#!/usr/bin/env ts-node
/**
 * PDF Datasheet Generator - Industrial Engineering Documentation Style
 * STYLEGUIDE.md compliant: industrial, technical, restrained
 */

import * as fs from 'fs';
import * as path from 'path';
import { PDFDocument, rgb, StandardFonts, PDFFont, PDFPage, PDFImage } from 'pdf-lib';

let sharpFn: ((input?: any, options?: any) => any) | null = null;
async function getSharp(): Promise<(input?: any, options?: any) => any> {
  if (sharpFn) return sharpFn;
  // `sharp` is CJS but this script runs as ESM via ts-node.
  // Dynamic import gives stable interop.
  const mod: any = await import('sharp');
  sharpFn = (mod?.default || mod) as (input?: any, options?: any) => any;
  return sharpFn;
}

const CONFIG = {
  productsFile: path.join(process.cwd(), 'data/processed/products.json'),
  outputDir: path.join(process.cwd(), 'public/datasheets'),
  chunkSize: 10,
  siteUrl: 'https://klz-cables.com',
};

const ASSET_MAP_FILE = path.join(process.cwd(), 'data/processed/asset-map.json');
const PUBLIC_DIR = path.join(process.cwd(), 'public');

type AssetMap = Record<string, string>;

function readAssetMap(): AssetMap {
  try {
    if (!fs.existsSync(ASSET_MAP_FILE)) return {};
    return JSON.parse(fs.readFileSync(ASSET_MAP_FILE, 'utf8')) as AssetMap;
  } catch {
    return {};
  }
}

const ASSET_MAP: AssetMap = readAssetMap();

interface ProductData {
  id: number;
  name: string;
  shortDescriptionHtml: string;
  descriptionHtml: string;
  images: string[];
  featuredImage: string | null;
  sku: string;
  slug?: string;
  path?: string;
  translationKey?: string;
  locale?: 'en' | 'de';
  categories: Array<{ name: string }>;
  attributes: Array<{
    name: string;
    options: string[];
  }>;
}

function getProductUrl(product: ProductData): string | null {
  if (!product.path) return null;
  return `https://klz-cables.com${product.path}`;
}

function drawKeyValueGrid(args: {
  title: string;
  items: Array<{ label: string; value: string }>;
  newPage: () => number;
  getPage: () => PDFPage;
  page: PDFPage;
  y: number;
  margin: number;
  contentWidth: number;
  contentMinY: number;
  font: PDFFont;
  fontBold: PDFFont;
  navy: ReturnType<typeof rgb>;
  darkGray: ReturnType<typeof rgb>;
  mediumGray: ReturnType<typeof rgb>;
  lightGray?: ReturnType<typeof rgb>;
  almostWhite?: ReturnType<typeof rgb>;
  allowNewPage?: boolean;
  boxed?: boolean;
}): number {
  let { title, items, newPage, getPage, page, y, margin, contentWidth, contentMinY, font, fontBold, navy, darkGray, mediumGray } = args;
  const allowNewPage = args.allowNewPage ?? true;
  const boxed = args.boxed ?? false;

  const lightGray = args.lightGray ?? rgb(0.9020, 0.9137, 0.9294);
  const almostWhite = args.almostWhite ?? rgb(0.9725, 0.9765, 0.9804);

  // Inner layout (boxed vs. plain)
  // Keep a strict spacing system for more professional datasheets.
  const padX = boxed ? 16 : 0;
  const padY = boxed ? 14 : 0;
  const xBase = margin + padX;
  const innerWidth = contentWidth - padX * 2;
  const colGap = 16;
  const colW = (innerWidth - colGap) / 2;
  const rowH = 24;
  const headerH = boxed ? 22 : 0;

  // Draw a strict rectangular section container (no rounding)
  if (boxed && items.length) {
    const rows = Math.ceil(items.length / 2);
    const boxH = padY + headerH + rows * rowH + padY;
    const bottomY = y - boxH;
    if (bottomY < contentMinY) {
      if (!allowNewPage) return contentMinY - 1;
      y = newPage();
    }

    page = getPage();
    page.drawRectangle({
      x: margin,
      y: y - boxH,
      width: contentWidth,
      height: boxH,
      borderColor: lightGray,
      borderWidth: 1,
      color: rgb(1, 1, 1),
    });

    // Header band for the title
    page.drawRectangle({
      x: margin,
      y: y - headerH,
      width: contentWidth,
      height: headerH,
      color: almostWhite,
    });
  }

  const drawTitle = () => {
    page = getPage();
    if (boxed) {
      // Align title inside the header band.
      page.drawText(title, { x: xBase, y: y - 15, size: 11, font: fontBold, color: navy });
      // Divider line below header band
      page.drawLine({
        start: { x: margin, y: y - headerH },
        end: { x: margin + contentWidth, y: y - headerH },
        thickness: 0.75,
        color: lightGray,
      });
      y -= headerH + padY;
    } else {
      page.drawText(title, { x: margin, y, size: 10, font: fontBold, color: navy });
      y -= 16;
    }
  };

  if (y - 22 < contentMinY) {
    if (!allowNewPage) return contentMinY - 1;
    y = newPage();
  }
  page = getPage();
  drawTitle();

  let rowY = y;
  for (let i = 0; i < items.length; i++) {
    const col = i % 2;
    const x = xBase + col * (colW + colGap);
    const { label, value } = items[i];

    if (col === 0 && rowY - rowH < contentMinY) {
      if (!allowNewPage) return contentMinY - 1;
      y = newPage();
      page = getPage();
      drawTitle();
      rowY = y;
    }

    page.drawText(label, { x, y: rowY, size: 7.5, font: fontBold, color: mediumGray, maxWidth: colW });
    page.drawText(value, { x, y: rowY - 12, size: 9.5, font, color: darkGray, maxWidth: colW });

    if (col === 1) rowY -= rowH;
  }

  return boxed ? rowY - rowH - padY : rowY - rowH;
}

function ensureOutputDir(): void {
  if (!fs.existsSync(CONFIG.outputDir)) {
    fs.mkdirSync(CONFIG.outputDir, { recursive: true });
  }
}

const stripHtml = (html: string): string => {
  if (!html) return '';
  // IMPORTANT: Keep umlauts and common Latin-1 chars (e.g. ü/ö/ä/ß) for DE PDFs.
  // pdf-lib's StandardFonts cover WinAnsi; we only normalize “problematic” typography.
  let text = html.replace(/<[^>]*>/g, '').normalize('NFC');
  text = text
    // whitespace normalization
    .replace(/[\u00A0\u202F]/g, ' ') // nbsp / narrow nbsp
    // typography normalization
    .replace(/[\u2013\u2014]/g, '-') // en/em dash
    .replace(/[\u2018\u2019]/g, "'") // curly single quotes
    .replace(/[\u201C\u201D]/g, '"') // curly double quotes
    .replace(/\u2026/g, '...') // ellipsis
    // symbols that can be missing in some encodings
    .replace(/[\u2022]/g, '·') // bullet
    // math symbols (WinAnsi can't encode these)
    .replace(/[\u2264]/g, '<=') // ≤
    .replace(/[\u2265]/g, '>=') // ≥
    .replace(/[\u2248]/g, '~') // ≈
    // electrical symbols (keep meaning; avoid encoding errors)
    .replace(/[\u03A9\u2126]/g, 'Ohm') // Ω / Ω
    // micro sign / greek mu (WinAnsi can't encode these reliably)
    .replace(/[\u00B5\u03BC]/g, 'u'); // µ / μ

