'use strict';

// ---------------------------------------------------------------------------
// Zeitschriften: das Heft und seine Artikel (docs/library.md, "Heft und Artikel").
// The issue stays the document — read through in the editors' order — and the article
// is the unit one moves in: its own state (gelesen / übersprungen), reading time, a
// running head ("Artikel 8 von 23") and a pause at its end. Each determines the other:
// reading the issue through marks the articles one passes; reading articles moves the
// issue on ("7 von 23"); "Im Heft weiterlesen" goes to the next one not read yet.
//
// The index comes from the file, on the device (the server never sees it): an EPUB's
// table of contents (its leaves are the articles, their parents the Rubriken) or a PDF's
// outline (page ranges). It is kept in the book's encrypted meta (`issue`), the states
// too (`issueRead`, `issueAt`), so every device has them; a state that couldn't be saved
// (offline) waits in localStorage and goes with the next save. Chrome-61-safe (tolino).
// ---------------------------------------------------------------------------

const ISSUE_WPM = 200;                       // words per minute, for the reading times
const ISSUE_INDEX_V = 2;                     // an index of another version is built anew
const _issuePendingKey = 'diora_issue_pending';

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

const _issueMeta = b => (b && (bookMetaCache[b.id] || {})) || {};
function _issueIndexOf(b) {
  const m = _issueMeta(b);
  const ix = m.issue || (b && b.issue);
  return ix && ix.v === ISSUE_INDEX_V && ix.a && ix.a.length ? ix.a : null;
}
// An issue whose file has no usable table of contents (under this version's rules).
function _issueNone(b) {
  const ix = _issueMeta(b).issue || (b && b.issue);
  return !!(ix && ix.v === ISSUE_INDEX_V && ix.none);
}

// ---- state: {href: 'r' (gelesen) | 's' (übersprungen)} and the article one was in -----------

function _issuePending() {
  try { return JSON.parse(localStorage.getItem(_issuePendingKey) || '{}') || {}; } catch (e) { return {}; }
}
function _issueSetPending(all) {
  try { localStorage.setItem(_issuePendingKey, JSON.stringify(all)); } catch (e) {}
}

function _issueState(b) {
  const m = _issueMeta(b);
  const read = Object.assign({}, m.issueRead || b.issueRead || {});
  let at = m.issueAt || b.issueAt || '';
  const p = _issuePending()[b.id];
  if (p) {
    Object.keys(p.read || {}).forEach(h => { if (p.read[h]) read[h] = p.read[h]; else delete read[h]; });
    if (p.at) at = p.at;
  }
  return {read, at};
}

// What the issue amounts to: counts, the next article to read, the time still to read.
function _issueSummary(b) {
  const arts = _issueIndexOf(b);
  if (!arts) return null;
  const st = _issueState(b);
  let read = 0, skipped = 0, left = 0;
  arts.forEach(a => {
    const s = st.read[a.h];
    if (s === 'r') read++;
    else if (s === 's') skipped++;
    else left += a.m || 0;
  });
  const at = arts.findIndex(a => a.h === st.at);
  const open = i => !st.read[arts[i].h];
  let next = -1;
  if (at >= 0 && open(at)) next = at;
  for (let i = at + 1; next < 0 && i < arts.length; i++) if (open(i)) next = i;
  for (let i = 0; next < 0 && i < arts.length; i++) if (open(i)) next = i;
  return {arts, st, total: arts.length, read, skipped, left, next, at, started: at >= 0 && open(at)};
}

function _issueMinutes(m) {
  if (m < 60) return Math.max(1, Math.round(m)) + ' min';
  const h = Math.floor(m / 60);
  const r = Math.round(m - h * 60);
  return r >= 45 ? 'knapp ' + (h + 1) + ' h' : r >= 15 ? 'gut ' + h + ' h' : h + ' h';
}

// One bar for the issue, one segment per article: read (full), skipped (hatched), open
// (empty), the one one is in (accent). `now`: index of the article shown right now.
function _issueSegments(sum, now, cls) {
  return `<span class="iss-seg${cls ? ' ' + cls : ''}" aria-label="${sum.read} von ${sum.total} Artikeln gelesen">` +
    sum.arts.map((a, i) => {
      const s = sum.st.read[a.h];
      const k = i === now ? 'iss-s-now' : s === 'r' ? 'iss-s-read' : s === 's' ? 'iss-s-skip' : i === sum.at ? 'iss-s-at' : '';
      return `<span class="${k}"></span>`;
    }).join('') + '</span>';
}

function _issueCounts(sum) {
  const parts = [`${sum.read} von ${sum.total} gelesen`];
  if (sum.skipped) parts.push(`${sum.skipped} übersprungen`);
  return parts.join(' · ');
}

let _issueSaveTimer = {};
function _issueMark(bookId, href, state, at) {
  const all = _issuePending();
  const p = all[bookId] || {read: {}};
  if (href) p.read[href] = state || '';
  if (at) p.at = at;
  all[bookId] = p;
  _issueSetPending(all);
  clearTimeout(_issueSaveTimer[bookId]);
  _issueSaveTimer[bookId] = setTimeout(() => _issueFlush(bookId), 2500);
}

async function _issueFlush(bookId) {
  const all = _issuePending();
  const p = all[bookId];
  const b = _lastBookListData.find(x => x.id === bookId);
  if (!p || !b) return;
  const st = _issueState(b);
  try {
    await _updateBookMeta(bookId, {issueRead: st.read, issueAt: st.at});
    const now = _issuePending();
    if (JSON.stringify(now[bookId]) === JSON.stringify(p)) { delete now[bookId]; _issueSetPending(now); }
  } catch (e) { /* offline: it waits and goes with the next save */ }
}
window.addEventListener('online', () => Object.keys(_issuePending()).forEach(id => _issueFlush(Number(id))));

// ---- the index -----------------------------------------------------------------------------------

// The articles of a table of contents. An EPUB's (byFile): an article is a file — the
// first entry pointing into it; the entries after it into the same file are its sections
// (whatever their depth), and an entry whose children point into other files is a Rubrik.
// Otherwise (one file for all, a PDF's outline): the leaves, each under the entry above it.
// Entries that are word processors' leftovers (_Hlk…, _Toc…) don't count. [{h, t, r}]
const _issueJunk = label => /^_?(Hlk|Toc|Ref|GoBack)\d*$/i.test(String(label || '').trim());

function _issueArticlesFromToc(toc, byFile) {
  toc = toc.filter(e => !_issueJunk(e.label));
  const fileOf = h => String(h || '').split('#')[0];
  if (byFile) {
    const out = [];
    const seen = new Set();
    for (let i = 0; i < toc.length; i++) {
      const e = toc[i];
      if (!e.href) continue;
      const f = fileOf(e.href);
      let container = false;
      for (let k = i + 1; k < toc.length && toc[k].depth > e.depth; k++) {
        if (toc[k].href && fileOf(toc[k].href) !== f) { container = true; break; }
      }
      if (container || seen.has(f)) continue;
      seen.add(f);
      let r = '';
      for (let k = i - 1, d = e.depth; k >= 0 && d > 0; k--) {
        if (toc[k].depth >= d) continue;
        d = toc[k].depth;
        if (!toc[k].href || fileOf(toc[k].href) !== f) { r = toc[k].label || ''; break; }
      }
      out.push({h: e.href, t: (e.label || '').replace(/\s+/g, ' ').trim() || 'Ohne Titel', r: r.replace(/\s+/g, ' ').trim()});
    }
    if (out.length >= 2) return out;
  }
  const out = [];
  const seen = new Set();
  const parents = [];
  for (let i = 0; i < toc.length; i++) {
    const e = toc[i];
    parents[e.depth] = e.label;
    parents.length = e.depth + 1;
    const nxt = toc[i + 1];
    const leaf = !nxt || nxt.depth <= e.depth;
    if (!leaf || !e.href || seen.has(e.href)) continue;
    seen.add(e.href);
    out.push({h: e.href, t: (e.label || '').trim() || 'Ohne Titel', r: e.depth > 0 ? (parents[e.depth - 1] || '').trim() : ''});
  }
  return out;
}

