update.php

<?php

include 'components/connect.php';

if(isset($_POST['submit'])){

   $select_user = $conn->prepare("SELECT * FROM `users` WHERE id = ? LIMIT 1");
   $select_user->execute([$user_id]);
   $fetch_user = $select_user->fetch(PDO::FETCH_ASSOC);

   $name = $_POST['name'];
   $name = filter_var($name, FILTER_SANITIZE_STRING);
   $email = $_POST['email'];
   $email = filter_var($email, FILTER_SANITIZE_STRING);

   if(!empty($name)){
      $update_name = $conn->prepare("UPDATE `users` SET name = ? WHERE id = ?");
      $update_name->execute([$name, $user_id]);
      $success_msg[] = 'Username updated!';
   }

   if(!empty($email)){
      $verify_email = $conn->prepare("SELECT * FROM `users` WHERE email = ?");
      $verify_email->execute([$email]);
      if($verify_email->rowCount() > 0){
         $warning_msg[] = 'Email already taken!';
      }else{
         $update_email = $conn->prepare("UPDATE `users` SET email = ? WHERE id = ?");
         $update_email->execute([$email, $user_id]);
         $success_msg[] = 'Email updated!';
      }
   }

   $image = $_FILES['image']['name'];
   $image = filter_var($image, FILTER_SANITIZE_STRING);
   $ext = pathinfo($image, PATHINFO_EXTENSION);
   $rename = create_unique_id().'.'.$ext;
   $image_size = $_FILES['image']['size'];
   $image_tmp_name = $_FILES['image']['tmp_name'];
   $image_folder = 'uploaded_files/'.$rename;

  if(!empty($image)){
   if($image_size > 2000000){
      $warning_msg[] = 'Image size is too large!';
   }else{
      $update_image = $conn->prepare("UPDATE `users` SET image = ? WHERE id = ?");
      $update_image->execute([$rename, $user_id]);
      move_uploaded_file($image_tmp_name, $image_folder);
      if($fetch_user['image'] != ''){
         unlink('uploaded_files/'.$fetch_user['image']);
      }
      $success_msg[] = 'Image updated!';
   }
  }

  $prev_pass = $fetch_user['password'];

  $old_pass = password_hash($_POST['old_pass'], PASSWORD_DEFAULT);
  $old_pass = filter_var($old_pass, FILTER_SANITIZE_STRING);

  $empty_old = password_verify('', $old_pass);

  $new_pass = password_hash($_POST['new_pass'], PASSWORD_DEFAULT);
  $new_pass = filter_var($new_pass, FILTER_SANITIZE_STRING);

  $empty_new = password_verify('', $new_pass);

  $c_pass = password_verify($_POST['c_pass'], $new_pass);
  $c_pass = filter_var($c_pass, FILTER_SANITIZE_STRING);