  // Remove control chars, keep all printable unicode.
  text = text.replace(/[\u0000-\u001F\u007F]/g, '');
  return text.replace(/\s+/g, ' ').trim();
};

const getLabels = (locale: 'en' | 'de') => ({
  en: {
    datasheet: 'PRODUCT DATASHEET',
    description: 'DESCRIPTION',
    specs: 'TECHNICAL SPECIFICATIONS',
    crossSection: 'CROSS-SECTION DATA',
    categories: 'CATEGORIES',
    sku: 'SKU',
  },
  de: {
    datasheet: 'PRODUKTDATENBLATT',
    description: 'BESCHREIBUNG',
    specs: 'TECHNISCHE SPEZIFIKATIONEN',
    crossSection: 'QUERSCHNITTSDATEN',
    categories: 'KATEGORIEN',
    sku: 'ARTIKELNUMMER',
  },
})[locale];

const generateFileName = (product: ProductData, locale: 'en' | 'de'): string => {
  const baseName = product.slug || product.translationKey || `product-${product.id}`;
  const cleanSlug = baseName.toLowerCase().replace(/[^a-z0-9-]/g, '-').replace(/-+/g, '-').replace(/^-|-$/g, '');
  return `${cleanSlug}-${locale}.pdf`;
};

function wrapText(text: string, font: PDFFont, fontSize: number, maxWidth: number): string[] {
  const words = text.split(' ');
  const lines: string[] = [];
  let currentLine = '';

  for (const word of words) {
    const testLine = currentLine ? `${currentLine} ${word}` : word;
    if (font.widthOfTextAtSize(testLine, fontSize) <= maxWidth) {
      currentLine = testLine;
    } else {
      if (currentLine) lines.push(currentLine);
      currentLine = word;
    }
  }
  if (currentLine) lines.push(currentLine);
  return lines;
}

function resolveMediaToLocalPath(urlOrPath: string | null | undefined): string | null {
  if (!urlOrPath) return null;

  // 1) Already public-relative.
  if (urlOrPath.startsWith('/')) return urlOrPath;

  // 2) Some datasets store "media/..." without leading slash.
  if (/^media\//i.test(urlOrPath)) return `/${urlOrPath}`;

  // 3) Asset-map can return a few different shapes; normalize them.
  const mapped = ASSET_MAP[urlOrPath];
  if (mapped) {
    if (mapped.startsWith('/')) return mapped;
    if (/^public\//i.test(mapped)) return `/${mapped.replace(/^public\//i, '')}`;
    if (/^media\//i.test(mapped)) return `/${mapped}`;
    return mapped;
  }

  // 4) Fallback (remote URL or unrecognized local path).
  return urlOrPath;
}

async function fetchBytes(url: string): Promise<Uint8Array> {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`Failed to fetch ${url}: ${res.status} ${res.statusText}`);
  return new Uint8Array(await res.arrayBuffer());
}

async function readBytesFromPublic(localPath: string): Promise<Uint8Array> {
  const abs = path.join(PUBLIC_DIR, localPath.replace(/^\//, ''));
  return new Uint8Array(fs.readFileSync(abs));
}

function transformLogoSvgToPrintBlack(svg: string): string {
  // Our source logo is white-on-transparent (for dark headers). For print (white page), we need dark fills.
  // Keep it simple: replace fill white with KLZ navy.
  return svg
    .replace(/fill\s*:\s*white/gi, 'fill:#0E2A47')
    .replace(/fill\s*=\s*"white"/gi, 'fill="#0E2A47"')
    .replace(/fill\s*=\s*'white'/gi, "fill='#0E2A47'");
}

async function toPngBytes(inputBytes: Uint8Array, inputHint: string): Promise<Uint8Array> {
  // pdf-lib supports PNG/JPG. We normalize everything (webp/svg/jpg/png) to PNG to keep embedding simple.
  const ext = (path.extname(inputHint).toLowerCase() || '').replace('.', '');
  if (ext === 'png') return inputBytes;

  // Special-case the logo SVG to render as dark for print.
  if (ext === 'svg' && /\/media\/logo\.svg$/i.test(inputHint)) {
    const svg = Buffer.from(inputBytes).toString('utf8');
    inputBytes = new Uint8Array(Buffer.from(transformLogoSvgToPrintBlack(svg), 'utf8'));
  }

  const sharp = await getSharp();
  // Preserve alpha where present (some product images are transparent).
  return new Uint8Array(await sharp(Buffer.from(inputBytes)).png().toBuffer());
}

type TableColumn = {
  label: string;
  get: (rowIndex: number) => string;
};

function buildProductAttrIndex(product: ProductData): Record<string, ProductData['attributes'][number]> {
  const idx: Record<string, ProductData['attributes'][number]> = {};
  for (const a of product.attributes || []) {
    idx[normalizeValue(a.name).toLowerCase()] = a;
  }
  return idx;
}

function getAttrCellValue(attr: ProductData['attributes'][number] | undefined, rowIndex: number, rowCount: number): string {
  if (!attr) return '';
  if (!attr.options || attr.options.length === 0) return '';
  if (rowCount > 0 && attr.options.length === rowCount) return normalizeValue(attr.options[rowIndex]);
  if (attr.options.length === 1) return normalizeValue(attr.options[0]);
  // Unknown mapping: do NOT guess (this was the main source of "wrong" tables).
  return '';
}

function drawTableChunked(args: {
  title: string;
  configRows: string[];
  columns: Array<{ key: string; label: string; get: (rowIndex: number) => string }>;
  locale: 'en' | 'de';
  newPage: () => number;
  getPage: () => PDFPage;
  page: PDFPage;
  y: number;
  margin: number;
  contentWidth: number;
  contentMinY: number;
  font: PDFFont;
  fontBold: PDFFont;
  navy: ReturnType<typeof rgb>;
  darkGray: ReturnType<typeof rgb>;
  lightGray: ReturnType<typeof rgb>;
  almostWhite: ReturnType<typeof rgb>;
  maxDataColsPerTable: number;
}): number {
  let {
    title,
    configRows,
    columns,
    newPage,
    getPage,
    page,
    y,
    margin,
    contentWidth,
    contentMinY,
    font,
    fontBold,
    navy,
    darkGray,
    lightGray,
    almostWhite,
    maxDataColsPerTable,
  } = args;

  const headerH = 16;
  const rowH = 13;

