InvoiceFlow

InvoiceFlow is a comprehensive business management platform designed for small to medium-sized businesses and freelancers. It provides complete invoice lifecycle management, real-time inventory tracking, customer relationship management, and advanced business analytics through a unified, cloud-native mobile application.

What InvoiceFlow Does

InvoiceFlow helps businesses:

• Create & Manage Invoices - Professional sales and purchase invoices with smart numbering
• Track Payments - Monitor outstanding balances and send WhatsApp payment reminders
• Manage Inventory - Real-time stock tracking with automatic updates and low stock alerts
• Process Returns - Handle sales and purchase returns with inventory adjustments
• Analyze Performance - Real-time dashboards with revenue analytics and business KPIs
• Stay Organized - Automated notifications for follow-ups and unpaid invoices
• Sync Everywhere - Cloud-based sync across all devices via Firebase

Key Features

Invoice Management

• Dual Invoice Types: Sales invoices (customer billing) and Purchase invoices (vendor/expense tracking)
• Smart Numbering: Auto-generated invoice numbers with format INV-YYYYMM###
• Flexible Dating: Backdate or future-date invoices as needed
• Invoice Lifecycle: Draft → Posted → Paid/Cancelled with full status tracking
• Payment Tracking: Record partial/full payments with multiple payment methods (Cash, Online, Cheque)
• Follow-up Scheduling: Set and track follow-up dates for unpaid invoices
• PDF Export: Generate professional invoice PDFs for sharing
• WhatsApp Integration: Send payment reminders directly via WhatsApp

Customer Management

• Complete Profiles: Store contact information, address, email, and phone
• Purchase History: View complete invoice timeline for each customer
• Outstanding Balances: Real-time tracking of amounts due
• Smart Lookup: Phone-based customer search with duplicate prevention
• Customer Analytics: Spending patterns, revenue contribution, and lifetime value
• Pending Returns: Track refund amounts awaiting application

Inventory System

• Real-Time Stock Tracking: Automatic updates from sales and purchase invoices
• Movement Audit Trail: Complete history with 6 movement types (IN, OUT, ADJUSTMENT, RETURN_IN, RETURN_OUT, REVERSAL_OUT)
• Low Stock Alerts: Automated notifications when items reach reorder points
• Barcode Support: Product identification and scanning
• Inventory Valuation: Real-time calculation of inventory worth
• Stock Movement Reversal: Undo operations for cancelled invoices
• Negative Stock Prevention: Validation to prevent overselling
• Admin Override: Force operations with comprehensive audit trail

Returns Management

• Sales Returns: Process customer returns with automatic stock increases
• Purchase Returns: Return goods to suppliers with stock decreases
• Refund Tracking: Monitor pending refund amounts per customer
• Return Reasons: Document why items were returned
• Inventory Integration: Automatic stock adjustments on return processing

Analytics Dashboard

• 7-Card Layout: Overview KPIs, Revenue Analytics, Items & Sales, Inventory Health, Due Reminders, Analytics Table, Visual Charts
• Real-Time Metrics: Revenue, profit, payment collection efficiency
• Date Range Filtering: Last 7/30/90 days, This year, All time, Custom ranges
• Customer Analytics: Revenue by customer, outstanding balances
• Item Analytics: Top-performing products and categories
• Inventory Health: Stock distribution, turnover rates, aging analysis
• Performance Optimized: 30-minute cache with smart invalidation

Notifications & Reminders

• Follow-up Reminders: Daily notifications at 10:00 AM for invoices requiring follow-up
• Unpaid Purchase Reminders: Daily alerts at 2:00 PM for outstanding vendor payments
• Low Stock Alerts: Automatic notifications for reorder points
• User Preferences: Configurable notification settings
• Background Service: Automatic rescheduling on app startup

Business Catalogues

Pre-configured product catalogues for multiple industries:

• Bakery (50+ items)
• Clothing (100+ items)
• Electronics (80+ items)
• Grocery (120+ items)
• Hardware (70+ items)
• Pharmacy (90+ items)
• Stationery (133+ items with pricing)

Technology Stack

Frontend

• Flutter 3.6.0+: Cross-platform mobile framework
• Material Design 3: Modern, responsive UI components
• Dart: Primary programming language
• Provider: State management with ChangeNotifier pattern
• Sizer: Responsive design across devices
• FL Charts: Interactive data visualizations

