package listadt;

import java.util.function.Function;

/**
 * This is the implementation of a generic list. Specifically it implements
 * the listadt.ListADT interface
 */
public class ListADTImpl<T> implements ListADT<T> {
  private GenericListADTNode<T> head;

  public ListADTImpl() {
    head = new GenericEmptyNode();
  }

  //a private constructor that is used internally (see map)
  private ListADTImpl(GenericListADTNode<T> head) {
    this.head = head;
  }

  @Override
  public void addFront(T b) {
    head = head.addFront(b);
  }

  @Override
  public void addBack(T b) {
    head = head.addBack(b);
  }

  @Override
  public void add(int index, T b) {
    head = head.add(index,b);
  }

  @Override
  public int getSize() {
    return head.count();
  }

  @Override
  public void remove(T b) {
    head = head.remove(b);
  }

  @Override
  public T get(int index) throws IllegalArgumentException{
    if ((index>=0) && (index<getSize())) {
      return head.get(index);
    } else throw new IllegalArgumentException("Invalid index");

  }

  @Override
  public <R> ListADT<R> map(Function<T,R> converter) {
    return new ListADTImpl(head.map(converter));
  }

  @Override
  public String toString() {
    return "("+head.toString()+")";
  }
}