const fs = require('fs');
const path = require('path');
const puppeteer = require('puppeteer');
const storage = require('./utils/storage');

function fileToDataUri(fullPath) {
  try {
    const buf = fs.readFileSync(fullPath);
    const ext = path.extname(fullPath).toLowerCase().replace('.', '');
    const mime = { jpg: 'jpeg', jpeg: 'jpeg', png: 'png', gif: 'gif', webp: 'webp' }[ext] || 'jpeg';
    return `data:image/${mime};base64,${buf.toString('base64')}`;
  } catch (e) {
    return null;
  }
}

function esc(str) {
  return String(str || '').replace(/[&<>"']/g, (c) => (
    { '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' }[c]
  ));
}

const ROTATIONS = [-4, 3, -2, 5, -3, 2, -5, 4];
const COVER_MAX_STICKERS = 30;

// Gleicher deterministischer Pseudo-Zufallsgenerator wie im Buch-Viewer (book.js)
function seededRandom(seed) {
  let t = (seed += 0x6d2b79f5);
  t = Math.imul(t ^ (t >>> 15), t | 1);
  t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
  return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
}

function collectStickerImages(friends) {
  const imgs = [];
  friends.forEach((f) => {
    const uploadsDir = path.join(storage.friendFolderPath(f.folderName), 'uploads');
    if (f.profileImage) imgs.push(path.join(uploadsDir, f.profileImage));
    (f.blocks || []).forEach((b) => {
      if (b.type === 'image' && b.filename) imgs.push(path.join(uploadsDir, b.filename));
      if (b.type === 'audio' && b.coverFilename) imgs.push(path.join(uploadsDir, b.coverFilename));
    });
  });
  return imgs;
}

function buildCoverPageHtml(title, friends) {
  let files = collectStickerImages(friends);
  if (files.length > COVER_MAX_STICKERS) {
    const step = files.length / COVER_MAX_STICKERS;
    files = Array.from({ length: COVER_MAX_STICKERS }, (_, i) => files[Math.floor(i * step)]);
  }

  const cols = Math.min(6, Math.max(3, Math.ceil(Math.sqrt(files.length * 1.6)) || 3));
  const rows = Math.max(1, Math.ceil(files.length / cols));

  const stickers = files
    .map((filePath, i) => {
      const uri = fileToDataUri(filePath);
      if (!uri) return '';
      const cellX = i % cols;
      const cellY = Math.floor(i / cols);
      const rx = seededRandom(i * 13 + 1);
      const ry = seededRandom(i * 17 + 2);
      const rr = seededRandom(i * 7 + 3);
      const rs = seededRandom(i * 5 + 4);
      const leftPct = ((cellX + 0.1 + rx * 0.8) / cols) * 100;
      const topPct = ((cellY + 0.1 + ry * 0.8) / rows) * 100;
      const rot = (rr * 50 - 25).toFixed(1);
      const sizeMm = Math.round(28 + rs * 20);
      return `<img class="cover-sticker" style="left:${leftPct}%; top:${topPct}%; width:${sizeMm}mm; height:${sizeMm}mm; transform: rotate(${rot}deg);" src="${uri}" />`;
    })
    .join('');

  return `
  <section class="page cover-page">
    <div class="cover-stickers">${stickers}</div>
    <div class="cover-title-wrap">
      <div class="tape" style="position:static; margin: 0 auto 6mm; transform: rotate(-4deg);"></div>
      <h1 class="cover-title">${esc(title)}</h1>
    </div>
  </section>`;
}

function buildFriendPageHtml(friend, folder) {
  const uploadsDir = path.join(storage.friendFolderPath(folder), 'uploads');
  const profileUri = friend.profileImage ? fileToDataUri(path.join(uploadsDir, friend.profileImage)) : null;

