🚀 CodeAlert

Competitive Programming Tracker & Contest Reminder

CodeAlert is a full-stack mobile application built to centralize competitive programming activities across multiple coding platforms.

Track ratings, solved questions, upcoming contests, and reminders — all from one dashboard.

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📌 Features

✅ User Authentication (Signup/Login)

✅ JWT Session Management

✅ Platform Handle Integration

✅ Contest Tracking

✅ Contest Countdown Timer

✅ Coding Profile Monitoring

✅ Theme Support (Dark / Light)

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🏗️ High Level Design (HLD)

System Overview

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📖 Use Case Diagram

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⚙️ Low Level Design (LLD)

Frontend Structure

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Backend Structure

backend/
│
├── app/
│
├── routers/
│   ├── users.py
│   ├── dashboard.py
│   ├── contests.py
│   ├── leetcode.py
│   ├── codeforces.py
│   ├── reminders.py
│
├── auth/
│   └── auth_handler.py
│
├── database/
│   └── database.py
│
└── main.py

🔐 Authentication Flow

CodeAlert uses a dual-token authentication strategy.

• Access Token

  • JWT
  • Short-lived (60 minutes)
  • Sent in the Authorization header

• Refresh Token

  • Opaque UUID
  • Stored securely in MongoDB
  • Long-lived (30 days)
  • Automatically rotated on every refresh request

Session Flow

Login
   │
   ▼
Access Token + Refresh Token
   │
   ▼
Access Token Expires
   │
   ▼
Flutter calls /auth/refresh
   │
   ▼
New Access Token
+
New Refresh Token
   │
   ▼
Retry Original Request

Security Features

• Refresh token rotation
• Server-side refresh token revocation
• Single-device logout
• Logout from all devices
• Automatic expiration using MongoDB TTL indexes

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🗄️ Entity Relationship Diagram (ER Diagram)

The following diagram illustrates the logical relationships between the MongoDB collections used in CodeAlert.

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🧩 System Architecture

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🗄️ Database Schemas

users

{
 "_id":"ObjectId",
 "name":"Revant",
 "email":"user@gmail.com",
 "password":"****",
 "handles":{
   "cf_handle":"abc",
   "lc_handle":"xyz"
 }
}

refresh_tokens

{
  "_id": "ObjectId",
  "token": "3d13fd70-5d0f-45d8-83b9-5a2a09a57d8d",
  "user_id": "6865b7ef3f62d5cb3b92cb0a",

  "created_at": "2026-07-10T16:25:13Z",
  "expires_at": "2026-08-09T16:25:13Z",

  "revoked": false,
  "revoked_at": null,

  "device_hint": "Flutter"
}

---

lc_profile

{
  "_id": "ObjectId",

  "user_id": "6865b7ef3f62d5cb3b92cb0a",
  "lc_handle": "abc@123",

  "rating": 1345,

  "global_ranking": 419189,

  "problems_solved": 109
}

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cf_profile

{
  "_id": "ObjectId",

  "user_id": "6865b7ef3f62d5cb3b92cb0a",
  "cf_handle": "abc@123",
  "rating": 364,
  "max_rating": 465,
  "rank": "newbie",
  "problems_solved": 124
}

cc_profile

{
  "_id": "ObjectId",

  "user_id": "6865b7ef3f62d5cb3b92cb0a",
  "cc_handle": "abc@123",

  "rating": 399,

  "stars": "1★",

  "global_ranking": 442451,

  "problems_solved": 39
}

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contests

{
"name":"Weekly Contest",
"platform":"LeetCode",
"start_time":"timestamp"
}

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reminders

{
 "_id": "ObjectId",
"user_id":"123",
"contest_name":"Codeforces Round",
"reminder_time":"timestamp"
}

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🔌 API Endpoints

Auth

POST /signup
POST /login
POST /auth/refresh
POST /auth/logout
POST /auth/logout-all

User

PUT /handles
PATCH /update-password
POST /dashboard/sync

Contest

GET /contests

Reminder

POST /reminder
GET /reminders

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🛠️ Tech Stack

Frontend

Backend

Database

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External APIs

• LeetCode GraphQL
• Codeforces API
• CodeChef Data Source

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📈 Current Progress

Completed

• User Authentication
• JWT Access Tokens
• Refresh Token Rotation
• Automatic Session Refresh
• Secure Logout
• Logout from All Devices
• Contest Fetch
• Contest Countdown
• Profile Page
• Platform Handle Setup
• Dashboard Sync
• Rating Tracking
• Questions Solved Tracking
• Theme Support
• Auto Refresh

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In Progress

• Notification Integration
• Profile Analytics
• Contest Filtering
• Better Error Handling
• Background Sync

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Planned

• Push Notifications
• Redis Contest Caching
• AI Contest Recommendation
• Statistics Dashboard
• Leaderboards
• Activity Graph
• Active Device Management

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🚀 Installation

git clone <repo>

cd codealert

flutter pub get

flutter run

Backend:

cd backend

uvicorn app.main:app --host 0.0.0.0 --reload

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👨‍💻 Contributors

Built with ❤️ using Flutter + FastAPI + MongoDB