LeetCode Tracker

A Spring Boot web application that fetches and visualizes LeetCode user statistics via LeetCode's public GraphQL API. Built with Thymeleaf, Bootstrap 5.3, and Chart.js.

Features

• 4 Ring Charts — doughnut charts for Easy, Medium, Hard, and Total solved counts
• Topic Tags — grouped by Advanced, Intermediate, Fundamental with solved counts (format: Array x109)
• Language Stats — progress bars showing problem counts per language
• 30-Day Solved Trend — line chart tracking daily solved counts over time
• User Comparison — side-by-side comparison of any two LeetCode users
• Dark / Light Theme — persistent theme toggle (Bootstrap 5.3 data-bs-theme)
• Auto Refresh — daily cron refreshes stats for all tracked users

Tech Stack

Layer	Technology
Backend	Java 21, Spring Boot 3.4.4, Spring Data JPA
Frontend	Thymeleaf, Bootstrap 5.3, Chart.js 4.4, Bootstrap Icons
Database	H2 in-memory (dev), PostgreSQL (production)
Build	Maven

Quick Start

git clone <repo-url>
cd leetcode-tracker
mvn spring-boot:run

Open http://localhost:8080, enter a LeetCode username, and hit Search.

Usage

1. Search — enter a LeetCode username on the home page to fetch and display their stats
2. Dashboard — view solved counts, acceptance rate, ranking, topic tags, language breakdown, recent submissions, and the 30-day solved trend
3. Compare — navigate to /compare (or click Compare in the navbar) to view two users side-by-side
4. Theme — click the sun/moon icon in the navbar to toggle between light and dark mode

Project Structure

src/main/java/com/leetcode/tracker/
├── LeetCodeTrackerApplication.java   — entry point, RestTemplate bean, scheduling
├── model/
│   ├── LeetCodeUser.java             — user stats entity
│   └── DailySnapshot.java            — daily snapshot entity for trend chart
├── repository/                       — Spring Data JPA repositories
├── service/
│   └── LeetCodeService.java          — GraphQL queries, data mapping, cron refresh
└── controller/
    ├── TrackerController.java        — web endpoints
    └── GlobalExceptionHandler.java   — global error handling

src/main/resources/
├── application.properties            — dev config (H2, port 8080)
├── application-prod.properties       — prod config (PostgreSQL)
└── templates/
    ├── index.html                    — search form
    ├── dashboard.html                — main stats dashboard
    └── compare.html                  — user comparison page

Deploy to Render

1. Set the active profile to prod
2. Add a DATABASE_URL environment variable pointing to your PostgreSQL instance
3. The production profile disables the H2 console and uses PostgreSQL

What's Not Public

The userProgressQuestionList GraphQL query requires authentication and cannot list a specific user's solved/attempted problems publicly. The /api/problems/{username} endpoint exists but returns empty for unauthenticated requests.