function _issueTextStats(text, title) {
  let t = String(text || '').replace(/\s+/g, ' ').trim();
  const words = t ? t.split(' ').length : 0;
  if (title && t.toLowerCase().indexOf(title.toLowerCase()) === 0) t = t.slice(title.length).trim();
  const x = t.length > 110 ? t.slice(0, 110).replace(/\s+\S*$/, '') + ' …' : t;
  return {x, m: Math.max(1, Math.round(words / ISSUE_WPM))};
}

const _issueHtmlText = html => String(html || '')
  .replace(/<head\b[\s\S]*?<\/head>/gi, ' ')
  .replace(/<(script|style)\b[\s\S]*?<\/\1>/gi, ' ')
  .replace(/<[^>]+>/g, ' ')
  .replace(/&#x([0-9a-f]+);/gi, (m, h) => String.fromCharCode(parseInt(h, 16)))
  .replace(/&#(\d+);/g, (m, d) => String.fromCharCode(parseInt(d, 10)))
  .replace(/ /g, ' ')
  .replace(/&nbsp;/g, ' ').replace(/&amp;/g, '&').replace(/&lt;/g, '<').replace(/&gt;/g, '>').replace(/&quot;/g, '"').replace(/&#39;/g, "'");

async function _issueIndexEpub(bytes) {
  const zip = await JSZip.loadAsync(bytes);
  const container = zip.file('META-INF/container.xml');
  if (!container) return null;
  const cdoc = new DOMParser().parseFromString(await container.async('text'), 'application/xml');
  const root = cdoc.querySelector('rootfile');
  if (!root) return null;
  const opfPath = root.getAttribute('full-path');
  const opfDir = opfPath.indexOf('/') >= 0 ? opfPath.slice(0, opfPath.lastIndexOf('/') + 1) : '';
  const opfDoc = new DOMParser().parseFromString(await zip.file(opfPath).async('text'), 'application/xml');
  const manifest = {};
  Array.prototype.forEach.call(opfDoc.querySelectorAll('manifest > item'), item => {
    manifest[item.getAttribute('id')] = {href: opfDir + item.getAttribute('href'),
      mediaType: item.getAttribute('media-type') || '', properties: item.getAttribute('properties') || ''};
  });
  const spine = Array.prototype.map.call(opfDoc.querySelectorAll('spine > itemref'), r => (manifest[r.getAttribute('idref')] || {}).href).filter(Boolean);
  let arts = _issueArticlesFromToc(await _parseEpubToc(zip, opfDoc, manifest), true);
  const files = {};
  const fileText = async path => {
    if (!(path in files)) {
      const f = zip.file(path) || zip.file(decodeURIComponent(path));
      files[path] = f ? await f.async('text') : '';
    }
    return files[path];
  };
  if (arts.length < 2) {
    // No usable table of contents: one article per spine file with some text in it.
    arts = [];
    for (const path of spine) {
      const html = await fileText(path);
      const m = /<h[1-3][^>]*>([\s\S]*?)<\/h[1-3]>/i.exec(html);
      const text = _issueHtmlText(html);
      if (text.replace(/\s+/g, '').length < 300) continue;
      arts.push({h: path, t: m ? _issueHtmlText(m[1]).replace(/\s+/g, ' ').trim() : 'Artikel ' + (arts.length + 1), r: ''});
    }
  }
  // Each article's text: from its target to the next article's (within a file by the
  // fragment's place, across files along the spine).
  const split = h => { const k = h.indexOf('#'); return k >= 0 ? [h.slice(0, k), h.slice(k + 1)] : [h, '']; };
  const posIn = (html, frag) => {
    if (!frag) return 0;
    const m = new RegExp('id\\s*=\\s*["\']' + frag.replace(/[.*+?^${}()|[\]\\]/g, '\\$&') + '["\']').exec(html);
    if (!m) return 0;
    return html.lastIndexOf('<', m.index);
  };
  for (let i = 0; i < arts.length; i++) {
    const [file, frag] = split(arts[i].h);
    const [nFile, nFrag] = i + 1 < arts.length ? split(arts[i + 1].h) : ['', ''];
    let html = '';
    const startIdx = spine.indexOf(file);
    if (nFile === file) {
      const whole = await fileText(file);
      html = whole.slice(posIn(whole, frag), nFrag ? posIn(whole, nFrag) : whole.length);
    } else {
      const whole = await fileText(file);
      html = whole.slice(posIn(whole, frag));
      const endIdx = nFile ? spine.indexOf(nFile) : spine.length;
      for (let s = startIdx + 1; startIdx >= 0 && s < (endIdx < 0 ? spine.length : endIdx); s++) html += await fileText(spine[s]);
      if (nFile && nFrag) { const n = await fileText(nFile); html += n.slice(0, posIn(n, nFrag)); }
    }
    const st = _issueTextStats(_issueHtmlText(html), arts[i].t);
    // The headings before the first paragraph that the title doesn't already say (a
    // magazine's headline under its kicker): the teaser; else the text's beginning.
    const body = html.replace(/<head\b[\s\S]*?<\/head>/i, '');
    const firstP = body.search(/<p[\s>]/i);
    const heads = [];
    const re = /<h[1-4]\b[^>]*>([\s\S]*?)<\/h[1-4]>/gi;
    let m;
    while ((m = re.exec(body)) && (firstP < 0 || m.index < firstP)) {
      const t = _issueHtmlText(m[1]).replace(/\s+/g, ' ').trim();
      // Not one of the article's own numbered sections ("I. Verarmung …", "1. …").
      if (t && !/^([IVXL]+|\d+)\.\s/.test(t) && _issueNorm(arts[i].t).indexOf(_issueNorm(t)) < 0) heads.push(t);
    }
    if (heads.length) st.x = heads.join(' – ');
    else if (firstP >= 0) st.x = _issueTextStats(_issueHtmlText(body.slice(firstP)), '').x;
    Object.assign(arts[i], st);
  }
  return arts;
}

const _issueNorm = s => String(s || '').toLowerCase().replace(/ß/g, 'ss').normalize('NFKD').replace(/[^a-z0-9]/g, '');

async function _issueIndexPdf(bytes) {
  if (typeof pdfjsLib === 'undefined') return null;
  const pdf = await _pdfLoad(new Uint8Array(bytes)).promise;
  try {
    return await _issuePdfArticles(pdf);
  } finally {
    try { pdf.destroy(); } catch (e) {}
  }
}

// A PDF's articles: from its outline where it has a real one, else from the contents
// page printed in the issue (most magazines' PDFs have no outline).
async function _issuePdfArticles(pdf) {
  const pageText = {};
  const textOf = async n => {
    if (!(n in pageText)) {
      try {
        const c = await (await pdf.getPage(n)).getTextContent();
        pageText[n] = c.items.map(it => it.str).join(' ');
      } catch (e) { pageText[n] = ''; }
    }
    return pageText[n];
  };
  let arts = [];
  const outline = await pdf.getOutline().catch(() => null);
  if (outline && outline.length && typeof _parsePdfOutline === 'function') {
    arts = _issueArticlesFromToc(await _parsePdfOutline(pdf, outline))
      .filter(a => /^#pdf-page-\d+$/.test(a.h))
      .map(a => Object.assign(a, {p: parseInt(a.h.slice(10), 10)}));
  }
  if (arts.length < 3) arts = await _issuePrintedToc(pdf, textOf);
  if (arts.length < 2) return [];
  arts.sort((a, b) => a.p - b.p);
  for (let i = 0; i < arts.length; i++) {
    const a = arts[i];
    a.h = '#pdf-page-' + a.p;
    a.e = i + 1 < arts.length ? Math.max(a.p, arts[i + 1].p - 1) : pdf.numPages;
    let text = '';
    for (let n = a.p; n <= Math.min(a.e, a.p + 40); n++) text += ' ' + await textOf(n);
    const s = _issueTextStats(text, '');
    // From a printed contents page: no teaser (a page's running heads and captions come
    // first in its text); the author stands there instead.
    if (a.a !== undefined) s.x = a.x || '';
    else if (!a.x) {
      // The teaser: what follows the title on its first page, if it stands there.
      const first = (await textOf(a.p)).replace(/\s+/g, ' ');
      const k = _issueFind(first, a.t);
      s.x = _issueTextStats(k >= 0 ? first.slice(k) : '', '').x;
    } else s.x = a.x;
    Object.assign(a, s);
  }
  return arts;
}

