// Light previews of office files for the file manager, with no libraries:
// docx, xlsx and ods are zip archives of XML, opened with the browser's own
// DecompressionStream; csv and tsv are parsed here; an old binary .doc only
// gives up its text. Each turns into plain HTML the page styles itself.
(function () {
  'use strict';

  const esc = s => String(s).replace(/[&<>"]/g, c => ({'&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;'}[c]));

  // ---------- zip ----------
  // Reads the central directory; a file is inflated only when asked for.
  function openZip(buf) {
    const b = buf instanceof Uint8Array ? buf : new Uint8Array(buf);
    const dv = new DataView(b.buffer, b.byteOffset, b.byteLength);
    let eocd = -1;
    for (let i = b.length - 22; i >= Math.max(0, b.length - 65557); i--) {
      if (dv.getUint32(i, true) === 0x06054b50) { eocd = i; break; }
    }
    if (eocd < 0) throw new Error('не zip-архив');
    const count = dv.getUint16(eocd + 10, true);
    let p = dv.getUint32(eocd + 16, true);
    const files = new Map();
    const dec = new TextDecoder();
    for (let n = 0; n < count && dv.getUint32(p, true) === 0x02014b50; n++) {
      const method = dv.getUint16(p + 10, true), size = dv.getUint32(p + 20, true);
      const nameLen = dv.getUint16(p + 28, true), extra = dv.getUint16(p + 30, true), comment = dv.getUint16(p + 32, true);
      const local = dv.getUint32(p + 42, true);
      files.set(dec.decode(b.subarray(p + 46, p + 46 + nameLen)), {method, size, local});
      p += 46 + nameLen + extra + comment;
    }
    async function bytes(name) {
      const f = files.get(name);
      if (!f) return null;
      const start = f.local + 30 + dv.getUint16(f.local + 26, true) + dv.getUint16(f.local + 28, true);
      const raw = b.subarray(start, start + f.size);
      if (f.method === 0) return raw;
      if (f.method !== 8) throw new Error('сжатие zip, которое браузер не знает');
      const out = new Blob([raw]).stream().pipeThrough(new DecompressionStream('deflate-raw'));
      return new Uint8Array(await new Response(out).arrayBuffer());
    }
    async function xml(name) {
      const raw = await bytes(name);
      return raw ? new DOMParser().parseFromString(new TextDecoder().decode(raw), 'application/xml') : null;
    }
    return {files, bytes, xml};
  }

  // Children of an element by local name, whatever the namespace prefix.
  const kids = (el, name) => el ? Array.from(el.children).filter(c => c.localName === name) : [];
  const kid = (el, name) => kids(el, name)[0] || null;
  const attr = (el, name) => {
    if (!el) return null;
    for (const a of el.attributes) if (a.localName === name) return a.value;
    return null;
  };

