Un mismo texto en cuatro estilos de cita

// ═══ Postext Cookbook · Nº 093 · One text in four citation styles ════════════════
// https://postext.dev/en/cookbook/one-text-four-citation-styles
// Code: MIT · Text: original (CC BY 4.0) · Pictures: none
// Fonts: Source Serif 4, Source Sans 3 (SIL OFL 1.1) · Needs postext ≥ 1.12.0
import {
  buildDocument, renderPageToCanvas, clearMeasurementCache, registerCitationEngine,
} from 'https://esm.sh/postext';
import { createCiteprocEngine, STYLES, LOCALES } from 'https://esm.sh/postext-citeproc';

const LANG = 'es'; // @lang: the language of the sample document ('en' | 'es')
const RECIPE = 'one-text-four-citation-styles';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
// #region palette: one ink, and a colour for each style's band
const palette = {
  ink: '#1d1b19', muted: '#66605a', rule: '#cfc8bf', paper: '#ffffff',
  apa: '#2f5d8a', chicago: '#8c2f2b', ieee: '#24476b', iso: '#3c6b4f', // the four bands
};
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
// Each document points main-color at its own band, so any default left follows it.
const colorPalette = (band) => Object.entries({ ...palette, 'main-color': palette[band] })
  .map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } }));
// #endregion
const [SERIF, SANS] = ['Source Serif 4', 'Source Sans 3'];
const LEAD = 14; // pt

// #region answer: the style is one setting; everything else stays the same
// Citations are written once, Pandoc's way: [@key], [@a; @b], [-@key] without the author,
// @key [p. 17] inside the sentence. citeproc-js writes them, and the list, in the style named.
registerCitationEngine(createCiteprocEngine({ styles: STYLES, locales: LOCALES }));
const SHOWN = [ // the same text, built once per entry
  { style: 'apa', band: 'apa', name: 'APA 7', system: t({ en: 'author-date', es: 'autor-año' }) },
  { style: 'chicago-author-date', band: 'chicago', name: 'Chicago',
    system: t({ en: 'author-date', es: 'autor-año' }) },
  { style: 'ieee', band: 'ieee', name: 'IEEE', system: t({ en: 'numbered', es: 'numérico' }) },
  { style: t({ en: 'iso690-author-date-en', es: 'iso690-author-date-es' }), band: 'iso',
    name: 'ISO 690', system: t({ en: 'author-date', es: 'autor-año' }) },
];
const citations = (style) => ({
  style, // 'apa' → '(Warde, 1955)'; 'ieee' → '[1]'; the list is sorted and set to match
  link: true,
  bibliography: { fontSize: em(0.85), lineHeight: pt(11.2), hangingIndent: mm(6),
    entrySpacing: pt(2), labelWidth: mm(6), doi: 'hide' },
});
// #endregion

// #region band: the style's name, large, in a band of its colour
const opener = (s, i) => ({
  enabled: true,
  minHeight: mm(41), // from the top margin to under the title, 63 mm from the trim
  slot: { elements: [
    { kind: 'box', id: 'band', style: { backgroundColor: col(s.band) },
      placement: { anchor: { to: 'page', edge: 'top-left' },
        size: { width: 'fill', height: mm(44) } } },
    { kind: 'text', id: 'kicker', content: `${t({ en: 'Citation style', es: 'Estilo de cita' })}`
      + ` · ${i + 1} / ${SHOWN.length} · ${s.system}`, fontFamily: SANS, fontSize: pt(8),
    fontWeight: 600, letterSpacing: pt(1.4), textTransform: 'uppercase', color: col('paper'),
    align: 'left',
    placement: { anchor: { to: 'page', edge: 'top-left' }, offset: { x: mm(18), y: mm(12) } } },
    { kind: 'text', id: 'name', content: s.name, fontFamily: SERIF, fontSize: pt(54),
      fontWeight: 600, lineHeight: 1, color: col('paper'), align: 'left', overflow: 'clip',
      placement: { anchor: { to: '#kicker', edge: 'below' }, offset: { x: mm(0), y: mm(5) },
        size: { width: mm(119), height: 'auto' } } },
    { kind: 'text', id: 'title', content: '{titleText}', fontFamily: SERIF, fontSize: pt(20),
      fontWeight: 600, lineHeight: 1.15, color: col('ink'), align: 'left', overflow: 'wrap',
      placement: { anchor: { to: 'page', edge: 'top-left' }, offset: { x: mm(18), y: mm(52) },
        size: { width: mm(119), height: 'auto' } } },
  ] },
});
// #endregion