  // Always include configuration as first col.
  const configCol = {
    key: 'configuration',
    label: args.locale === 'de' ? 'Konfiguration' : 'Configuration',
    get: (i: number) => normalizeValue(configRows[i] || ''),
  };

  const chunks: Array<typeof columns> = [];
  for (let i = 0; i < columns.length; i += maxDataColsPerTable) {
    chunks.push(columns.slice(i, i + maxDataColsPerTable));
  }

  for (let ci = 0; ci < Math.max(1, chunks.length); ci++) {
    // Ensure we always draw on the current page reference.
    page = getPage();

    const chunkCols = chunks.length ? chunks[ci] : [];
    const chunkTitle = chunks.length > 1 ? `${title} (${ci + 1}/${chunks.length})` : title;
    const tableCols: TableColumn[] = [configCol, ...chunkCols];

    // Width distribution (keeps configuration readable)
    const configW = 0.32;
    const remainingW = 1 - configW;
    const perW = remainingW / Math.max(1, tableCols.length - 1);
    const widths = tableCols.map((_, idx) => (idx === 0 ? configW : perW));

    const ensureSpace = (needed: number) => {
      if (y - needed < contentMinY) y = newPage();
      page = getPage();
    };

    ensureSpace(18 + headerH + rowH * 2);
    page.drawText(chunkTitle, {
      x: margin,
      y,
      size: 10,
      font: fontBold,
      color: navy,
    });
    y -= 16;

    // If we are too close to the footer after the title, break before drawing the header.
    if (y - headerH - rowH < contentMinY) {
      y = newPage();
      page = getPage();
      page.drawText(chunkTitle, {
        x: margin,
        y,
        size: 10,
        font: fontBold,
        color: navy,
      });
      y -= 16;
    }

    const drawHeader = () => {
      page = getPage();
      page.drawRectangle({
        x: margin,
        y: y - headerH,
        width: contentWidth,
        height: headerH,
        color: lightGray,
      });
      let x = margin;
      for (let i = 0; i < tableCols.length; i++) {
        page.drawText(tableCols[i].label, {
          x: x + 6,
          y: y - 11,
          size: 8,
          font: fontBold,
          color: navy,
          maxWidth: contentWidth * widths[i] - 12,
        });
        x += contentWidth * widths[i];
      }
      y -= headerH;
    };

    drawHeader();

    for (let r = 0; r < configRows.length; r++) {
      if (y - rowH < contentMinY) {
        y = newPage();
        page = getPage();
        page.drawText(chunkTitle, {
          x: margin,
          y,
          size: 12,
          font: fontBold,
          color: navy,
        });
        y -= 16;
        drawHeader();
      }

      if (r % 2 === 0) {
        page.drawRectangle({
          x: margin,
          y: y - rowH,
          width: contentWidth,
          height: rowH,
          color: almostWhite,
        });
      }

      let x = margin;
      for (let c = 0; c < tableCols.length; c++) {
        page.drawText(tableCols[c].get(r), {
          x: x + 6,
          y: y - 10,
          size: 8,
          font,
          color: darkGray,
          maxWidth: contentWidth * widths[c] - 12,
        });
        x += contentWidth * widths[c];
      }

      y -= rowH;
    }

    y -= 18;
  }

  return y;
}

async function loadEmbeddablePng(
  src: string | null | undefined,
): Promise<{ pngBytes: Uint8Array; debugLabel: string } | null> {
  const resolved = resolveMediaToLocalPath(src);
  if (!resolved) return null;

  try {
    // Prefer local files for stability and speed.
    if (resolved.startsWith('/')) {
      const bytes = await readBytesFromPublic(resolved);
      return { pngBytes: await toPngBytes(bytes, resolved), debugLabel: resolved };
    }

    // Remote (fallback)
    const bytes = await fetchBytes(resolved);
    return { pngBytes: await toPngBytes(bytes, resolved), debugLabel: resolved };
  } catch {
    return null;
  }
}

async function loadQrPng(data: string): Promise<{ pngBytes: Uint8Array; debugLabel: string } | null> {
  // External QR generator (no extra dependency). This must stay resilient; if it fails, we fall back to URL text.
  try {
    const safe = encodeURIComponent(data);
    const url = `https://api.qrserver.com/v1/create-qr-code/?size=180x180&data=${safe}`;
    const bytes = await fetchBytes(url);
    // Already PNG but normalize anyway.
    return { pngBytes: await toPngBytes(bytes, url), debugLabel: url };
  } catch {
    return null;
  }
}

type SectionDrawContext = {
  pdfDoc: PDFDocument;
  page: PDFPage;
  width: number;
  height: number;
  margin: number;
  contentWidth: number;
  footerY: number;
  contentMinY: number;
  headerDividerY: number;
  colors: {
    navy: ReturnType<typeof rgb>;
    mediumGray: ReturnType<typeof rgb>;
    darkGray: ReturnType<typeof rgb>;
    almostWhite: ReturnType<typeof rgb>;
    lightGray: ReturnType<typeof rgb>;
    headerBg: ReturnType<typeof rgb>;
  };
  fonts: {
    regular: PDFFont;
    bold: PDFFont;
  };
  labels: ReturnType<typeof getLabels>;
  product: ProductData;
  locale: 'en' | 'de';
  logoImage: PDFImage | null;
  qrImage: PDFImage | null;
  qrUrl: string;
};

function drawFooter(ctx: SectionDrawContext): void {
  const { page, width, margin, footerY, fonts, colors, locale } = ctx;

  page.drawLine({
    start: { x: margin, y: footerY + 14 },
    end: { x: width - margin, y: footerY + 14 },
    thickness: 0.75,
    color: colors.lightGray,
  });

  // Left: site URL (always)
  page.drawText(CONFIG.siteUrl, {
    x: margin,
    y: footerY,
    size: 8,
    font: fonts.regular,
    color: colors.mediumGray,
  });

  const dateStr = new Date().toLocaleDateString(locale === 'en' ? 'en-US' : 'de-DE', {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
  });

  // Right: date + page number (page number filled in after rendering)
  const rightText = dateStr;
  page.drawText(rightText, {
    x: width - margin - fonts.regular.widthOfTextAtSize(rightText, 8),
    y: footerY,
    size: 8,
    font: fonts.regular,
    color: colors.mediumGray,
  });
}

function stampPageNumbers(pdfDoc: PDFDocument, fonts: { regular: PDFFont }, colors: { mediumGray: ReturnType<typeof rgb> }, margin: number, footerY: number): void {
  const pages = pdfDoc.getPages();
  const total = pages.length;
  for (let i = 0; i < total; i++) {
    const page = pages[i];
    const { width } = page.getSize();
    const text = `${i + 1}/${total}`;
    page.drawText(text, {
      x: width - margin - fonts.regular.widthOfTextAtSize(text, 8),
      y: footerY - 12,
      size: 8,
      font: fonts.regular,
      color: colors.mediumGray,
    });
  }
}

function drawHeader(ctx: SectionDrawContext, yStart: number): number {
  const { page, width, margin, contentWidth, fonts, colors, logoImage, qrImage, qrUrl, labels, product } = ctx;