  const steckbriefRows = Object.entries(friend.steckbrief || {})
    .filter(([, v]) => v && String(v).trim())
    .map(([k, v]) => `<div class="sb-row"><span class="sb-key">${esc(k)}</span><span class="sb-val">${esc(v)}</span></div>`)
    .join('');

  const blocks = [...(friend.blocks || [])].sort((a, b) => a.order - b.order);
  const blockHtml = blocks
    .map((b, i) => {
      const rot = ROTATIONS[i % ROTATIONS.length];
      if (b.type === 'text') {
        return `<div class="pdf-block text-block" style="transform: rotate(${rot * 0.4}deg)">
          <p>${esc(b.content).replace(/\n/g, '<br/>')}</p>
          ${b.caption ? `<div class="cap">${esc(b.caption)}</div>` : ''}
        </div>`;
      }
      if (b.type === 'image') {
        const uri = fileToDataUri(path.join(uploadsDir, b.filename));
        if (!uri) return '';
        return `<div class="pdf-block image-block polaroid" style="transform: rotate(${rot}deg)">
          <img src="${uri}" />
          ${b.caption ? `<div class="cap">${esc(b.caption)}</div>` : ''}
        </div>`;
      }
      if (b.type === 'audio') {
        const coverUri = b.coverFilename ? fileToDataUri(path.join(uploadsDir, b.coverFilename)) : null;
        return `<div class="pdf-block audio-block" style="transform: rotate(${rot * 0.5}deg)">
          ${coverUri ? `<img class="audio-cover" src="${coverUri}" />` : ''}
          <div class="audio-note">&#127925; Audio-Erinnerung${b.caption ? ': ' + esc(b.caption) : ''}<br/><small>(im Web-Freundesbuch anh&ouml;rbar)</small></div>
        </div>`;
      }
      return '';
    })
    .join('\n');

  return `
  <section class="page">
    <div class="tape tape-tl"></div><div class="tape tape-tr"></div>
    <header class="page-head">
      ${profileUri ? `<img class="profile-pic" src="${profileUri}" />` : '<div class="profile-pic placeholder">?</div>'}
      <h1>${esc(friend.name)}</h1>
    </header>
    <div class="steckbrief">
      <h2>Steckbrief</h2>
      ${steckbriefRows || '<p class="muted">Noch nichts eingetragen.</p>'}
    </div>
    <div class="blocks">
      ${blockHtml || '<p class="muted">Noch keine Erinnerungen hinzugef&uuml;gt.</p>'}
    </div>
  </section>`;
}

function buildFullHtml(friends, bookTitle) {
  const coverPage = buildCoverPageHtml(bookTitle || 'Unser Freundesbuch', friends);
  const pages = friends
    .map((f) => buildFriendPageHtml(f, f.folderName))
    .join('\n');

