# Flutter Finance App - Python API Integration Guide

This guide explains how to connect the Flutter Finance App front-end with a Python API backend for the chat interface and database interactions.

## Architecture Overview

![Architecture Overview](https://mermaid.ink/img/pako:eNp1kU9PwzAMxb9K5BNIHeq2tOVvtQtIcODAgRMXqw1bRJuUJGVIqN-dnUy0Gxw8-fnnt-SnFLYQkY5oRaNw27LPUcaiLnredSg5vD-_vgSy9lr9gfXZdTEtKk6NtGXhsGZGjBi1EFxR6M4x8MpiGxHnxN1baD6E9GW0kGLPtlgGQZxblzA86Z9KP3QPgWbQaHujbgxkWIj5ijwPAN-xHEZVLuul0xQXM8P1wiToXoyJrPrwhm3awaeQ4qlJPbMpZzAl36GmeF9HfdBh5npWD5tRPUERXYG-6FTJCfPP4f1rKb9huA1hG-TBf4z6b7z5Mol2KEQl2bnCjnWhNxOXhRsh2XG9JaeL0YhRcb2luujG75tSbFGTsfKEn-ckZLtp9Z-TPsDsDz8_)

## 1. Setting up the Python API Server

### Requirements
- Python 3.8+
- Flask/FastAPI
- SQL.js connector or alternative database library

### Step 1: Create a Flask API

```python
from flask import Flask, request, jsonify
from flask_cors import CORS
import sqlite3
import json

app = Flask(__name__)
CORS(app)  # Enable Cross-Origin Resource Sharing

# Database connection
def get_db_connection():
    conn = sqlite3.connect('finance_app.db')
    conn.row_factory = sqlite3.Row
    return conn

# Create tables if they don't exist
def init_db():
    conn = get_db_connection()
    conn.execute('''
    CREATE TABLE IF NOT EXISTS transactions (
        id TEXT PRIMARY KEY,
        title TEXT NOT NULL,
        amount REAL NOT NULL,
        type TEXT NOT NULL,
        category TEXT NOT NULL,
        date TEXT NOT NULL,
        note TEXT,
        message TEXT
    )
    ''')
    
    conn.execute('''
    CREATE TABLE IF NOT EXISTS products (
        id TEXT PRIMARY KEY,
        name TEXT NOT NULL,
        sku TEXT NOT NULL,
        quantity INTEGER NOT NULL,
        price REAL NOT NULL,
        category TEXT NOT NULL,
        last_updated TEXT NOT NULL,
        reorder_point INTEGER DEFAULT 5,
        trend TEXT DEFAULT 'stable',
        demand TEXT DEFAULT 'medium'
    )
    ''')
    
    conn.commit()
    conn.close()

# Initialize database on startup
init_db()

# Chat endpoints
@app.route('/api/messages', methods=['GET'])
def get_messages():
    conn = get_db_connection()
    messages = conn.execute('SELECT * FROM messages ORDER BY timestamp').fetchall()
    conn.close()
    return jsonify([dict(message) for message in messages])

@app.route('/api/messages', methods=['POST'])
def send_message():
    data = request.json
    conn = get_db_connection()
    conn.execute(
        'INSERT INTO messages (user_id, content, timestamp) VALUES (?, ?, ?)',
        (data['user_id'], data['content'], data['timestamp'])
    )
    conn.commit()
    conn.close()
    
    # Here you can implement AI response logic
    return jsonify({"status": "success", "message": "Message sent"})

# Transaction endpoints
@app.route('/api/transactions', methods=['GET'])
def get_transactions():
    conn = get_db_connection()
    transactions = conn.execute('SELECT * FROM transactions').fetchall()
    conn.close()
    return jsonify([dict(tx) for tx in transactions])

@app.route('/api/transactions', methods=['POST'])
def add_transaction():
    data = request.json
    conn = get_db_connection()
    conn.execute(
        'INSERT INTO transactions (id, title, amount, type, category, date, note, message) VALUES (?, ?, ?, ?, ?, ?, ?, ?)',
        (data['id'], data['title'], data['amount'], data['type'], data['category'], data['date'], data.get('note'), data.get('message'))
    )
    conn.commit()
    conn.close()
    return jsonify({"status": "success"})

# Product/Stock endpoints
@app.route('/api/products', methods=['GET'])
def get_products():
    conn = get_db_connection()
    products = conn.execute('SELECT * FROM products ORDER BY name').fetchall()
    conn.close()
    return jsonify([dict(product) for product in products])

@app.route('/api/products/low', methods=['GET'])
def get_low_stock_products():
    conn = get_db_connection()
    products = conn.execute('SELECT * FROM products WHERE quantity <= reorder_point ORDER BY quantity').fetchall()
    conn.close()
    return jsonify([dict(product) for product in products])

@app.route('/api/products/<product_id>', methods=['GET'])
def get_product(product_id):
    conn = get_db_connection()
    product = conn.execute('SELECT * FROM products WHERE id = ?', (product_id,)).fetchone()
    conn.close()
    
    if not product:
        return jsonify({"error": "Product not found"}), 404
        
