export const DASHBOARD_PDF_CAPTURE_ROOT_ID = 'dashboard-pdf-capture-root'

/**
 * @param {{ scale?: number, filenameBase?: string }} [opts]
 */
export async function exportDashboardToPdf(opts = {}) {
  const scale = opts.scale ?? 2
  const filenameBase = opts.filenameBase ?? 'mitai-uebersicht'

  const [{ default: html2canvas }, { jsPDF }] = await Promise.all([
    import('html2canvas'),
    import('jspdf'),
  ])

  const el = document.getElementById(DASHBOARD_PDF_CAPTURE_ROOT_ID)
  if (!el) throw new Error('Dashboard-Inhalt nicht gefunden (interner Fehler).')

  const prevScroll = window.scrollY
  window.scrollTo(0, 0)
  await new Promise((r) => requestAnimationFrame(r))
  await new Promise((r) => requestAnimationFrame(r))
  await new Promise((r) => setTimeout(r, 320))

  try {
    const canvas = await html2canvas(el, {
      scale,
      useCORS: true,
      allowTaint: true,
      logging: false,
      backgroundColor: '#ffffff',
      ignoreElements: (node) => node?.getAttribute?.('data-dashboard-pdf-exclude') === 'true',
      scrollX: 0,
      scrollY: 0,
      width: el.scrollWidth,
      height: el.scrollHeight,
      windowWidth: el.scrollWidth,
      windowHeight: el.scrollHeight,
    })

    const imgData = canvas.toDataURL('image/png', 1.0)
    const pdf = new jsPDF({ orientation: 'p', unit: 'mm', format: 'a4', compress: true })
    const pageW = pdf.internal.pageSize.getWidth()
    const pageH = pdf.internal.pageSize.getHeight()
    const margin = 8
    const innerW = pageW - 2 * margin
    const innerH = pageH - 2 * margin
    const imgW = innerW
    const imgH = (canvas.height * imgW) / canvas.width

    let position = margin

    pdf.addImage(imgData, 'PNG', margin, position, imgW, imgH, undefined, 'FAST')
    let heightLeft = imgH - innerH

    while (heightLeft > 0) {
      position = margin - (imgH - heightLeft)
      pdf.addPage()
      pdf.addImage(imgData, 'PNG', margin, position, imgW, imgH, undefined, 'FAST')
      heightLeft -= innerH
    }

    const safe = String(filenameBase)
      .replace(/[\\/:*?"<>|]+/g, '')
      .trim()
    pdf.save(`${safe || 'bericht'}.pdf`)
  } finally {
    window.scrollTo(0, prevScroll)
  }
}