using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;

public class List<T> : IEnumerable<T> {
	private readonly Node<T> head;

    public List() {
        this.head = new headNode<T>();
    }

	// T...はC#だとparamsらしい 可変引数型というみたいだ
	public List(params T[] attributes) {
		List<T> list = new List<T> ();
		foreach (T attribute_local in attributes) {
			list = list.addLast (attribute_local);
		}
	}

    private List(Node<T> head) {
        this.head = head;
    }

    public Node<T> getHead() {
        return head;
    }

	public List<T> add(int num, T attribute) {
        Node<T> newHead = head.add(0, num, attribute);
        if (newHead == null)
            return this;
        return new List<T>(newHead);
    }

    public List<T> addLast(T attribute) {
        Node<T> newHead = head.addLast(attribute);
		return new List<T>(newHead);
    }


    public T index(int num) {
        int count = 0;
        Node<T> currentNode = head.getNext();
        while (currentNode != null) {
			if (count == num) {
				return currentNode.getAttribute ();
			}
            currentNode = currentNode.getNext();
            count++;
        }
        return default(T);
    }

	public IEnumerator<T> iterator() {
		Node<T> currentNode = head.getNext();
		int count = 0;
		int len = currentNode.length();
		while (len != count) {
			yield return (T)currentNode.getAttribute();
			currentNode = currentNode.getNext ();
			count++;
		}
	}

	IEnumerator IEnumerable.GetEnumerator()
	{
		return this.GetEnumerator();
	}

	public IEnumerator<T> GetEnumerator()
	{
		return iterator ();
	}
		

	public List<T> delete(int num) {
		Node<T> newNode = head.delete(0, num);
		if (newNode == null)
			return this;
		return new List<T>(newNode);
	}

	public List<T> replace(int num, T attribute) {
		Node<T> newHead = head.replaceNode(0, num, attribute);
		if (newHead == null)
			return this;
		return new List<T>(newHead);
	}

	public T tail() {
		return index(length() - 1);
	}

	// java code head.
	public T headList() {
		return index(0);
	}

	public List<T> deleteLast() {
		return delete(head.length() - 1);
	}

	public List<T> deleteHead() {
		return delete(0);
	}

	public int length() {
		return head.length();
	}

	public List<T> append(List<T> list) {
		IEnumerator<T> iterator = list.iterator();
		List<T> newList = this;
		while (iterator.MoveNext()) {
			T attribute = iterator.Current;
			newList = newList.addLast(attribute);
		}
		return newList;
	}
}