import jsPDF from 'jspdf';

const W = 792;
const H = 612;
const MARGIN = 36;
const ACCENT = [245, 165, 35];
const DARK = [18, 18, 18];
const HEADER_H = 64;

function formatDate(dateStr) {
  if (!dateStr) return '-';
  const d = new Date(`${dateStr}T12:00:00`);
  return d.toLocaleDateString('en-US', { month: 'long', day: 'numeric', year: 'numeric' });
}

async function blobToDataUrl(blob) {
  return new Promise((resolve) => {
    const reader = new FileReader();
    reader.onload = (event) => resolve(event.target?.result || null);
    reader.onerror = () => resolve(null);
    reader.readAsDataURL(blob);
  });
}

async function resolvePhoto(source) {
  if (!source) return null;
  if (source instanceof File || source instanceof Blob) {
    return blobToDataUrl(source);
  }
  if (typeof source === 'string') return source.startsWith('data:') ? source : null;
  return null;
}

function getFormat(dataUrl) {
  return dataUrl?.startsWith('data:image/png') ? 'PNG' : 'JPEG';
}

function loadImage(src) {
  return new Promise((resolve) => {
    if (!src) return resolve(null);
    const img = new Image();
    img.onload = () => resolve(img);
    img.onerror = () => resolve(null);
    img.src = src;
  });
}

const PX_PER_PT = 300 / 72;

function toPrintJpeg(dataUrl, img, displayPtW, displayPtH, quality = 0.82) {
  if (!dataUrl || dataUrl.startsWith('data:image/png')) return dataUrl;
  const tW = Math.round(displayPtW * PX_PER_PT);
  const tH = Math.round(displayPtH * PX_PER_PT);
  if (img.naturalWidth <= tW && img.naturalHeight <= tH) return dataUrl;
  const canvas = document.createElement('canvas');
  canvas.width = tW;
  canvas.height = tH;
  canvas.getContext('2d').drawImage(img, 0, 0, tW, tH);
  return canvas.toDataURL('image/jpeg', quality);
}

function addHeader(doc, title, pageNum, totalPages) {
  doc.setFillColor(255, 255, 255);
  doc.rect(0, 0, W, HEADER_H, 'F');
  doc.setFillColor(...ACCENT);
  doc.rect(0, 0, 4, HEADER_H, 'F');
  doc.setDrawColor(220, 220, 220);
  doc.setLineWidth(0.3);
  doc.line(0, HEADER_H, W, HEADER_H);

  doc.setFontSize(10);
  doc.setFont('helvetica', 'bold');
  doc.setTextColor(...DARK);
  doc.text(title.toUpperCase(), MARGIN, HEADER_H / 2 + 4);

  doc.setFontSize(8);
  doc.setFont('helvetica', 'normal');
  doc.setTextColor(140, 140, 140);
  doc.text(`${pageNum} / ${totalPages}`, W - MARGIN, HEADER_H / 2 + 4, { align: 'right' });
}

function drawCoverImage(doc, dataUrl, img, x, y, w, h) {
  if (!dataUrl || !img) return;
  const srcAspect = img.naturalWidth / img.naturalHeight;
  const boxAspect = w / h;
  let drawW;
  let drawH;
  let drawX;
  let drawY;

  if (srcAspect > boxAspect) {
    drawW = w;
    drawH = w / srcAspect;
    drawX = x;
    drawY = y + (h - drawH) / 2;
  } else {
    drawH = h;
    drawW = h * srcAspect;
    drawX = x + (w - drawW) / 2;
    drawY = y;
  }

  const printableDataUrl = toPrintJpeg(dataUrl, img, drawW, drawH);
  doc.addImage(printableDataUrl, getFormat(printableDataUrl), drawX, drawY, drawW, drawH);
}

export async function generateSurveyMakerPdf(data) {
  const { clientName, siteAddress, surveyDate, preparedBy, projectName, signs } = data;
  const doc = new jsPDF({ orientation: 'landscape', format: 'letter', unit: 'pt', compress: true });

  const signPhotos = await Promise.all((signs || []).map(async (sign) => {
    const mainDataUrl = await resolvePhoto(sign.mainPhoto);
    const contextDataUrls = await Promise.all([
      resolvePhoto(sign.contextPhoto1),
      resolvePhoto(sign.contextPhoto2),
      resolvePhoto(sign.contextPhoto3),
    ]);
    const mainImage = mainDataUrl ? await loadImage(mainDataUrl) : null;
    const contextImages = await Promise.all(contextDataUrls.map(async (dataUrl) => (dataUrl ? loadImage(dataUrl) : null)));

    return { mainDataUrl, mainImage, contextDataUrls, contextImages };
  }));

  const totalPages = Math.max(1, 1 + signs.length);