  // Cable-industry look: calm, engineered header with right-aligned meta.
  const headerH = 64;
  const dividerY = yStart - headerH;
  ctx.headerDividerY = dividerY;

  page.drawRectangle({
    x: 0,
    y: dividerY,
    width,
    height: headerH,
    color: colors.headerBg,
  });

  const qrSize = 44;
  const qrGap = 12;
  const rightReserved = qrImage ? qrSize + qrGap : 0;

  // Left: logo (preferred) or typographic fallback
  if (logoImage) {
    const maxLogoW = 120;
    const maxLogoH = 30;
    const scale = Math.min(maxLogoW / logoImage.width, maxLogoH / logoImage.height);
    const w = logoImage.width * scale;
    const h = logoImage.height * scale;
    const logoY = dividerY + Math.round((headerH - h) / 2);
    page.drawImage(logoImage, {
      x: margin,
      y: logoY,
      width: w,
      height: h,
    });
  } else {
    const baseY = dividerY + 22;
    page.drawText('KLZ', {
      x: margin,
      y: baseY,
      size: 22,
      font: fonts.bold,
      color: colors.navy,
    });
    page.drawText('Cables', {
      x: margin + fonts.bold.widthOfTextAtSize('KLZ', 22) + 4,
      y: baseY + 2,
      size: 10,
      font: fonts.regular,
      color: colors.mediumGray,
    });
  }

  // Right: datasheet meta + QR (if available)
  const metaRightEdge = width - margin - rightReserved;
  const metaTitle = labels.datasheet;
  const metaTitleSize = 9;
  const metaSkuSize = 8;
  const skuText = product.sku ? `${labels.sku}: ${stripHtml(product.sku)}` : '';

  const mtW = fonts.bold.widthOfTextAtSize(metaTitle, metaTitleSize);
  page.drawText(metaTitle, {
    x: metaRightEdge - mtW,
    y: dividerY + 38,
    size: metaTitleSize,
    font: fonts.bold,
    color: colors.navy,
  });

  if (skuText) {
    const skuW = fonts.regular.widthOfTextAtSize(skuText, metaSkuSize);
    page.drawText(skuText, {
      x: metaRightEdge - skuW,
      y: dividerY + 24,
      size: metaSkuSize,
      font: fonts.regular,
      color: colors.mediumGray,
    });
  }

  if (qrImage) {
    const qrX = width - margin - qrSize;
    const qrY = dividerY + Math.round((headerH - qrSize) / 2);
    page.drawImage(qrImage, { x: qrX, y: qrY, width: qrSize, height: qrSize });
  } else {
    // If QR generation failed, keep the URL available as a compact line.
    const maxW = 260;
    const urlLines = wrapText(qrUrl, fonts.regular, 8, maxW).slice(0, 1);
    if (urlLines.length) {
      const line = urlLines[0];
      const w = fonts.regular.widthOfTextAtSize(line, 8);
      page.drawText(line, {
        x: width - margin - w,
        y: dividerY + 12,
        size: 8,
        font: fonts.regular,
        color: colors.mediumGray,
      });
    }
  }

  // Divider line
  page.drawLine({
    start: { x: margin, y: dividerY },
    end: { x: margin + contentWidth, y: dividerY },
    thickness: 0.75,
    color: colors.lightGray,
  });

  // Content start: provide real breathing room below the header.
  return dividerY - 40;
}

function drawCrossSectionChipsRow(args: {
  title: string;
  configRows: string[];
  locale: 'en' | 'de';
  getPage: () => PDFPage;
  page: PDFPage;
  y: number;
  margin: number;
  contentWidth: number;
  contentMinY: number;
  font: PDFFont;
  fontBold: PDFFont;
  navy: ReturnType<typeof rgb>;
  darkGray: ReturnType<typeof rgb>;
  mediumGray: ReturnType<typeof rgb>;
  lightGray: ReturnType<typeof rgb>;
  almostWhite: ReturnType<typeof rgb>;
}): number {
  let { title, configRows, locale, getPage, page, y, margin, contentWidth, contentMinY, font, fontBold, navy, darkGray, mediumGray, lightGray, almostWhite } = args;

  // Single-page rule: if we can't fit the block, stop.
  const titleH = 12;
  const summaryH = 12;
  const chipH = 16;
  const lineGap = 8;
  const gapY = 10;
  const minLines = 2;
  const needed = titleH + summaryH + (chipH * minLines) + (lineGap * (minLines - 1)) + gapY;
  if (y - needed < contentMinY) return contentMinY - 1;

  page = getPage();

  // Normalize: keep only cross-section part, de-dupe, sort.
  const itemsRaw = configRows
    .map(r => splitConfig(r).crossSection)
    .map(s => normalizeValue(s))
    .filter(Boolean);

  const seen = new Set<string>();
  const items = itemsRaw.filter(v => (seen.has(v) ? false : (seen.add(v), true)));

  items.sort((a, b) => {
    const pa = parseCoresAndMm2(a);
    const pb = parseCoresAndMm2(b);
    if (pa.cores !== null && pb.cores !== null && pa.cores !== pb.cores) return pa.cores - pb.cores;
    if (pa.mm2 !== null && pb.mm2 !== null && pa.mm2 !== pb.mm2) return pa.mm2 - pb.mm2;
    return a.localeCompare(b);
  });

  const total = items.length;
  const parsed = items.map(parseCoresAndMm2).filter(p => p.cores !== null && p.mm2 !== null) as Array<{ cores: number; mm2: number }>;
  const uniqueCores = Array.from(new Set(parsed.map(p => p.cores))).sort((a, b) => a - b);
  const mm2Vals = parsed.map(p => p.mm2).sort((a, b) => a - b);
  const mm2Min = mm2Vals.length ? mm2Vals[0] : null;
  const mm2Max = mm2Vals.length ? mm2Vals[mm2Vals.length - 1] : null;

  page.drawText(title, { x: margin, y, size: 11, font: fontBold, color: navy });
  y -= titleH;

  const summaryParts: string[] = [];
  summaryParts.push(locale === 'de' ? `Varianten: ${total}` : `Options: ${total}`);
  if (uniqueCores.length) summaryParts.push((locale === 'de' ? 'Adern' : 'Cores') + `: ${uniqueCores.join(', ')}`);
  if (mm2Min !== null && mm2Max !== null) summaryParts.push(`mm²: ${mm2Min}${mm2Max !== mm2Min ? `–${mm2Max}` : ''}`);
  page.drawText(summaryParts.join(' · '), { x: margin, y, size: 8, font, color: mediumGray, maxWidth: contentWidth });
  y -= summaryH;