    return jsonify(dict(product))

@app.route('/api/products', methods=['POST'])
def add_product():
    data = request.json
    conn = get_db_connection()
    
    try:
        conn.execute(
            'INSERT INTO products (id, name, sku, quantity, price, category, last_updated, reorder_point) VALUES (?, ?, ?, ?, ?, ?, ?, ?)',
            (
                data['id'], 
                data['name'], 
                data['sku'], 
                data['quantity'], 
                data['price'], 
                data['category'], 
                data['last_updated'],
                data.get('reorder_point', 5)
            )
        )
        conn.commit()
        return jsonify({"status": "success", "message": "Product added successfully"})
    except Exception as e:
        conn.rollback()
        return jsonify({"status": "error", "message": str(e)}), 400
    finally:
        conn.close()

@app.route('/api/products/<product_id>', methods=['PUT'])
def update_product(product_id):
    data = request.json
    conn = get_db_connection()
    
    try:
        # Check if product exists
        product = conn.execute('SELECT * FROM products WHERE id = ?', (product_id,)).fetchone()
        if not product:
            return jsonify({"error": "Product not found"}), 404
            
        # Update product
        conn.execute(
            '''
            UPDATE products 
            SET name = ?, sku = ?, quantity = ?, price = ?, 
                category = ?, last_updated = ?, reorder_point = ?
            WHERE id = ?
            ''',
            (
                data['name'], 
                data['sku'], 
                data['quantity'], 
                data['price'], 
                data['category'], 
                data['last_updated'],
                data.get('reorder_point', 5),
                product_id
            )
        )
        conn.commit()
        return jsonify({"status": "success", "message": "Product updated successfully"})
    except Exception as e:
        conn.rollback()
        return jsonify({"error": str(e)}), 400
    finally:
        conn.close()

@app.route('/api/products/<product_id>', methods=['DELETE'])
def delete_product(product_id):
    conn = get_db_connection()
    
    try:
        # Check if product exists
        product = conn.execute('SELECT * FROM products WHERE id = ?', (product_id,)).fetchone()
        if not product:
            return jsonify({"error": "Product not found"}), 404
            
        # Delete product
        conn.execute('DELETE FROM products WHERE id = ?', (product_id,))
        conn.commit()
        return jsonify({"status": "success", "message": "Product deleted successfully"})
    except Exception as e:
        conn.rollback()
        return jsonify({"error": str(e)}), 400
    finally:
        conn.close()

@app.route('/api/stock/analytics', methods=['GET'])
def get_stock_analytics():
    conn = get_db_connection()
    
    try:
        # Get total product count
        total_count = conn.execute('SELECT COUNT(*) as count FROM products').fetchone()['count']
        
        # Get total inventory value
        total_value = conn.execute('SELECT SUM(quantity * price) as value FROM products').fetchone()['value']
        
        # Get low stock count
        low_stock = conn.execute('SELECT COUNT(*) as count FROM products WHERE quantity <= reorder_point').fetchone()['count']
        
        # Get top categories
        categories = conn.execute('''
            SELECT category, COUNT(*) as count, SUM(quantity * price) as value
            FROM products
            GROUP BY category
            ORDER BY count DESC
            LIMIT 5
        ''').fetchall()
        
        return jsonify({
            "total_count": total_count,
            "total_value": total_value or 0,
            "low_stock_count": low_stock,
            "categories": [dict(category) for category in categories]
        })
    except Exception as e:
        return jsonify({"error": str(e)}), 400
    finally:
        conn.close()

if __name__ == '__main__':
    app.run(debug=True, port=5000)
```

### Step 2: Set up a virtual environment

```bash
# Create a virtual environment
python -m venv venv

# Activate it (Windows)
venv\Scripts\activate

# Activate it (macOS/Linux)
source venv/bin/activate

# Install dependencies
pip install flask flask-cors sqlite3
```

