import jsPDF from 'jspdf';
import html2canvas from 'html2canvas';

export const exportAsPdf = async (elementId: string, fileName: string, action: 'preview' | 'download'): Promise<void> => {
  const input = document.getElementById(elementId);
  if (!input) {
    console.error(`Element with id ${elementId} not found.`);
    return;
  }

  try {
    const canvas = await html2canvas(input, {
      scale: 2, // Higher scale improves quality
      useCORS: true,
      logging: false,
    });
    
    const imgData = canvas.toDataURL('image/png');
    
    // A4 dimensions in mm: 210 x 297
    const pdf = new jsPDF({
      orientation: 'portrait',
      unit: 'mm',
      format: 'a4',
    });

    const pdfWidth = pdf.internal.pageSize.getWidth();
    const pdfHeight = pdf.internal.pageSize.getHeight();
    const canvasWidth = canvas.width;
    const canvasHeight = canvas.height;
    
    // Calculate the aspect ratio
    const ratio = canvasWidth / canvasHeight;
    let imgWidth = pdfWidth;
    let imgHeight = imgWidth / ratio;
    
    // If the calculated height is greater than the page height, scale down
    if (imgHeight > pdfHeight) {
      imgHeight = pdfHeight;
      imgWidth = imgHeight * ratio;
    }

    const x = (pdfWidth - imgWidth) / 2;
    const y = 0;

    pdf.addImage(imgData, 'PNG', x, y, imgWidth, imgHeight);

    if (action === 'download') {
      pdf.save(`${fileName}.pdf`);
    } else {
      const pdfBlob = pdf.output('blob');
      const pdfUrl = URL.createObjectURL(pdfBlob);
      window.open(pdfUrl, '_blank');
      URL.revokeObjectURL(pdfUrl);
    }
  } catch (error) {
    console.error("Error generating PDF:", error);
  }
};