import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.export.*;
import net.sf.jasperreports.export.*;
import java.io.*;
import java.util.*;
import java.awt.image.*;
import javax.imageio.*;

/**
 * Minimal JRXML → PNG renderer for pixel-level fidelity comparison.
 * Usage: java JrxmlRenderer input.jrxml output.png [scale]
 *   scale: optional zoom factor (default 2.0 for readable text)
 *
 * Uses JasperReports 7.x exporter API (SimpleExporterInput / SimpleGraphics2DExporterOutput).
 */
public class JrxmlRenderer {
    public static void main(String[] args) throws Exception {
        if (args.length < 2) {
            System.err.println("Usage: java JrxmlRenderer <input.jrxml> <output.png> [scale]");
            System.exit(1);
        }

        String jrxmlPath = args[0];
        String outputPath = args[1];
        float scale = args.length >= 3 ? Float.parseFloat(args[2]) : 2.0f;

        File jrxmlFile = new File(jrxmlPath);
        if (!jrxmlFile.exists()) {
            System.err.println("ERROR: JRXML file not found: " + jrxmlPath);
            System.exit(2);
        }

        try {
            // 1. Compile JRXML → JasperReport
            JasperReport report = JasperCompileManager.compileReport(jrxmlPath);

            // 2. Fill with empty data source
            Map<String, Object> params = new HashMap<>();
            JasperPrint print = JasperFillManager.fillReport(report, params, new JREmptyDataSource());

            int pages = print.getPages().size();
            if (pages == 0) {
                System.err.println("ERROR: Report has 0 pages after filling");
                System.exit(4);
            }

            // 3. Calculate image dimensions from page size
            // JasperReports uses 72 DPI, convert to pixels with scale
            int pageWidth = (int) Math.ceil(report.getPageWidth() * scale);
            int pageHeight = (int) Math.ceil(report.getPageHeight() * scale);

            // 4. Render each page to a BufferedImage
            java.util.List<BufferedImage> pageImages = new ArrayList<>();

            for (int i = 0; i < pages; i++) {
                BufferedImage pageImage = new BufferedImage(pageWidth, pageHeight, BufferedImage.TYPE_INT_RGB);
                java.awt.Graphics2D g2d = pageImage.createGraphics();
                g2d.setColor(java.awt.Color.WHITE);
                g2d.fillRect(0, 0, pageWidth, pageHeight);
                // Scale the graphics context
                g2d.scale(scale, scale);

                JRGraphics2DExporter exporter = new JRGraphics2DExporter();
                exporter.setExporterInput(new SimpleExporterInput(print));

                SimpleGraphics2DExporterOutput output = new SimpleGraphics2DExporterOutput();
                output.setGraphics2D(g2d);
                exporter.setExporterOutput(output);

                SimpleGraphics2DReportConfiguration config = new SimpleGraphics2DReportConfiguration();
                config.setPageIndex(i);
                exporter.setConfiguration(config);

                exporter.exportReport();
                g2d.dispose();
                pageImages.add(pageImage);
            }

            // 5. Combine pages into single tall image
            int totalHeight = 0;
            for (BufferedImage img : pageImages) {
                totalHeight += img.getHeight();
            }

            BufferedImage combined = new BufferedImage(pageWidth, totalHeight, BufferedImage.TYPE_INT_RGB);
            java.awt.Graphics2D g = combined.createGraphics();
            g.setColor(java.awt.Color.WHITE);
            g.fillRect(0, 0, pageWidth, totalHeight);

            int yOffset = 0;
            for (BufferedImage img : pageImages) {
                g.drawImage(img, 0, yOffset, null);
                yOffset += img.getHeight();
            }
            g.dispose();

            // 6. Write PNG
            ImageIO.write(combined, "png", new File(outputPath));

            System.out.println("OK: " + outputPath
                + " (pages=" + pages
                + ", size=" + pageWidth + "x" + totalHeight
                + ", scale=" + scale + ")");
        } catch (JRException e) {
            System.err.println("JASPER_ERROR: " + e.getMessage());
            e.printStackTrace();
            System.exit(3);
        }
    }
}