Final commit. Consists of game, ecommerce website and chat app

AKSHAT_YADAV/CHAT-APP/.env.example

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+# .env.example
+
+# LLM Keys
+OPENROUTER_API_KEY=
+
+# Firebase
+FIREBASE_API_KEY=
+FIREBASE_PROJECT_ID=
+FIREBASE_AUTH_DOMAIN=
+
+# PostgreSQL
+POSTGRES_URL=postgresql://username:password@localhost:5432/llm_chat_db
+
+# App
+SECRET_KEY=

AKSHAT_YADAV/CHAT-APP/.gitignore

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+.env
+__pycache__/
+venv/
+*.pyc
+*.pyo
+*.pyd
+.DS_Store
+*.sqlite3
+*.log
+node_modules/
+FRONTEND/__pycache__/
+BACKEND/__pycache__/
+FRONTEND/venv/
+BACKEND/venv/

AKSHAT_YADAV/CHAT-APP/BACKEND/db.py

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+import os
+import psycopg2
+from dotenv import load_dotenv
+
+load_dotenv()
+
+def get_db_connection():
+    conn = psycopg2.connect(os.getenv("POSTGRES_URL"))
+    return conn

AKSHAT_YADAV/CHAT-APP/BACKEND/main.py

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+# backend/main.py
+from fastapi import FastAPI, HTTPException, Body
+from fastapi.middleware.cors import CORSMiddleware
+from db import get_db_connection
+from pydantic import BaseModel
+from models.openrouter import call_openrouter
+import uuid
+import os
+import psycopg2
+from typing import List
+from dotenv import load_dotenv
+
+# Load environment variables
+load_dotenv()
+
+app = FastAPI()
+
+# Add CORS middleware
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],  # Allows all origins
+    allow_credentials=True,
+    allow_methods=["*"],  # Allows all methods
+    allow_headers=["*"],  # Allows all headers
+)
+
+@app.get("/")
+def read_root():
+    return {"msg": "LLM Chat Backend is running"}
+
+
+# Pydantic models
+class SessionRequest(BaseModel):
+    user_id: str = None  # Optional, but not required anymore
+
+class SessionResponse(BaseModel):
+    session_id: str
+
+class ChatMessage(BaseModel):
+    role: str  # "user" or "assistant"
+    content: str
+
+class ChatRequest(BaseModel):
+    session_id: str
+    model: str
+    message: str
+
+class ChatResponse(BaseModel):
+    response: str
+
+class ChatHistoryResponse(BaseModel):
+    history: List[ChatMessage]
+
+@app.get("/db-test")
+def db_test():
+    try:
+        conn = get_db_connection()
+        cur = conn.cursor()
+        cur.execute("SELECT 1;")
+        result = cur.fetchone()
+        cur.close()
+        conn.close()
+        return {"db_connection": "success", "result": result}
+    except Exception as e:
+        return {"db_connection": "failed", "error": str(e)}
+
+
+# /chat/session endpoint
+@app.post("/chat/session", response_model=SessionResponse)
+def chat_session(payload: SessionRequest):
+    conn = get_db_connection()
+    cur = conn.cursor()
+    # Create new session (no user required)
+    session_id = str(uuid.uuid4())
+    cur.execute("INSERT INTO sessions (session_id) VALUES (%s)", (session_id,))
+    conn.commit()
+    cur.close()
+    conn.close()
+    return SessionResponse(session_id=session_id)
+
+@app.post("/chat", response_model=ChatResponse)
+def chat(request: ChatRequest):
+    conn = get_db_connection()
+    cur = conn.cursor()
+    # Get previous messages for context
+    cur.execute("SELECT role, message FROM chat_messages WHERE session_id = %s ORDER BY timestamp ASC", (request.session_id,))
+    history = [{"role": row[0], "content": row[1]} for row in cur.fetchall()]
+    # Add the new user message
+    history.append({"role": "user", "content": request.message})
+    # Call the LLM
+    response = call_openrouter(request.model, history)
+    # Save user message
+    cur.execute(
+        "INSERT INTO chat_messages (id, session_id, role, message, model) VALUES (%s, %s, %s, %s, %s)",
+        (str(uuid.uuid4()), request.session_id, "user", request.message, request.model)
+    )
+    # Save assistant message
+    cur.execute(
+        "INSERT INTO chat_messages (id, session_id, role, message, model) VALUES (%s, %s, %s, %s, %s)",
+        (str(uuid.uuid4()), request.session_id, "assistant", response, request.model)
+    )
+    conn.commit()
+    cur.close()
+    conn.close()
+    return ChatResponse(response=response)
+
+@app.get("/chat/history", response_model=ChatHistoryResponse)
+def chat_history(session_id: str):
+    conn = get_db_connection()
+    cur = conn.cursor()
+    cur.execute("SELECT role, message FROM chat_messages WHERE session_id = %s ORDER BY timestamp ASC", (session_id,))
+    history = [ChatMessage(role=row[0], content=row[1]) for row in cur.fetchall()]
+    cur.close()
+    conn.close()
+    return ChatHistoryResponse(history=history)
+
+# --- New endpoint to list all sessions (for sidebar)
+@app.get("/chat/sessions")
+def list_sessions():
+    conn = get_db_connection()
+    cur = conn.cursor()
+    cur.execute("SELECT session_id FROM sessions ORDER BY session_id DESC")
+    sessions = [row[0] for row in cur.fetchall()]
+    cur.close()
+    conn.close()
+    return {"sessions": sessions}