let at = 0; // the entry of SHOWN being built
const config = () => ({ // a factory: the engine caches resolved configs per object
  locale: t({ en: 'en-us', es: 'es' }),
  colorPalette: colorPalette(SHOWN[at].band),
  citations: citations(SHOWN[at].style),
  page: { sizePreset: 'custom', width: mm(155), height: mm(235), dpi: 150,
    margins: { top: mm(22), bottom: mm(20), left: mm(18), right: mm(18) } },
  layout: { layoutType: 'single' },
  bodyText: {
    fontFamily: SERIF, fontSize: pt(10), lineHeight: pt(LEAD), color: col('ink'),
    boldColor: col('ink'), italicColor: col('ink'), referenceColor: col('ink'),
    textAlign: 'justify', firstLineIndent: mm(4.5), indentAfterHeading: false,
    hyphenation: { enabled: true }, optimalLineBreaking: true,
    avoidWidows: true, avoidOrphans: true, avoidRunts: true,
  },
  headings: { fontFamily: SERIF, color: col('ink'), levels: [
    { level: 1, breakBefore: { enabled: true, parity: 'any' }, // gotcha: headings-drop-h1-break
      advancedDesign: opener(SHOWN[at], at) },
  ] },
  header: { elements: [] },
  footer: { elements: [
    { kind: 'text', id: 'colophon', content: t({
      en: 'Set in Source Serif 4 and Source Sans 3 (SIL OFL) · Text: original, CC BY 4.0',
      es: 'Compuesto en Source Serif 4 y Source Sans 3 (SIL OFL) · Texto: original, CC BY 4.0' }),
    fontFamily: SANS, fontSize: pt(7), color: col('muted'),
    placement: { anchor: { to: 'page', edge: 'bottom-left' }, offset: { x: mm(18), y: mm(-11) } } },
  ] },
});

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Muestra en Markdown · 33 líneas · content.es.md
title: "La página invisible"
author: "Recetario de Postext"
---

# La página que no se ve

La buena tipografía está hecha para pasar inadvertida. @warde1955 lo dijo con una imagen que los impresores aún citan: la página debe ser una copa de cristal, un vidrio transparente que deja ver el vino, y no un cáliz de oro que lo esconde. Tschichold defendió algo parecido sobre el libro, que en sus ensayos sirve a su lector antes que a su diseñador [-@tschichold1991]. El argumento es tan moral como práctico, y @bringhurst2004 [pág. 17] lo convierte en el primer principio de su manual: la tipografía existe para honrar el contenido.

La mitad práctica tiene pruebas a su favor. Los ensayos de legibilidad midieron cómo cambian la velocidad de lectura el tamaño de la letra, la longitud de la línea y el interlineado, y el estudio de los movimientos oculares explicó después por qué importa una textura uniforme: el ojo capta unas pocas letras en cada fijación y planea el salto siguiente según la forma de la línea que tiene delante [@tinker1963; @rayner1998]. Una página que llama la atención sobre sí misma le cuesta algo al lector, por poco que sea. Nada de esto reduce el diseño a una cuestión de gusto. El lector que nunca repara en una página bien hecha repara enseguida en una mal hecha, y la gramática de una buena puede enseñarse [@lupton2010].

:::references{format=bibtex}
@book{warde1955,
  author = {Warde, Beatrice}, title = {The Crystal Goblet: Sixteen Essays on Typography},
  editor = {Jacob, Henry}, publisher = {Sylvan Press}, address = {London}, year = 1955}
@book{tschichold1991,
  author = {Tschichold, Jan}, title = {The Form of the Book: Essays on the Morality of Good Design},
  translator = {Hadeler, Hajo}, publisher = {Hartley \& Marks}, address = {Point Roberts, WA},
  year = 1991}
@book{bringhurst2004,
  author = {Bringhurst, Robert}, title = {The Elements of Typographic Style}, edition = {3},
  publisher = {Hartley \& Marks}, address = {Point Roberts, WA}, year = 2004}
@book{tinker1963,
  author = {Tinker, Miles A.}, title = {Legibility of Print},
  publisher = {Iowa State University Press}, address = {Ames, IA}, year = 1963}
@article{rayner1998,
  author = {Rayner, Keith},
  title = {Eye movements in reading and information processing: 20 years of research},
  journal = {Psychological Bulletin}, volume = 124, number = 3, pages = {372--422}, year = 1998,
  doi = {10.1037/0033-2909.124.3.372}}
@book{lupton2010,
  author = {Lupton, Ellen}, title = {Thinking with Type}, edition = {2},
  publisher = {Princeton Architectural Press}, address = {New York}, year = 2010}
:::
`;