## 2. Connecting the React App to the Python API

### Step 1: Create an API Service in the React App

Create a new file `src/services/api.ts`:

```typescript
const API_URL = 'http://localhost:5000/api';

// Messages API
export const fetchMessages = async () => {
  const response = await fetch(`${API_URL}/messages`);
  if (!response.ok) {
    throw new Error('Failed to fetch messages');
  }
  return response.json();
};

export const sendMessage = async (message: {
  user_id: string;
  content: string;
  timestamp: string;
}) => {
  const response = await fetch(`${API_URL}/messages`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(message),
  });
  
  if (!response.ok) {
    throw new Error('Failed to send message');
  }
  
  return response.json();
};

// Transactions API
export const fetchTransactions = async () => {
  const response = await fetch(`${API_URL}/transactions`);
  if (!response.ok) {
    throw new Error('Failed to fetch transactions');
  }
  return response.json();
};

export const addTransaction = async (transaction: any) => {
  const response = await fetch(`${API_URL}/transactions`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(transaction),
  });
  
  if (!response.ok) {
    throw new Error('Failed to add transaction');
  }
  
  return response.json();
};

// Products/Stock API
export const fetchProducts = async () => {
  const response = await fetch(`${API_URL}/products`);
  if (!response.ok) {
    throw new Error('Failed to fetch products');
  }
  return response.json();
};

export const fetchLowStockProducts = async () => {
  const response = await fetch(`${API_URL}/products/low`);
  if (!response.ok) {
    throw new Error('Failed to fetch low stock products');
  }
  return response.json();
};

export const fetchProductById = async (id: string) => {
  const response = await fetch(`${API_URL}/products/${id}`);
  if (!response.ok) {
    throw new Error('Failed to fetch product');
  }
  return response.json();
};

export const addProduct = async (product: any) => {
  const response = await fetch(`${API_URL}/products`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(product),
  });
  
  if (!response.ok) {
    throw new Error('Failed to add product');
  }
  
  return response.json();
};

export const updateProduct = async (id: string, product: any) => {
  const response = await fetch(`${API_URL}/products/${id}`, {
    method: 'PUT',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(product),
  });
  
  if (!response.ok) {
    throw new Error('Failed to update product');
  }
  
  return response.json();
};

export const deleteProduct = async (id: string) => {
  const response = await fetch(`${API_URL}/products/${id}`, {
    method: 'DELETE',
    headers: {
      'Content-Type': 'application/json',
    },
  });
  
  if (!response.ok) {
    throw new Error('Failed to delete product');
  }
  
  return response.json();
};

export const fetchStockAnalytics = async () => {
  const response = await fetch(`${API_URL}/stock/analytics`);
  if (!response.ok) {
    throw new Error('Failed to fetch stock analytics');
  }
  return response.json();
};
```