  // Tags (wrapping). Rectangular, engineered (no playful rounding).
  const padX = 8;
  const chipFontSize = 8;
  const chipGap = 8;
  const chipPadTop = 5;

  const startY = y - chipH; // baseline for first chip row
  const maxLines = Math.max(1, Math.floor((startY - contentMinY + lineGap) / (chipH + lineGap)));

  const chipWidth = (text: string) => font.widthOfTextAtSize(text, chipFontSize) + padX * 2;

  type Placement = { text: string; x: number; y: number; w: number; variant: 'normal' | 'more' };

  const layout = (texts: string[], includeMoreChip: boolean, moreText: string): { placements: Placement[]; shown: number } => {
    const placements: Placement[] = [];
    let x = margin;
    let line = 0;
    let cy = startY;

    const advanceLine = () => {
      line += 1;
      if (line >= maxLines) return false;
      x = margin;
      cy -= chipH + lineGap;
      return true;
    };

    const tryPlace = (text: string, variant: 'normal' | 'more'): boolean => {
      const w = chipWidth(text);
      if (w > contentWidth) return false;
      if (x + w > margin + contentWidth) {
        if (!advanceLine()) return false;
      }
      placements.push({ text, x, y: cy, w, variant });
      x += w + chipGap;
      return true;
    };

    let shown = 0;
    for (let i = 0; i < texts.length; i++) {
      if (!tryPlace(texts[i], 'normal')) break;
      shown++;
    }

    if (includeMoreChip) {
      tryPlace(moreText, 'more');
    }
    return { placements, shown };
  };

  // Group by cores: label on the left, mm² tags to the right.
  const byCores = new Map<number, number[]>();
  const other: string[] = [];
  for (const cs of items) {
    const p = parseCoresAndMm2(cs);
    if (p.cores !== null && p.mm2 !== null) {
      const arr = byCores.get(p.cores) ?? [];
      arr.push(p.mm2);
      byCores.set(p.cores, arr);
    } else {
      other.push(cs);
    }
  }

  const coreKeys = Array.from(byCores.keys()).sort((a, b) => a - b);
  for (const k of coreKeys) {
    const uniq = Array.from(new Set(byCores.get(k) ?? [])).sort((a, b) => a - b);
    byCores.set(k, uniq);
  }

  const fmtMm2 = (v: number) => {
    const s = Number.isInteger(v) ? String(v) : String(v).replace(/\.0+$/, '');
    return s;
  };

  // Layout engine with group labels.
  const labelW = 38;
  const placements: Placement[] = [];
  let line = 0;
  let cy = startY;
  let x = margin + labelW;

  const canAdvanceLine = () => line + 1 < maxLines;
  const advanceLine = () => {
    if (!canAdvanceLine()) return false;
    line += 1;
    cy -= chipH + lineGap;
    x = margin + labelW;
    return true;
  };

  const drawGroupLabel = (label: string) => {
    // Draw label on each new line for the group (keeps readability when wrapping).
    page.drawText(label, {
      x: margin,
      y: cy + 4,
      size: 8,
      font: fontBold,
      color: mediumGray,
      maxWidth: labelW - 4,
    });
  };

  const placeChip = (text: string, variant: 'normal' | 'more') => {
    const w = chipWidth(text);
    if (w > contentWidth - labelW) return false;
    if (x + w > margin + contentWidth) {
      if (!advanceLine()) return false;
    }
    placements.push({ text, x, y: cy, w, variant });
    x += w + chipGap;
    return true;
  };

  let truncated = false;
  let renderedCount = 0;
  const totalChips = coreKeys.reduce((sum, k) => sum + (byCores.get(k)?.length ?? 0), 0) + other.length;

  for (const cores of coreKeys) {
    const values = byCores.get(cores) ?? [];
    const label = `${cores}×`;
    // Ensure label is shown at least once per line block.
    drawGroupLabel(label);
    for (const v of values) {
      const ok = placeChip(fmtMm2(v), 'normal');
      if (!ok) {
        truncated = true;
        break;
      }
      renderedCount++;
    }
    if (truncated) break;
    // Add a tiny gap between core groups (only if we have room on the current line)
    x += 4;
    if (x > margin + contentWidth - 20) {
      if (!advanceLine()) {
        // out of vertical space; stop
        truncated = true;
        break;
      }
    }
  }

  if (!truncated && other.length) {
    const label = locale === 'de' ? 'Sonst.' : 'Other';
    drawGroupLabel(label);
    for (const t of other) {
      const ok = placeChip(t, 'normal');
      if (!ok) {
        truncated = true;
        break;
      }
      renderedCount++;
    }
  }

  if (truncated) {
    const remaining = Math.max(0, totalChips - renderedCount);
    const moreText = locale === 'de' ? `+${remaining} weitere` : `+${remaining} more`;
    // Try to place on current line; if not possible, try next line.
    if (!placeChip(moreText, 'more')) {
      if (advanceLine()) {
        placeChip(moreText, 'more');
      }
    }
  }

  // Draw placements
  for (const p of placements) {
    page.drawRectangle({
      x: p.x,
      y: p.y,
      width: p.w,
      height: chipH,
      borderColor: lightGray,
      borderWidth: 1,
      color: rgb(1, 1, 1),
    });
    page.drawText(p.text, {
      x: p.x + padX,
      y: p.y + chipPadTop,
      size: chipFontSize,
      font,
      color: p.variant === 'more' ? navy : darkGray,
      maxWidth: p.w - padX * 2,
    });
  }

  // Return cursor below the last line drawn
  const linesUsed = placements.length ? Math.max(...placements.map(p => Math.round((startY - p.y) / (chipH + lineGap)))) + 1 : 1;
  const bottomY = startY - (linesUsed - 1) * (chipH + lineGap);
  // Consistent section spacing after block.
  // IMPORTANT: never return below contentMinY if we actually rendered,
  // otherwise callers may think it "didn't fit" and draw a fallback on top (duplicate “Options” lines).
  return Math.max(bottomY - 24, contentMinY);
}

function drawCompactList(args: {
  items: string[];
  x: number;
  y: number;
  colW: number;
  cols: number;
  rowH: number;
  maxRows: number;
  page: PDFPage;
  font: PDFFont;
  fontSize: number;
  color: ReturnType<typeof rgb>;
}): number {
  const { items, x, colW, cols, rowH, maxRows, page, font, fontSize, color } = args;
  let y = args.y;
  const shown = items.slice(0, cols * maxRows);
  for (let i = 0; i < shown.length; i++) {
    const col = Math.floor(i / maxRows);
    const row = i % maxRows;
    const ix = x + col * colW;
    const iy = y - row * rowH;
    page.drawText(shown[i], {
      x: ix,
      y: iy,
      size: fontSize,
      font,
      color,
      maxWidth: colW - 6,
    });
  }
  return y - maxRows * rowH;
}

