<?php

class FileSystemNode {
    private $path;
    private $isFile;    // 是否为文件
    private $subNodes = [];     // 当前节点的子节点
    private $father;        // 当前节点的父节点
    private $fileNum ;      // 当前文件下的文件个数,包含自身
    private $fileSize;  // 当前文件大小，对于空目录而言为0
  
    public function __construct($path, $isFile) {
      $this->path = $path;
      $this->isFile = $isFile;
      $this->fileNum = 1;
      $this->fileSize = $this->isFile ? getFileSize($this->path) : 0;
    }
  
    protected function setFather(FileSystemNode $father){
        $this->father = $father;
        $this->refreshFather($this->countSizeOfFiles(), $this->countNumOfFiles());
    }

    protected function removeFather(){
        $this->refreshFather(-$this->countSizeOfFiles(), -$this->countNumOfFiles());
        $this->father = null;
    }

    // 更新父节点的文件数量和文件大小
    public function refreshFather($changeSize, $changeNum){
        if(!$this->father){
            return;
        }
        $this->father->setFileSize($this->father->countSizeOfFiles() + $changeSize);
        $this->father->setFileNum($this->father->countNumOfFiles() + $changeNum);

        $this->father->refreshFather($changeSize, $changeNum);  // 递归
    }

    public function setFileNum($num){
        $this->fileNum = $num;
    }

    public function setFileSize($size){
        $this->fileSize = $size;
    }

    public function countNumOfFiles() {
       return $this->isFile ? $this->fileNum : $this->fileNum-1;
    }
  
    public function countSizeOfFiles() {
      return $this->fileSize;
    }
  
    public function getPath() {
      return $this->path;
    }
  
    public function addSubNode(FileSystemNode $fileOrDir) {
      $this->subNodes[] = $fileOrDir;
      $fileOrDir->setFather($this);
    }
  
    public function removeSubNode(FileSystemNode $fileOrDir) {
        foreach($this->subNodes as $i => $subNode){
            if($subNode->getPath() == $fileOrDir->getPath()){
                unset($this->subNodes[$i]);
                $fileOrDir->removeFather();
                break;
            }
        }
    }
    
    // 遍历本目录下所有的文件路径(这里使用树的前序遍历)
    public function iterate(){
        echo $this->getPath() . "\n";
        foreach($this->subNodes as $subNode){
            $subNode->iterate();
        }
    }
  }