// Where `title` stands in `text` (letters and digits only, any case): the index in
// `text` just after it, or -1.
function _issueFind(text, title) {
  const want = _issueNorm(title).slice(0, 40);
  if (want.length < 4) return -1;
  let norm = '';
  const map = [];
  for (let i = 0; i < text.length; i++) {
    const c = _issueNorm(text[i]);
    for (let k = 0; k < c.length; k++) { norm += c[k]; map.push(i + 1); }
  }
  const at = norm.indexOf(want);
  return at < 0 ? -1 : map[at + want.length - 1];
}

function _issueSpan(text, title) {
  const end = _issueFind(text, title);
  if (end < 0) return '';
  const want = _issueNorm(title).slice(0, 40);
  let n = 0, i = end;
  while (i > 0 && n < want.length) { i--; n += _issueNorm(text[i]).length; }
  return text.slice(i, end);
}

// The lines of a page as pdf.js lays its text out: pieces on one baseline that sit close
// together make a segment; far apart (another column), two. [{x, y, size, text}]
async function _issuePdfSegments(pdf, n) {
  const page = await pdf.getPage(n);
  const c = await page.getTextContent();
  const items = c.items.filter(it => it.str && it.str.trim())
    .map(it => ({x: it.transform[4], y: it.transform[5], w: it.width, size: Math.hypot(it.transform[2], it.transform[3]) || it.height || 10, s: it.str}));
  items.sort((a, b) => (b.y - a.y) || (a.x - b.x));
  const segs = [];
  let line = [];
  const flush = () => {
    if (!line.length) return;
    line.sort((a, b) => a.x - b.x);
    let seg = null;
    for (const it of line) {
      if (seg && it.x - seg.end > Math.max(24, it.size * 3)) { segs.push(seg); seg = null; }
      if (!seg) seg = {x: it.x, y: it.y, size: it.size, text: it.s, end: it.x + it.w};
      else {
        seg.text += (it.x - seg.end > it.size * 0.15 && !/\s$/.test(seg.text) && !/^\s/.test(it.s) ? ' ' : '') + it.s;
        seg.end = Math.max(seg.end, it.x + it.w);
        seg.size = Math.max(seg.size, it.size);
      }
    }
    if (seg) segs.push(seg);
    line = [];
  };
  for (const it of items) {
    if (line.length && Math.abs(line[0].y - it.y) > Math.min(line[0].size, it.size) * 0.5) flush();
    line.push(it);
  }
  flush();
  segs.forEach(s => { s.text = s.text.replace(/\s+/g, ' ').trim(); });
  return segs.filter(s => s.text);
}

// The contents page printed in the issue. Its rows: a page number at the start
// ("14 Der Krieg gegen Palästina") or at the end, maybe with the author before the title
// in a column of its own ("Nathan Sperber | Beyond Neoliberalism? | 23"); the rows just
// under one, indented alike in its type size, continue it (more title, the author);
// capitals make a heading (the Rubrik). The printed numbers are matched to the file's
// pages by finding the titles there.
const _ISSUE_L = 'A-Za-zÀ-ÖØ-öø-ÿĀ-ſ';
const _issueNameLike = t => t.length <= 45 &&
  /^[A-ZÀ-ÖØ-ÞĀ-ſ][A-Za-zÀ-ÖØ-öø-ÿĀ-ſ.'’-]*(\s+((und|and|&|von|van|de|der|del|y|bin)\s+)?[A-ZÀ-ÖØ-ÞĀ-ſ][A-Za-zÀ-ÖØ-öø-ÿĀ-ſ.'’-]*){1,4}$/.test(t);

function _issueTocRows(segs, N) {
  const rows = [];
  segs.slice().sort((a, b) => (b.y - a.y) || (a.x - b.x)).forEach(s => {
    const row = rows.filter(r => Math.abs(r.y - s.y) < Math.min(r.size, s.size) * 0.4)[0];
    if (row) { row.segs.push(s); row.size = Math.max(row.size, s.size); } else rows.push({y: s.y, size: s.size, segs: [s]});
  });
  const items = [];
  const isNum = t => /^\d{1,3}$/.test(t) && parseInt(t, 10) >= 1 && parseInt(t, 10) <= N + 20;
  const letters = t => new RegExp('[' + _ISSUE_L + ']{3}').test(t);
  rows.forEach(r => {
    const g = r.segs.sort((a, b) => a.x - b.x);
    const last = g[g.length - 1];
    const textSegs = g.filter(x => !isNum(x.text));
    if (g.length >= 2 && isNum(last.text) && textSegs.length && letters(textSegs[textSegs.length - 1].text)) {
      // … title | number (an author in a column before the title)
      const title = textSegs[textSegs.length - 1];
      items.push({entry: true, printed: parseInt(last.text, 10), lines: [title.text], lead: false,
        author: textSegs.length > 1 ? textSegs.slice(0, -1).map(x => x.text).join(' ') : '',
        x: title.x, y: r.y, y0: r.y, size: title.size});
      return;
    }
    const tail = /^(.*\S)\s+(\d{1,3})$/.exec(last.text);
    if (g.length >= 2 && tail && isNum(tail[2]) && letters(tail[1]) && letters(g[0].text)) {
      // author | title 57
      items.push({entry: true, printed: parseInt(tail[2], 10), lines: [tail[1]], lead: false,
        author: g.slice(0, -1).map(x => x.text).join(' '), x: last.x, y: r.y, y0: r.y, size: last.size});
      return;
    }
    if (g.length >= 2 && isNum(g[0].text) && letters(g[1].text)) {
      items.push({entry: true, printed: parseInt(g[0].text, 10), lines: [g.slice(1).map(x => x.text).join(' ')], lead: true,
        author: '', x: g[1].x, y: r.y, y0: r.y, size: g[1].size});
      return;
    }
    g.forEach(seg => {
      let m = /^(\d{1,3})\s+(\S.*)$/.exec(seg.text);
      let lead = true;
      if (!m) { m = /^(.*\S)\s+(\d{1,3})$/.exec(seg.text); lead = false; }
      const n = m ? parseInt(lead ? m[1] : m[2], 10) : 0;
      const t = m ? (lead ? m[2] : m[1]) : '';
      if (m && n >= 1 && n <= N + 20 && letters(t)) {
        items.push({entry: true, printed: n, lines: [t], lead, author: '', x: seg.x, y: seg.y, y0: seg.y, size: seg.size});
      } else items.push({entry: false, seg});
    });
  });
  return items;
}

