PHP File Upload

Copy<form action="" method="post" enctype="multipart/form-data">
  Select image to upload:
  <input type="file" name="fileToUpload">
  <input type="submit" value="Upload Image" name="submit">
</form>

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
  $target_dir = "uploads/";
  $target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
  $uploadOk = 1;
  $imageFileType = strtolower(pathinfo($target_file, PATHINFO_EXTENSION));

  $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
  if($check !== false) {
    echo "File is an image - " . $check["mime"] . ".";
    $uploadOk = 1;
  } else {
    echo "File is not an image.";
    $uploadOk = 0;
  }

  if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    $uploadOk = 0;
  }

  if ($_FILES["fileToUpload"]["size"] > 500000) {
    echo "Sorry, your file is too large.";
    $uploadOk = 0;
  }

  if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg") {
    echo "Sorry, only JPG, JPEG, & PNG files are allowed.";
    $uploadOk = 0;
  }

  if ($uploadOk == 1) {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
      echo "The file ". htmlspecialchars(basename($_FILES["fileToUpload"]["name"])). " has been uploaded.";
      echo "
";
    } else {
      echo "Sorry, there was an error uploading your file.";
    }
  }
}
?>