function findAttr(product: ProductData, includes: RegExp): ProductData['attributes'][number] | undefined {
  return product.attributes?.find(a => includes.test(a.name));
}

function normalizeValue(value: string): string {
  return stripHtml(value).replace(/\s+/g, ' ').trim();
}

function splitConfig(config: string): { crossSection: string; voltage: string } {
  const raw = normalizeValue(config);
  const parts = raw.split(/\s*-\s*/);
  if (parts.length >= 2) {
    return { crossSection: parts[0], voltage: parts.slice(1).join(' - ') };
  }
  return { crossSection: raw, voltage: '' };
}

function parseCoresAndMm2(crossSection: string): { cores: number | null; mm2: number | null } {
  const s = normalizeValue(crossSection)
    .replace(/\s+/g, '')
    .replace(/×/g, 'x')
    .replace(/,/g, '.');

  // Typical: 3x1.5, 4x25, 1x70
  const m = s.match(/(\d{1,3})x(\d{1,4}(?:\.\d{1,2})?)/i);
  if (!m) return { cores: null, mm2: null };
  const cores = Number(m[1]);
  const mm2 = Number(m[2]);
  return {
    cores: Number.isFinite(cores) ? cores : null,
    mm2: Number.isFinite(mm2) ? mm2 : null,
  };
}

async function generatePDF(product: ProductData, locale: 'en' | 'de'): Promise<Buffer> {
  try {
    const labels = getLabels(locale);
    const pdfDoc = await PDFDocument.create();
    const pageSize: [number, number] = [595.28, 841.89]; // A4
    let page = pdfDoc.addPage(pageSize);
    const { width, height } = page.getSize();

    // STYLEGUIDE.md colors
    const navy = rgb(0.0549, 0.1647, 0.2784); // #0E2A47
    const mediumGray = rgb(0.4196, 0.4471, 0.5020); // #6B7280
    const darkGray = rgb(0.1216, 0.1608, 0.2); // #1F2933
    const almostWhite = rgb(0.9725, 0.9765, 0.9804); // #F8F9FA
    const lightGray = rgb(0.9020, 0.9137, 0.9294); // #E6E9ED
    const headerBg = rgb(0.965, 0.972, 0.98); // calm, print-friendly tint

    // Small design system: consistent type + spacing for professional datasheets.
    const DS = {
      space: { xs: 4, sm: 8, md: 12, lg: 16, xl: 24 },
      type: { h1: 20, h2: 11, body: 10.5, small: 8 },
      rule: { thin: 0.75 },
    } as const;

    // Line-heights (explicit so vertical rhythm doesn't drift / overlap)
    const LH = {
      h1: 24,
      h2: 16,
      body: 14,
      small: 10,
    } as const;

    const font = await pdfDoc.embedFont(StandardFonts.Helvetica);
    const fontBold = await pdfDoc.embedFont(StandardFonts.HelveticaBold);

    // Assets
    // Prefer a raster logo for reliability (sharp SVG support can vary between environments).
    const logoPng = (await loadEmbeddablePng('/media/logo.png')) || (await loadEmbeddablePng('/media/logo.svg'));
    const logoImage = logoPng ? await pdfDoc.embedPng(logoPng.pngBytes) : null;

    // Some products in the processed dataset have no images/attributes.
    // Always fall back to a deterministic site hero so the PDF is never "empty".
    const fallbackHero = '/media/10648-low-voltage-scaled.webp';
    const heroSrc = product.featuredImage || product.images?.[0] || fallbackHero;
    const heroPng = await loadEmbeddablePng(heroSrc);

    const productUrl = getProductUrl(product) || CONFIG.siteUrl;
    const qrPng = await loadQrPng(productUrl);
    const qrImage = qrPng ? await pdfDoc.embedPng(qrPng.pngBytes) : null;

    // Engineered page frame (A4): slightly narrower margins but consistent rhythm.
    const margin = 54;
    const footerY = 54;
    const contentMinY = footerY + 42; // keep clear of footer + page numbers
    const contentWidth = width - 2 * margin;

    const ctx: SectionDrawContext = {
      pdfDoc,
      page,
      width,
      height,
      margin,
      contentWidth,
      footerY,
      contentMinY,
      headerDividerY: 0,
      colors: { navy, mediumGray, darkGray, almostWhite, lightGray, headerBg },
      fonts: { regular: font, bold: fontBold },
      labels,
      product,
      locale,
      logoImage,
      qrImage,
      qrUrl: productUrl,
    };

    // Hard requirement: one-page PDFs.
    // We never create a second page; we truncate sections to fit.
    const newPage = (): number => contentMinY - 1;
    const hasSpace = (needed: number) => y - needed >= contentMinY;

    // ---- Layout helpers (eliminate magic numbers; enforce consistent rhythm) ----
    const rule = (gapAbove: number = DS.space.md, gapBelow: number = DS.space.lg) => {
      // One-page rule: if we can't fit a divider with its spacing, do nothing.
      if (!hasSpace(gapAbove + gapBelow + DS.rule.thin)) return;

      y -= gapAbove;
      page.drawLine({
        start: { x: margin, y },
        end: { x: margin + contentWidth, y },
        thickness: DS.rule.thin,
        color: lightGray,
      });
      y -= gapBelow;
    };

    const sectionTitle = (text: string) => {
      // One-page rule: if we can't fit the heading + its gap, do nothing.
      if (!hasSpace(DS.type.h2 + DS.space.md)) return;

      page.drawText(text, {
        x: margin,
        y,
        size: DS.type.h2,
        font: fontBold,
        color: navy,
      });
      // Use a real line-height to avoid title/body overlap.
      y -= LH.h2;
    };

    // Page 1
    // Page background (print-friendly)
    page.drawRectangle({
      x: 0,
      y: 0,
      width,
      height,
      color: rgb(1, 1, 1),
    });

    drawFooter(ctx);
    let y = drawHeader(ctx, height - margin);

    // === PRODUCT HEADER ===
    const productName = stripHtml(product.name);
    const cats = (product.categories || []).map(c => stripHtml(c.name)).join(' • ');

    const titleW = contentWidth;
    const titleLineH = LH.h1;
    const nameLines = wrapText(productName, fontBold, DS.type.h1, titleW);
    const shownNameLines = nameLines.slice(0, 2);
    for (const line of shownNameLines) {
      if (y - titleLineH < contentMinY) y = newPage();
      page.drawText(line, {
        x: margin,
        y,
        size: DS.type.h1,
        font: fontBold,
        color: navy,
        maxWidth: titleW,
      });
      y -= titleLineH;
    }

    if (cats) {
      if (y - 18 < contentMinY) y = newPage();
      page.drawText(cats, {
        x: margin,
        y,
        size: 10.5,
        font,
        color: mediumGray,
        maxWidth: titleW,
      });
      y -= DS.space.lg;
    }

