2 step contact form in wordpress

/*
 * Function to create form shortcode
 */
function request_form_func($atts, $content = null){
	extract(shortcode_atts(array(
		'id'			=> false,
		'class'			=> false,
		'title'         => false,
		'subtitle'      => false,
		'action'		=> "/thanks",
		'key'		    => false,
		'button_text' => "Submit"
	), $atts));

	if( $class ) {  $class = ' ' . $class; }
	else { $class = ''; }

	if( empty($_GET) ){
		$next_step = false;
		$db_name = '';
		$db_email = '';
	}
	if(isset($_GET['hid'])){
		$email_hash = trim($_GET['hid']);

		$table = "wp_new_user";
		$project_data = new wpdb('root','root','wordpress','localhost');  // Testserver
		$rows = $project_data->get_results( $project_data->prepare(
			"
		      	SELECT id,name, email, hash FROM " . $table . "
				WHERE hash = %d
			",
			$email_hash
		) );

		$db_hash = $rows[0]->hash;
		if( $db_hash == $email_hash ) {
			$field_id = $rows[0]->id;
			$db_name = $rows[0]->name;
			$db_email = $rows[0]->email;
			$next_step = true;
		}
	}

	$out = '';

	if($id) { $id = '-'.$id; }

	$out .= '<div class="request_form'.$class.'">';
	$out .= '<div class="form-wrap">';
	if($title) {
		$out .= '<span class="title">' . $title . '</span>';
	}
	$out .= '<form id="step-form" class="cf" method="post" action="'.$action.'">';
	$out .= '<div class="field-wrap"><label for="fullname'.$id.'"><span class="desc">Name</span>';
	$out .= '<input type="text" id="fullname'.$id.'" name="fullname" data-required="true" placeholder="Jon Doe" value="'.$db_name.'"></label></div>';

	$out .= '<div class="field-wrap"><label for="email'.$id.'"><span class="desc">E-Mail</span>';
	$out .= '<input type="email" id="email'.$id.'" name="email" data-required="true" placeholder="name@domain.com" value="'.$db_email.'"></label></div>';

	if($next_step){
		$out .= '<div class="field-wrap"><label for="username'.$id.'"><span class="desc">Username</span>';
		$out .= '<input type="text" id="username'.$id.'" name="username" data-required="true" placeholder="username"></label></div>';

		$out .= '<div class="field-wrap"><label for="password'.$id.'"><span class="desc">Password</span>';
		$out .= '<input type="password" id="password'.$id.'" name="password" data-required="true" placeholder="password"></label></div>';

		$out .= '<input type="hidden" id="hash" name="hash" value="'.$email_hash.'" >';
	}
	$out .= '<div class="field-wrap submit-wrap"><input type="submit"  value="' .$button_text. '" name="submit"></div>';

	$out .= wp_nonce_field('step_form', 'step_form_nonce'.$id, true, false);
	$out .= '</form>';
	$out .= '</div>';
	$out .= '</div>';
	return $out;
}
add_shortcode('request_form', 'request_form_func');

/*
 * Thanks shortcode to take care data
 */
function thanks_func($atts, $content = null){
	$out = '';

	if(!empty($_POST) || wp_verify_nonce($_POST['step_form_nonce'],'step_form')){
	}
	else {
		$out .= '<div class="content-area">';
		$out .= '<h2 class="h1 page-title">Something went wrong</h2>';
		$out .= '<p class="block">Please Re-Submit your form again</p>';
		$out .= '</div>';

		return $out;
	}

	if(isset($_POST['fullname'])){ $fullname = trim($_POST['fullname']); }
	if(isset($_POST['email'])){ $email = trim($_POST['email']); }

	if(isset($_POST['username'])){ $username = trim($_POST['username']); }
	if(isset($_POST['password'])){ $password = trim($_POST['password']); }
	if(isset($_POST['hash'])){ $db_hash = trim($_POST['hash']); }
	$hash = md5( rand(0,1000) ); // Generate random 32 character hash and assign it to a local variable.

	$header .= "MIME-Version: 1.0\n";
	$header .= "Content-Type: text/html; charset=utf-8\n";
	$header .= "From:" . "admin@domain.com";

	$confirmation_text = "Thanks for Submitting your first form";
	$confirmation_body_text = "/registration/?hid='.$hash.'";

	$subject = "Please click the link below";
	$message = "Name: $fullname\n";
	$message .= "Email Address: $email\n";
	$message .= "Click the link: $confirmation_body_text\n";

	if (!empty($username) && !empty($password) && !empty($db_hash)){
		update_custom_user($username, $password, $db_hash);
	} else if (create_custom_user($fullname, $email, $hash) && wp_mail($email, $subject, $message, $header)){

	}

	$out .= '<div class="content-area">';
	$content = do_shortcode($content);
	$out .= $content;
	$out .= '</div>';

	return $out;
}
add_shortcode('thanks', 'thanks_func');

/*
 * Function to create new record in specified table
 */
function create_custom_user($fullname, $email, $hash){
	global $wpdb;
	$table_name = $wpdb->prefix . "new_user";

	$cur_date = new DateTime();
	$cur_date->setTimezone(new DateTimeZone('Europe/Berlin'));
	$cur_date = $cur_date->format('d.m.Y').', '.$cur_date->format('G:i');


	$wpdb->insert( $table_name, array(
		'name' => $fullname,
		'email' => $email,
		'hash' => $hash,
		'created_at' => $cur_date

	) );

	return true;
}
/*
 * Function to update new record in specified table
 */
function update_custom_user($username, $password, $hash){
	global $wpdb;
	$table_name = $wpdb->prefix . "new_user";

	$cur_date = new DateTime();
	$cur_date->setTimezone(new DateTimeZone('Europe/Berlin'));
	$cur_date = $cur_date->format('d.m.Y').', '.$cur_date->format('G:i');


	$wpdb->update( $table_name, array(
		'username' => $username,
		'password' => $password,
		'updated_at' => $cur_date
	),
		array(
			"hash" => $hash
		) );

	return true;
}