Why is this code wrong? http://localhost/testing_programs_1.19.20/index.php

[Alexander_20]

<?php
class Post {
private $user_obj;
private $con;

public function __construct($con, $user){
$this->con = $con;
$this->user_obj = new User($con, $user);
}

public function submitPost($body, $user_to) {
$body = strip_tags($body); 
$body = mysqli_real_escape_string($this->con, $body);
$check_empty = preg_replace('/\s+/', '', $body);

if($check_empty != "") {

$date_added = date("Y-m-d H:i:s");
$added_by = $this->user_obj->getUsername();

if($user_to == $added_by) {
    $user_to = "none";
}

    $query = mysqli_query($this->con, "INSERT INTO posts VALUES('', '$body', '$added_by', '$user_to', '$date_added', 'no', 'no', '0')");
    $returned_id = mysqli_insert_id($this->con);
    $num_posts = $this->user_obj->getNumPosts();
    $num_posts++;
    $update_query = mysqli_query($this->con, "UPDATE users SET num_posts='$num_posts' WHERE username='$added_by'");

        }
    }

        public function loadPostsFriends() {
        $str = ""; //String to return 
        $data = mysqli_query($this->con, "SELECT * FROM posts WHERE deleted='no' ORDER BY id DESC");

        while($row = mysqli_fetch_array($data)) {
                $id = $row['id'];
                $body = $row['body'];
                $added_by = $row['added_by'];
                $date_time = $row['date_added'];

                //Prepare user_to string so it can be included even if not posted to a user
                if($row['user_to'] == "none") {
                $user_to = "";              
            }
            else {

            $user_to_obj = new User($con, $row['user_to']);         
            $user_to_name = $user_to_obj->getFirstAndLastName();
            $user_to = "to <a href='" . $row['user_to'] ."'>" . $user_to_name . "</a>";
            }

                //Check if user who posted, has their account closed
                $added_by_obj = new User($this->con, $added_by);    
                if($added_by_obj->isClosed()) {
                    continue;
            }

            $user_details_query = mysqli_query($this->con, "SELECT first_name, last_name, profile_pic FROM users WHERE username='$added_by'");          
            $user_row = mysqli_fetch_array($user_details_query);
            $first_name = $user_row['first_name'];
            $profile_pic = $user_row['profile_pic'];

            //Timeframe     
            $date_time_now = date("Y-m-d H:i:s");
            $start_date = new DateTime($date_time); //Time of post
            $end_date = new DateTime($date_time_now); //Current time    
            $interval = $start_date->diff($end_date); //Difference between dates    
            if($interval->y >= 1) { 
                if($interval == 1)          
                    $time_message = $interval->y . " year ago"; //1 year ago
                else
                    $time_message = $interval->y . " years ago"; //1+ year ago
            }
            else if ($interval-> m >= 1) {          
                if($interval->d == 0) {
                    $days = " ago";             

                }
                else if($interval->d == 1) {
                    $days = $interval->d . " day ago";
                }
                else {
                    $days = $interval->d . " days ago";
                }

                if($interval->m == 1) {
                    $time_message = $interval->m . " month". $days;
                }
                else {
                    $time_message = $interval->m . " months". $days;
                }

            }
            else if($interval->d >= 1) {
                if($interval->d == 1) {
                    $time_message = "Yesterday";
                }
                else {
                    $time_message = $interval->d . " days ago";
                }
            }
            else if($interval->h >= 1) {
                if($interval->h == 1) {
                    $time_message = $interval->h . " hour ago";
                }
                else {
                    $time_message = $interval->h . " hours ago";
                }   
            }
            else if($interval->i >= 1) {
                if($interval->i == 1) {
                    $time_message = $interval->i . " minute ago";
                }
                else {
                    $time_message = $interval->i . " minutes ago";
                }   
            }
            else {
                if($interval->s < 30) {
                    $time_message = "Just now";
                }
                else {
                    $time_message = $interval->s . " seconds ago";
                }   
            }

            $str .= "<div class='status_post'>
                    <div class='post_profile_pic'>
                        <img src='$profile_pic' width='50'>
                    </div>

                    <div class='posted_by' style='color:#ACACAC;'>
                        <a href='$added_by'> $first_name $last_name </a> $user_to &nbsp;&nbsp;&nbsp;&nbsp;$time_message             
                    </div>
                    <div id='post_body'>
                    $body
                    <br>
                    </div>                      

                </div>";

        }

        echo $str;

    }
}

?>

[pritaeas]

Define "wrong". What is it supposed to do, and what part doesn't work, any errors perhaps?