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# Real-Time Giveaway System

**Date:** August 2025
**Technologies:** TypeScript, Elysia.js

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## Project Overview

The Real-Time Giveaway System is a WebSocket-powered engine for conducting live giveaways during GDGoC UAM events. It replaces manual entry collection (spreadsheets, paper forms, social media comments) with a unified digital pipeline where participants register via the website, entries are weighted by engagement criteria, and winners are selected in real time with audience-visible animations.

The system is designed for high-energy event environments where reliability and visual feedback matter. Organizers configure giveaways through the admin panel, set eligibility rules, and launch the drawing from a dedicated presenter view. Participants see their entry status update live, and the audience watches winner selection unfold through animated reveals.

## Technical Stack

- **Real-Time Communication**: Elysia WebSocket plugin (server) with native WebSocket API (client)
- **Backend**: Elysia.js with MongoDB
- **Frontend**: Next.js with Framer Motion for winner reveal animations
- **State Management**: In-memory giveaway state with MongoDB persistence for audit

## Architecture Highlights

### Weighted Entry System

Entries are not uniformly random. The system supports weighted probabilities based on participant criteria:

- **Base weight**: All verified attendees receive one entry
- **Bonus weights**: Additional entries for early registration, social media sharing, or completing event feedback forms
- **Cap**: Maximum entries per participant to prevent dominance by a single user

Weights are computed at draw time from participant metadata, ensuring the giveaway can be reconfigured (rules changed, bonuses adjusted) up until the moment of selection without invalidating existing entries.

### Real-Time State Synchronization

The giveaway lifecycle (registration open → registration closed → drawing in progress → winner announced) is broadcast to all connected clients via WebSocket. The presenter view and participant views receive the same state updates, eliminating the need for manual refreshes.

When an organizer triggers the draw, the server:

1. Locks the giveaway to prevent new entries
2. Computes the weighted probability distribution
3. Selects winners using reservoir sampling for fairness
4. Broadcasts results with staggered timing for dramatic effect

### Presenter View

The presenter view is a full-screen interface designed for projection during events. It displays:

- Current giveaway status and participant count
- Live entry feed (anonymized, showing only that "someone" entered)
- Animated winner reveal with confetti effects via Framer Motion
- Historical winners for multi-prize giveaways

The presenter view operates independently of the participant view, allowing organizers to control the pacing of reveals while participants see only the current state.

### Audit Trail

Every giveaway generates an audit document recording:

- Participant list with weights at draw time
- Random seed used for selection (for reproducibility)
- Winner IDs and prize assignments
- Timestamp of each lifecycle transition

This satisfies organizational requirements for transparency and allows dispute resolution if participants question the fairness of a draw.