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
const FONTS = {
  'Source Serif 4': ['400', '400i', '600', '600i', '700', '700i'], // 700: the list's title
  'Source Sans 3': ['400', '600'],
};

// ─── 4 · Build & show ───────────────────────────────────────────────────────
await loadFonts(FONTS, markdown);
// #region build: one text, four documents, shown as two spreads
// The style is set for the whole document, so each style is a build of its own.
const docs = [];
for (at = 0; at < SHOWN.length; at++) {
  // pageIndexOffset makes each page the next one of a book, so the desk pairs them:
  // APA beside Chicago, IEEE beside ISO 690.
  const content = { markdown, continuation: { pageIndexOffset: at + 1 } };
  docs.push(await buildWithFonts(() => buildDocument(content, config()), markdown));
}
// #endregion
showPages(docs, { title: t({ en: 'One text, four styles', es: 'Un texto, cuatro estilos' }) });

Kit · core, fonts, viewer: igual en todas las recetas · 235 líneas
// ─── Kit ── helpers shared by every Cookbook recipe · postext.dev/cookbook ─────

// ─── Kit · core v1 ── the same in every recipe · postext.dev/cookbook ─────────
function mm(value) { return { value, unit: 'mm' }; }
function pt(value) { return { value, unit: 'pt' }; }
function em(value) { return { value, unit: 'em' }; }
/** The sample language's string: t({ en: 'Figure', es: 'Figura' }). */
function t(strings) { return strings[LANG] ?? Object.values(strings)[0]; }
/** A file in this recipe's assets folder, served from the Postext repo by jsDelivr. */
function asset(file) { return `https://cdn.jsdelivr.net/gh/drnachio/postext@main/cookbook/${RECIPE}/assets/${file}`; }

// ─── Kit · fonts v1 ── the same in every recipe · postext.dev/cookbook ────────
// Postext measures text with the faces the browser has loaded, and caches the
// widths, so every face must be ready before the first build. Faces come from
// Fontsource: the same static files the PDF embeds, so screen and PDF agree.

/** faces = { 'Family Name': ['400', '400i', '700'] }. `text` is the sample:
 *  letters beyond Latin-1 (č, ł, ő…) also load the latin-ext files. With
 *  `optional`, a face Fontsource does not ship is skipped instead of failing.
 *  Resolves to the number of faces added. */
async function loadFonts(faces, text = '', { optional = false } = {}) {
  kitStatus('Loading fonts…');
  const ranges = {
    latin: 'U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,'
      + 'U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD',
    'latin-ext': 'U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+0304,U+0308,U+0329,'
      + 'U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF',
  };
  const subsets = /[Ā-˿Ḁ-ỿ]/.test(text) ? ['latin', 'latin-ext'] : ['latin'];
  const jobs = [];
  let added = 0;
  for (const [family, specs] of Object.entries(faces)) {
    const id = fontsourceId(family);
    const meta = optional ? await fontsourceMeta(family) : null;
    for (const spec of new Set(specs)) {
      const weight = parseInt(spec, 10);
      const style = spec.endsWith('i') ? 'italic' : 'normal';
      if (hasFace(family, weight, style)) continue;
      if (optional && !(meta?.weights.includes(weight) && meta.styles.includes(style))) continue;
      for (const subset of subsets) {
        const url = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-${subset}-${weight}-${style}.woff2`;
        const face = new FontFace(family, `url(${url}) format('woff2')`,
          { weight: String(weight), style, unicodeRange: ranges[subset] });
        jobs.push(face.load().then((ready) => { document.fonts.add(ready); added++; }, () => {
          if (subset === 'latin' && !optional) throw new Error(`Fontsource has no ${family} ${weight} ${style}`);
        }));
      }
    }
  }
  await Promise.all(jobs).catch((error) => { kitFail(error); throw error; });
  return added;
}