  // ---------- docx ----------
  async function docx(buf) {
    const z = openZip(buf);
    const doc = await z.xml('word/document.xml');
    if (!doc) throw new Error('в архиве нет word/document.xml');
    // Style ids to names, to know headings whatever the language of Word.
    const styles = {};
    const st = await z.xml('word/styles.xml');
    if (st) for (const s of st.getElementsByTagNameNS('*', 'style')) {
      styles[attr(s, 'styleId')] = (attr(kid(s, 'name'), 'val') || '').toLowerCase();
    }
    const body = doc.getElementsByTagNameNS('*', 'body')[0];
    return '<div class="dv-doc">' + blocks(body, styles) + '</div>';
  }
  function blocks(el, styles) {
    let html = '', list = false;
    for (const c of el ? el.children : []) {
      if (c.localName === 'p') {
        const pPr = kid(c, 'pPr');
        const isList = !!kid(pPr, 'numPr');
        if (isList && !list) { html += '<ul>'; list = true; }
        if (!isList && list) { html += '</ul>'; list = false; }
        html += para(c, pPr, styles, isList);
      } else {
        if (list) { html += '</ul>'; list = false; }
        if (c.localName === 'tbl') html += table(c, styles);
        else if (c.localName === 'sdt') html += blocks(kid(c, 'sdtContent'), styles);
      }
    }
    return html + (list ? '</ul>' : '');
  }
  function para(p, pPr, styles, isList) {
    const name = styles[attr(kid(pPr, 'pStyle'), 'val')] || '';
    const h = /^heading (\d)/.exec(name);
    const tag = isList ? 'li' : name === 'title' ? 'h1' : h ? 'h' + Math.min(6, +h[1] + 1) : 'p';
    const jc = attr(kid(pPr, 'jc'), 'val');
    const align = jc === 'center' ? 'center' : (jc === 'right' || jc === 'end') ? 'right' : (jc === 'both' ? 'justify' : '');
    const inner = runs(p);
    return '<' + tag + (align ? ' style="text-align:' + align + '"' : '') + '>' + (inner || '&nbsp;') + '</' + tag + '>';
  }
  function runs(el) {
    let html = '';
    for (const c of el.children) {
      if (c.localName === 'r') html += run(c);
      else if (c.localName === 'hyperlink' || c.localName === 'smartTag' || c.localName === 'ins' || c.localName === 'sdt' || c.localName === 'sdtContent' || c.localName === 'fldSimple') {
        const inner = runs(c);
        html += c.localName === 'hyperlink' ? '<u class="dv-link">' + inner + '</u>' : inner;
      }
    }
    return html;
  }
  function run(r) {
    const pr = kid(r, 'rPr');
    const on = n => { const e = kid(pr, n); return !!e && attr(e, 'val') !== '0' && attr(e, 'val') !== 'false'; };
    let t = '';
    for (const c of r.children) {
      if (c.localName === 't') t += esc(c.textContent);
      else if (c.localName === 'tab') t += '&emsp;';
      else if (c.localName === 'br' || c.localName === 'cr') t += '<br>';
    }
    if (!t) return '';
    if (on('b')) t = '<b>' + t + '</b>';
    if (on('i')) t = '<i>' + t + '</i>';
    if (kid(pr, 'u') && attr(kid(pr, 'u'), 'val') !== 'none') t = '<u>' + t + '</u>';
    if (on('strike')) t = '<s>' + t + '</s>';
    // A size set on the run itself, as many documents do instead of styles.
    const sz = +attr(kid(pr, 'sz'), 'val');
    if (sz && sz !== 24) t = '<span style="font-size:' + Math.max(9, Math.min(36, sz / 2)) + 'pt">' + t + '</span>';
    const va = attr(kid(pr, 'vertAlign'), 'val');
    if (va === 'superscript') t = '<sup>' + t + '</sup>';
    else if (va === 'subscript') t = '<sub>' + t + '</sub>';
    return t;
  }
  function table(tbl, styles) {
    let html = '<div class="dv-scroll"><table class="dv-table">';
    for (const tr of kids(tbl, 'tr')) {
      html += '<tr>';
      for (const tc of kids(tr, 'tc')) {
        const span = attr(kid(kid(tc, 'tcPr'), 'gridSpan'), 'val');
        html += '<td' + (span > 1 ? ' colspan="' + span + '"' : '') + '>' + blocks(tc, styles) + '</td>';
      }
      html += '</tr>';
    }
    return html + '</table></div>';
  }