async function _issuePrintedToc(pdf, textOf) {
  const N = pdf.numPages;
  const caps = t => t.length >= 3 && t.length <= 40 && !/\d/.test(t) &&
    t.replace(new RegExp('[^' + _ISSUE_L + ']', 'g'), '').length >= 3 && t === t.toUpperCase();
  // The contents page: among the first pages the one with most numbered rows whose
  // numbers aren't a mere count (1, 2, 3 … is a list, not a contents).
  const pages = [];
  for (let n = 1; n <= Math.min(16, N); n++) {
    const items = _issueTocRows(await _issuePdfSegments(pdf, n), N);
    const nums = items.filter(x => x.entry);
    const sorted = nums.map(x => x.printed).sort((a, b) => a - b);
    let steps = 0;
    for (let i = 1; i < sorted.length; i++) if (sorted[i] - sorted[i - 1] === 1) steps++;
    pages.push({n, items, score: nums.length * (steps > sorted.length * 0.6 ? 0.2 : 1)});
  }
  let best = null;
  pages.forEach(pg => { if (pg.score >= 4 && (!best || pg.score > best.score)) best = pg; });
  if (!best) return [];
  // A contents running over several pages: the neighbours with entries too.
  best.best = true;
  const use = [best];
  for (let k = best.n; k < pages.length && pages[k].score >= 2; k++) use.push(pages[k]);
  for (let k = best.n - 2; k >= 0 && pages[k].score >= 2; k--) use.unshift(pages[k]);
  const isCaps = t => t === t.toUpperCase() && new RegExp('[' + _ISSUE_L + ']{3}').test(t);
  const entries = [];
  use.forEach(pg => {
    const ents = [];
    const headings = [];
    const capsRun = [];   // capitals just above, not used yet: a title's beginning or a heading
    pg.items.forEach(it => {
      if (it.entry) {
        const e = it;
        // A title in capitals may begin on the lines above its number ("DAS POLITISCHE FELD
        // NACH LINKS / 14 VERSCHIEBEN"); a lone word on top of them is a heading (GESPRÄCH).
        if (isCaps(e.lines[0])) {
          const above = capsRun.filter(c => c.x >= e.x - 8 && c.x - e.x < 60 && c.y > e.y && c.y - e.y < c.size * 2.2 * (capsRun.length + 1));
          above.sort((a, b) => b.y - a.y);
          let prev = e.y;
          const chain = [];
          for (let k = above.length - 1; k >= 0; k--) {
            if (above[k].y - prev > above[k].size * 2.4) break;
            chain.unshift(above[k]);
            prev = above[k].y;
          }
          if (chain.length >= 1 && !/\s/.test(chain[0].text)) { e.kicker = chain[0].text; chain.shift(); }
          chain.forEach(c => { c.used = true; });
          if (chain.length) e.lines[0] = chain.map(c => c.text).concat([e.lines[0]]).join(' ').replace(/(\w)- (?=\w)/g, '$1-');
        }
        e.fromNeighbour = !pg.best;
        ents.push(e);
        return;
      }
      const s = it.seg;
      if (/^\d+$/.test(s.text)) return;
      if (caps(s.text)) {
        const c = {y: s.y, x: s.x, t: s.text, text: s.text, size: s.size};
        headings.push(c);
        capsRun.push(c);
        return;
      }
      const e = ents.filter(x => s.x >= x.x - 8 && s.x - x.x < 60 && x.y - s.y > 0 && x.y - s.y < Math.max(x.size, s.size) * 3 && x.lines.length < 6).pop();
      if (!e) return;
      const by = /^(Von|Mit|By|With)\s+(.+)$/.exec(s.text);
      if (by && !e.author) { e.author = by[2]; e.y = s.y; e.done = true; return; }
      if (e.done && /(,|&|\bund)$/.test(e.author)) { e.author += ' ' + s.text; e.y = s.y; return; }
      if (e.done) return;
      if (Math.abs(s.size - e.size) < 2.5) e.lines.push(s.text);   // more title, or the author
      else (e.sub = e.sub || []).push(s.text);                      // a line under it in other type
      e.y = s.y;
    });
    // Each entry's heading: the nearest capitals above it in the contents' type size (a
    // title's beginning is no heading; a kicker on top of one is).
    ents.forEach(e => {
      const h = headings.filter(x => x.y > e.y0 && Math.abs(x.x - e.x) < 200 && x.size < e.size * 1.6 &&
        !x.used).sort((a, b) => a.y - b.y)[0];
      e.r = e.kicker || (h && !isCaps(e.lines[0]) ? h.t : '');
    });
    entries.push.apply(entries, ents);
  });
  const sizes = entries.map(e => e.size).sort((a, b) => a - b);
  const median = sizes[Math.floor(sizes.length / 2)] || 10;
  for (let i = entries.length - 1; i >= 0; i--) if (entries[i].size > median * 1.6) entries.splice(i, 1);
  const capsShare = entries.filter(e => isCaps(e.lines[0])).length / entries.length;
  for (let i = entries.length - 1; i >= 0; i--) {
    if (capsShare < 0.5 && isCaps(entries[i].lines[0]) && !/\s/.test(entries[i].lines[0])) entries.splice(i, 1);
  }
  if (entries.length < 3) return [];
  entries.forEach(e => {
    // An author on the last line: the title is the lines before it.
    if (!e.author && e.lines.length > 1 && _issueNameLike(e.lines[e.lines.length - 1])) e.author = e.lines.pop();
    // "Name: Title" (manuskripte)
    const m = /^([^:]{3,45}):\s+(.{3,})$/.exec(e.lines[0]);
    if (!e.author && m && _issueNameLike(m[1])) { e.author = m[1]; e.lines[0] = m[2]; }
    e.author = (e.author || '').replace(/\s+/g, ' ').trim();
  });
  // The printed numbers onto the file's pages: the offset most titles agree on.
  const votes = {};
  const found = {};
  for (const e of entries) {
    // The title as printed; where the number stands at the end of one run of text, maybe
    // with a name before the title ("Marcus Verhagen Grenfell's Fire 121").
    const t = e.lines.join(' ');
    const words = t.split(' ');
    const cands = [t].concat(!e.lead && !e.author && words.length > 3 ? [words.slice(2).join(' '), words.slice(3).join(' ')] : []);
    for (let off = -2; off <= 8; off++) {
      const p = e.printed + off;
      if (p < 1 || p > N) continue;
      const text = await textOf(p);
      const hits = cands.filter(c => _issueNorm(c).length >= 8 && _issueFind(text, c) >= 0);
      const upper = hits.filter(c => { const sp = _issueSpan(text, c); return sp && /[A-ZÄÖÜ]/.test(sp) && sp === sp.toUpperCase(); });
      const hit = upper[0] || hits[0];
      if (hit) {
        votes[off] = (votes[off] || 0) + 1;
        (found[off] = found[off] || []).push([e, hit]);
      }
    }
  }
  const offs = Object.keys(votes).sort((a, b) => votes[b] - votes[a]);
  const off = offs.length ? parseInt(offs[0], 10) : 0;
  const titled = new Map((found[off] || []).map(x => [x[0], x[1]]));
  const runningHead = async t => {
    let n = 0;
    for (const q of [Math.round(N * 0.3), Math.round(N * 0.55), Math.round(N * 0.8)]) if (_issueFind(await textOf(q), t) >= 0) n++;
    return n >= 2;
  };
  for (let i = entries.length - 1; i >= 0; i--) {
    const e = entries[i];
    const t = e.lines.join(' ');
    // On a further contents page, an entry its page doesn't confirm must look like a title:
    // capitals, or a few words without a comma (not a sentence running on).
    const plausible = isCaps(t) || (t.length <= 80 && !/,/.test(t) && /\s/.test(t) && /^[^a-zäöüß]/.test(t));
    if (await runningHead(t) || (e.fromNeighbour && !titled.get(e) && !plausible)) entries.splice(i, 1);
  }
  const out = [];
  const seen = new Set();
  entries.forEach(e => {
    const p = e.printed + off;
    if (p < 1 || p > N) return;
    const full = e.lines.join(' ');
    const t = titled.get(e) || full;
    let author = e.author;
    let title = t;
    if (!author && t !== full && full.indexOf(t) > 0) author = full.slice(0, full.indexOf(t)).trim();
    if (!author && !e.lead && !titled.get(e)) {
      const w = full.split(' ');
      for (const k of [2, 3]) {
        if (w.length > k + 1 && _issueNameLike(w.slice(0, k).join(' '))) { author = w.slice(0, k).join(' '); title = w.slice(k).join(' '); break; }
      }
    }
    const key = p + '|' + _issueNorm(title);
    if (seen.has(key)) return;
    seen.add(key);
    out.push({p, t: title.replace(/\s+/g, ' ').trim(), r: (e.r || '').replace(/\s+/g, ' ').trim(), a: author,
      x: e.sub ? e.sub.join(' ').replace(/(\w)- (?=[a-zäöüß])/g, '$1').replace(/\s+/g, ' ').trim() : ''});
  });
  return out;
}