Backend & Services

• Firebase Authentication: Email/Password + Google Sign-In
• Cloud Firestore: NoSQL database with real-time sync
• Firebase Storage: File and document storage
• Firebase Analytics: User behavior tracking
• Firebase Cloud Messaging: Push notifications

Key Packages

• firebase_core, firebase_auth, cloud_firestore: Firebase integration
• google_sign_in: OAuth authentication
• fl_chart: Charts and graphs
• pdf: PDF generation
• csv: Data import/export
• shared_preferences: Local data persistence
• url_launcher: WhatsApp and external links
• flutter_local_notifications: Local push notifications
• uuid: Unique identifier generation

Installation & Setup

Prerequisites

• Flutter SDK (^3.6.0)
• Dart SDK
• Android Studio / VS Code with Flutter extensions
• Android SDK / Xcode (for iOS development)
• Firebase account with active project

Step 1: Clone the Repository

git clone https://github.com/yourusername/invoiceflow.git
cd invoiceflow

Step 2: Install Dependencies

flutter pub get

Step 3: Firebase Configuration

Android Configuration

1. Go to Firebase Console
2. Create a new project or select existing project invoiceflow-deafa
3. Add an Android app to your Firebase project
4. Download google-services.json
5. Place it in android/app/google-services.json

iOS Configuration (Optional)

1. Add an iOS app in Firebase Console
2. Download GoogleService-Info.plist
3. Place it in ios/Runner/GoogleService-Info.plist

Web Configuration

1. Add a Web app in Firebase Console
2. Copy the Firebase configuration
3. Update lib/firebase_options.dart with your configuration

Step 4: Firestore Setup

Enable Firestore Database

1. In Firebase Console, go to Firestore Database
2. Click "Create Database"
3. Start in production mode or test mode (for development)
4. Choose a location for your database

Deploy Security Rules

firebase deploy --only firestore:rules

Deploy Indexes

firebase deploy --only firestore:indexes

Step 5: Enable Authentication

1. In Firebase Console, go to Authentication
2. Enable Email/Password sign-in method
3. Enable Google sign-in method (optional)

Step 6: Run the Application

# Debug mode
flutter run

# Release mode (Android)
flutter run --release

# Web
flutter run -d chrome

Project Structure

invoiceflow/
├── android/                    # Android-specific configuration
├── ios/                        # iOS-specific configuration
├── lib/
│   ├── main.dart              # Application entry point
│   ├── models/                # Data models
│   │   ├── invoice_model.dart
│   │   ├── customer_model.dart
│   │   ├── inventory_item.dart
│   │   ├── stock_movement.dart
│   │   └── return_model.dart
│   ├── screens/               # UI screens (30+ screens)
│   │   ├── home/
│   │   ├── invoices/
│   │   ├── customers/
│   │   ├── inventory/
│   │   ├── analytics/
│   │   └── profile/
│   ├── services/              # Business logic layer
│   │   ├── auth_service.dart
│   │   ├── firestore_service.dart
│   │   ├── inventory_service.dart
│   │   ├── customer_service.dart
│   │   ├── analytics_service.dart
│   │   ├── return_service.dart
│   │   └── notification_service.dart
│   ├── providers/             # State management
│   │   ├── auth_provider.dart
│   │   ├── invoice_provider.dart
│   │   └── inventory_provider.dart
│   ├── widgets/               # Reusable UI components
│   ├── utils/                 # Helper utilities
│   └── theme/                 # App theming
├── assets/                    # Static assets
├── firebase.json              # Firebase configuration
├── firestore.rules            # Firestore security rules
├── firestore.indexes.json     # Firestore indexes
├── pubspec.yaml               # Dependencies
└── README.md                  # This file

Architecture

InvoiceFlow follows Clean Architecture principles with clear separation of concerns:

Layers

1. Presentation Layer (screens/, widgets/): UI components and user interactions
2. Business Logic Layer (services/): Business rules and operations
3. Data Layer (models/, Firebase): Data models and persistence
4. State Management (providers/): Application state with Provider pattern

Design Patterns

• Repository Pattern: Data access abstraction via services
• Singleton Pattern: Service instances (AuthService, FirestoreService, etc.)
• Observer Pattern: Real-time updates via Firestore streams
• Factory Pattern: Model instantiation from JSON

