green trip: AI powered sustainable travel agent

full-stack web application that generates optimized eco-friendly travel itineraries using AI and live API integrations

built during hackprinceton fall 25

demo: https://youtu.be/GqZLsIdueTE

Tech Stack

• Frontend: Next.js 14 + TailwindCSS + Chart.js
• Backend: FastAPI (Python 3.11+)
• AI Layer: Dedalus API, Open AI API
• iMessage Integration: Photon
• External APIs:
  • Flights API (flights)
  • Amadeus (hotels)
  • Google Places API (attractions + geocoding)
  • Google Maps API (maps + transportation optimization)
  • OpenWeather API (forecast)
  • Climatiq API (CO₂ estimation)

Quick Start

Prerequisites

• Node.js >= 18.0.0 (for Photon iMessage integration)
• Python 3.11+ (for backend)
• macOS (required for Photon iMessage features)

Install All Dependencies

From the root directory:

# Install all npm dependencies (root, photon, backend, frontend)
npm install

# Or install individually:
npm run install:photon    # Photon iMessage dependencies
npm run install:backend  # Backend npm dependencies (if any)
npm run install:frontend # Frontend dependencies

Backend Setup

cd backend
source .venv/bin/activate  # or create venv if needed
pip install -r requirements.txt
npm start  # or: uvicorn app:app --reload

The backend will run at http://localhost:8000

Frontend Setup

cd frontend
npm install
npm run dev

The frontend will run at http://localhost:3000

Photon iMessage Setup (macOS only)

The Photon integration requires macOS and Node.js:

cd photon
npm install

Required dependencies:

• @photon-ai/imessage-kit - iMessage SDK
• better-sqlite3 - SQLite driver for Node.js

Note: If using Bun instead of Node.js, better-sqlite3 is not needed as Bun has built-in SQLite support.

Environment Variables

Create a .env file in backend/:

DEDALUS_API_KEY=your_dedalus_key
AMADEUS_API_KEY=your_amadeus_key
AMADEUS_API_SECRET=your_amadeus_secret
OPENWEATHER_KEY=your_openweather_key
GOOGLE_PLACES_KEY=your_google_places_key
CLIMATIQ_KEY=your_climatiq_key

Note: The backend gracefully falls back to sample data if API keys are missing, so you can prototype without them.

Features

1. Smart Itinerary Generation

   • Enter destination, number of days, budget, and preferences
   • Choose optimization mode: "💸 Price-Optimal" or "🌱 Balanced (Eco + Price)"
   • AI generates optimized itinerary using Dedalus

2. Live API Integration

   • Real-time flight and hotel data from Amadeus
   • Weather forecasts from OpenWeather
   • Attractions from Google Places
   • CO₂ emissions estimation from Climatiq

3. Results Dashboard

   • Daily itinerary breakdown (morning, afternoon, evening)
   • Cost and emissions totals
   • Eco score (0-100 sustainability rating)
   • Comparison charts
   • Regenerate in different mode

API Endpoints

• GET /plan - Health check
• POST /generate_itinerary - Generate GreenTrip itinerary

  {
    "destination": "Paris, France",
    "num_days": 5,
    "budget": 2000,
    "preferences": ["food", "art", "outdoors"],
    "mode": "balanced"
  }

• POST /plan - Legacy GreenTrip endpoint
• POST /bookings - Create booking

Project Structure

/backend
  app.py                    # FastAPI application
  schemas.py                # Pydantic models
  services/
    itinerary_generator.py  # Main itinerary generation logic
    dedalus_client.py       # Dedalus API integration
    amadeus_flights.py      # Amadeus flight search
    amadeus_hotels.py       # Amadeus hotel search
    openweather_service.py  # OpenWeather integration
    google_places_service.py # Google Places integration
    climatiq_service.py     # Climatiq emissions estimation
    prompt_builder.py       # Dedalus prompt construction
    ...                     # Other services

/frontend
  pages/
    index.tsx              # Main form page
    results.tsx             # Results display page
  ...

Development

The backend uses absolute imports (e.g., from schemas import ...). Make sure you're running from the backend/ directory.

The frontend uses TypeScript. If you encounter issues, you can convert .tsx files to .js and remove type annotations.

Notes

• All API keys are read server-side through dotenv - never exposed to the client
• The system includes fallback data for development without API keys
• Dedalus API requires proper JSON response format - the prompt builder ensures this