### Step 2: Update Messages Component to use the API

Update the Messages component to fetch and send messages via the API:

```typescript
import { useState, useEffect } from "react";
import { fetchMessages, sendMessage } from "../services/api";
import { Send, Search } from "lucide-react";
import AppLayout from "@/components/layout/AppLayout";
import { Input } from "@/components/ui/input";
import { Button } from "@/components/ui/button";
import { Avatar } from "@/components/ui/avatar";
import { ScrollArea } from "@/components/ui/scroll-area";
import { cn } from "@/lib/utils";
import { motion } from "framer-motion";

// Sample data for messages
const initialContacts = [
  { id: 1, name: "AI Assistant", avatar: "A", lastMessage: "How can I help with your finances?", time: "10:30 AM", unread: 2 },
  { id: 2, name: "Budget Bot", avatar: "B", lastMessage: "Your weekly spending report is ready", time: "Yesterday", unread: 0 },
  { id: 3, name: "Investment Advisor", avatar: "I", lastMessage: "Consider these stocks for your portfolio", time: "Yesterday", unread: 1 },
  { id: 4, name: "Expense Tracker", avatar: "E", lastMessage: "You've exceeded your dining budget", time: "Monday", unread: 0 },
  { id: 5, name: "Financial Coach", avatar: "F", lastMessage: "Let's review your saving goals", time: "08/12/23", unread: 0 },
];

const initialMessages = [
  { id: 1, sender: "client", text: "Hello! I need some help understanding my recent transactions.", time: "10:30 AM" },
  { id: 2, sender: "me", text: "Hi there! I'd be happy to help you analyze your spending patterns. What specifically would you like to know?", time: "10:32 AM" },
  { id: 3, sender: "client", text: "I noticed some unusual activity in my account", time: "10:33 AM" },
  { id: 4, sender: "me", text: "I can check that for you. Could you tell me which transactions look suspicious?", time: "10:35 AM" },
  { id: 5, sender: "me", text: "Based on your spending history, the transaction at 'Tech Store' for $349.99 is unusual for you.", time: "10:36 AM" },
  { id: 6, sender: "client", text: "Yes, that's the one I was concerned about. I don't remember making that purchase.", time: "10:38 AM" },
];

const Messages = () => {
  const [contacts, setContacts] = useState(initialContacts);
  const [selectedContact, setSelectedContact] = useState(initialContacts[0]);
  const [messages, setMessages] = useState([]);
  const [loading, setLoading] = useState(true);
  const [newMessage, setNewMessage] = useState("");
  const [searchTerm, setSearchTerm] = useState("");

  useEffect(() => {
    // Fetch messages when component mounts
    const getMessages = async () => {
      try {
        setLoading(true);
        const data = await fetchMessages();
        setMessages(data);
      } catch (error) {
        console.error('Failed to fetch messages:', error);
      } finally {
        setLoading(false);
      }
    };
    
    getMessages();
  }, []);
  
  const handleSendMessage = async () => {
    if (newMessage.trim() === "") return;
    
    const messageData = {
      user_id: "user123", // Replace with actual user id
      content: newMessage,
      timestamp: new Date().toISOString()
    };
    
    try {
      await sendMessage(messageData);
      // Refetch messages or add the new one to state
      setMessages([...messages, {
        id: Date.now(),
        sender: "me",
        text: newMessage,
        time: new Date().toLocaleTimeString([], {hour: '2-digit', minute: '2-digit'})
      }]);
      setNewMessage("");
    } catch (error) {
      console.error('Failed to send message:', error);
    }
  };
  
  const filteredContacts = contacts.filter(contact => 
    contact.name.toLowerCase().includes(searchTerm.toLowerCase())
  );

  return (
    <AppLayout>
      <div className="max-w-6xl mx-auto h-full p-4">
        <h1 className="text-xl font-bold mb-4 text-slate-800">Messages</h1>
        
        <div className="flex h-[calc(100vh-180px)] rounded-2xl overflow-hidden bg-white/80 backdrop-blur-lg border border-slate-200 shadow-lg">
          {/* Contacts sidebar */}
          <div className="w-full max-w-xs border-r border-slate-200 hidden md:flex flex-col">
            <div className="p-3 border-b border-slate-200">
              <div className="relative">
                <Search className="absolute left-3 top-1/2 transform -translate-y-1/2 text-slate-400 h-4 w-4" />
                <Input
                  placeholder="Search contacts..."
                  className="pl-10 bg-slate-50 border-slate-200 text-slate-800"
                  value={searchTerm}
                  onChange={(e) => setSearchTerm(e.target.value)}
                />
              </div>
            </div>
            
            <ScrollArea className="flex-1">
              {filteredContacts.map(contact => (
                <div 
                  key={contact.id}
                  className={cn(
                    "p-3 flex items-center gap-3 cursor-pointer hover:bg-slate-50 transition-colors",
                    selectedContact.id === contact.id ? "bg-slate-50" : ""
                  )}
                  onClick={() => setSelectedContact(contact)}
                >
                  <Avatar className="h-10 w-10 bg-blue-600 text-white">
                    <div>{contact.avatar}</div>
                  </Avatar>
                  
                  <div className="flex-1 min-w-0">
                    <div className="flex justify-between items-center">
                      <span className="font-medium truncate text-slate-800">{contact.name}</span>
                      <span className="text-xs text-slate-500">{contact.time}</span>
                    </div>
                    <p className="text-sm text-slate-500 truncate">{contact.lastMessage}</p>
                  </div>
                  
                  {contact.unread > 0 && (
                    <div className="bg-blue-600 text-white text-xs rounded-full h-5 w-5 flex items-center justify-center">
                      {contact.unread}
                    </div>
                  )}
                </div>
              ))}
            </ScrollArea>
          </div>
          
          {/* Chat area */}
          <div className="flex-1 flex flex-col">
            <div className="p-3 border-b border-slate-200 flex items-center gap-3">
              <Avatar className="h-8 w-8 bg-blue-600 text-white md:hidden">
                <div>{selectedContact.avatar}</div>
              </Avatar>
              <div>
                <h3 className="font-medium text-slate-800">{selectedContact.name}</h3>
              </div>
            </div>
            
            <ScrollArea className="flex-1 p-4">
              <div className="space-y-4">
                {messages.map((message, index) => (
                  <motion.div 
                    key={message.id} 
                    initial={{ opacity: 0, y: 10 }}
                    animate={{ opacity: 1, y: 0 }}
                    transition={{ duration: 0.3, delay: index * 0.1 }}
                    className={cn(
                      "flex",
                      message.sender === "me" ? "justify-end" : "justify-start"
                    )}
                  >
                    <div 
                      className={cn(
                        "max-w-[80%] p-3 rounded-2xl shadow-sm",
                        message.sender === "me" 
                          ? "bg-blue-600 text-white rounded-tr-none" 
                          : "bg-slate-100 text-slate-800 rounded-tl-none"
                      )}
                    >
                      <p>{message.text}</p>
                      <span className={cn(
                        "text-xs block mt-1",
                        message.sender === "me" 
                          ? "text-white/70" 
                          : "text-slate-500"
                      )}>
                        {message.time}
                      </span>
                    </div>
                  </motion.div>
                ))}
              </div>
            </ScrollArea>
            
            <div className="p-3 border-t border-slate-200 flex items-center gap-2">
              <Input
                placeholder="Type a message..."
                value={newMessage}
                onChange={(e) => setNewMessage(e.target.value)}
                onKeyDown={(e) => {
                  if (e.key === "Enter") {
                    handleSendMessage();
                  }
                }}
                className="flex-1 bg-slate-50 border-slate-200 text-slate-800"
              />
              <Button size="icon" className="bg-blue-600 hover:bg-blue-700" onClick={handleSendMessage}>
                <Send size={18} />
              </Button>
            </div>
          </div>
        </div>
      </div>
    </AppLayout>
  );
};
```