  return `<!DOCTYPE html>
<html lang="de">
<head>
<meta charset="utf-8" />
<style>
  @page { size: A4; margin: 0; }
  * { box-sizing: border-box; }
  body {
    margin: 0;
    font-family: 'Comic Sans MS', 'Segoe Print', 'Bradley Hand', cursive, sans-serif;
    background: #faf3e6;
    color: #3a3350;
  }
  .page {
    position: relative;
    width: 210mm;
    min-height: 297mm;
    padding: 18mm 16mm;
    page-break-after: always;
    background: #faf3e6;
    background-image: radial-gradient(circle at 10% 10%, rgba(232,168,191,0.15), transparent 40%),
                       radial-gradient(circle at 90% 85%, rgba(168,213,186,0.18), transparent 45%);
    overflow: hidden;
  }
  .page:last-child { page-break-after: auto; }
  .tape { position: absolute; width: 70px; height: 26px; background: rgba(232,184,75,0.55); }
  .tape-tl { top: 6mm; left: 20mm; transform: rotate(-8deg); }
  .tape-tr { top: 6mm; right: 20mm; transform: rotate(9deg); }
  .page-head { text-align: center; margin-bottom: 8mm; }
  .profile-pic {
    width: 42mm; height: 42mm; object-fit: cover; border-radius: 50%;
    border: 6px solid #fff; box-shadow: 0 4px 14px rgba(0,0,0,0.18);
    transform: rotate(-3deg);
  }
  .profile-pic.placeholder {
    display: flex; align-items: center; justify-content: center;
    font-size: 30px; color: #b9a9d8; background: #fff;
  }
  .page-head h1 {
    font-size: 34px; margin: 6mm 0 0; color: #6b4f8c;
    text-shadow: 1px 1px 0 rgba(255,255,255,0.6);
  }
  .steckbrief {
    background: #fffdf7; border: 2px dashed #d9b568; border-radius: 10px;
    padding: 6mm 8mm; margin-bottom: 8mm; transform: rotate(-0.6deg);
  }
  .steckbrief h2 { margin: 0 0 4mm; font-size: 20px; color: #b5652f; }
  .sb-row { display: flex; gap: 6px; font-size: 13px; margin-bottom: 2mm; font-family: Georgia, serif; }
  .sb-key { font-weight: bold; min-width: 32mm; color: #6b4f8c; }
  .muted { color: #9a8fb0; font-style: italic; font-size: 12px; font-family: Georgia, serif; }
  .blocks { display: flex; flex-wrap: wrap; gap: 6mm; }
  .pdf-block { background: #fff; padding: 4mm; box-shadow: 0 3px 10px rgba(0,0,0,0.15); }
  .polaroid { padding: 4mm 4mm 10mm; width: 58mm; }
  .polaroid img { width: 100%; height: 48mm; object-fit: cover; display: block; }
  .text-block { width: 58mm; min-height: 40mm; background: #fef7d6; font-family: Georgia, serif; font-size: 12px; }
  .audio-block { width: 58mm; min-height: 30mm; background: #e8f3ec; display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center; font-size: 13px; padding: 3mm; }
  .audio-cover { width: 100%; height: 30mm; object-fit: cover; border-radius: 4px; margin-bottom: 2mm; }
  .cap { font-family: Georgia, serif; font-size: 11px; color: #6b4f8c; margin-top: 2mm; text-align: center; }

  /* Deckblatt */
  .cover-page { display: flex; align-items: center; justify-content: center; padding: 0; }
  .cover-stickers { position: absolute; inset: 0; }
  .cover-sticker {
    position: absolute; object-fit: cover; border: 4px solid #fff; border-radius: 6px;
    box-shadow: 0 3px 10px rgba(0,0,0,0.25);
  }
  .cover-title-wrap { position: relative; z-index: 5; text-align: center; padding: 0 12mm; }
  .cover-title {
    display: inline-block; font-size: 52px; background: rgba(255,253,247,0.94);
    padding: 6mm 10mm; border-radius: 8px; box-shadow: 0 4px 14px rgba(0,0,0,0.2);
    transform: rotate(-2deg); color: #6b4f8c; max-width: 160mm;
  }
</style>
</head>
<body>
${coverPage}
${pages || '<section class="page"><h1>Noch keine Freunde angelegt.</h1></section>'}
</body>
</html>`;
}

async function generateBookPdf() {
  const friends = storage.getAllFriendsMeta();
  const settings = storage.readSettings();
  const html = buildFullHtml(friends, settings.bookTitle);

  const browser = await puppeteer.launch({
    executablePath: process.env.PUPPETEER_EXECUTABLE_PATH || undefined,
    headless: true,
    args: ['--no-sandbox', '--disable-setuid-sandbox'],
  });
  try {
    const page = await browser.newPage();
    await page.setContent(html, { waitUntil: 'networkidle0' });
    const buffer = await page.pdf({ format: 'A4', printBackground: true });
    return buffer;
  } finally {
    await browser.close();
  }
}

module.exports = { generateBookPdf, buildFullHtml };