Untitled

package com.comp301.a05driver;

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

public class ExpandingProximityIterator implements Iterator<Driver> {
  private final Iterable<Driver> driverPool;
  private final Position clientPosition;
  private final int expansionStep;
  private Driver nextDriver;
  private int size;
  private int tracker;
  private Iterator<Driver> driverPoolCollection;
  private int i;

  public ExpandingProximityIterator(
      Iterable<Driver> driverPool, Position clientPosition, int expansionStep)
      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;
    this.clientPosition = clientPosition;
    this.expansionStep = expansionStep;
    nextDriver = null;
    tracker = 0;
    for (Driver driver : driverPool) {
      size += 1;
    }
    driverPoolCollection = driverPool.iterator();
    i = -1;
  }

  private void loadNextDriverR() {
    if (nextDriver == null) {
      while (driverPoolCollection.hasNext()) {
        Driver currentDriver = driverPoolCollection.next();
        if (clientPosition.getManhattanDistanceTo(currentDriver.getVehicle().getPosition())
                > 1 + i * expansionStep
            && clientPosition.getManhattanDistanceTo(currentDriver.getVehicle().getPosition())
                <= 1 + (i + 1) * expansionStep) {
          nextDriver = currentDriver;
          tracker++;
          return;
        }
      }
      if (tracker != size) {
        i++;
        driverPoolCollection = driverPool.iterator();
        loadNextDriverR();
      }
    }
  }

  private void loadNextDriver() {
    if (nextDriver == null) {
      while (driverPoolCollection.hasNext()) {
        Driver currentDriver = driverPoolCollection.next();
        if (clientPosition.getManhattanDistanceTo(currentDriver.getVehicle().getPosition())
                > 1 + i * expansionStep
            && clientPosition.getManhattanDistanceTo(currentDriver.getVehicle().getPosition())
                <= 1 + (i + 1) * expansionStep) {
          nextDriver = currentDriver;
          tracker++;
          return;
        }
      }
      while (tracker != size) {
        i++;
        driverPoolCollection = driverPool.iterator();
        if (nextDriver == null) {
          while (driverPoolCollection.hasNext()) {
            Driver currentDriver = driverPoolCollection.next();
            if (clientPosition.getManhattanDistanceTo(currentDriver.getVehicle().getPosition())
                    > 1 + i * expansionStep
                && clientPosition.getManhattanDistanceTo(currentDriver.getVehicle().getPosition())
                    <= 1 + (i + 1) * expansionStep) {
              nextDriver = currentDriver;
              tracker++;
              return;
            }
          }
        }
      }
    }
  }

  @Override
  public boolean hasNext() {
    if (tracker == size) {
      return false;
    }
    loadNextDriver();
    return true;
  }

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