## 3. Deploying the Python API

### Option 1: Docker Deployment

Create a `Dockerfile` for the Python API:

```dockerfile
FROM python:3.9-slim

WORKDIR /app

COPY requirements.txt .
RUN pip install -r requirements.txt

COPY . .

EXPOSE 5000

CMD ["python", "app.py"]
```

Create a `requirements.txt` file:

```
flask>=2.0.0
flask-cors>=3.0.10
```

Update the `docker-compose.yml` to include the Python API:

```yaml
version: '3.8'

services:
  app:
    build: .
    ports:
      - "8080:80"
    restart: unless-stopped
    depends_on:
      - api
  
  api:
    build: ./api
    ports:
      - "5000:5000"
    restart: unless-stopped
    volumes:
      - ./api/data:/app/data
```

### Option 2: Cloud Deployment

Deploy the Python API to a cloud service like:
- Heroku
- AWS Lambda + API Gateway
- Google Cloud Functions
- Azure Functions

## 4. Advanced Integration: AI Chat Assistant

To enhance the chat interface with AI capabilities, you can integrate with OpenAI's API:

```python
import openai

# Set your OpenAI API key
openai.api_key = "your-api-key"

@app.route('/api/chat', methods=['POST'])
def chat():
    data = request.json
    user_message = data['message']
    
    # Save user message to database
    conn = get_db_connection()
    conn.execute(
        'INSERT INTO messages (user_id, content, timestamp, is_ai) VALUES (?, ?, ?, ?)',
        (data['user_id'], user_message, data['timestamp'], 0)
    )
    conn.commit()
    
    # Get AI response
    response = openai.ChatCompletion.create(
        model="gpt-3.5-turbo",
        messages=[
            {"role": "system", "content": "You are a helpful financial assistant."},
            {"role": "user", "content": user_message}
        ]
    )
    
    ai_message = response.choices[0].message.content
    
    # Save AI response to database
    conn.execute(
        'INSERT INTO messages (user_id, content, timestamp, is_ai) VALUES (?, ?, ?, ?)',
        ('assistant', ai_message, data['timestamp'], 1)
    )
    conn.commit()
    conn.close()
    
    return jsonify({
        "message": ai_message,
        "timestamp": data['timestamp']
    })
```

## 5. Running Both Applications Together

1. Start the Python API:
```bash
cd api
python app.py
```

2. Start the React app:
```bash
npm run dev
```

## 6. Security Considerations

1. Implement proper authentication for API endpoints
2. Use HTTPS for production
3. Validate and sanitize all user inputs
4. Use environment variables for sensitive information
5. Implement rate limiting to prevent abuse

## 7. Troubleshooting

### Common Issues:
- **CORS errors**: Ensure CORS is properly configured in both the React app and the Python API
- **Database connection errors**: Check file paths and permissions
- **API connection issues**: Verify the API URL and port are correct

## 8. Resources

- [Flask Documentation](https://flask.palletsprojects.com/)
- [React Query Documentation](https://react-query.tanstack.com/)
- [SQLite Documentation](https://www.sqlite.org/docs.html)

## 9. License

This integration guide is provided under the same license as the Flutter Finance App.