Assign a delivery to the nearest available driver

 Great — you already have clean Mongoose models! To assign a delivery to the nearest available driver, you'll implement a geo-based query on the Driver collection to find a driver close to the restaurant’s location and available.

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✅ Step-by-Step Logic

1. Get the Restaurant Location

From the Restaurant model:

js
const restaurant = await Restaurant.findById(restaurantId);
const { lat, lng } = restaurant.address.coordinates;

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2. Find the Nearest Available Driver

You can use MongoDB's geoNear feature if you convert currentLocation into a 2dsphere index:

🛠 Modify Driver model:

js
driverSchema.index({ currentLocation: "2dsphere" });

✅ This lets MongoDB understand lat/lng for spatial queries.

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3. Query for Nearby Available Drivers

js
const nearbyDrivers = await Driver.find({
  status: 'available',
  currentLocation: {
    $near: {
      $geometry: {
        type: "Point",
        coordinates: [lng, lat], // Mongo expects [lng, lat]
      },
      $maxDistance: 5000 // meters = 5 km
    }
  }
}).limit(1); // Pick the closest one

You can adjust maxDistance using restaurant.deliveryRadius * 1000.

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4. Assign Delivery to the Driver

js
if (nearbyDrivers.length > 0) {
  const driver = nearbyDrivers[0];

  const newDelivery = new Delivery({
    orderId,
    driverId: driver.driverId,
    pickupLocation: `${restaurant.address.street}, ${restaurant.address.city}`,
    deliveryLocation: customerAddress,
    assignedAt: new Date()
  });

  await newDelivery.save();

  // Update driver status to "busy"
  driver.status = "busy";
  await driver.save();

  return res.status(200).json({ message: "Delivery assigned", driver });
} else {
  return res.status(404).json({ message: "No available drivers nearby" });
}

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🔄 Summary Flow

1. Get restaurant coordinates.

2. Query MongoDB for the closest driver within radius.

3. Create a new Delivery record with driver info.

4. Update driver status.

5. Done 🎉

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⚠️ Important Notes

• MongoDB geo queries require 2dsphere index.

• MongoDB uses [lng, lat] (reverse order from usual).

• Always check driver availability before assigning.

• Optional: Implement a retry or queue if no drivers are found.

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Want this wrapped as an Express route or want me to write a reusable service function?