HLD: Design Uber - Ride Sharing at Scale

public class LocationService {
    private QuadTree driverLocations;
    private RedisTemplate<String, DriverLocation> redis;
    
    public void updateDriverLocation(String driverId, double lat, double lng) {
        DriverLocation location = new DriverLocation(driverId, lat, lng);
        
        redis.opsForValue().set("driver:" + driverId, location, Duration.ofSeconds(30));
        
        driverLocations.update(driverId, lat, lng);
        
        kafkaTemplate.send("location-updates", location);
    }
    
    public List<String> findNearbyDrivers(double lat, double lng, double radiusKm, int limit) {
        return driverLocations.findNearby(lat, lng, radiusKm, limit);
    }
}

public class MatchingService {
    public RideMatch matchRide(RideRequest request) {
        List<String> nearbyDrivers = locationService.findNearbyDrivers(
            request.getPickupLat(),
            request.getPickupLng(),
            5.0,
            10
        );
        
        List<DriverScore> scores = new ArrayList<>();
        for (String driverId : nearbyDrivers) {
            Driver driver = driverService.getDriver(driverId);
            if (!driver.isAvailable()) continue;
            
            double eta = etaService.calculate(driver.getLocation(), request.getPickup());
            double rating = driver.getRating();
            double score = calculateScore(eta, rating, driver.getAcceptanceRate());
            
            scores.add(new DriverScore(driverId, score, eta));
        }
        
        scores.sort(Comparator.comparing(DriverScore::getScore).reversed());
        
        for (DriverScore ds : scores) {
            boolean accepted = notifyDriver(ds.getDriverId(), request, 15);
            if (accepted) {
                return new RideMatch(request.getRideId(), ds.getDriverId(), ds.getEta());
            }
        }
        
        throw new NoDriverAvailableException();
    }
}

public class SurgePricingService {
    public double getSurgeMultiplier(double lat, double lng) {
        String gridCell = getGridCell(lat, lng);
        
        int activeRiders = getActiveRideRequests(gridCell);
        int availableDrivers = getAvailableDrivers(gridCell);
        
        double ratio = (double) activeRiders / Math.max(1, availableDrivers);
        
        if (ratio > 2.0) return 2.0;
        if (ratio > 1.5) return 1.5;
        if (ratio > 1.2) return 1.25;
        return 1.0;
    }
}

public class ETAService {
    public int calculateETA(Location from, Location to) {
        double distance = haversineDistance(from, to);
        
        TrafficData traffic = trafficService.getTraffic(from, to);
        
        double baseSpeed = 30;
        double adjustedSpeed = baseSpeed * traffic.getSpeedFactor();
        
        int etaMinutes = (int) Math.ceil((distance / adjustedSpeed) * 60);
        
        return etaMinutes;
    }
}

CREATE TABLE rides (
    ride_id UUID PRIMARY KEY,
    rider_id UUID,
    driver_id UUID,
    pickup_lat DECIMAL(10, 8),
    pickup_lng DECIMAL(11, 8),
    dropoff_lat DECIMAL(10, 8),
    dropoff_lng DECIMAL(11, 8),
    status VARCHAR(20),
    fare DECIMAL(10, 2),
    surge_multiplier DECIMAL(3, 2),
    started_at TIMESTAMP,
    completed_at TIMESTAMP
);
CREATE TABLE driver_locations (
    driver_id UUID PRIMARY KEY,
    lat DECIMAL(10, 8),
    lng DECIMAL(11, 8),
    updated_at TIMESTAMP
);