<?php
$file = $_FILES['img'];

$obj = new File();
$res = $obj->upload($file,'upload');
if($res){
    echo $res;
}else{
    echo File::$error;
}

//sleep(30);

//Array ( [name] => wjdk.png [type] => image/png [tmp_name] => C:\Windows\php955D.tmp [error] => 0 [size] => 668730 )

class File
 
{

    //設定屬性：儲存允許上傳的Mime型別
    private static $types = array('image/jpg','imgae/jpeg','image/pjpeg','image/png');

    //修改允許上傳的檔案型別
    public static function setType($type=array()){
        if(!empty($type)){
            self::$types = $type;
        }
    }
    public static $error;
    //記錄檔案上傳過程中出現的錯誤

    //上傳方法
 


    public static function upload($file,$path,$max = 2000000){
        //判斷檔案有效性
        if(!isset($file['error']) || count($file) != 5){
            self::$error = '錯誤的上傳檔案';
            return false;
        }
        if(!is_dir($path)){
            self::$error = '檔案路徑不存在';
            return false;
        }
        
 
//判定檔案是否正確上傳
        switch ($file['error']){
            case 1:
            case 2:
                self::$error = '檔案超過伺服器允許大小';
                return false;
            case 3:
                self::$error = '檔案只有部分被上傳';
                return false;
            case 4:
                self::$error = '沒有選中要上傳的檔案';
                return false;
            case 6:
                self::$error = '找不到臨時資料夾';
                return false;
            case 7:
                self::$error = '檔案寫入失敗';
                return false;
        }
        //判定檔案型別
        if(!in_array($file['type'],self::$types)){
            self::$error = '當前上傳的檔案型別不允許';
            return false;
        }

        //判斷檔案大小
        if($file['size'] > $max){
            self::$error = '當前上傳的檔案超過允許的大小,當前允許的大小為'.string()($max/1024/1024).'M';
            return false;
        }

        $filename = self::getRandomName($file['name']);

        if(move_uploaded_file($file['tmp_name'],$path.'/'.$filename)){
            return $filename;
        }else{
            self::$error = '檔案移動失敗';
            return false;
        }
    }

    public static function getRandomName($filename,$prefix = 'image'){
        $ext = strrchr($filename,'.');
        $new_name = $prefix.date('YmdHis');
        for($i=0;$i<6;$i++){
            $new_name .= chr(mt_rand(65,90));
        }
        return $new_name.$ext;

    }
}