AI Chat — Full-Stack FastAPI, MySQL & Gemini Application

A professional, state-of-the-art AI Chat client powered by FastAPI, MySQL, and the Gemini 2.5 Flash API. This project delivers a premium Single Page Application (SPA) experience with custom styling, robust authentication, persistent conversation history, and real-time response streaming.

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🌟 Key Features

1. Advanced Architecture

• FastAPI Backend: Lightweight, high-performance asynchronous API layer.
• Token-Based JWT Security: Stateless authorization containing password hashing via bcrypt and session tokens with PyJWT.
• Persistent Chat History: Automatic database schema generation and full one-to-many model mappings for users, conversations, and messages using SQLAlchemy and MySQL.
• Real-time Streaming: Seamless server-sent streaming chunk-by-chunk using FastAPI StreamingResponse to eliminate response lag.
• Stateful AI Memory: Automatically aggregates and builds a sliding contextual memory window of recent message history to provide stateful, interactive conversations.

2. Responsive Frontend SPA

• Fluid Responsive UX: Custom Vanilla CSS Grid & Flexbox system. Built-in sidebar drawer for mobile viewports ($\le 680\text{px}$) with overlay dismissals.
• Adaptive Glassmorphism & Theme Toggle: Seamless switching between sleeker Deep Purple Dark Mode and vibrant Ice-Blue Light Mode, saving user preferences automatically via localStorage.
• Intelligent Hash Routing: Integrated HTML5 hash routing (#/c/{id}, #/new) that coordinates with browser navigation. Re-opening links or reloading the page keeps the exact active conversation.
• Client & Server-Side Validation: Inline validation on authentication forms. Parse Pydantic 422 Unprocessable Entity payload arrays gracefully into clear human-friendly notices.
• Micro-interactive Confirmations: In-app overlay modals for sensitive actions (e.g. permanent chat deletion or signing out) with fluid transition animations.

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📁 Project Structure

ai-chat-fastapi-python/
├── routes/
│   ├── auth_routes.py      # User registration, login, and token generation
│   └── chat_routes.py      # Stateful chat streams, message & conversation DB endpoints
├── static/
│   ├── app.js              # State management, routing, validation, UI rendering
│   ├── index.html          # Clean HTML layout
│   └── style.css           # Premium responsive custom theme system
├── .env                    # System-wide secrets & parameters
├── .gitignore              # Ignored local files (.env, .venv, etc.)
├── app.py                  # Primary application bootstrapper & static mounts
├── auth.py                 # Core JWT verification, passwords, and security dependencies
├── database.py             # SQLAlchemy engine pool config & active thread sessions
├── models.py               # Declarative ORM schemas (Users, Conversations, Messages)
├── pyproject.toml          # uv configuration & core project packaging details
└── schemas.py              # Pydantic schema schemas (ChatRequest, UserAuth, etc.)

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🚀 Getting Started

1. Prerequisites

• Python 3.11+
• MySQL Server running locally or remotely
• uv (Extremely fast Python package installer and runner)

2. Database Setup

Create an empty MySQL database named ai_chat:

CREATE DATABASE ai_chat CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

3. Environment Configurations

Create a .env file in the root directory:

GEMINI_API_KEY="your-gemini-api-key"
GEMINI_MODEL="gemini-2.5-flash"

# Database Configuration (MySQL)
DATABASE_URL="mysql+pymysql://<user>:<password>@localhost:3306/ai_chat"

# JWT Token Secret Key
SECRET_KEY="generate-a-secure-secret-key"

4. Running the Application

Install dependencies and run the server instantly using uv:

uv run uvicorn app:app --reload

Once uvicorn is running, open the application in your browser: 🔗 http://127.0.0.1:8000

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🛠️ Built With

• FastAPI - Python web framework for APIs.
• SQLAlchemy - Database Toolkit & ORM.
• PyMySQL & Cryptography - MySQL connector and data layer encryption.
• Bcrypt - Industry standard password hashing.
• Google GenAI Client - Integration with Gemini 2.5 Flash.
• Vanilla JS, CSS & HTML5 - Responsive frontend SPA.