\documentclass[a4paper,11pt]{memoir}
\input{po}

\ServiceProvider{%
SAMSONG\\
763-10 Bugok-dong Sangnok-gu\\
Ansan
}

\ProviderContact{James Bond}

\PurchaseOrderNumber{J9216A}
\PurchaseOrderDate{16th February 2009}

\SIstyle{Switzerland}

\begin{document}

\thispagestyle{empty}

\directlua0{
        array = {
                {"Desktop computer: DW-101X", 8, 1200},
                {"Laptop computer: LW-804K", 4, 2500}
        }
}
\PurchaseOrder
\end{document}

\usepackage{sistyle}

\newcommand{\paymentcurrency}{}
\newcommand{\PaymentCurrency}[1]{\renewcommand\paymentcurrency{#1}}
\PaymentCurrency{\EUR}


\AddToSIstyle{Europe}{
\SIgroupfourfalse
\SIthousandsep{\,}
\SIdecimalsign{,}
\PaymentCurrency{\EUR}
}

\AddToSIstyle{Switzerland}{
\SIgroupfourfalse
\SIthousandsep{'}
\SIdecimalsign{,}
\PaymentCurrency{CHF}
}

\AddToSIstyle{UK}{
\SIgroupfourfalse
\SIthousandsep{,}
\SIdecimalsign{.}
\PaymentCurrency{\pounds}
}

\AddToSIstyle{USA}{
\SIgroupfourfalse
\SIthousandsep{,}
\SIdecimalsign{.}
\PaymentCurrency{\$}
}

\setulmarginsandblock{3cm}{3cm}{*}
\setheadfoot{1.5cm}{1cm}
\setlrmarginsandblock{2.5cm}{2.5cm}{*}
\checkandfixthelayout
\makeoddhead{empty}{}{}{KTUG}

\newcommand{\purchaseordernumber}{}
\newcommand{\PurchaseOrderNumber}[1]{\renewcommand\purchaseordernumber{#1}}
\newcommand{\purchaseorderdate}{}
\newcommand{\PurchaseOrderDate}[1]{\renewcommand\purchaseorderdate{#1}}

\newcommand{\serviceprovider}{}
\newcommand{\ServiceProvider}[1]{\renewcommand\serviceprovider{#1}}
\newcommand{\providercontact}{}
\newcommand{\ProviderContact}[1]{\renewcommand\providercontact{\textbf{#1} }}

\newcommand{\servicepurchaser}{}
\newcommand{\ServicePurchaser}[1]{\renewcommand\servicepurchaser{#1}}
\newcommand{\purchasercontact}{}
\newcommand{\PurchaserContact}[1]{\renewcommand\purchasercontact{\textbf{#1} }}
\newcommand{\purchasersignature}{}
\newcommand{\PurchaserSignature}[1]{\renewcommand\purchasersignature{#1}}
\newcommand{\purchaserremark}{}
\newcommand{\PurchaserRemark}[1]{\renewcommand\purchaserremark{\textbf{Remark}:\\#1}}

\newcommand{\breakdownfont}{}

\newcommand{\tmpamount}{}

\ServicePurchaser{%
TOPFIELD Co., Ltd.\\
Topfield Bldg. 207 Geumgok-dong Bundang-gu Seongnam Korea 463-869\\
+82 31 778 0845
}
\PurchaserContact{Jimmy LEE}
\PurchaserSignature{JimmyLEE}

\newcommand{\PurchaseOrder}{
\sffamily\vspace*{2ex}

\serviceprovider

\providercontact

\vspace{2ex}
\centerline{\Huge\textsc{Purchase Order}}
\vspace{2ex}

Number \purchaseordernumber

Please execute the following order under the terms and conditions stated below.

\PurchaseOrderBreakdown

\vspace{4ex}
\purchaserremark

\purchaseorderdate
\vspace{2ex}

\servicepurchaser

\purchasercontact

\hspace*{1cm}\purchasersignature
}

\newcommand{\PurchaseOrderBreakdown}{
\breakdownfont
\begin{tabularx}{\textwidth}{|X|r|r|r|}
\hline
Description & Quantity & Unit Price & Amount \tabularnewline
\hline
%
\directlua0{
        CurRow = 1
        TotRow = 10
        i = 1
        total = 0
        while array[i] do
                array[i][4] = array[i][2] * array[i][3]
                total = total + array[i][4]
                str = array[i][1].."&"..array[i][2].."& \string\\num{"..array[i][3].."}\string\\,\string\\paymentcurrency & \string\\num{"..array[i][4].."}\string\\,\string\\paymentcurrency\string\\tabularnewline\string\\hline"
                tex.print(str)
                CurRow = CurRow + 1
                i=i+1
        end
        while CurRow <= TotRow do
                str = "& & & \string\\tabularnewline\string\\hline"
                tex.print(str)
                CurRow = CurRow + 1
        end
}
\multicolumn{3}{|r|}{\textsc{Total}} & \num{\directlua0{tex.print(total)}}\,\paymentcurrency\tabularnewline
\hline
\end{tabularx}
}

\setlength{\parindent}{0em}
\endinput