/** Runs `build` (a buildDocument or buildBundle call) and checks the faces
 *  the pages use. A regular face missing from FONTS is loaded with a warning;
 *  bold and italic variants are loaded when the family ships them. Then the
 *  measurement caches are cleared and the build runs again. */
async function buildWithFonts(build, text = '') {
  const tried = new Set();
  for (let round = 0; round < 3; round++) {
    kitStatus('Laying out…');
    await new Promise(requestAnimationFrame);          // let the status paint first
    const result = await Promise.resolve().then(build).catch((error) => { kitFail(error); throw error; });
    const wanted = { base: {}, variants: {} };
    for (const { font, base } of [result].flat().flatMap(fontStringsOf)) {
      const { family, weight, style } = parseFont(font);
      const key = `${family}|${weight}|${style}`;
      if (tried.has(key) || hasFace(family, weight, style)) continue;
      tried.add(key);
      (wanted[base ? 'base' : 'variants'][family] ??= []).push(`${weight}${style === 'italic' ? 'i' : ''}`);
    }
    if (Object.keys(wanted.base).length) {
      console.warn(`[cookbook] FONTS does not list ${JSON.stringify(wanted.base)}: loading them.`);
    }
    const added = await loadFonts(wanted.base, text) + await loadFonts(wanted.variants, text, { optional: true });
    if (added === 0) return result;
    clearMeasurementCache();
  }
  throw new Error('The fonts did not settle after three builds.');
}

/** Every font string of the layout. `base` marks a block's own face; its
 *  bold, italic and bold-italic variants are listed whether or not used. */
function fontStringsOf(doc) {
  const found = new Map();
  const walk = (node) => {
    if (!node || typeof node !== 'object') return;
    if (Array.isArray(node)) { node.forEach(walk); return; }
    for (const [key, value] of Object.entries(node)) {
      if (typeof value === 'string' && /fontString$/i.test(key)) {
        found.set(value, found.get(value) || key === 'fontString');
      } else if (value && typeof value === 'object') walk(value);
    }
  };
  walk(doc.pages);
  walk(doc.blocks);
  return [...found].map(([font, base]) => ({ font, base }));
}

/** '700 37.5px Open Sans' / 'italic 400 13px "Source Serif 4"' → { family, weight, style }.
 *  A string with no weight ('95.8px Young Serif', from a design text) is 400. */
function parseFont(font) {
  const m = /^(?:(italic|oblique)\s+)?(?:small-caps\s+)?(?:(\d+|bold|normal)\s+)?[\d.]+px\s+(.+)$/.exec(font.trim());
  if (!m) throw new Error(`Unexpected font string: ${font}`);
  const weight = m[2] === 'bold' ? 700 : !m[2] || m[2] === 'normal' ? 400 : Number(m[2]);
  return { family: m[3].replace(/^["']|["']$/g, ''), weight, style: m[1] ? 'italic' : 'normal' };
}

/** True when a loaded FontFace covers exactly this family, weight and style
 *  (document.fonts.check() is also true for families nobody declared). */
function hasFace(family, weight, style) {
  for (const face of document.fonts) {
    if (face.status !== 'loaded' || face.style !== style) continue;
    if (face.family.replace(/^["']|["']$/g, '') !== family) continue;
    const [low, high = low] = face.weight.split(' ').map(Number);
    if (weight >= low && weight <= high) return true;
  }
  return false;
}

/** Fontsource's id for a family: 'Source Serif 4' → 'source-serif-4'. */
function fontsourceId(family) { return family.toLowerCase().replace(/\s+/g, '-'); }

/** The weights and styles a family ships ({ weights: [400, 700], styles: ['normal', 'italic'] }), or null. */
function fontsourceMeta(family) {
  fontsourceMeta.cache ??= new Map();
  const id = fontsourceId(family);
  if (!fontsourceMeta.cache.has(id)) {
    fontsourceMeta.cache.set(id, fetch(`https://api.fontsource.org/v1/fonts/${id}`)
      .then((res) => (res.ok ? res.json() : null), () => null));
  }
  return fontsourceMeta.cache.get(id);
}

