A hiragana picture book, spaced by phrase

// ═══ Postext Cookbook · Nº 127 · A hiragana picture book, spaced by phrase ══════════
// https://postext.dev/en/cookbook/hiragana-picture-book
// Code: MIT · Story and pictures: written and drawn for the recipe (CC BY 4.0)
// Fonts: Klee One, Zen Maru Gothic (SIL OFL 1.1) · Needs postext ≥ 1.16.1
// A picture book for small readers: hiragana only, a space between phrases, vertical.
import {
  buildDocument, renderPageToCanvas, clearMeasurementCache, registerResourceImage,
  loadVerticalAlternates,
} from 'https://esm.sh/postext';
import { renderToPdf, decompressWoff2 } from 'https://esm.sh/postext-pdf';

const LANG = 'en'; // @lang: the language of the frame; the story is Japanese in both editions
const RECIPE = 'hiragana-picture-book';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
// #region palette: the paper boat's red, river blues, a warm paper
const palette = {
  ink: '#2e2a26', // the text: a soft near-black
  boat: '#cf4430', // the boat, the title (4.6:1 on the paper)
  river: '#5d93ad',
  grass: '#86b665',
  muted: '#6e675f', // the colophon
  paper: '#fbf6ea',
};
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
const colorPalette = [
  ...Object.entries(palette).map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } })),
  { id: 'main-color', name: 'boat (defaults)', value: { hex: palette.boat, model: 'hex' } },
];
// #endregion

const HAND = 'Klee One'; // 教科書体: the hand a child learns to write kana from
const ROUND = 'Zen Maru Gothic'; // the cover's title
const [BODY, LEAD] = [20, 36]; // pt: large kana, a line gap of 0.8 em
const PT = 25.4 / 72; // mm in a point
const TRIM = { w: 260, h: 200 }; // mm: a landscape picture book (横長)
const [CHARS, PICTURE, LINES] = [8, 14, 17]; // characters: text tier, picture tier; lines
const ART = { w: LINES * LEAD * PT, h: PICTURE * BODY * PT }; // mm: 215.9 × 98.8

// #region answer: わかち書き — a space between phrases, and lines that break only there
// The story is typed with an ordinary space (U+0020) after each phrase (文節). Japanese
// text may break between any two kana, so the space alone does not keep a phrase whole:
// keep-all drops the breaks between two letters and keeps those at a space, after 、。」
// and before 「. Kinsoku still applies.
const phrases = { wordBreak: 'keep-all' }; // cjk.wordBreak
const bodyText = {
  fontFamily: HAND, fontSize: pt(BODY), lineHeight: pt(LEAD), color: col('ink'),
  boldColor: col('ink'), italicColor: col('ink'), referenceColor: col('ink'),
  // Ragged: a justified line would stretch its spaces and its kana to fill the tier.
  textAlign: 'left', firstLineIndent: em(0),
};
// #endregion

// #region layout: the picture tier above, eight characters of text below it
// In vertical text 'left' is the top of the page: the side column is a tier that takes
// the pictures (floats), and the text runs in the tier under it, right to left.
const layout = {
  layoutType: 'oneAndHalf', writingMode: 'vertical-rl', sideColumnRole: 'floats',
  sideColumnSide: 'left', sideColumnPercent: 58, gutterWidth: pt(2 * BODY),
};
const cjk = { ...phrases, grid: { enabled: true, charsPerLine: CHARS, linesPerPage: LINES } };
const resourceTypes = [{ id: 'picture', name: 'え', shortLabel: 'え', numberingTemplate: '{n}',
  resetOn: 'never', counterFormat: 'decimal', captionPrefix: '' }]; // pictures, no captions
// #endregion

// #region cover: the first picture across the page, the title down its sky
// In the flow frame of a vertical page x runs down the sheet and y leftward from its right
// edge; a box's width runs down the sheet.
const at = (down, across) => ({ anchor: { to: 'page', edge: 'top-left' },
  offset: { x: mm(down), y: mm(across) } });
const cover = {
  id: 'cover', numbered: false, toc: false, span: 'page', header: { elements: [] },
  breakBefore: { enabled: true, parity: 'any' },
  advancedDesign: { enabled: true, minHeight: mm(TRIM.w - 40), slot: { elements: [
    { kind: 'image', id: 'art', resourceId: 'cover', decorative: true,
      placement: { anchor: { to: 'bleed', edge: 'top-left' },
        size: { width: mm(TRIM.h), height: mm(TRIM.w) } } },
    { kind: 'text', id: 'title', content: '{titleText}', fontFamily: ROUND, fontWeight: 700,
      fontSize: pt(60), lineHeight: 1, letterSpacing: pt(6), color: col('boat'),
      placement: at(22, 34) },
    { kind: 'text', id: 'latin', content: '{attr.latin}', fontFamily: ROUND, fontWeight: 700,
      fontSize: pt(9), lineHeight: 1.4, color: col('ink'), placement: at(22, 62) },
  ] } },
};
// #endregion

