package com.se.day03.aGenericity.eDataStructrue;

/**
 * 自定义一个双链表的数据结构。
 *
 */

public class MyDoubleList<E> {
    //新创建容器时，头部和尾部元素都是null,size0;
    private Node head; //头部元素
    private Node tail;  //尾部元素
    private int size;  // 元素个数

    public void add(E e){
        //先创建一个节点，当前节点的element是e ,
        Node newNode = new Node(e);
        if(head == null){
            //说明该节点是第一个节点添加进来，所以既是头也是尾
            head = newNode;
        }else{
            tail.nextNode = newNode;
            newNode.preNode = tail;
        }
        tail = newNode;
        size++;
    }

    public void addFirst(E e){
        Node newNode = new Node(e);
        if(head == null){
            tail = newNode;
        }else{
            newNode.nextNode =head;
            head.preNode = newNode;
        }
        head = newNode;
        size++;
    }

    /**
     * 向指定索引index处添加索引
     * @param e
     * @param index
     */
    public void add(E e,int index){
        Node newNode = head;
        Node indexNode = new Node(e);
        if(index < 0 || index > size){
            throw new IndexOutOfBoundsException();
        }
        //添加到末尾
        if(index == size){
            add(e);
        } else if (index == 0){
            indexNode.nextNode=head;
            head.preNode=indexNode;
            head = indexNode;
            size++;
        } else if(index<size) {
            for (int i = 0; i < index; i++) {
                newNode =newNode.nextNode;
            }
            indexNode.nextNode =newNode;
            indexNode.preNode = newNode.preNode;
            newNode.preNode.nextNode =indexNode;
            newNode.preNode =indexNode;
            size++;
        }
    }

    public E get(int index){
        if(index < 0 || index > size){
            throw new IndexOutOfBoundsException();
        }
        Node newNode = head;
        if(index == 0){
            return head.element;
        }
        for (int i = 0; i < index; i++) {
            newNode = newNode.nextNode;
        }
        return newNode.element;
    }
    public E set(int index, E e){
        if(index < 0 || index > size){
            throw new IndexOutOfBoundsException();
        }
        Node newNode = head;
        if(index == 0){
            E ret= head.element;
            head.element = e;
            return ret;
        }else{
            for (int i = 0; i < index; i++) {
                newNode = newNode.nextNode;
            }
            E ret= newNode.element;
            newNode.element=e;
            return ret;
        }
    }

    public E remove(int index){
        Node newNode = head;
        if(index < 1 || index > size){
            throw new IndexOutOfBoundsException();
        }
        for(int i = 1; i < index; i++){
            newNode =newNode.nextNode;
        }
        E e = newNode.element;
        newNode.preNode.nextNode =newNode.nextNode;
        newNode.nextNode =newNode.preNode;
        size--;
        return e;
    }

    public String toString(){
        StringBuilder str = new StringBuilder();
        Node temp = head;
        if(temp == null){
            return str.toString();
        }
        for (int i= 0; i <size-1; i++){
            str.append(temp.element).append("<===>");
            temp = temp.nextNode;
        }
        str.append(temp.element).append("   size:").append(size);
        return str.toString();
    }

    public int getSize(){
        return size;
    }
    public void initate(){
        head = null;
        tail = null;
        size = 0;
        System.out.println("----初始化完毕----");
    }

    private class Node{
        E element ;
        Node nextNode;//后一个节点
        Node preNode; //前一个节点
        public Node(){}
        //提供一个参数构造器给当前元素赋值
        public Node(E element){
            this.element = element;
        }
        public Node(E element, Node nextNode, Node preNode){
            this.element = element;
            this.nextNode = nextNode;
            this.preNode = preNode;
        }
    }

    public MyDoubleList(){}
    public MyDoubleList(Node head, Node tail){
        this.head = head;
        this.tail = tail;
    }


    public static void main(String[] args) {
        MyDoubleList<Integer> list = new MyDoubleList<>();
        for (int i = 0; i < 10; i++) {
            list.add(i);
        }
        System.out.println(list);
        list.add(111,10);
        System.out.println(list);
        System.out.println("下标为10的元素是"+list.get(10));
        System.out.println("替换的元素是： "+list.set(1,5));
        System.out.println(list);
        System.out.println("删除的元素是"+list.remove(8));
        System.out.println(list);
        list.initate();

    }
}

输出结果：