iOS

CI/CD

Current Setup

• Manual Deployment: Manual deployment process
• Git-Based: Deployment triggered by git push (Netlify)
• Environment Separation: Development and production environments

Planned CI/CD

• GitHub Actions: Automated testing and deployment
• Automated Tests: Run tests before deployment
• Staging Environment: Separate staging for testing
• Rollback Strategy: Quick rollback capability

Environment Variables

Backend (.env)

# Server
PORT=5000
NODE_ENV=production

# Database
MONGO_URL=mongodb+srv://...
DB_NAME=sharkstage

# Authentication
JWT_SECRET=your-secret-key
GOOGLE_CLIENT_ID=...
GOOGLE_CLIENT_SECRET=...

# Payment
PAYMENT_PROVIDER=mock
PAYMENT_CURRENCY=USD

# Cloudinary
CLOUDINARY_CLOUD_NAME=...
CLOUDINARY_API_KEY=...
CLOUDINARY_API_SECRET=...

# AI
GROQ_API_KEY=...
OPENAI_API_KEY=...

Frontend (.env.local)

NEXT_PUBLIC_API_URL=https://api.sharkstage.com
NEXT_PUBLIC_GOOGLE_CLIENT_ID=...
NEXT_PUBLIC_SOCKET_URL=https://api.sharkstage.com

Mobile (Build Configuration)

• API base URL configured in main.dart
• Firebase configuration in firebase_options.dart
• Google Sign-In configuration in platform-specific files

Build Process

Web

1. Install dependencies: npm install
2. Build: npm run build
3. Start: npm start (production) or npm run dev (development)

Backend

1. Install dependencies: npm install
2. Set environment variables
3. Start: npm start (production) or npm run dev (development)

Mobile

1. Install dependencies: flutter pub get
2. Build Android: flutter build apk --release
3. Build iOS: flutter build ios --release

---

12. What I Learned

Technical Lessons

1. Full-Stack Development

• Integration Challenges: Learned to handle integration between frontend, backend, and database
• API Design: Understood importance of well-designed RESTful APIs
• State Management: Gained expertise in different state management approaches (Redux, Provider)

2. Real-Time Communication

• Socket.IO: Learned WebSocket communication and real-time features
• Connection Management: Understood challenges of maintaining persistent connections
• Scalability: Learned about scaling real-time applications

3. Payment Processing

• Payment Gateways: Understood payment processing flow
• Security: Learned importance of secure payment handling
• Abstraction: Applied design patterns for flexible architecture

4. Cross-Platform Development

• Flutter: Gained experience in cross-platform mobile development
• Code Reuse: Learned to maximize code reuse between platforms
• Platform Differences: Understood platform-specific considerations

5. Authentication & Security

• JWT: Deep understanding of token-based authentication
• OAuth: Learned OAuth 2.0 flow implementation
• Security Best Practices: Applied security measures throughout the application

6. Database Design

• MongoDB: Learned NoSQL database design and querying
• Relationships: Understood how to model relationships in document databases
• Indexing: Learned importance of database indexing

Soft Skills

1. Problem-Solving

• Debugging: Improved debugging skills across multiple technologies
• Research: Learned to research and find solutions independently
• Critical Thinking: Developed ability to analyze and solve complex problems

2. Time Management

• Prioritization: Learned to prioritize features and tasks
• Deadline Management: Managed project timeline effectively
• Scope Management: Learned to balance features with time constraints

3. Documentation

• Technical Writing: Improved technical documentation skills
• Code Comments: Learned importance of clear code comments
• API Documentation: Created comprehensive API documentation

Team Collaboration Insights

1. Communication

• Clear Communication: Learned importance of clear communication in team projects
• Documentation: Understood that good documentation reduces communication overhead

2. Code Organization

• Modular Code: Learned that well-organized code is easier for teams to work with
• Consistent Patterns: Understood importance of consistent coding patterns

3. Version Control

• Git Workflow: Improved Git workflow and collaboration
• Branch Management: Learned effective branch management strategies

