WordPress PHP Form Code Error

Hi all,
I’m looking for a bit of help. I’m a bit of a noob when it comes to php and I’ve put together the following code. What I’m trying to do is give the subscriber 3 dropdowns, and I then want to use those three dropdowns as well as their Surname as found in their user info to rename a file they are uploading. This is what I have so far, but I keep getting errors saying that wp_get_current_user is a call to an undefined function etc… Can anyone pls help?

<?php
require_once('/wp-includes/pluggable.php');
global $current_user;
$current_user = wp_get_current_user();
$current_user->user_lastname;
 $submittedValue = "";
 $submittedValue1 = "";
 $submittedValue2 = "";
        $value0 = "";
        $value1 = "FMOT";
        $value2 = "FMBM";
        $value3 = "FMCC";
		$value4 = "FMHS";
		$value5 = "FMSP";
		$value6 = "FMFin";
		$value7 = "FMSS";
		$value8 = "Assignment";
		$value9 = "Assignment Attachment";
		$value10 = "Logbook";
		$value11 = "Logbook Attachment";
		$value12 = "1";
		$value13 = "2";
		$date = date('Y m d H i s');
	if (isset($_POST["Subject"])) {
            $submittedValue = $_POST["Subject"];
        }
	if (isset($_POST["DocType"])) {
            $submittedValue = $_POST["DocType"];
        }
	if (isset($_POST["AssNo"])) {
            $submittedValue = $_POST["AssNo"];
        }
// Your file name you are uploading
$file_name = $HTTP_POST_FILES['ufile']['name'];

// random 4 digit to add to our file name
// some people use date and time in stead of random digit
$random_digit=rand(0000,9999);

//combine random digit to you file name to create new file name
//use dot (.) to combile these two variables

$new_file_name= $user_lastname.$submittedValue.$submittedValue1.$submittedValue2.$date.$file_name;

//set where you want to store files
//in this example we keep file in folder upload
//$new_file_name = new upload file name
//for example upload file name cartoon.gif . $path will be upload/cartoon.gif
$path= "wp-content/uploads/assignment/".$new_file_name;
if($ufile !=none)
{
if(copy($HTTP_POST_FILES['ufile']['tmp_name'], $path))
{
echo "Successful"; 

//$new_file_name = new file name
//$HTTP_POST_FILES['ufile']['size'] = file size
//$HTTP_POST_FILES['ufile']['type'] = type of file
echo "File Name :".$new_file_name."";
echo "File Size :".$HTTP_POST_FILES['ufile']['size']."";
echo "File Type :".$HTTP_POST_FILES['ufile']['type']."";
}
else
{
echo "Error";
}
}
?>

My Form Code:

<form action="getfile.php" name="a4fm" method="post">
        <select project="Subject" id="Subject" name="Subject">
         <option value = "<?php echo $value0; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value0; ?></option>
         <option value = "<?php echo $value1; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value1; ?></option>
         <option value = "<?php echo $value2; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value2; ?></option>
         <option value = "<?php echo $value3; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value3; ?></option>
		 <option value = "<?php echo $value4; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value3; ?></option>
		 <option value = "<?php echo $value5; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value3; ?></option>
		 <option value = "<?php echo $value6; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value3; ?></option>
		 <option value = "<?php echo $value7; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value3; ?></option>
        </select>
		<select project="DocType" id="DocType" name="DocType">
         <option value = "<?php echo $value0; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value0; ?></option>
         <option value = "<?php echo $value8; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value1; ?></option>
         <option value = "<?php echo $value9; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value2; ?></option>
         <option value = "<?php echo $value10; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value3; ?></option>
		 <option value = "<?php echo $value11; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value3; ?></option>
        </select>
		<select project="AssNo" id="AssNo" name="AssNo">
         <option value = "<?php echo $value0; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value0; ?></option>
         <option value = "<?php echo $value12; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value1; ?></option>
         <option value = "<?php echo $value13; ?>"<?php echo ($value0 == $submittedValue)?" SELECTED":""?>><?php echo $value2; ?></option>
        </select>
        Type (or select) Filename: <input type="file" name="uploadFile">
		<input type="submit" value="Upload File">
        </form>