<?php
include('connectdb.php');

$_backButton = '<div class="container"><form action="choice.php"><button type="submit">Go Back</button></form></div>';

if (!isset($_POST['del'])) {
    echo '<h4>No choices selected for removal.</h4>';
    echo $_backButton;
    exit;
}

$db = connectdb();

$username = $_SESSION['username'];
$courses = $_POST['del'];

$query = <<<EOF
select user_id from students where username='$username';
EOF;

$res = pg_query($db, $query);
$userid = pg_fetch_row($res)[0];

foreach ($courses as $coursename) {
    $query = <<<EOF
select course_id from courses where course_name='$coursename';
EOF;
    $res = pg_query($db, $query);
    $courseid = pg_fetch_row($res)[0];

    $query = <<<EOF
select * from summer2019 where course_id=$courseid and user_id=$userid;
EOF;

    $res = pg_query($db, $query);
    if ($res) {
        $query = <<<EOF
delete from summer2019 where course_id=$courseid and user_id=$userid;
EOF;
        $res = pg_query($db, $query);
        if (!res) {
            pg_last_error($db);
        }
        echo 'Course choice <b>' . $coursename . '</b> removed.<br>';
    } else {
        echo 'Course choice <b>' . $coursename . '</b> already removed.';
    }
}
echo $_backButton;

?>