Reddit Clone - Android Social Platform

A fully functional, high-performance Reddit clone built natively for Android. This project demonstrates modern Android development practices, real-time database synchronization, and complex state management.

🚀 Features

• Robust Authentication: Secure email/password login and registration.
• Real-time Feed: Scrollable, dynamic feed of user-generated posts ordered by timestamp.
• Optimistic UI Voting System: Lightning-fast upvote/downvote interactions. The UI updates instantly while Firestore transactions sync in the background to prevent race conditions and duplicate votes.
• Media Uploads: Users can upload images with their posts. Includes background image compression (WebP) to minimize bandwidth and storage costs.
• Smart Throttling: Built-in debounce and cooldown logic to prevent database spamming during rapid user interactions.
• Seamless State Management: Handles Android lifecycle events smoothly, pausing the task in the background rather than destroying it when navigating away.

🛠 Tech Stack

• Language: Kotlin
• UI: XML / ViewBinding
• Backend: Firebase (Authentication, Firestore, Storage)
• Image Loading: Glide
• Image Compression: Zelory Compressor
• Asynchronous Programming: Kotlin Coroutines & Lifecycle Scopes

📸 Screenshots

Login Screen	Feed Layout	Image Upload

🧠 Architecture Highlights

Firestore Transactional Voting

To ensure mathematical accuracy when multiple users vote on a viral post simultaneously, this app uses Firebase Transactions. It stores individual votes in a subcollection (/posts/{postId}/votes/{userId}) rather than just incrementing a single integer, preventing duplicate voting and race conditions.

Optimistic UI & Cooldowns

To provide a zero-latency experience, UI elements (like the Reddit Orange upvote arrow) update instantly upon clicking. A 10-second local lockout prevents users from spamming the database, while background coroutines handle the server synchronization.

💻 Installation & Setup

To run this project locally, you will need to connect it to your own Firebase project.

1. Clone the repository:

   git clone https://github.com/SujalSinghNegi/reddit.git

2. Open the project in Android Studio.
3. Go to the Firebase Console and create a new project.
4. Add an Android app to the Firebase project and download the google-services.json file.
5. Place the google-services.json file into the app/ directory of this project.
6. Enable Authentication (Email/Password), Firestore, and Storage in your Firebase console.
7. Sync the Gradle files and run the app on an emulator or physical device.

🔒 Firestore Rules

For the app to function correctly, ensure your Firestore rules are set up to handle the shallow subcollections:

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    // Allows public read, authenticated create, and author-only delete
    match /posts/{postId} {
      allow read: if true;
      allow create, update: if request.auth != null;
      allow delete: if request.auth != null && request.auth.uid == resource.data.authorId;
    }
    // Secures individual user votes
    match /posts/{postId}/votes/{voteUserId} {
      allow read: if true;
      allow write: if request.auth != null && request.auth.uid == voteUserId;
    }
  }
}