// The file, decrypted (the browser's cache, or — in the apps — their store).
async function _issueBytes(id) {
  let rec = typeof _getCachedBook === 'function' ? await _getCachedBook(id) : null;
  if (!rec) {
    const r = await fetch('/books/' + id + '/data/', {credentials: 'same-origin'});
    if (r.ok) rec = await r.json();
  }
  if (!rec || !rec.data_ct) return null;
  return decryptBytes(await getOrCreateEncKey(), rec.data_iv, rec.data_ct);
}

const _issueBuilding = new Map();
// The index of an issue, built once (and kept in its meta) if it has none yet.
function _issueEnsureIndex(bookId) {
  const b = _lastBookListData.find(x => x.id === bookId);
  if (!b) return Promise.resolve(null);
  const have = _issueIndexOf(b);
  if (have || _issueNone(b)) return Promise.resolve(have);
  if (_issueBuilding.has(bookId)) return _issueBuilding.get(bookId);
  const job = (async () => {
    const bytes = await _issueBytes(bookId);
    if (!bytes) return null;
    const pdf = (_issueMeta(b).type || b.type) === 'pdf';
    const arts = pdf ? await _issueIndexPdf(bytes) : await _issueIndexEpub(bytes);
    if (!arts) return null;
    // An issue without a usable table of contents stays a whole (and isn't tried again).
    const issue = arts.length >= 2 ? {v: ISSUE_INDEX_V, a: arts} : {v: ISSUE_INDEX_V, a: [], none: true};
    try { await _updateBookMeta(bookId, {issue}); } catch (e) {
      bookMetaCache[bookId] = Object.assign({}, bookMetaCache[bookId] || {}, {issue});
    }
    return issue.a.length ? issue.a : null;
  })().catch(() => null);
  _issueBuilding.set(bookId, job);
  job.then(() => _issueBuilding.delete(bookId));
  return job;
}

// Issues still without an index: one after the other, when nothing else goes on (not on
// an e-reader: there an issue's index is built when it's opened, or comes from elsewhere).
let _issueQueueBusy = false;
function _issueIndexLater(books) {
  if (_issueQueueBusy || (typeof _LIB_EINK === 'function' && _LIB_EINK())) return;
  const todo = books.filter(b => _isMagazine(b) && b.keyOk !== false && !_issueIndexOf(b) && !_issueNone(b));
  if (!todo.length) return;
  _issueQueueBusy = true;
  const idle = window.requestIdleCallback || (fn => setTimeout(fn, 1500));
  idle(async () => {
    const reader = document.getElementById('reader-overlay');
    if (reader && reader.style.display !== 'none') { _issueQueueBusy = false; return; }
    await _issueEnsureIndex(todo[0].id);
    _issueQueueBusy = false;
    if (typeof renderBookList === 'function') renderBookList(_lastBookListData);
  });
}

// ---- the library: an issue opened (its contents) --------------------------------------------------

function _issueView(b) {
  const sum = _issueSummary(b);
  const back = `<div class="iss-top"><button type="button" class="iss-back" data-issue-act="up">‹ Zeitschriften</button>
    <button type="button" class="lib-more iss-more" data-lib-more="${b.id}" aria-label="Optionen">⋮</button></div>`;
  const head = `<div class="iss-head">${_libCover(b, 'iss-cover')}
    <span class="iss-head-text"><span class="iss-title">${_issueEsc(b.title)}</span>
    ${b.author ? `<span class="lib-meta">${_issueEsc(b.author)}</span>` : ''}
    ${sum ? `<span class="lib-meta">${sum.total} Artikel · ${_issueMinutes(sum.arts.reduce((n, a) => n + (a.m || 0), 0))}</span>` : ''}</span></div>`;
  if (!sum) {
    const none = _issueNone(b);
    return back + head + (none
      ? `<p class="lib-empty">Dieses Heft hat kein Inhaltsverzeichnis, aus dem sich Artikel ablesen lassen – es liest sich als Ganzes.</p>
         <button type="button" class="iss-go" data-issue-act="read">▶ Lesen</button>`
      : '<p class="lib-empty">Das Inhaltsverzeichnis wird gelesen …</p>');
  }
  const nx = sum.next >= 0 ? sum.arts[sum.next] : null;
  let h = back + head + `<div class="iss-sum">${_issueSegments(sum, -1)}
    <span class="lib-meta">${_issueCounts(sum)}${sum.left ? ' · noch ' + _issueMinutes(sum.left) : ''}</span>
    <span class="iss-actions">
      ${nx ? `<button type="button" class="iss-go" data-issue-act="continue">▶ ${sum.started ? 'Im Heft weiterlesen' : 'Weiter mit Artikel ' + (sum.next + 1)}</button>`
        : '<span class="lib-meta">Alles gelesen oder übersprungen.</span>'}
      ${nx ? '<button type="button" class="iss-btn" data-issue-act="finish">Heft abschließen</button>' : '<button type="button" class="iss-btn" data-issue-act="reopen">Wieder öffnen</button>'}
    </span></div>`;
  let rubrik = null;
  sum.arts.forEach((a, i) => {
    if (a.r !== rubrik) {
      rubrik = a.r;
      if (rubrik) h += `<h3 class="iss-rubrik">${_issueEsc(rubrik)}</h3>`;
    }
    const s = sum.st.read[a.h];
    const mark = s === 'r' ? '✓' : s === 's' ? '–' : i === sum.at ? '◐' : '○';
    const cls = s === 'r' ? ' iss-read' : s === 's' ? ' iss-skip' : i === sum.next ? ' iss-next' : '';
    h += `<div class="iss-row${cls}">
      <button type="button" class="iss-mark" data-issue-mark="${i}" aria-label="Artikel ${i + 1}: Stand ändern">${mark}</button>
      <button type="button" class="iss-art" data-issue-art="${i}">
        <span class="iss-n">${i + 1}</span>
        <span class="iss-art-text"><span class="iss-art-title">${_issueEsc(a.t)}</span>
        ${a.a || a.x ? `<span class="iss-teaser">${_issueEsc([a.a, a.x].filter(Boolean).join(' · '))}</span>` : ''}</span>
        <span class="iss-min">${a.m ? a.m + ' min' : ''}</span></button></div>`;
  });
  return h;
}