  // ---------- tables: one grid per sheet ----------
  const MAX_ROWS = 2000, MAX_COLS = 60;
  function colName(i) { let s = ''; for (i++; i > 0; i = Math.floor((i - 1) / 26)) s = String.fromCharCode(65 + (i - 1) % 26) + s; return s; }
  function grid(rows) {
    let cols = 0;
    for (const r of rows) cols = Math.max(cols, r.length);
    cols = Math.min(cols, MAX_COLS);
    const cut = rows.length > MAX_ROWS || rows.some(r => r.length > MAX_COLS);
    let html = '<div class="dv-scroll dv-grid"><table class="dv-sheet"><thead><tr><th></th>';
    for (let c = 0; c < cols; c++) html += '<th>' + colName(c) + '</th>';
    html += '</tr></thead><tbody>';
    rows.slice(0, MAX_ROWS).forEach((r, i) => {
      html += '<tr><th>' + (i + 1) + '</th>';
      for (let c = 0; c < cols; c++) {
        const v = r[c] == null ? '' : r[c];
        html += '<td' + (typeof v === 'number' ? ' class="n"' : '') + '>' + esc(v) + '</td>';
      }
      html += '</tr>';
    });
    html += '</tbody></table></div>';
    return {html, cut};
  }
  // Several sheets: tabs over the grid.
  function sheets(list) {
    if (!list.length) return '<p class="dv-note">в книге нет листов</p>';
    let html = '';
    if (list.length > 1) {
      html += '<div class="dv-tabs">' + list.map((s, i) => '<button type="button" data-sheet="' + i + '"' + (i ? '' : ' class="on"') + '>' + esc(s.name) + '</button>').join('') + '</div>';
    }
    list.forEach((s, i) => {
      const g = grid(s.rows);
      html += '<div class="dv-pane" data-pane="' + i + '"' + (i ? ' hidden' : '') + '>' + g.html +
        (g.cut ? '<p class="dv-note">показаны первые ' + MAX_ROWS + ' строк и ' + MAX_COLS + ' столбцов</p>' : '') + '</div>';
    });
    return html;
  }
  function bindTabs(root) {
    root.querySelectorAll('[data-sheet]').forEach(b => b.onclick = () => {
      root.querySelectorAll('[data-sheet]').forEach(x => x.classList.toggle('on', x === b));
      root.querySelectorAll('[data-pane]').forEach(p => p.hidden = p.dataset.pane !== b.dataset.sheet);
    });
  }

  // ---------- xlsx ----------
  async function xlsx(buf) {
    const z = openZip(buf);
    const wb = await z.xml('xl/workbook.xml');
    if (!wb) throw new Error('в архиве нет xl/workbook.xml');
    const rels = {};
    const rx = await z.xml('xl/_rels/workbook.xml.rels');
    if (rx) for (const r of rx.getElementsByTagNameNS('*', 'Relationship')) rels[r.getAttribute('Id')] = r.getAttribute('Target');
    const shared = [];
    const ss = await z.xml('xl/sharedStrings.xml');
    if (ss) for (const si of ss.getElementsByTagNameNS('*', 'si')) {
      shared.push(Array.from(si.getElementsByTagNameNS('*', 't')).filter(t => t.parentElement.localName !== 'rPh').map(t => t.textContent).join(''));
    }
    const list = [];
    for (const s of wb.getElementsByTagNameNS('*', 'sheet')) {
      let target = rels[attr(s, 'id')] || '';
      target = target.startsWith('/') ? target.slice(1) : 'xl/' + target.replace(/^\.\//, '');
      const doc = await z.xml(target);
      list.push({name: s.getAttribute('name') || '?', rows: doc ? xlsxRows(doc, shared) : []});
    }
    return sheets(list);
  }
  function xlsxRows(doc, shared) {
    const rows = [];
    for (const row of doc.getElementsByTagNameNS('*', 'row')) {
      const ri = (+row.getAttribute('r') || rows.length + 1) - 1;
      if (ri >= MAX_ROWS) break;
      const out = rows[ri] = rows[ri] || [];
      let next = 0;
      for (const c of kids(row, 'c')) {
        const ref = /^([A-Z]+)/.exec(c.getAttribute('r') || '');
        let ci = next;
        if (ref) { ci = 0; for (const ch of ref[1]) ci = ci * 26 + ch.charCodeAt(0) - 64; ci--; }
        next = ci + 1;
        if (ci >= MAX_COLS + 1) continue;
        const t = c.getAttribute('t'), v = kid(c, 'v');
        let val = v ? v.textContent : '';
        if (t === 's') val = shared[+val] || '';
        else if (t === 'inlineStr') val = Array.from(c.getElementsByTagNameNS('*', 't')).map(x => x.textContent).join('');
        else if (t === 'b') val = val === '1' ? 'TRUE' : 'FALSE';
        else if (t !== 'str' && t !== 'e' && val !== '' && !isNaN(val)) val = +val;
        out[ci] = val;
      }
    }
    for (let i = 0; i < rows.length; i++) rows[i] = rows[i] || [];
    return rows;
  }