AKSHAT_YADAV/CHAT-APP/BACKEND/models/openrouter.py

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+import os
+import requests
+import json
+
+OPENROUTER_API_KEY = os.getenv("OPENROUTER_API_KEY")
+OPENROUTER_API_URL = "https://openrouter.ai/api/v1/chat/completions"
+
+def call_openrouter(model: str, messages: list):
+    if not OPENROUTER_API_KEY:
+        raise ValueError("OPENROUTER_API_KEY not found in environment variables")
+
+    headers = {
+        "Authorization": f"Bearer {OPENROUTER_API_KEY}",
+        "Content-Type": "application/json",
+        "HTTP-Referer": "http://localhost:3000",  # Optional: your site URL
+        "X-Title": "LLM Chat App"  # Optional: your app name
+    }
+    data = {
+        "model": model,
+        "messages": messages
+    }
+
+    try:
+        response = requests.post(OPENROUTER_API_URL, headers=headers, json=data)
+        print(f"OpenRouter response status: {response.status_code}")
+        print(f"OpenRouter response: {response.text}")
+        response.raise_for_status()
+        return response.json()["choices"][0]["message"]["content"]
+    except requests.exceptions.HTTPError as e:
+        print(f"OpenRouter API Error: {e}")
+        print(f"Request data: {json.dumps(data, indent=2)}")
+        raise e

AKSHAT_YADAV/CHAT-APP/FRONTEND/README.md

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+# LLM Chat App - Frontend
+
+A modern web-based chat interface for interacting with Large Language Models through OpenRouter API.
+
+## Features
+
+- **Modern UI**: Clean, responsive design inspired by ChatGPT
+- **Multiple Models**: Support for 5 different LLM models
+- **Session Management**: Create new chats and browse chat history
+- **Real-time Chat**: Instant messaging with typing indicators
+- **Responsive Design**: Works on desktop and mobile devices
+- **Auto-save**: All conversations are automatically saved
+
+## How to Run
+
+### Prerequisites
+- Backend server running on `http://localhost:8000`
+- Modern web browser (Chrome, Firefox, Safari, Edge)
+
+### Running the Frontend
+
+1. **Simple Method**: Just open `index.html` in your web browser
+   - Double-click the `index.html` file
+   - Or right-click and select "Open with browser"
+
+2. **Local Server Method** (recommended for development):
+   ```bash
+   # Using Python (if you have Python installed)
+   python -m http.server 8080
+
+   # Or using Node.js live-server (if you have Node.js)
+   npx live-server --port=8080
+
+   # Then open http://localhost:8080 in your browser
+   ```
+
+3. **VS Code Live Server Extension**:
+   - Install "Live Server" extension in VS Code
+   - Right-click on `index.html` and select "Open with Live Server"
+
+### Backend Setup
+Make sure your FastAPI backend is running:
+```bash
+cd ../BACKEND
+uvicorn main:app --reload
+```
+
+## File Structure
+
+```
+FRONTEND/
+├── index.html      # Main HTML structure
+├── styles.css      # All CSS styling
+├── script.js       # JavaScript functionality
+└── README.md       # This file
+```
+
+## Features Overview
+
+### Chat Interface
+- Clean, modern design with user and AI message bubbles
+- Typing indicators when AI is responding
+- Auto-scroll to latest messages
+- Timestamp for each message
+
+### Model Selection
+- Dropdown to choose between 5 LLM models:
+  - Mistral 7B Instruct
+  - OpenChat 3.5
+  - NeuralBeagle 7B
+  - Meta LLaMA 3 8B Instruct
+  - HuggingFace Zephyr 7B Beta
+
+### Session Management
+- Create new chat sessions
+- View all previous sessions in sidebar
+- Click on any session to load its history
+- Sessions are automatically saved in the database
+
+### User Experience
+- **Enter key** to send messages
+- **Shift+Enter** for new lines
+- Auto-resizing text input
+- Loading states and error handling
+- Connection status indicator
+- Mobile-responsive design
+
+## Browser Compatibility
+
+- Chrome 60+
+- Firefox 55+
+- Safari 12+
+- Edge 79+
+
+## Troubleshooting
+
+### Common Issues
+
+1. **"Failed to connect to backend"**
+   - Make sure the backend server is running on `http://localhost:8000`
+   - Check if there are any CORS issues in the browser console
+
+2. **Messages not sending**
+   - Verify your OpenRouter API key is set in the backend `.env` file
+   - Check browser console for JavaScript errors
+
+3. **Sessions not loading**
+   - Ensure PostgreSQL database is running
+   - Check if the database tables exist
+
+4. **Styling issues**
+   - Make sure all three files (HTML, CSS, JS) are in the same directory
+   - Check browser console for any file loading errors
+
+### Development Tips
+
+- Open browser Developer Tools (F12) to debug issues
+- Check the Network tab for API call failures
+- Console tab will show JavaScript errors
+- Use the responsive design mode to test mobile layout
+
+## API Endpoints Used
+
+The frontend communicates with these backend endpoints:
+
+- `GET /` - Health check
+- `POST /chat/session` - Create new session
+- `GET /chat/sessions` - Get all sessions
+- `POST /chat` - Send message
+- `GET /chat/history` - Get chat history
+
+## Customization
+
+### Styling
+Edit `styles.css` to customize:
+- Colors and themes
+- Layout and spacing
+- Animation effects
+- Mobile responsiveness
+
+### Functionality
+Edit `script.js` to modify:
+- API endpoints
+- Message formatting
+- User interactions
+- Error handling
+
+### Layout
+Edit `index.html` to change:
+- Page structure
+- UI components
+- Meta tags and title