// What to open for "Im Heft weiterlesen": the article one was in (at its place), else the next one open.
function _issueContinue(bookId) {
  const b = _lastBookListData.find(x => x.id === bookId);
  const sum = b && _issueSummary(b);
  if (!sum || sum.next < 0) { openBook(bookId); return; }
  if (sum.started && sum.next === sum.at) { openBook(bookId); return; }
  _issueOpenAt(bookId, sum.next);
}

async function _issueOpenAt(bookId, index) {
  const b = _lastBookListData.find(x => x.id === bookId);
  const arts = b && _issueIndexOf(b);
  if (!arts || !arts[index]) { openBook(bookId); return; }
  _issueMark(bookId, null, null, arts[index].h);
  await openBook(bookId);
  if (currentBookId !== bookId) return;
  _issueJump(arts[index]);
}

function _issueJump(a) {
  if (a.p && typeof currentPdfDoc !== 'undefined' && currentPdfDoc && readerSettings.pdfPaginated &&
      typeof enterPdfPaginatedMode === 'function') {
    if (typeof pdfGoToPage === 'function') pdfGoToPage(a.p);
    else { pdfCurrentPage = a.p; enterPdfPaginatedMode(); }
    return;
  }
  if (typeof jumpToTocEntry === 'function') jumpToTocEntry(a.h);
}

function _issueSheet(bookId, i) {
  const b = _lastBookListData.find(x => x.id === bookId);
  const sum = b && _issueSummary(b);
  if (!sum) return;
  const a = sum.arts[i];
  const s = sum.st.read[a.h];
  const set = v => { _issueMark(bookId, a.h, v); renderBookList(_lastBookListData); };
  const items = [
    ['Lesen', () => _issueOpenAt(bookId, i)],
    s === 'r' ? ['Als ungelesen markieren', () => set('')] : ['Als gelesen markieren', () => set('r')],
    s === 's' ? ['Nicht mehr überspringen', () => set('')] : ['Überspringen', () => set('s')],
  ];
  const wrap = document.createElement('div');
  wrap.className = 'dfo-scrim';
  wrap.innerHTML = `<div class="dfo-sheet" role="dialog"><div class="dfo-head"><strong>${i + 1} · ${_issueEsc(a.t)}</strong>
    <button type="button" class="dfo-x" data-x="1" aria-label="Schließen">✕</button></div>
    ${items.map((it, k) => `<button type="button" class="lib-sheet-item" data-i="${k}">${it[0]}</button>`).join('')}</div>`;
  wrap.addEventListener('click', e => {
    const t = e.target.closest('[data-i]');
    if (e.target === wrap || e.target.closest('[data-x]')) { wrap.remove(); return; }
    if (t) { wrap.remove(); items[Number(t.dataset.i)][1](); }
  });
  document.body.appendChild(wrap);
}

function _issueFinish(bookId, reopen) {
  const b = _lastBookListData.find(x => x.id === bookId);
  const sum = b && _issueSummary(b);
  if (!sum) return;
  sum.arts.forEach(a => {
    const s = sum.st.read[a.h];
    if (!reopen && !s) _issueMark(bookId, a.h, 's');
    if (reopen && s === 's') _issueMark(bookId, a.h, '');
  });
  renderBookList(_lastBookListData);
}

(function () {
  const listEl = document.getElementById('book-list');
  if (!listEl) return;
  listEl.addEventListener('click', e => {
    const id = _lib.issue;
    if (id == null) return;
    const act = e.target.closest('[data-issue-act]');
    const mark = e.target.closest('[data-issue-mark]');
    const art = e.target.closest('[data-issue-art]');
    if (!act && !mark && !art) return;
    e.stopPropagation();
    if (art) { _issueOpenAt(id, Number(art.dataset.issueArt)); return; }
    if (mark) { _issueSheet(id, Number(mark.dataset.issueMark)); return; }
    const a = act.dataset.issueAct;
    if (a === 'up') { _lib.issue = null; renderBookList(_lastBookListData); }
    else if (a === 'continue') _issueContinue(id);
    else if (a === 'read') openBook(id);
    else if (a === 'finish') _issueFinish(id, false);
    else if (a === 'reopen') _issueFinish(id, true);
  });
})();

// Opened from the library: its contents (built first if needed).
function _issueOpen(bookId) {
  _lib.issue = bookId;
  renderBookList(_lastBookListData);
  const sc = document.querySelector('.main-content');
  if (sc) sc.scrollTop = 0;
  window.scrollTo(0, 0);
  _issueEnsureIndex(bookId).then(() => { if (_lib.issue === bookId) renderBookList(_lastBookListData); });
}

// ---- the reader: the running head, the article one is in, the pause at its end ----------------

let _issueR = null;   // {bookId, pdf, arts, els, cur, seen}

function _issueRunLabel() {
  if (!_issueR || _issueR.cur < 0) return '';
  const a = _issueR.arts[_issueR.cur];
  return `Artikel ${_issueR.cur + 1}/${_issueR.arts.length} · ${a.t}`;
}
window._issueRunLabel = _issueRunLabel;

async function _issueReaderOpened(bookId, isPdf) {
  _issueReaderClosed();
  const b = _lastBookListData.find(x => x.id === bookId);
  if (!b || !_isMagazine(b)) return;
  const arts = _issueIndexOf(b) || await _issueEnsureIndex(bookId);
  if (!arts || currentBookId !== bookId) return;
  const contentEl = document.getElementById('reader-content');
  _issueR = {bookId, pdf: !!isPdf, arts, els: [], cur: -1, seen: new Set(), shown: new Set()};
  if (!isPdf) {
    const target = h => {
      const k = h.indexOf('#');
      const file = k >= 0 ? h.slice(0, k) : h;
      const frag = k >= 0 ? h.slice(k + 1) : '';
      let el = null;
      if (frag) { try { el = contentEl.querySelector('#' + CSS.escape(frag)); } catch (e) {} }
      if (!el) el = Array.prototype.find.call(contentEl.querySelectorAll('[data-epub-src]'), c => c.getAttribute('data-epub-src') === file) || null;
      return el;
    };
    _issueR.els = arts.map(a => target(a.h));
    // The pauses push the text down: the place shown stays where it is.
    const anchor = typeof getPositionAnchor === 'function' ? getPositionAnchor(contentEl) : '';
    // A pause at each article's end: before the next one starts (inside its chapter, so an
    // e-reader showing one chapter at a time shows it with the article).
    arts.forEach((a, i) => {
      const el = _issueR.els[i];
      if (!el) return;
      const aside = document.createElement('aside');
      aside.className = 'iss-end';
      aside.dataset.issueEnd = i;
      aside.innerHTML = _issueEndHtml(i);
      const next = _issueR.els[i + 1];
      if (next && !next.hasAttribute('data-epub-src')) next.parentNode.insertBefore(aside, next);
      else {
        // The chapter just before the next article; the last article: its own (what follows
        // it — notices, the imprint — is no part of it).
        let ch = next ? next.previousElementSibling : el.closest('[data-epub-src]');
        while (ch && !ch.hasAttribute('data-epub-src')) ch = ch.previousElementSibling;
        (ch || el.closest('[data-epub-src]') || contentEl).appendChild(aside);
      }
    });
    contentEl.addEventListener('click', _issueEndClick);
    if (anchor && typeof restoreFromAnchor === 'function') {
      if (typeof _suppressScrollJumpDetect === 'function') _suppressScrollJumpDetect();
      restoreFromAnchor(contentEl, anchor);
    }
  } else {
    // Pages turned one by one (paginated PDF) don't scroll: look now and then.
    _issueR.poll = setInterval(_issueTrack, 1200);
  }
  _issueEnsureHead();
  contentEl.addEventListener('scroll', _issueScrollLater, {passive: true});
  _issueTrack();
}

function _issueReaderClosed() {
  if (!_issueR) return;
  const contentEl = document.getElementById('reader-content');
  if (contentEl) {
    contentEl.removeEventListener('scroll', _issueScrollLater);
    contentEl.removeEventListener('click', _issueEndClick);
  }
  const head = document.getElementById('iss-runhead');
  if (head) head.remove();
  const bar = document.getElementById('iss-pdf-end');
  if (bar) bar.remove();
  const id = _issueR.bookId;
  clearInterval(_issueR.poll);
  _issueR = null;
  if (_issuePending()[id]) _issueFlush(id);
}

function _issueEnsureHead() {
  let head = document.getElementById('iss-runhead');
  if (!head) {
    head = document.createElement('div');
    head.id = 'iss-runhead';
    const header = document.querySelector('#reader-overlay .reader-header');
    if (header && header.parentNode) header.parentNode.insertBefore(head, header.nextSibling);
    else return;
  }
  _issueRenderHead();
}

function _issueRenderHead() {
  const head = document.getElementById('iss-runhead');
  const b = _issueR && _lastBookListData.find(x => x.id === _issueR.bookId);
  const sum = b && _issueSummary(b);
  if (!head || !sum) return;
  const a = _issueR.cur >= 0 ? sum.arts[_issueR.cur] : null;
  head.innerHTML = `<span class="iss-rh-text">${a && a.r ? `<span class="iss-rh-rubrik">${_issueEsc(a.r)}</span>` : ''}
    <span class="iss-rh-title">${a ? `Artikel ${_issueR.cur + 1} von ${sum.total} · ${_issueEsc(a.t)}` : `${sum.total} Artikel`}</span></span>
    ${_issueSegments(sum, _issueR.cur, 'iss-seg-thin')}`;
  if (window.DioraUI && DioraUI.updateFooter) DioraUI.updateFooter();
}

let _issueScrollTimer = 0;
function _issueScrollLater() {
  clearTimeout(_issueScrollTimer);
  _issueScrollTimer = setTimeout(_issueTrack, 160);
}