// ─── Kit · viewer v1 ── the same in every recipe · postext.dev/cookbook ───────
/** Shows the pages as facing spreads on a dark desk: the first page is a
 *  recto on its own, then verso | recto pairs, as in a bound book. Pages
 *  are painted when they scroll near the screen. */
function showPages(docs, { title, width = 460 } = {}) {
  const root = viewer(title);
  const pages = [docs].flat().flatMap((doc) =>
    doc.pages.map((page) => ({ doc, page, n: (doc.pageIndexOffset ?? 0) + page.index })));
  const spreads = [];
  let verso = null;
  for (const p of pages) {
    if (p.n % 2 === 1) { if (verso) spreads.push([verso, null]); verso = p; }
    else { spreads.push([verso, p]); verso = null; }
  }
  if (verso) spreads.push([verso, null]);
  const density = Math.min(window.devicePixelRatio || 1, 2);
  showPages.painter?.disconnect();
  const painter = new IntersectionObserver((entries) => {
    for (const { isIntersecting, target } of entries) {
      if (!isIntersecting) continue;
      painter.unobserve(target);
      const { doc, page } = target.postext;
      renderPageToCanvas(page, doc, target, { scale: (width * density) / page.width });
    }
  }, { rootMargin: '800px' });
  showPages.painter = painter;
  root.replaceChildren(...spreads.map((pair) => {
    const spread = document.createElement('div');
    spread.className = 'pt-spread';
    for (const p of pair) {
      const figure = document.createElement('figure');
      if (p) {
        const label = p.page.pageLabel || String(p.n + 1);
        const canvas = document.createElement('canvas');
        canvas.postext = p;
        canvas.style.aspectRatio = `${p.page.width} / ${p.page.height}`;
        canvas.setAttribute('role', 'img');
        canvas.setAttribute('aria-label', `Page ${label}`);
        const folio = document.createElement('figcaption');
        folio.textContent = label;
        figure.append(canvas, folio);
        painter.observe(canvas);
      } else figure.className = 'pt-blank';
      spread.append(figure);
    }
    return spread;
  }));
  kitStatus(`${pages.length} ${pages.length === 1 ? 'page' : 'pages'}`);
  document.documentElement.dataset.postext = 'ready';
  return pages.length;
}

/** The desk, the bar and the error reporting, created once. */
function viewer(title) {
  if (!document.getElementById('pt-kit')) {
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit">
      :root { color-scheme: dark; }
      body { margin: 0; background: #0e1014; color: #b9bcc4; font: 13px/1.45 system-ui, sans-serif; }
      #pt-bar { position: sticky; top: 0; z-index: 1; display: flex; flex-wrap: wrap; align-items: center;
        gap: 6px 16px; padding: 10px 16px; background: rgb(14 16 20 / .92); backdrop-filter: blur(6px);
        border-bottom: 1px solid #23262d; }
      #pt-bar strong { color: #f4f1ea; font-weight: 600; }
      #pt-actions { display: flex; gap: 12px; margin-left: auto; }
      #pt-actions a, #pt-actions button { color: #d8a21a; font: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
      #pages { display: grid; justify-items: center; gap: 48px; padding: 32px 16px 72px; }
      .pt-spread { display: flex; }
      .pt-spread figure { margin: 0; width: min(460px, 44vw); }
      .pt-spread canvas { display: block; width: 100%; background: #fff;
        box-shadow: 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figure:first-child canvas { box-shadow: inset -14px 0 14px -14px rgb(0 0 0 / .18), 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figcaption { margin-top: 10px; text-align: center; font: 600 10px/1 system-ui, sans-serif;
        letter-spacing: .18em; text-transform: uppercase; color: #6c7079; }
      .pt-blank { visibility: hidden; }
      @media (max-width: 760px) {
        .pt-spread { flex-direction: column; gap: 32px; }
        .pt-spread figure { width: min(460px, 92vw); }
        .pt-blank { display: none; }
      }
    </style>`);
    document.body.insertAdjacentHTML('afterbegin',
      '<header id="pt-bar"><strong id="pt-title"></strong><span id="pt-status" role="status"></span><span id="pt-actions"></span></header>');
    document.getElementById('pt-title').textContent = document.title || 'Postext';
    addEventListener('error', (event) => kitFail(event.error ?? event.message));
    addEventListener('unhandledrejection', (event) => kitFail(event.reason));
  }
  if (title) document.getElementById('pt-title').textContent = title;
  return document.getElementById('pages')
    ?? document.body.appendChild(Object.assign(document.createElement('main'), { id: 'pages' }));
}

function kitStatus(text) {
  viewer();
  document.getElementById('pt-status').textContent = text;
}

function kitFail(error) {
  document.documentElement.dataset.postext = 'error';
  kitStatus(`Error: ${error?.message ?? error}`);
}

// ─── /Kit ───────────────────────────────────────────────────────────────────────