    // Separator after product header
    rule(DS.space.sm, DS.space.lg);

    // === HERO IMAGE (full width) ===
    let heroH = 160;
    const afterHeroGap = DS.space.xl;
    if (!hasSpace(heroH + afterHeroGap)) {
      // Shrink to remaining space (but keep it usable).
      heroH = Math.max(120, Math.floor(y - contentMinY - afterHeroGap));
    }

    const heroBoxX = margin;
    const heroBoxY = y - heroH;
    page.drawRectangle({
      x: heroBoxX,
      y: heroBoxY,
      width: contentWidth,
      height: heroH,
      // Calm frame; gives images consistent presence even with transparency.
      color: almostWhite,
      borderColor: lightGray,
      borderWidth: 1,
    });

    if (heroPng) {
      const pad = DS.space.md;
      const boxW = contentWidth - pad * 2;
      const boxH = heroH - pad * 2;

      // Pre-crop the image to the target aspect ratio (prevents overflow and removes top/bottom whitespace).
      const sharp = await getSharp();
      const cropped = await sharp(Buffer.from(heroPng.pngBytes))
        .resize({
          width: 1200,
          height: Math.round((1200 * boxH) / boxW),
          fit: 'cover',
          position: 'attention',
        })
        .png()
        .toBuffer();
      const heroImage = await pdfDoc.embedPng(cropped);

      // Exact-fit (we already cropped to this aspect ratio).
      page.drawImage(heroImage, {
        x: heroBoxX + pad,
        y: heroBoxY + pad,
        width: boxW,
        height: boxH,
      });
    } else {
      page.drawText(locale === 'de' ? 'Kein Bild verfügbar' : 'No image available', {
        x: heroBoxX + 12,
        y: heroBoxY + heroH / 2,
        size: 8,
        font,
        color: mediumGray,
        maxWidth: contentWidth - 24,
      });
    }

    y = heroBoxY - afterHeroGap;

    // === DESCRIPTION ===
    if (product.shortDescriptionHtml || product.descriptionHtml) {
      const desc = stripHtml(product.shortDescriptionHtml || product.descriptionHtml);
      const descLineH = 14;
      const descMaxLines = 3;
      const boxPadX = DS.space.md;
      const boxPadY = DS.space.md;
      const boxH = boxPadY * 2 + descLineH * descMaxLines;
      const descNeeded = DS.type.h2 + DS.space.md + boxH + DS.space.lg + DS.space.xl;

      // One-page rule: only render description if we can fit it cleanly.
      if (hasSpace(descNeeded)) {
        sectionTitle(labels.description);

        const boxTop = y + DS.space.xs;
        const boxBottom = boxTop - boxH;
        page.drawRectangle({
          x: margin,
          y: boxBottom,
          width: contentWidth,
          height: boxH,
          color: rgb(1, 1, 1),
          borderColor: lightGray,
          borderWidth: 1,
        });

        const descLines = wrapText(desc, font, DS.type.body, contentWidth - boxPadX * 2);
        let ty = boxTop - boxPadY - DS.type.body;
        for (const line of descLines.slice(0, descMaxLines)) {
          page.drawText(line, {
            x: margin + boxPadX,
            y: ty,
            size: DS.type.body,
            font,
            color: darkGray,
            maxWidth: contentWidth - boxPadX * 2,
          });
          ty -= descLineH;
        }

        y = boxBottom - DS.space.lg;
        rule(0, DS.space.xl);
      }
    }

    // === TECHNICAL DATA (shared across all cross-sections) ===
    const configAttr = findAttr(product, /configuration|konfiguration|aufbau|bezeichnung/i);
    const crossSectionAttr =
      configAttr ||
      findAttr(product, /number of cores and cross-section|querschnitt|cross.?section|mm²|mm2/i);
    const rowCount = crossSectionAttr?.options?.length || 0;
    const hasCrossSectionData = Boolean(crossSectionAttr && rowCount > 0);

    // Compact mode approach:
    // - show constant (non-row) attributes as key/value grid
    // - show only a small configuration sample + total count
    // - optionally render full tables with PDF_MODE=full

    const constantAttrs = (product.attributes || []).filter(a => a.options.length === 1);
    const constantItemsAll = constantAttrs
      .map(a => ({ label: normalizeValue(a.name), value: normalizeValue(a.options[0]) }))
      .filter(i => i.label && i.value)
      .slice(0, 12);

      // Intentionally do NOT include SKU/categories here (they are already shown in the product header).

    // TECH DATA must never crowd out cross-section.
    // IMPORTANT: `drawKeyValueGrid()` will return `contentMinY - 1` when it can't fit.
    // We must avoid calling it unless we're sure it fits.
    const techBox = {
      // Keep in sync with `drawKeyValueGrid()` boxed metrics
      padY: 14,
      headerH: 22,
      rowH: 24,
    } as const;

    // Reserve enough space so cross-sections are actually visible when present.
    // Mirror `drawCrossSectionChipsRow()` minimum-needed math (+ a bit of padding).
    const minCrossBlockH = 12 /*title*/ + 12 /*summary*/ + (16 * 2) /*chips*/ + 8 /*lineGap*/ + 10 /*gapY*/ + 24 /*after*/;
    const reservedForCross = hasCrossSectionData ? minCrossBlockH : 0;

    const techTitle = locale === 'de' ? 'TECHNISCHE DATEN' : 'TECHNICAL DATA';

    const techBoxHeightFor = (itemsCount: number) => {
      const rows = Math.ceil(itemsCount / 2);
      return techBox.padY + techBox.headerH + rows * techBox.rowH + techBox.padY;
    };

    const canFitTechWith = (itemsCount: number) => {
      if (itemsCount <= 0) return false;
      const techH = techBoxHeightFor(itemsCount);
      const afterTechGap = DS.space.lg;
      // We need to keep reserved space for cross-section below.
      return y - (techH + afterTechGap + reservedForCross) >= contentMinY;
    };

