Worst set of codes from 2015 me

<?php 

/**
* Errors in this function:
* 1. in the while loop, the 
* speed has drastically been reduced to one iteration
* per second because the value of time() only changes once every second.
* 
* This function would however still work in a short time, if ALL files 
* in the folder are generated by this function, since they will always 
* be unique, thanks to time();
* 
* 2. For concatenating the strings. implode() would have been faster instead of the for loop
* like this 
* 		$art=explode(".", "$file_name");
* 		$time=time()-1491262093;
*       $art[0]=$art[0]."_copy".$time;
*       $rname = implode(".", $art);
*/
function dmmp(){
//....truncated function
	if (file_exists($saveto)){
		while (file_exists($saveto)) {
			$art=explode(".", "$file_name");
			$time=time()-1491262093;
			$rname=$art[0]."_copy".$time;
			for ($i=0; $i <count($art) ; $i++) { 
				if($i==0){
					$rname=$art[0]."_copy".$time;
				}
				else{
					$rname=$rname.".".$art[$i];
				}
			}
			$rty++;
				// 
			$saveto = loc()."$store_at/$rty/$rname";
		}
	}
//....truncated function
}


/***
* the breaks in the switch after each image/(*) strings are redundant
* Solution 
* 		case "image/gif":    
* 		case "image/jpeg":  
* 		case "image/jpeg":  
* 		case "image/png": 
* 			return true; 
* 		default:           
* 			return false; 
* Another shorter solution would have been 
* return in_array($file_type, ["image/gif", "image/jpeg", "image/jpeg", "image/png"]);
* since there are only 4 strings to check
*/
function is_image($file_type){
	$typeok = TRUE; 
	switch($file_type)
	{
		case "image/gif":    
		break;
		case "image/jpeg":  
      		// Both regular and progressive jpegs
		case "image/jpeg":  
		break;
		case "image/png":   
		break;
		default:            
		$typeok = FALSE; 
		break;
	}
	return $typeok;

}

/**
* this function tries to get a user friendly date string
* from time() in seconds e.g 1592523448
* this is unneccesarily complex and long
* shorter solution 
* return (intval($time) > 0)? date('d-m-Y at H:i:s', intval($time)):0; 
*/
function formatThisForHr($time){    
	if($time>0){                            
		$time_array=getdate($time);
		
		return $time_array['mday']."-".$time_array['mon']."-".$time_array['year']." at ".$time_array['hours'].":".$time_array['minutes'].":".$time_array['seconds'];
	}else{
		return 0;
	}
}

/*for the if block
* a shorter solution would have been 
*if ($ert[$i]=="." || if ($ert[$i]==".."){
*	continue;
* }else{
*	...
* } */
function getFiles($link){
	$user=getUsername_();
	$query="SELECT * FROM assign_teach WHERE ass_code='$link' AND username='$user'";
	$num=querynum($query);
	if ($num>0){				
		$rt=$this->loc().$link;
		if(!is_dir($rt)){
			@mkdir($rt);
		}
		$ert=scandir($rt);
		$ee=count($ert);
		$svdh=array();
		$row=array();

		$res=queryMysql($query);
		$arr=$res->fetch_array(MYSQLI_ASSOC);
		array_push($row, $arr);

		for($i=0; $i<$ee; $i++){
			if ($ert[$i]==".") {
				continue;
			}else if ($ert[$i]==".."){
				continue;
			}else{
				$gdygfg=$rt."/".$ert[$i];
				$file_about=file_about($gdygfg);
				//put file content _here
				array_push($svdh, $file_about);
			}
		}

		$e=count($svdh);
		$rowl=array("total"=>$e);
		array_push($row, $svdh);
		array_push($row, $rowl);
		return $row;
	}
	return error(6476);
}


/** of course SQL.
* This function deactivates all 
* assignments older than now 
*
* shorter solution:
* 
* $time=time();
* $query="UPDATE assign_teach SET deactivated_=1, deactivated_time=$time WHERE deactivated_=0 AND deactivated_time < $time";
* queryMysql($query);
*/
function deactivateAll_(){
	$qr="SELECT * FROM assign_teach WHERE deactivated_=0";
	$rows=fetch_assoc($qr);
	$time=time();
	for ($i=0; $i<count($rows); $i++){
		$id=$rows[$i]['id'];
		$deact=$rows[$i]['deactivation_time'];
		if ($time>$deact){
			$query="UPDATE assign_teach SET deactivated_=1, deactivated_time=$time WHERE id=$id";
			queryMysql($query);	
		}		
	}	
}


/**
* check if an API ID is correct. LMAO
* a tenary would have made this look better and shorter
* an even better solution is
* return (getAppId_()==appidee);
**/
function verifyAppid(){
	$id=getAppId_();
	if ($id==appidee){
		return true;
	}
	return false;		
}

/**
* Ensures an ip address is both a valid IP and does not fall within
* a private network range.
* 
* shorter solution
* return !(filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) === false);
*/
function validate_ip($ip){
	if (filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE) === false) {
		return false;
	}
	return true;
}

?>