Untitled

package com.comp301.a05driver;

import java.util.Iterator;
import java.util.NoSuchElementException;

public class ProximityIterator implements Iterator<Driver> {
  private final Iterator<Driver> driverPool;
  private final Position clientPosition;
  private final int proximityRange;
  private Driver nextDriver;

  public ProximityIterator(Iterable<Driver> driverPool, Position clientPosition, int proximityRange)
      throws IllegalArgumentException {
    if (driverPool == null) {
      throw new IllegalArgumentException("Driver pool is null");
    }
    if (clientPosition == null) {
      throw new IllegalArgumentException("Client position is null");
    }
    this.driverPool = driverPool.iterator();
    this.clientPosition = clientPosition;
    this.proximityRange = proximityRange;
    nextDriver = null;
  }

  private void loadNextDriver() {
    if (nextDriver == null) {
      while (driverPool.hasNext()) {
        Driver currentDriver = driverPool.next();
        if (clientPosition.getManhattanDistanceTo(currentDriver.getVehicle().getPosition())
            <= proximityRange) {
          nextDriver = currentDriver;
          break;
        }
      }
    }
  }

  @Override
  public boolean hasNext() {
    loadNextDriver();
    return (nextDriver != null);
  }

  @Override
  public Driver next() throws NoSuchElementException {
    if (hasNext()) {
      Driver driver = nextDriver;
      nextDriver = null;
      return driver;
    } else {
      throw new NoSuchElementException();
    }
  }
}