  // ---------- ods / odt ----------
  async function ods(buf) {
    const z = openZip(buf);
    const doc = await z.xml('content.xml');
    if (!doc) throw new Error('в архиве нет content.xml');
    const list = [];
    for (const t of doc.getElementsByTagNameNS('*', 'table')) {
      if (t.parentElement && t.parentElement.localName === 'table-cell') continue;
      const rows = [];
      for (const r of t.getElementsByTagNameNS('*', 'table-row')) {
        const cells = [];
        for (const c of r.children) {
          if (c.localName !== 'table-cell' && c.localName !== 'covered-table-cell') continue;
          const rep = Math.min(+attr(c, 'number-columns-repeated') || 1, MAX_COLS + 1 - cells.length);
          const num = attr(c, 'value');
          const text = Array.from(c.getElementsByTagNameNS('*', 'p')).map(p => p.textContent).join('\n');
          const val = attr(c, 'value-type') === 'float' && num != null ? +num : text;
          for (let i = 0; i < rep; i++) cells.push(val);
          if (cells.length > MAX_COLS) break;
        }
        while (cells.length && cells[cells.length - 1] === '') cells.pop();
        const rep = Math.min(+attr(r, 'number-rows-repeated') || 1, MAX_ROWS + 1 - rows.length);
        for (let i = 0; i < rep; i++) rows.push(cells);
        if (rows.length > MAX_ROWS) break;
      }
      while (rows.length && !rows[rows.length - 1].length) rows.pop();
      list.push({name: attr(t, 'name') || '?', rows});
    }
    return sheets(list);
  }
  async function odt(buf) {
    const z = openZip(buf);
    const doc = await z.xml('content.xml');
    const body = doc && doc.getElementsByTagNameNS('*', 'text')[0];
    if (!body) throw new Error('в архиве нет текста');
    // Runs of spaces, tabs and breaks are elements of their own in ODF.
    const inline = el => {
      let html = '';
      for (const n of el.childNodes) {
        if (n.nodeType === 3) html += esc(n.nodeValue);
        else if (n.localName === 's') html += ' '.repeat(+attr(n, 'c') || 1);
        else if (n.localName === 'tab') html += '&emsp;';
        else if (n.localName === 'line-break') html += '<br>';
        else if (n.nodeType === 1) html += inline(n);
      }
      return html;
    };
    const walk = el => {
      let html = '';
      for (const c of el.children) {
        if (c.localName === 'h') { const l = Math.min(6, (+attr(c, 'outline-level') || 1) + 1); html += '<h' + l + '>' + inline(c) + '</h' + l + '>'; }
        else if (c.localName === 'p') html += '<p>' + (inline(c) || '&nbsp;') + '</p>';
        else if (c.localName === 'list') html += '<ul>' + kids(c, 'list-item').map(li => '<li>' + walk(li) + '</li>').join('') + '</ul>';
        else if (c.localName === 'table') html += '<div class="dv-scroll"><table class="dv-table">' + Array.from(c.getElementsByTagNameNS('*', 'table-row')).map(r =>
          '<tr>' + kids(r, 'table-cell').map(td => '<td>' + walk(td) + '</td>').join('') + '</tr>').join('') + '</table></div>';
        else if (c.localName === 'section') html += walk(c);
      }
      return html;
    };
    return '<div class="dv-doc">' + walk(body) + '</div>';
  }

  // ---------- csv / tsv ----------
  function csv(text, tab) {
    const first = text.slice(0, text.indexOf('\n') >>> 0 || text.length);
    const sep = tab ? '\t' : (first.split(';').length > first.split(',').length ? ';' : ',');
    const rows = [];
    let row = [], f = '', q = false;
    for (let i = 0; i < text.length; i++) {
      const c = text[i];
      if (q) {
        if (c === '"') { if (text[i + 1] === '"') { f += '"'; i++; } else q = false; }
        else f += c;
      } else if (c === '"' && f === '') q = true;
      else if (c === sep) { row.push(f); f = ''; }
      else if (c === '\n' || c === '\r') {
        if (c === '\r' && text[i + 1] === '\n') i++;
        row.push(f); f = ''; rows.push(row); row = [];
        if (rows.length > MAX_ROWS) break;
      } else f += c;
    }
    if (f !== '' || row.length) { row.push(f); rows.push(row); }
    return sheets([{name: '', rows: rows.map(r => r.map(v => v !== '' && !isNaN(v) && /^-?[\d.]+$/.test(v.trim()) ? +v : v))}]);
  }