// Which article is shown, which ends were reached: an article one was in and whose end
// came into view counts as read.
function _issueTrack() {
  if (!_issueR) return;
  const contentEl = document.getElementById('reader-content');
  if (!contentEl) return;
  let cur = _issueR.cur;
  if (_issueR.pdf) {
    const page = typeof pdfCurrentPage !== 'undefined' && readerSettings.pdfPaginated ? pdfCurrentPage : _issuePdfPage(contentEl);
    let c = -1;
    _issueR.arts.forEach((a, i) => { if (a.p <= page) c = i; });
    const prev = _issueR.cur;
    const last = _issueR.page;
    cur = c;
    // Read on from an article's last page onto the next one: that article was read
    // (a jump — the contents, "Weiter" — reads nothing).
    if (prev >= 0 && cur === prev + 1 && last != null && page === last + 1 &&
        last >= (_issueR.arts[prev].e || last) && _issueR.seen.has(prev)) _issueEnded(prev);
    _issueR.page = page;
  } else {
    const r = contentEl.getBoundingClientRect();
    const top = r.top + 60;
    let c = -1, best = -Infinity;
    _issueR.els.forEach((el, i) => {
      if (!el || !el.getClientRects().length) return;
      const t = el.getBoundingClientRect().top;
      if (t <= top && t > best) { best = t; c = i; }
    });
    if (c >= 0) cur = c;
    contentEl.querySelectorAll('aside.iss-end').forEach(aside => {
      const i = Number(aside.dataset.issueEnd);
      if (!aside.getClientRects().length) return;
      const ar = aside.getBoundingClientRect();
      if (ar.top < r.bottom - 40 && ar.bottom > r.top) {
        if (_issueR.seen.has(i) && !_issueR.shown.has(i)) { _issueR.shown.add(i); _issueEnded(i); }
        else _issueRenderEnd(aside, i);
      }
    });
  }
  if (cur !== _issueR.cur && cur >= 0) {
    _issueR.cur = cur;
    _issueR.seen.add(cur);
    _issueMark(_issueR.bookId, null, null, _issueR.arts[cur].h);
  }
  _issueRenderHead();
}

function _issuePdfPage(contentEl) {
  const top = contentEl.getBoundingClientRect().top + 20;
  const wrappers = contentEl.querySelectorAll('.pdf-page-wrapper');
  for (const w of wrappers) {
    if (w.getBoundingClientRect().bottom > top) return parseInt(w.id.replace('pdf-page-', ''), 10) || 1;
  }
  return 1;
}

// The end of article i reached: read (unless already decided otherwise).
function _issueEnded(i) {
  const b = _lastBookListData.find(x => x.id === _issueR.bookId);
  const st = b && _issueState(b);
  const a = _issueR.arts[i];
  if (st && !st.read[a.h]) _issueMark(_issueR.bookId, a.h, 'r');
  if (_issueR.pdf) _issuePdfEnd(i);
  else {
    const aside = document.querySelector(`#reader-content aside.iss-end[data-issue-end="${i}"]`);
    if (aside) _issueRenderEnd(aside, i);
  }
}

// The next article to read after i, skipping those read or skipped.
function _issueNextAfter(sum, i) {
  for (let k = i + 1; k < sum.arts.length; k++) if (!sum.st.read[sum.arts[k].h]) return k;
  for (let k = 0; k < i; k++) if (!sum.st.read[sum.arts[k].h]) return k;
  return -1;
}

function _issueEndHtml(i) {
  const b = _lastBookListData.find(x => x.id === _issueR.bookId);
  const sum = _issueSummary(b);
  const a = sum.arts[i];
  const s = sum.st.read[a.h];
  const n = _issueNextAfter(sum, i);
  // On a PDF the next article is usually the page one just turned to: no need to offer it.
  const na = n >= 0 && !(_issueR.pdf && n === _issueR.cur) ? sum.arts[n] : null;
  const jumped = n > i + 1 ? `<span class="iss-end-hint">„Weiter“ überspringt ${n - i - 1 === 1 ? 'Artikel ' + (i + 2) : 'die Artikel ' + (i + 2) + '–' + n} (schon gelesen oder übersprungen).</span>` : '';
  return `<span class="iss-end-state"><strong>${s === 'r' ? '✓ ' : ''}„${_issueEsc(a.t)}“${s === 'r' ? ' gelesen' : s === 's' ? ' übersprungen' : ' – Ende'}</strong>
      <span class="lib-meta">${_issueEsc(b.title)}: ${_issueCounts(sum)}${sum.left ? ' · noch ' + _issueMinutes(sum.left) : ''}</span></span>
    ${na ? `<button type="button" class="iss-end-next" data-issue-end-act="next" data-n="${n}">
        <span class="iss-end-kicker">Weiter im Heft · Artikel ${n + 1}${na.r ? ' · ' + _issueEsc(na.r) : ''}${na.m ? ' · ' + na.m + ' min' : ''}</span>
        <span class="iss-end-title">${_issueEsc(na.t)}</span></button>${jumped}`
      : '<span class="lib-meta">Das Heft ist durch.</span>'}
    <span class="iss-end-actions">
      <button type="button" class="iss-btn" data-issue-end-act="toc">Zum Inhalt</button>
      ${na && n === i + 1 ? `<button type="button" class="iss-btn" data-issue-end-act="skip" data-n="${n}">Artikel ${n + 1} überspringen</button>` : ''}
      ${s === 'r' ? `<button type="button" class="iss-btn" data-issue-end-act="unread" data-i="${i}">Doch nicht gelesen</button>` : ''}
    </span>`;
}

function _issueRenderEnd(aside, i) {
  const html = _issueEndHtml(i);
  if (aside.innerHTML !== html) aside.innerHTML = html;
}

function _issuePdfEnd(i) {
  let bar = document.getElementById('iss-pdf-end');
  if (!bar) {
    bar = document.createElement('aside');
    bar.id = 'iss-pdf-end';
    bar.className = 'iss-end iss-end-float';
    bar.addEventListener('click', _issueEndClick);
    document.body.appendChild(bar);
  }
  bar.innerHTML = `<button type="button" class="dfo-x iss-end-x" data-issue-end-act="close" aria-label="Schließen">✕</button>` + _issueEndHtml(i);
  clearTimeout(bar.timer);
  bar.timer = setTimeout(() => bar.remove(), 12000);
}

function _issueEndClick(e) {
  const t = e.target.closest('[data-issue-end-act]');
  if (!t || !_issueR) return;
  e.stopPropagation();
  e.preventDefault();
  const id = _issueR.bookId;
  const act = t.dataset.issueEndAct;
  const bar = document.getElementById('iss-pdf-end');
  if (act === 'close') { if (bar) bar.remove(); return; }
  if (act === 'next') {
    if (bar) bar.remove();
    const n = Number(t.dataset.n);
    _issueR.seen.add(n);
    _issueJump(_issueR.arts[n]);
  } else if (act === 'toc') {
    if (bar) bar.remove();
    closeReader();
    if (window.DioraNav) DioraNav.go('magazines');
    _issueOpen(id);
  } else if (act === 'skip') {
    _issueMark(id, _issueR.arts[Number(t.dataset.n)].h, 's');
  } else if (act === 'unread') {
    _issueMark(id, _issueR.arts[Number(t.dataset.i)].h, '');
  }
  setTimeout(() => {
    if (!_issueR) return;
    document.querySelectorAll('aside.iss-end[data-issue-end]').forEach(a => _issueRenderEnd(a, Number(a.dataset.issueEnd)));
    if (bar && bar.isConnected) bar.remove();
    _issueRenderHead();
  }, 0);
}

