/* Slim Uiltjies — PDF generation
   Renders an invoice (or statement) HTML node into a PDF using
   html2canvas + jsPDF. Uses JPEG (more reliable than PNG for jsPDF).
*/
(function () {
  'use strict';

  function nextFrame() {
    return new Promise((r) => requestAnimationFrame(() => r()));
  }

  async function renderNodeToCanvas(node, scale = 2) {
    // Wait for fonts to be ready so capture is stable
    if (document.fonts && document.fonts.ready) {
      try { await document.fonts.ready; } catch {}
    }
    await nextFrame();
    return window.html2canvas(node, {
      scale,
      backgroundColor: '#FFF8E7',
      useCORS: true,
      allowTaint: true,
      logging: false,
      windowWidth: node.scrollWidth,
      windowHeight: node.scrollHeight,
    });
  }

  async function nodeToPdfBlob(node, { filename = 'document.pdf', scale = 2 } = {}) {
    const { jsPDF } = window.jspdf;
    const canvas = await renderNodeToCanvas(node, scale);

    // A4 portrait, units in pt
    const pdf = new jsPDF({ orientation: 'portrait', unit: 'pt', format: 'a4' });
    const pageW = pdf.internal.pageSize.getWidth();
    const pageH = pdf.internal.pageSize.getHeight();

    // Calculate scaling
    const imgW = pageW;
    const scaleFactor = imgW / canvas.width;
    const pageCanvasH = pageH / scaleFactor; // canvas px that fits one page

    let renderedH = 0;
    let first = true;
    while (renderedH < canvas.height) {
      const sliceH = Math.min(pageCanvasH, canvas.height - renderedH);
      const slice = document.createElement('canvas');
      slice.width = canvas.width;
      slice.height = sliceH;
      const ctx = slice.getContext('2d');
      ctx.fillStyle = '#FFF8E7';
      ctx.fillRect(0, 0, slice.width, slice.height);
      ctx.drawImage(
        canvas,
        0, renderedH, canvas.width, sliceH,
        0, 0, slice.width, sliceH
      );
      // Use JPEG for reliability (PNG can fail with large images in jsPDF)
      const dataUrl = slice.toDataURL('image/jpeg', 0.92);
      if (!first) pdf.addPage();
      const sliceImgH = sliceH * scaleFactor;
      pdf.addImage(dataUrl, 'JPEG', 0, 0, imgW, sliceImgH, undefined, 'FAST');
      renderedH += sliceH;
      first = false;
    }

    const blob = pdf.output('blob');
    blob.name = filename;
    return blob;
  }

  async function nodeToPdfDataUri(node, options = {}) {
    const blob = await nodeToPdfBlob(node, options);
    return new Promise((resolve, reject) => {
      const reader = new FileReader();
      reader.onload = () => resolve(reader.result);
      reader.onerror = () => reject(reader.error);
      reader.readAsDataURL(blob);
    });
  }

  window.SUPDF = { nodeToPdfBlob, nodeToPdfDataUri };
})();