  doc.setFillColor(255, 255, 255);
  doc.rect(0, 0, W, H, 'F');
  doc.setFillColor(...ACCENT);
  doc.rect(0, 0, W, 5, 'F');
  doc.rect(0, H - 5, W, 5, 'F');

  doc.setFontSize(30);
  doc.setFont('helvetica', 'bold');
  doc.setTextColor(...DARK);
  doc.text(projectName || 'Sign Survey', MARGIN, 88);

  const details = [
    ['Client', clientName || '-'],
    ['Site Address', siteAddress || '-'],
    ['Survey Date', formatDate(surveyDate)],
    ['Prepared By', preparedBy || '-'],
    ['Sign Count', String(signs.length)],
  ];

  let y = 148;
  details.forEach(([label, value]) => {
    doc.setFontSize(9);
    doc.setFont('helvetica', 'bold');
    doc.setTextColor(150, 150, 150);
    doc.text(label.toUpperCase(), MARGIN, y);
    y += 16;
    doc.setFontSize(14);
    doc.setFont('helvetica', 'normal');
    doc.setTextColor(40, 40, 40);
    const lines = doc.splitTextToSize(value, 320);
    doc.text(lines, MARGIN, y);
    y += lines.length * 16 + 18;
  });

  if (signPhotos[0]?.mainDataUrl && signPhotos[0]?.mainImage) {
    const photoX = 410;
    const photoY = 110;
    const photoW = W - photoX - MARGIN;
    const photoH = 360;
    drawCoverImage(doc, signPhotos[0].mainDataUrl, signPhotos[0].mainImage, photoX, photoY, photoW, photoH);
  }

  doc.setFontSize(8);
  doc.setTextColor(140, 140, 140);
  doc.text('1 / ' + totalPages, W - MARGIN, H - 18, { align: 'right' });

  for (let index = 0; index < signs.length; index += 1) {
    const sign = signs[index];
    const photo = signPhotos[index];
    doc.addPage();
    addHeader(doc, sign.signName || `Sign ${index + 1}`, index + 2, totalPages);

    const top = HEADER_H + 20;
    const leftW = 270;
    const rightX = MARGIN + leftW + 20;
    const rightW = W - rightX - MARGIN;
    const mainPhotoH = 280;
    const contextGap = 10;
    const contextPhotoY = top + mainPhotoH + 12;
    const contextPhotoW = (rightW - contextGap * 2) / 3;
    const contextPhotoH = H - contextPhotoY - 36;

    doc.setFontSize(18);
    doc.setFont('helvetica', 'bold');
    doc.setTextColor(...DARK);
    doc.text(sign.signName || `Sign ${index + 1}`, MARGIN, top + 10);

    let textY = top + 42;
    const blocks = [
      ['Measurements', sign.measurements || '-'],
      ['Notes', sign.notes || '-'],
    ];

    blocks.forEach(([label, value]) => {
      doc.setFontSize(9);
      doc.setFont('helvetica', 'bold');
      doc.setTextColor(150, 150, 150);
      doc.text(label.toUpperCase(), MARGIN, textY);
      textY += 16;
      doc.setFontSize(11);
      doc.setFont('helvetica', 'normal');
      doc.setTextColor(50, 50, 50);
      const lines = doc.splitTextToSize(value, leftW);
      doc.text(lines, MARGIN, textY);
      textY += lines.length * 14 + 24;
    });

    if (photo?.mainDataUrl && photo?.mainImage) {
      drawCoverImage(doc, photo.mainDataUrl, photo.mainImage, rightX, top, rightW, mainPhotoH);
    } else {
      doc.setFontSize(10);
      doc.setTextColor(170, 170, 170);
      doc.text('No Main Photo', rightX + rightW / 2, top + mainPhotoH / 2, { align: 'center' });
    }

    for (let contextIndex = 0; contextIndex < 3; contextIndex += 1) {
      const x = rightX + contextIndex * (contextPhotoW + contextGap);

      const contextDataUrl = photo?.contextDataUrls?.[contextIndex];
      const contextImage = photo?.contextImages?.[contextIndex];
      if (contextDataUrl && contextImage) {
        drawCoverImage(doc, contextDataUrl, contextImage, x, contextPhotoY, contextPhotoW, contextPhotoH);
      } else {
        doc.setFontSize(9);
        doc.setTextColor(180, 180, 180);
        doc.text(`Context ${contextIndex + 1}`, x + contextPhotoW / 2, contextPhotoY + contextPhotoH / 2, { align: 'center' });
      }
    }
  }

  const safe = (value) => (value || '').replace(/[^a-zA-Z0-9 ]/g, '').trim().replace(/\s+/g, ' ');
  const filename = [safe(projectName || 'Survey'), safe(clientName), formatDate(surveyDate).replace(/[^a-zA-Z0-9]/g, '')].filter(Boolean).join('.');
  doc.save(`${filename || 'SurveyMaker'}.pdf`);
}