// ---- styles ---------------------------------------------------------------------------------------

(function () {
  const style = document.createElement('style');
  style.textContent = [
    '.iss-seg { display: flex; gap: 2px; height: 8px; }',
    '.iss-seg > span { flex: 1; min-width: 2px; border-radius: 2px; background: var(--border, #2a2a2a); }',
    '.iss-seg > .iss-s-read { background: var(--fg, #eee); }',
    '.iss-seg > .iss-s-skip { background: repeating-linear-gradient(135deg, var(--muted, #9a9a9a) 0 2px, var(--border, #2a2a2a) 2px 4px); }',
    '.iss-seg > .iss-s-at { background: linear-gradient(90deg, var(--accent, #e63946) 45%, var(--border, #2a2a2a) 45%); }',
    '.iss-seg > .iss-s-now { background: var(--accent, #e63946); flex: 2.5; }',
    '.iss-seg-thin { height: 5px; }',
    '#book-list .lib-card .iss-seg, #book-list .lib-row .iss-seg, #book-list .lib-continue .iss-seg { margin-top: 4px; }',
    '#book-list .iss-top { display: flex; align-items: center; justify-content: space-between; margin: 0 0 8px; }',
    '#book-list .iss-back { min-height: 44px; padding: 0 6px; border: none; background: none; color: inherit; font: inherit; font-size: 15px; cursor: pointer; }',
    '#book-list .iss-top .iss-more { position: static; opacity: 1; border: none; background: none; color: inherit; font-size: 20px; width: 44px; height: 44px; }',
    '#book-list.iss-open .lib-head, #book-list.iss-open .lib-chips { display: none; }',
    '#book-list .iss-head { display: flex; gap: 14px; margin: 0 0 12px; }',
    '#book-list .iss-cover { flex: none; width: 96px; height: 144px; border-radius: 4px; object-fit: cover; }',
    '#book-list .iss-head-text { display: flex; flex-direction: column; gap: 4px; min-width: 0; }',
    '#book-list .iss-title { font-size: 21px; font-weight: 700; line-height: 1.25; }',
    '#book-list .iss-sum { display: flex; flex-direction: column; gap: 8px; margin: 0 0 8px; }',
    '#book-list .iss-actions { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }',
    '.iss-go { min-height: 44px; padding: 0 18px; border: none; border-radius: 22px; background: var(--accent, #e63946); color: var(--on-accent, #fff); font: inherit; font-size: 14px; font-weight: 600; cursor: pointer; }',
    '.iss-btn { min-height: 40px; padding: 0 14px; border: 1px solid var(--border-strong, #444); border-radius: 20px; background: none; color: inherit; font: inherit; font-size: 14px; cursor: pointer; }',
    '#book-list .iss-rubrik { margin: 18px 0 2px; font-size: 12px; font-weight: 400; letter-spacing: .08em; text-transform: uppercase; color: var(--muted, #9a9a9a); }',
    '#book-list .iss-row { display: flex; align-items: center; border-bottom: 1px solid var(--border, #2a2a2a); }',
    '#book-list .iss-row.iss-next { background: var(--card, #0b0b0b); border: 1px solid var(--accent, #e63946); border-radius: 8px; }',
    '#book-list .iss-mark { flex: none; width: 40px; min-height: 48px; border: none; background: none; color: var(--muted, #9a9a9a); font: inherit; font-size: 16px; cursor: pointer; }',
    '#book-list .iss-read .iss-mark { color: var(--fg, #eee); }',
    '#book-list .iss-next .iss-mark { color: var(--accent, #e63946); }',
    '#book-list .iss-art { flex: 1; min-width: 0; display: flex; align-items: center; gap: 8px; padding: 9px 8px 9px 0; border: none; background: none; color: inherit; font: inherit; text-align: left; cursor: pointer; }',
    '#book-list .iss-n { flex: none; width: 22px; font-size: 12px; color: var(--muted, #9a9a9a); text-align: right; }',
    '#book-list .iss-art-text { flex: 1; min-width: 0; display: flex; flex-direction: column; gap: 2px; }',
    '#book-list .iss-art-title { font-size: 15px; line-height: 1.3; }',
    '#book-list .iss-next .iss-art-title { font-weight: 700; }',
    '#book-list .iss-read .iss-art-title { color: var(--muted, #9a9a9a); }',
    '#book-list .iss-skip .iss-art-title { color: var(--muted, #9a9a9a); text-decoration: line-through; }',
    '#book-list .iss-teaser { font-size: 12px; color: var(--muted, #9a9a9a); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }',
    '#book-list .iss-min { flex: none; font-size: 12px; color: var(--muted, #9a9a9a); }',
    '#iss-runhead { display: flex; flex-direction: column; gap: 4px; padding: 4px 16px 6px; border-bottom: 1px solid var(--border, #2a2a2a); background: var(--bg, #000); }',
    'body.reader-immersive #iss-runhead { display: none; }',
    '.iss-rh-text { display: flex; flex-direction: column; min-width: 0; }',
    '.iss-rh-rubrik { font-size: 11px; letter-spacing: .08em; text-transform: uppercase; color: var(--muted, #9a9a9a); }',
    '.iss-rh-title { font-size: 13px; font-weight: 600; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }',
    'aside.iss-end { display: flex; flex-direction: column; gap: 12px; margin: 2.5em 0; padding: 16px; border: 1px solid currentColor; border-radius: 12px; font-family: system-ui, sans-serif; font-size: 15px; line-height: 1.35; text-indent: 0; }',
    '.iss-end-state { display: flex; flex-direction: column; gap: 3px; }',
    '.iss-end-next { display: flex; flex-direction: column; gap: 4px; padding: 12px 14px; border: none; border-radius: 10px; background: var(--accent, #e63946); color: var(--on-accent, #fff); font: inherit; text-align: left; cursor: pointer; }',
    '.iss-end-kicker { font-size: 12px; opacity: .9; }',
    '.iss-end-title { font-size: 17px; font-weight: 600; }',
    '.iss-end-hint { font-size: 12px; opacity: .75; }',
    '.iss-end-actions { display: flex; flex-wrap: wrap; gap: 8px; }',
    '.iss-end-float { position: fixed; left: 12px; right: 12px; bottom: 16px; z-index: 960; margin: 0; background: var(--panel, #161616); color: var(--fg, #eee); box-shadow: 0 4px 18px rgba(0,0,0,.4); }',
    '.iss-end-x { position: absolute; right: 6px; top: 6px; }',
    'body.eink .iss-seg > span { background: #fff; outline: 1px solid #000; outline-offset: -1px; border-radius: 0; }',
    'body.eink .iss-seg > .iss-s-read { background: #000; }',
    'body.eink .iss-seg > .iss-s-skip { background: repeating-linear-gradient(135deg, #000 0 1px, #fff 1px 4px); }',
    'body.eink .iss-seg > .iss-s-at, body.eink .iss-seg > .iss-s-now { background: linear-gradient(90deg, #000 50%, #fff 50%); }',
    'body.eink .iss-go, body.eink .iss-end-next { background: #000; color: #fff; }',
    'body.eink #book-list .iss-row.iss-next { background: #fff; border: 2px solid #000; }',
    'body.eink #book-list .iss-row, body.eink #iss-runhead { border-color: #000; }',
    'body.eink .iss-end-float { background: #fff; color: #000; border: 2px solid #000; box-shadow: none; }',
  ].join('\n');
  document.head.appendChild(style);
})();