package com.example.reporting.service;

import com.itextpdf.text.pdf.BaseFont;
import freemarker.cache.StringTemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.Template;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.io.IOUtils;
import org.springframework.ui.freemarker.FreeMarkerTemplateUtils;
import org.xhtmlrenderer.pdf.ITextFontResolver;
import org.xhtmlrenderer.pdf.ITextRenderer;

import java.io.File;
import java.io.FileOutputStream;
import java.util.HashMap;
import java.util.Map;

@Slf4j
public class HtmlToPdfConverter {

    private static final String FONT_FILENAME = "simhei.ttf";
    private static final String CHARSET = "UTF-8";
    public static final String STORAGE_DIRECTORY = "/opt/reporting/templates/";

    public static void convertHtmlTemplateToPdf(String rawTemplate, Map<String, Object> contextVariables, File outputPdfFile) {
        FileOutputStream fileOut = null;
        ITextRenderer pdfRenderer = new ITextRenderer();
        try {
            Configuration freemarkerConfig = new Configuration(Configuration.VERSION_2_3_31);
            StringTemplateLoader stringLoader = new StringTemplateLoader();
            stringLoader.putTemplate("reportTemplate", rawTemplate);
            freemarkerConfig.setTemplateLoader(stringLoader);
            freemarkerConfig.setDefaultEncoding(CHARSET);
            Template loadedTemplate = freemarkerConfig.getTemplate("reportTemplate");
            String renderedHtml = FreeMarkerTemplateUtils.processTemplateIntoString(loadedTemplate, contextVariables);
            fileOut = new FileOutputStream(outputPdfFile);
            ITextFontResolver fontHandler = pdfRenderer.getFontResolver();
            fontHandler.addFont(STORAGE_DIRECTORY + FONT_FILENAME, BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED);
            pdfRenderer.setDocumentFromString(renderedHtml);
            pdfRenderer.layout();
            pdfRenderer.createPDF(fileOut);
        } catch (Exception ex) {
            log.error("PDF conversion failed", ex);
        } finally {
            pdfRenderer.finishPDF();
            IOUtils.closeQuietly(fileOut);
        }
    }

    public static void main(String[] args) {
        Map<String, Object> reportContext = new HashMap<>(100);
        reportContext.put("invoiceTitle", "增值税普通发票");
        reportContext.put("transactionId", "TXN-789012");
        reportContext.put("orderId", "ORD-789012");
        reportContext.put("issueDate", "2024-10-05");
        reportContext.put("shipDate", "2024-10-05");
        reportContext.put("clientReference", "EXT-REF-789012");
        String pdfName = "invoice_export_" + System.currentTimeMillis() + ".pdf";
        String htmlTemplateInput = "";
        convertHtmlTemplateToPdf(htmlTemplateInput, reportContext, new File(STORAGE_DIRECTORY + pdfName));
        System.out.println("Generated PDF size (bytes): " + new File(STORAGE_DIRECTORY + pdfName).length());
    }
}