personal/arsenicum/invoicer/src/main/java/pl/hackerspace/service/TemplateService.java

package pl.hackerspace.service;

import com.lowagie.text.pdf.BaseFont;
import lombok.AccessLevel;
import lombok.NoArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.springframework.stereotype.Service;
import org.xhtmlrenderer.layout.SharedContext;
import org.xhtmlrenderer.pdf.ITextRenderer;
import pl.hackerspace.domain.Client;
import pl.hackerspace.dto.CustomInvoiceDataDto;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.HashSet;
import java.util.Optional;
import java.util.Set;
import java.util.function.Function;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

@Slf4j
@Service
@NoArgsConstructor(access = AccessLevel.PRIVATE)
public class TemplateService {

    public static final DecimalFormat MONEY_FORMAT = twoDecimalsFormatter();
    public static final DateTimeFormatter MONTH_FORMATTER = DateTimeFormatter.ofPattern("yyyy/MM");
    public static final String HTML_TEMPLATE_FILE = "invoiceTemplates/invoice_one_service.html";

    public static <A> A withTemplate(Function<String, A> execute) throws IOException {
        try (InputStream resourceAsStream = TemplateService.class.getClassLoader().getResourceAsStream(HTML_TEMPLATE_FILE)) {
            String template = new String(resourceAsStream.readAllBytes());
            return execute.apply(template);
        }
    }

    static String populateTemplate(String unprocessedTemplate, Client client, final String subscriptionMonth,
                                   final LocalDateTime invoiceCreationDate, final String invoiceTitle,
                                   CustomInvoiceDataDto customInvoiceData) {
        boolean isCustom = customInvoiceData != null;
        BigDecimal price = isCustom ? customInvoiceData.getCustomPrice() : client.getPrice();
        BigDecimal amount = isCustom ? customInvoiceData.getCustomAmount() : client.getAmount();
        BigDecimal vat = isCustom ? customInvoiceData.getCustomVat() : client.getVat();
        String serviceName = isCustom ? customInvoiceData.getCustomServiceName() : client.getServiceName();
        BigDecimal totalNet = amount.multiply(price);
        String processedHtml = unprocessedTemplate
                .replace("%client_name%", client.getName())
                .replace("%invoice_title%", invoiceTitle)
                .replace("%client_price%", formatAsMoney(price))
                .replace("%client_addressLine1%", client.getAddressLine1())
                .replace("%client_addressLine2%", client.getAddressLine2())
                .replace("%client_service_name%", serviceName)
                .replace("%client_nip%", Optional.ofNullable(client.getNip()).map(nip -> "NIP: " + nip).orElse(""))
                .replace("%client_total_net%", formatAsMoney(totalNet))
                .replace("%client_total_gross%", formatAsMoney(totalNet.add(percentageValue(totalNet, vat))))
                .replace("%client_amount%", formatAsMoney(amount))
                .replace("%client_vat%", formatAsMoney(vat))
                .replace("%client_total_tax%", formatAsMoney(percentageValue(totalNet, vat)))
                .replace("%invoice_month_string%", subscriptionMonth)
                .replace("%client_payment_date%", formatAsDate(invoiceCreationDate.plusDays(client.getPaymentOffsetDays())))
                .replace("%invoice_date%", formatAsDate(invoiceCreationDate));
        validateAllPlaceholdersSubstituted(processedHtml);
        return processedHtml;
    }

    private static String formatAsMoney(BigDecimal totalNet) {
        return MONEY_FORMAT.format(totalNet);
    }

    private static String formatAsDate(LocalDateTime invoiceCreationDate) {
        return invoiceCreationDate.format(DateTimeFormatter.ISO_LOCAL_DATE);
    }

    private static void validateAllPlaceholdersSubstituted(String processed) {
        Set<String> allMatches = new HashSet<>();
        Matcher m = Pattern.compile("%(\\w*?)%").matcher(processed);
        while (m.find()) {
            allMatches.add(m.group());
        }
        if (!allMatches.isEmpty()) {
            throw new IllegalStateException("There are unsubstituted placeholders in the template: " + allMatches);
        }
    }

    private static DecimalFormat twoDecimalsFormatter() {
        DecimalFormat df = new DecimalFormat();
        df.setMaximumFractionDigits(2);
        df.setMinimumFractionDigits(2);
        df.setGroupingUsed(false);
        return df;
    }

    public static BigDecimal percentageValue(BigDecimal base, BigDecimal pct) {
        return base.multiply(pct).divide(new BigDecimal(100), 2, RoundingMode.HALF_UP);
    }

    static byte[] convertHtmlToPdf(String unprocessedTemplate, Client client, final LocalDateTime creationDate,
                                   final String invoiceTitle, final String monthOfInvoice, CustomInvoiceDataDto customInvoiceData) {
        String processedHtml = populateTemplate(unprocessedTemplate, client, monthOfInvoice, creationDate, invoiceTitle,
                customInvoiceData);
        try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
            ITextRenderer renderer = new ITextRenderer();
            SharedContext sharedContext = renderer.getSharedContext();
            sharedContext.setPrint(true);
            sharedContext.setInteractive(false);
            renderer.getFontResolver().addFont("fonts/calibri.ttf", BaseFont.IDENTITY_H, true);
            renderer.setDocumentFromString(htmlToXhtml(processedHtml));
            renderer.layout();
            renderer.createPDF(outputStream);
            return outputStream.toByteArray();
        } catch (IOException e) {
            throw new RuntimeException("Exception during pdf conversion", e);
        }
    }

    private static String htmlToXhtml(String html) {
        Document document = Jsoup.parse(html);
        document.outputSettings().syntax(Document.OutputSettings.Syntax.xml);
        return document.html();
    }
}