  // ---------- old .doc ----------
  // Word 97-2003 is a binary format; without a full parser all that can be
  // shown is the text, picked out of the document's WordDocument stream as
  // the runs that read as words.
  function cfbStream(b, want) {
    const dv = new DataView(b.buffer, b.byteOffset, b.byteLength);
    if (dv.getUint32(0, true) !== 0xE011CFD0) return null;
    const ss = 1 << dv.getUint16(0x1E, true);
    const sector = n => 512 + n * ss;
    const fat = [];
    const addFat = n => { const o = sector(n); for (let i = 0; i < ss / 4; i++) fat.push(dv.getUint32(o + i * 4, true)); };
    for (let i = 0; i < 109; i++) { const n = dv.getUint32(0x4C + i * 4, true); if (n < 0xFFFFFFFA) addFat(n); }
    for (let n = dv.getUint32(0x44, true), k = 0; n < 0xFFFFFFFA && k < 1000; k++) {
      const o = sector(n);
      for (let i = 0; i < ss / 4 - 1; i++) { const m = dv.getUint32(o + i * 4, true); if (m < 0xFFFFFFFA) addFat(m); }
      n = dv.getUint32(o + ss - 4, true);
    }
    const chain = (start, size) => {
      const out = new Uint8Array(size);
      let n = start, at = 0;
      for (let guard = 0; n < 0xFFFFFFFA && at < size && guard < 1e6; guard++) {
        const o = sector(n), len = Math.min(ss, size - at);
        if (o + len > b.length) break;
        out.set(b.subarray(o, o + len), at);
        at += len;
        n = fat[n];
      }
      return out.subarray(0, at);
    };
    const dirStart = dv.getUint32(0x30, true);
    const dir = chain(dirStart, ss * 64);
    const dd = new DataView(dir.buffer, dir.byteOffset, dir.byteLength);
    for (let o = 0; o + 128 <= dir.length; o += 128) {
      const nameLen = dd.getUint16(o + 0x40, true);
      let name = '';
      for (let i = 0; i + 2 < nameLen; i += 2) name += String.fromCharCode(dd.getUint16(o + i, true));
      if (name === want && dd.getUint8(o + 0x42) === 2) return chain(dd.getUint32(o + 0x74, true), dd.getUint32(o + 0x78, true));
    }
    return null;
  }
  function doc(buf) {
    const all = new Uint8Array(buf);
    const b = cfbStream(all, 'WordDocument') || all;
    const ok = c => c === 9 || c === 10 || c === 13 || (c >= 32 && c < 127) || (c >= 0xA0 && c <= 0x24F) || (c >= 0x400 && c <= 0x4FF) || (c >= 0x2010 && c <= 0x2026) || c === 0x2116;
    const pieces = [];
    let cur = '';
    const flush = min => {
      const letters = (cur.match(/[A-Za-zА-Яа-яЁё0-9]/g) || []).length;
      if (cur.trim().length >= min && letters >= cur.trim().length * 0.5) pieces.push(cur);
      cur = '';
    };
    for (let i = 0; i + 1 < b.length; i += 2) {
      const c = b[i] | (b[i + 1] << 8);
      if (ok(c)) cur += String.fromCharCode(c); else flush(3);
    }
    flush(4);
    let text = pieces.join('\n');
    if (text.length < 40) { // a document that keeps its text 8-bit
      const p8 = [];
      for (let i = 0; i < b.length; i++) {
        const c = b[i];
        if (c === 9 || c === 10 || c === 13 || (c >= 32 && c < 127)) cur += String.fromCharCode(c);
        else { if (cur.trim().length >= 8 && (cur.match(/[A-Za-z]/g) || []).length >= cur.length * 0.5) p8.push(cur); cur = ''; }
      }
      text = p8.join('\n');
    }
    if (!text.trim()) throw new Error('текст не нашёлся');
    return '<p class="dv-note">старый формат .doc: показан только текст, без оформления</p><div class="dv-doc">' +
      text.split(/\r\n|\r|\n|\x07/).filter(l => l.trim()).map(l => '<p>' + esc(l) + '</p>').join('') + '</div>';
  }

  window.DocView = {docx, xlsx, ods, odt, csv, doc, bindTabs};
})();