    // Pick the largest "nice" amount of items that still guarantees cross-section visibility.
    const desiredCap = 8;
    let chosenCount = 0;
    for (let n = Math.min(desiredCap, constantItemsAll.length); n >= 1; n--) {
      if (canFitTechWith(n)) {
        chosenCount = n;
        break;
      }
    }

    if (chosenCount > 0) {
      const constantItems = constantItemsAll.slice(0, chosenCount);
      y = drawKeyValueGrid({
        title: techTitle,
        items: constantItems,
        newPage,
        getPage: () => page,
        page,
        y,
        margin,
        contentWidth,
        contentMinY,
        font,
        fontBold,
        navy,
        darkGray,
        mediumGray,
        lightGray,
        almostWhite,
        allowNewPage: false,
        boxed: true,
      });
    } else if (!hasCrossSectionData) {
      // If there is no cross-section block, we can afford to show a clear "no data" note.
      y = drawKeyValueGrid({
        title: techTitle,
        items: [
          {
            label: locale === 'de' ? 'Hinweis' : 'Note',
            value:
              locale === 'de'
                ? 'Für dieses Produkt sind derzeit keine technischen Daten hinterlegt.'
                : 'No technical data is available for this product yet.',
          },
        ],
        newPage,
        getPage: () => page,
        page,
        y,
        margin,
        contentWidth,
        contentMinY,
        font,
        fontBold,
        navy,
        darkGray,
        mediumGray,
        lightGray,
        almostWhite,
        allowNewPage: false,
        boxed: true,
      });
    }

    // Consistent spacing after the technical data block (but never push content below min Y)
    if (y - DS.space.lg >= contentMinY) y -= DS.space.lg;

    // === CROSS-SECTION TABLE (row-specific data) ===
    if (crossSectionAttr && rowCount > 0) {
      const configRows = crossSectionAttr.options;

      const findRowAttr = (re: RegExp) => {
        const a = product.attributes?.find(x => re.test(x.name));
        if (!a) return null;
        if (!a.options || a.options.length !== rowCount) return null;
        return a;
      };

      const candidateCols: Array<{ key: string; label: string; re: RegExp }> = [
        { key: 'outerDiameter', label: locale === 'de' ? 'Außen-Ø' : 'Outer Ø', re: /outer\s*diameter|außen\s*durchmesser|außen-?ø/i },
        { key: 'weight', label: locale === 'de' ? 'Gewicht' : 'Weight', re: /\bweight\b|gewicht/i },
        { key: 'maxResistance', label: locale === 'de' ? 'Max. Leiterwiderstand' : 'Max. conductor resistance', re: /maximum\s+resistance\s+of\s+conductor|max\.?\s*resistance|leiterwiderstand/i },
        { key: 'current', label: locale === 'de' ? 'Strombelastbarkeit' : 'Current rating', re: /current\s*(rating|carrying)|ampacity|strombelastbarkeit/i },
      ];

      // NOTE: One-page requirement: cross sections render as a dense list only.
      // Row-specific values are intentionally omitted to keep the sheet compact.
      const columns: Array<{ label: string; get: (rowIndex: number) => string }> = [];

      const yAfterCross = drawCrossSectionChipsRow({
        title: labels.crossSection,
        configRows,
        locale,
        getPage: () => page,
        page,
        y,
        margin,
        contentWidth,
        contentMinY,
        font,
        fontBold,
        navy,
        darkGray,
        mediumGray,
        lightGray,
        almostWhite,
      });

      // If the chips block can't fit at all, show a minimal summary line (no chips).
      // drawCrossSectionChipsRow returns (contentMinY - 1) in that case.
      if (yAfterCross < contentMinY) {
        sectionTitle(labels.crossSection);
        const total = configRows.length;
        const summary = locale === 'de' ? `Varianten: ${total}` : `Options: ${total}`;
        page.drawText(summary, {
          x: margin,
          y,
          size: DS.type.body,
          font,
          color: mediumGray,
          maxWidth: contentWidth,
        });
        y -= LH.body + DS.space.lg;
      } else {
        y = yAfterCross;
      }
    } else {
      // If there is no cross-section data, do not render the section at all.
    }

    // Add page numbers after all pages are created.
    stampPageNumbers(pdfDoc, { regular: font }, { mediumGray }, margin, footerY);

    const pdfBytes = await pdfDoc.save();
    return Buffer.from(pdfBytes);

  } catch (error: any) {
    throw new Error(`Failed to generate PDF for product ${product.id} (${locale}): ${error.message}`);
  }
}

async function processChunk(products: ProductData[], chunkIndex: number, totalChunks: number): Promise<void> {
  console.log(`\nProcessing chunk ${chunkIndex + 1}/${totalChunks} (${products.length} products)...`);

  for (const product of products) {
    try {
      const locale = product.locale || 'en';
      const buffer = await generatePDF(product, locale);
      const fileName = generateFileName(product, locale);
      fs.writeFileSync(path.join(CONFIG.outputDir, fileName), buffer);
      console.log(`✓ ${locale.toUpperCase()}: ${fileName}`);
      await new Promise(resolve => setTimeout(resolve, 50));
    } catch (error) {
      console.error(`✗ Failed to process product ${product.id}:`, error);
    }
  }
}

async function readProductsStream(): Promise<ProductData[]> {
  console.log('Reading products.json...');
  return new Promise((resolve, reject) => {
    const stream = fs.createReadStream(CONFIG.productsFile, { encoding: 'utf8' });
    let data = '';
    stream.on('data', (chunk) => { data += chunk; });
    stream.on('end', () => {
      try {
        const products = JSON.parse(data);
        console.log(`Loaded ${products.length} products`);
        resolve(products);
      } catch (error) {
        reject(new Error(`Failed to parse JSON: ${error}`));
      }
    });
    stream.on('error', (error) => reject(new Error(`Failed to read file: ${error}`)));
  });
}

async function processProductsInChunks(): Promise<void> {
  console.log('Starting PDF generation - Industrial engineering documentation style');
  ensureOutputDir();

  try {
    const allProducts = await readProductsStream();
    if (allProducts.length === 0) {
      console.log('No products found');
      return;
    }

    // Optional dev convenience: limit how many PDFs we render (useful for design iteration).
    // Default behavior remains unchanged.
    const limit = Number(process.env.PDF_LIMIT || '0');
    const products = Number.isFinite(limit) && limit > 0 ? allProducts.slice(0, limit) : allProducts;

    const enProducts = products.filter(p => p.locale === 'en');
    const deProducts = products.filter(p => p.locale === 'de');
    console.log(`Found ${enProducts.length} EN + ${deProducts.length} DE products`);

    const totalChunks = Math.ceil(products.length / CONFIG.chunkSize);
    for (let i = 0; i < totalChunks; i++) {
      const chunk = products.slice(i * CONFIG.chunkSize, (i + 1) * CONFIG.chunkSize);
      await processChunk(chunk, i, totalChunks);
    }

    console.log('\n✅ PDF generation completed!');
    console.log(`Generated ${enProducts.length} EN + ${deProducts.length} DE PDFs`);
    console.log(`Output: ${CONFIG.outputDir}`);

  } catch (error) {
    console.error('❌ Error:', error);
    throw error;
  }
}

async function main(): Promise<void> {
  const start = Date.now();
  try {
    await processProductsInChunks();
    console.log(`\nTime: ${((Date.now() - start) / 1000).toFixed(2)}s`);
  } catch (error) {
    console.error('Fatal error:', error);
    process.exit(1);
  }
}

main().catch(console.error);

export { main as generatePDFDatasheets };