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13. Possible Improvements

Features to Add

1. Advanced Search & Filtering

• Full-Text Search: Elasticsearch integration for advanced search
• Filter Combinations: Multiple filter combinations
• Saved Searches: Allow users to save search criteria

2. Analytics Dashboard

• User Analytics: Track user behavior and engagement
• Project Analytics: Project performance metrics
• Investment Analytics: Investment trends and insights

3. Notification System Enhancement

• Email Notifications: Email alerts for important events
• Push Notifications: Mobile push notifications
• Notification Preferences: User-customizable notification settings

4. Social Features

• User Profiles: Enhanced user profiles with portfolios
• Following System: Follow investors and entrepreneurs
• Activity Feed: User activity timeline
• Reviews & Ratings: Rate projects and investors

5. Advanced Payment Features

• Multiple Payment Methods: Support for more payment gateways (Stripe, PayPal)
• Recurring Payments: Subscription-based investments
• Escrow System: Secure escrow for large investments
• Multi-Currency: Support for multiple currencies

6. AI Enhancements

• Project Recommendations: AI-powered project recommendations
• Risk Assessment: AI-based investment risk analysis
• Chatbot Improvements: More sophisticated chatbot responses

Refactoring Ideas

1. TypeScript Migration

• Type Safety: Migrate to TypeScript for better type safety
• Better IDE Support: Improved autocomplete and error detection
• Refactoring Safety: Safer refactoring with types

2. Microservices Architecture

• Service Separation: Split into microservices (auth, payment, chat)
• Scalability: Better scalability and independent deployment
• Technology Diversity: Use best technology for each service

3. GraphQL API

• Flexible Queries: Allow clients to request only needed data
• Reduced Over-fetching: More efficient data fetching
• Strong Typing: GraphQL schema provides type safety

4. Testing Coverage

• Unit Tests: Comprehensive unit test coverage
• Integration Tests: API integration tests
• E2E Tests: End-to-end testing with Cypress/Playwright

5. Performance Optimization

• Caching Strategy: Implement Redis for caching
• Database Optimization: Query optimization and indexing
• CDN Integration: More aggressive CDN usage
• Image Optimization: Further image optimization

Scalability Improvements

1. Database Scaling

• Sharding: MongoDB sharding for horizontal scaling
• Read Replicas: Read replicas for better read performance
• Caching Layer: Redis for frequently accessed data

2. Server Scaling

• Load Balancing: Load balancer for multiple server instances
• Horizontal Scaling: Scale servers horizontally
• Containerization: Docker containers for consistent deployment

3. Real-Time Scaling

• Socket.IO Clustering: Multiple Socket.IO servers with Redis adapter
• Message Queue: RabbitMQ or similar for message queuing
• Horizontal Scaling: Scale Socket.IO servers horizontally

4. Mobile App Optimization

• Offline Support: Offline functionality with local database
• Background Sync: Background data synchronization
• App Size Optimization: Reduce app bundle size

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14. Interview Notes

Most Important Parts to Explain

1. Architecture Overview

• Three-Tier Architecture: Frontend (Web + Mobile), Backend API, Database
• Technology Choices: Why Next.js, Flutter, Node.js, MongoDB
• Separation of Concerns: Clear separation between layers

2. Payment System

• Service Layer Pattern: Abstract payment service with factory pattern
• Payment Flow: Complete payment flow from intent to completion
• Security: How payment data is secured
• Extensibility: How to add new payment providers

3. Real-Time Features

• Socket.IO Implementation: How real-time chat works
• Authentication: JWT authentication with Socket.IO
• Scalability: How to scale real-time features

4. Authentication System

• JWT Implementation: Token-based authentication
• OAuth Flow: Google OAuth integration
• Security Measures: Password hashing, token security

5. State Management

• Redux (Web): Why Redux and how it's structured
• Provider (Mobile): Flutter state management approach
• Data Flow: How data flows through the application

Common Interview Questions Related to This Project

Technical Questions

1. "How does the payment system work?"

