Buddeee

A community-driven Android application that helps isolated individuals connect through AI-powered event recommendations, interactive maps, and personalized event discovery.

Team Inherit The Past

Name
Tan Yoong Ken
Ting Ruo Chee
Rachel Phuar Yi Ling
Samantha Oh Jing Yi
See Shao Xin

Architecture

+----------------------------------------------------------------------+
|                       Android App (Frontend)                          |
|  Java · Android SDK (API 36) · Material Design 3                     |
|  Google Maps SDK · Retrofit 2 / OkHttp · Glide · ExoPlayer (Media3) |
|  Google Gemini 2.0 Flash (on-device event ranking)                   |
|  Room · Gson · Flexbox · ViewPager2                                  |
+----------------------------------+-----------------------------------+
                                   | HTTP / REST (Retrofit)
                                   v
+----------------------------------------------------------------------+
|                    Node.js Backend (Express.js)                       |
|  RESTful API · User Auth (bcrypt) · Event CRUD · Multer (uploads)    |
|  ----------------------------------------------------------------    |
|  RAG Chatbot Pipeline (LangGraph)                                    |
|    Retrieval  →  Synthesis  →  Constraint Checker                    |
|    LangChain MemoryVectorStore    Google Gemini 2.5 Flash            |
|    Gemini Embedding (gemini-embedding-001)                           |
+----------------------------------+-----------------------------------+
                                   |
                                   v
+----------------------------------------------------------------------+
|                         SQLite Database                               |
|  Events · Users · Interactions · Messages · Event Photos             |
+----------------------------------------------------------------------+

AI / ML Summary

Component	Model / Tool	Purpose
Event ranking	Google Gemini 2.0 Flash	Re-ranks personalized feed by relevance to user interests
Health-based recommendations	Rule engine	Filters events based on step count and heart rate
Chatbot (retrieval)	Gemini Embedding + LangChain MemoryVectorStore	Semantic search over events
Chatbot (synthesis)	Google Gemini 2.5 Flash	Generates natural-language responses with event context
Chatbot (orchestration)	LangGraph (StateGraph)	3-node RAG pipeline: retrieval → synthesis → constraint check

Features

• Personalized Feed — Events matched to user interests, re-ranked by Gemini AI
• Health-Based Recommendations — Events suggested based on step count & heart rate data
• Interactive Map — Google Maps with custom emoji markers for 70+ event categories
• Event Creation — Create events with photos, location, time, category, and participant limits
• AI Chatbot — RAG-powered chatbot using LangGraph + Gemini for event discovery
• Messaging — Direct messaging with event card sharing / invites
• Community Profile — Gamified isometric neighborhood with achievements and a decoration shop

Tech Stack

Layer	Technology
Frontend	Java, Android SDK (compileSdk 36), Material Design 3
AI (on-device)	Google Gemini 2.0 Flash (generative AI SDK)
AI (backend)	Google Gemini 2.5 Flash, Gemini Embedding, LangChain, LangGraph
Maps	Google Maps SDK for Android
Video	ExoPlayer (Media3)
Networking	Retrofit 2, OkHttp
Image Loading	Glide
Local DB	Room, SQLite
Backend	Node.js, Express.js, bcrypt, Multer
Backend DB	SQLite3
Build	Gradle 9.1.0, AGP 9.0.0

Project Structure

Beyond_Binary/
├── frontend/                     # Android application
│   ├── app/src/main/
│   │   ├── java/com/beyondbinary/app/
│   │   │   ├── agents/           # Gemini AI event ranking
│   │   │   ├── api/              # Retrofit API service
│   │   │   ├── chatbot/          # AI chatbot fragment
│   │   │   ├── data/             # Models, database, providers
│   │   │   ├── fyp/              # Home feed (Personalized + Recommended tabs)
│   │   │   ├── messaging/        # Chat activity + adapter
│   │   │   ├── onboarding/       # Interest selection
│   │   │   └── registration/     # Sign up / sign in
│   │   └── res/                  # Layouts, drawables, values
│   ├── build.gradle
│   └── local.properties          # API keys (gitignored)
│
├── backend/                      # Node.js REST API
│   ├── server.js                 # Express server with all endpoints
│   ├── chatbot/                  # LangGraph RAG pipeline
│   ├── init-database.js          # Database seeder (sample events)
│   ├── package.json
│   └── .env                      # Environment config (gitignored)
│
└── README.md

Setup

Prerequisites

• JDK 17+ (JDK 25 supported with Gradle 9.1.0)
• Android SDK API 36, build-tools 36.0.0
• Node.js v14+

1. Clone

git clone https://github.com/fearyj/Beyond_Binary.git
cd Beyond_Binary

2. API Keys

• Google Maps: Cloud Console — Enable Maps SDK for Android
• Google Gemini: AI Studio — For frontend ranking + backend chatbot

3. Backend

cd backend
npm install
npm run init-db    # Seed database with sample events
npm start          # Starts on port 3000

Create backend/.env:

PORT=3000
DATABASE_PATH=./database/events.db
NODE_ENV=development
GEMINI_API_KEY=YOUR_GEMINI_API_KEY

4. Frontend

Create frontend/local.properties:

sdk.dir=YOUR_ANDROID_SDK_PATH
geminiApiKey=YOUR_GEMINI_API_KEY
mapsApiKey=YOUR_GOOGLE_MAPS_API_KEY

Open Beyond_Binary/frontend in Android Studio, sync Gradle, and run.

CLI build (PowerShell):

cd frontend
$env:JAVA_HOME = "C:\Program Files\Java\jdk-25.0.2"
$env:ANDROID_HOME = "C:\Android"
.\gradlew.bat assembleDebug

Backend API

Base URL: http://localhost:3000/api (emulator: http://10.0.2.2:3000/api)

Method	Endpoint	Description
GET	/api/events	List all events
GET	/api/events/:id	Get event by ID
GET	/api/events/nearby?lat=&lng=&radius=	Nearby events
POST	/api/events	Create event
PUT	/api/events/:id	Update event
DELETE	/api/events/:id	Delete event
POST	/api/users	Register
POST	/api/users/login	Login
GET	/api/users/:id	Get user
PUT	/api/users/:id	Update profile
GET	/api/users/:userId/events	User's events
POST	/api/events/:id/photos	Upload photo
GET	/api/events/:id/photos	Get photos
POST	/api/messages/invite	Send event invite
POST	/api/messages	Send message
GET	/api/messages/:userId/:otherUserId	Conversation thread
POST	/api/chatbot/chat	AI chatbot
GET	/api/health	Health check
GET	/api/stats	System statistics

App Navigation

SplashActivity
    │
    v
MainActivity
├── Sign In / Register → Onboarding → Home
├── Home (FYP tabs)
│   ├── Personalized → Event Detail → Map
│   └── Recommended  → Event Detail → Map
├── Map View (emoji markers → Event Detail)
├── Add Event
├── My Events
├── AI Chatbot
├── Messages → Chat (text + event invites)
└── Profile (Achievement Community + Shop)

Troubleshooting

Problem	Solution
Gradle sync failed	Ensure JDK and SDK paths are correct in local.properties
Map not loading	Verify mapsApiKey; enable Maps SDK in Google Cloud
Backend connection failed	Ensure backend is running; emulator uses 10.0.2.2 not localhost
Events not loading	Check backend logs; verify Retrofit config
Chatbot not responding	Check GEMINI_API_KEY in backend .env