package Tree234;

public class Node {
	private static final int ORDER = 4;	//最多四个子节点
	private int numItems = 0;
	private Node parent;
	private Node childArray[] = new Node[this.ORDER];	//子节点集合
	private DataItem itemArray[] = new DataItem[this.ORDER-1];	//当前节点存储数据项
	
	/**
	 * 连接子节点
	 * @param childNum
	 * @param child
	 */
	public void connectChild(int childNum,Node child) {
		this.childArray[childNum] = child;
		if(child != null) {
			child.parent = this;
		}
	}
	
	/**
	 * 取消链接子节点
	 * @param childNum
	 * @return
	 */
	public Node disconnectChild(int childNum) {
		Node tempNode = this.childArray[childNum];
		this.childArray[childNum] = null;
		return tempNode;
	}
	
	/**
	 * 获取子节点
	 * @param childNum
	 * @return
	 */
	public Node getChild(int childNum) {
		return this.childArray[childNum];
	}
	
	/**
	 * 获取父节点
	 * @return
	 */
	public Node getParent() {
		return this.parent;
	}
	
	/**
	 * 当前节点是否是叶节点
	 * @return
	 */
	public boolean isLeaf() {
		return (this.childArray[0] == null) ? true : false;
	}
	
	/**
	 * 返回节点数
	 * @return
	 */
	public int getNumItems() {
		return this.numItems;
	}
	
	/**
	 * 获取数据项
	 * @param index
	 * @return
	 */
	public DataItem getDataItem(int index) {
		return this.itemArray[index];
	}
	
	/**
	 * 节点数据项是否已满
	 * @return
	 */
	public boolean isFull() {
		return (this.numItems == this.ORDER-1) ? true : false;
	}
	
	/**
	 * 查找某个数据项
	 * @param key
	 * @return
	 */
	public int findItem(long key) {
		for(int i=0;i<this.ORDER-1;i++) {
			if(this.itemArray[i] == null)
				break;
			else if(this.itemArray[i].dData == key)
				return i;
		}
		
		return -1;
	}
	
	public int insertItem(DataItem newItem) {
		this.numItems++;	//节点数据项+1
		long newKey = newItem.dData;
		
		for(int j=this.ORDER-2;j>=0;j--) {
			if(this.itemArray[j] == null) {
				continue;
			}else {
				long itsKey = this.itemArray[j].dData;
				if(newKey < itsKey) {
					this.itemArray[j+1] = this.itemArray[j];
				}else {
					this.itemArray[j+1] = newItem;
					return j+1;
				}
			}
		}
		
		this.itemArray[0] = newItem;
		return 0;
	}
	
	public DataItem removeItem() {
		DataItem temp = this.itemArray[this.numItems-1];
		this.itemArray[--this.numItems] = null;
		return temp;
	}
	
	public void displayNode() {
		for(int j=0;j<this.numItems;j++) {
			this.itemArray[j].displayItem();
		}
		
		System.out.println("/");
	}
}