Multi-Tenant Architecture

• User Isolation: All data scoped to authenticated user UID
• Firestore Structure: users/{uid}/invoices/{invoiceId}
• Security Rules: Server-side enforcement of user-based access
• Data Privacy: Complete isolation between user accounts

Data Models

Invoice Model

{
  id: String,
  invoiceNumber: String,         // Format: INV-YYYYMM###
  customerId: String,
  customerName: String,
  customerPhone: String,
  date: Timestamp,
  invoiceType: String,           // 'sales' or 'purchase'
  items: List<InvoiceItem>,
  subtotal: double,              // Computed from items
  total: double,
  amountPaid: double,
  paymentMethod: String,         // 'cash', 'online', 'cheque'
  status: String,                // 'draft', 'posted', 'cancelled'
  followUpDate: Timestamp,
  cancelledAt: Timestamp,
  cancelReason: String,
  refundAdjustment: double,
  modifiedFlag: bool,
  modifiedReason: String
}

Customer Model

{
  id: String,
  name: String,
  phoneNumber: String,
  email: String,
  address: String,
  totalSpent: double,            // Denormalized
  totalPaid: double,             // Denormalized
  invoiceCount: int,             // Denormalized
  pendingReturnAmount: double,
  lastPurchaseDate: Timestamp,
  createdAt: Timestamp
}

Inventory Item Model

{
  id: String,
  sku: String,
  name: String,
  category: String,
  unit: String,
  currentStock: double,
  openingStock: double,
  reorderPoint: double,
  avgCost: double,
  barcode: String,
  lastUpdated: Timestamp
}

Development

Running Tests

flutter test

Code Analysis

flutter analyze

Format Code

flutter format lib/

Build for Development

# Android
flutter build apk --debug

# iOS
flutter build ios --debug

# Web
flutter build web

Deployment

Android (APK)

# Build release APK
flutter build apk --release

# Build App Bundle for Play Store
flutter build appbundle --release

iOS (App Store)

# Build for iOS
flutter build ios --release

# Build IPA
flutter build ipa --release

Web (Firebase Hosting)

# Build web app
flutter build web --release

# Deploy to Firebase Hosting
firebase deploy --only hosting

Firebase Project Information

• Project ID: invoiceflow-deafa
• Firestore Database: (default)
• Firebase Hosting: Configured for web deployment
• Security Rules: User-scoped data access enforced

Environment Configuration

Development

• Uses Firebase development project
• Debug logging enabled
• Test notification features available

Production

• Firebase production project
• Analytics enabled
• Optimized builds with code minification

Features by Screen

Screen	Features
Home Dashboard	Recent invoices, Quick actions, Key metrics, Notification status
Invoices List	Search, Filter by type/status/date, Multi-select, Pagination
Invoice Detail	Full invoice view, Payment recording, PDF export, WhatsApp share, Returns
Create/Edit Invoice	Smart number generation, Customer lookup, Item selection, Payment entry
Customers	Customer list, Search, Outstanding balances, Purchase history, WhatsApp reminders
Inventory	Real-time stock display, Item details, Low stock highlighting, Stock movements
Analytics	7-card dashboard, Revenue charts, Customer analytics, Item performance, Inventory health
Returns	Create return, Select items, Apply refunds, Track pending returns
Profile	User settings, Notification preferences, Account management

Contributing

We welcome contributions! Please follow these steps:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Development Guidelines

• Follow Flutter/Dart style guide
• Write meaningful commit messages
• Add tests for new features
• Update documentation as needed
• Ensure code passes flutter analyze

Known Limitations

• Single User: No multi-user team collaboration features yet
• Currency: Fixed to INR (₹), multi-currency support planned
• Offline Mode: Limited offline capabilities, primarily cloud-dependent
• Payment Integration: Records manual payments only, no direct payment processing
• iOS Deployment: Not actively deployed to Apple App Store yet

Roadmap

• Multi-currency support
• Offline-first architecture with sync
• Payment gateway integration
• Advanced reporting and scheduled exports
• Team collaboration features
• Custom invoice templates
• Expense tracking and categorization
• Tax calculation automation

Support

For issues, questions, or feature requests:

• Open an issue on GitHub
• Contact: support@invoiceflow.com

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Built with Flutter & Dart
• Powered by Firebase
• Icons from Material Design Icons
• Charts powered by FL Chart

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Made with ❤️ for small businesses worldwide