   • Explain payment intent creation
   • Describe payment confirmation flow
   • Discuss service layer abstraction
   • Mention security measures

2. "How did you implement real-time chat?"

   • Socket.IO setup and configuration
   • JWT authentication with Socket.IO
   • Room-based messaging
   • Message persistence

3. "Why did you choose MongoDB over SQL?"

   • Flexibility for evolving schema
   • Document-based structure fits project data
   • Easy horizontal scaling
   • Trade-offs made

4. "How do you handle authentication across platforms?"

   • JWT tokens in HTTP-only cookies
   • Stateless authentication
   • Token validation middleware
   • OAuth integration

5. "How would you scale this application?"

   • Database sharding and read replicas
   • Load balancing
   • Caching with Redis
   • Microservices architecture

6. "What security measures did you implement?"

   • Password hashing with bcrypt
   • JWT security
   • Input validation
   • Rate limiting
   • XSS/CSRF protection

Design Questions

1. "How did you structure your codebase?"

   • Folder structure explanation
   • Separation of concerns
   • Reusable components
   • Service layer pattern

2. "How do you handle errors?"

   • Error handling at each layer
   • User-friendly error messages
   • Logging and monitoring
   • Error boundaries

3. "What design patterns did you use?"

   • Factory pattern (payment service)
   • Service layer pattern
   • Provider pattern (Flutter)
   • Middleware pattern

Weak Points to Avoid or Explain Carefully

1. Testing Coverage

• Weakness: Limited automated testing
• How to Address:
  • Acknowledge this as an area for improvement
  • Explain manual testing done
  • Discuss testing strategy for future
  • Show understanding of testing importance

2. Payment Gateway (Mock)

• Weakness: Using mock payment gateway
• How to Address:
  • Explain it's for development/testing
  • Show architecture allows easy switch to real gateway
  • Discuss security measures in place
  • Mention production readiness considerations

3. Scalability Concerns

• Weakness: Current setup may not scale to millions of users
• How to Address:
  • Acknowledge current limitations
  • Discuss scalability improvements planned
  • Show understanding of scaling challenges
  • Explain architecture allows for scaling

4. Error Handling

• Weakness: Some areas may need more comprehensive error handling
• How to Address:
  • Show examples of good error handling implemented
  • Discuss error handling strategy
  • Mention areas for improvement
  • Show understanding of error handling importance

5. Documentation

• Weakness: Some code may lack inline documentation
• How to Address:
  • Show this documentation as evidence of documentation skills
  • Mention areas with good documentation
  • Discuss importance of documentation
  • Show willingness to improve

Tips for Interview Discussion

1. Be Honest: Acknowledge limitations and areas for improvement
2. Show Learning: Discuss what you learned from challenges
3. Think Aloud: Explain your thought process when solving problems
4. Ask Questions: Show interest in interviewer's perspective
5. Be Specific: Use concrete examples from the project
6. Show Growth: Discuss how you would improve the project

Key Metrics to Mention

• Platforms: Web (Next.js) + Mobile (Flutter) + Backend (Node.js)
• Technologies: 15+ major technologies integrated
• Features: 10+ major features implemented
• Security: Multiple security measures implemented
• Scalability: Architecture designed for future scaling

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Conclusion

Shark-Stage represents a comprehensive full-stack application demonstrating skills in:

• Frontend Development: React/Next.js and Flutter
• Backend Development: Node.js/Express with MongoDB
• Real-Time Features: Socket.IO implementation
• Payment Processing: Secure payment system with abstraction layer
• Authentication: JWT and OAuth implementation
• Security: Multiple security measures
• Architecture: Clean, scalable architecture
• Problem-Solving: Complex feature implementations

The project showcases ability to work across the full stack, integrate multiple technologies, and build a production-ready application with attention to security, performance, and user experience.

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Document Version: 1.0
Last Updated: 2024
Project Status: Active Development