const config = () => ({ // a factory: the engine caches resolved configs per object
  locale: 'ja', // written out, never LANG (gotcha: ja-locale-tag)
  colorPalette,
  resourceTypes,
  page: {
    sizePreset: 'custom', width: mm(TRIM.w), height: mm(TRIM.h), dpi: 150,
    backgroundColor: col('paper'),
    margins: { top: mm(14), bottom: mm(16), left: mm(22), right: mm(22), mirror: true },
  },
  layout,
  cjk,
  bodyText,
  headings: { fontFamily: ROUND, color: col('boat'),
    levels: [{ level: 1, breakBefore: { enabled: true, parity: 'any' } }] }, // the H1 break
  headingStyles: [cover],
  paragraphStyles: [
    { id: 'end', fontFamily: ROUND, fontWeight: 700, color: col('boat'), textAlign: 'right',
      marginTop: pt(LEAD) }, // おしまい at the foot of its line
    { id: 'colophon', fontFamily: HAND, fontSize: pt(7.5), lineHeight: pt(LEAD),
      color: col('muted'), textAlign: 'left', marginTop: pt(LEAD) },
  ],
  header: { elements: [] }, // a picture book has no running heads and no folios
  footer: { elements: [] },
});

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Markdown sample · 65 lines · content.en.md
title: "かみの ふね"
author: "Postext Cookbook"
---

# かみの ふね {style="cover" latin="The Paper Boat: a picture book in hiragana"}

::resource{id="rain"}

あめが やんだ あさ、みいちゃんは あかい かみで ふねを おりました。

:::pagebreak

::resource{id="stream"}

「いって らっしゃい。」みいちゃんが そっと てを はなすと、ふねは すいすい ながれて いきました。

:::pagebreak

::resource{id="frog"}

いしの うえで、かえるが ききました。「どこへ いくの。」「うみまで。」と、ふねは こたえました。

:::pagebreak

::resource{id="bridge"}

はしの したを くぐると、ちいさな さかなが ついて きました。ぴちゃん、ぴちゃん。

:::pagebreak

::resource{id="heron"}

かわは だんだん ひろく なりました。きしでは さぎが いっぽんあしで みおくって います。

:::pagebreak

::resource{id="dusk"}

ゆうがた、そらが ももいろに そまりました。かぜの なかに、うみの においが します。

:::pagebreak

::resource{id="night"}

よるに なりました。おつきさまが みずに うつって、ふねの みちを てらして くれました。

:::pagebreak

::resource{id="sea"}

あさ、ふねは ひろい うみに でました。かもめが「ようこそ。」と いいました。

:::pagebreak

::resource{id="window"}

とおくの まちで、みいちゃんも まどを あけて、うみの ほうを みて いました。

:::paragraphs{style="end"}
おしまい
:::

:::paragraphs{style="colophon"}
Story and pictures written and drawn for this recipe (CC BY 4.0) · Set in Klee One and Zen Maru Gothic (SIL OFL)
:::
`; // content.<lang>.md, a space after each phrase

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
const FONTS = { 'Klee One': ['400'], 'Zen Maru Gothic': ['700'] };

// #region art: ten scenes drawn in code, a seeded hand for the waves and the stars
const W = 2186; // the art's width in its own units; its height is 1000 (ART is 2.186 : 1)
const COVER = Math.round((W * TRIM.h) / TRIM.w); // 1682: the cover is the page's shape
const P = palette;
function mulberry32(seed) {
  return () => {
    seed = (seed + 0x6d2b79f5) | 0;
    let t = Math.imul(seed ^ (seed >>> 15), 1 | seed);
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  };
}
const svgDoc = (body, h = 1000, w = W) => `<svg xmlns="http://www.w3.org/2000/svg" `
  + `width="${w}" height="${h}" viewBox="0 0 ${w} ${h}">${body}</svg>`;
const rect = (fill, y = 0, h = 1000, x = 0, w = W) =>
  `<rect x="${x}" y="${y}" width="${w}" height="${h}" fill="${fill}"/>`;
const wave = (y, amp, fill, seed, h = 1000, w = W) => { // a band whose top edge undulates
  const r = mulberry32(seed);
  let d = `M0 ${h} L0 ${y}`;
  for (let x = 0; x <= w; x += 120) d += ` Q${x + 60} ${y + (r() - 0.5) * 2 * amp} ${x + 120} ${y}`;
  return `<path d="${d} L${w} ${h} Z" fill="${fill}"/>`;
};
const ripples = (y0, y1, n, seed, stroke = '#ffffff') => {
  const r = mulberry32(seed);
  return Array.from({ length: n }, () => {
    const x = r() * (W - 160) + 40; const y = y0 + r() * (y1 - y0); const l = 40 + r() * 70;
    return `<path d="M${x} ${y} q${l / 2} -14 ${l} 0" fill="none" stroke="${stroke}" `
      + 'stroke-width="7" stroke-linecap="round" opacity=".7"/>';
  }).join('');
};
const boat = (x, y, s = 1) => `<g transform="translate(${x} ${y}) scale(${s})">`
  + `<path d="M-95 0 L95 0 L66 42 L-66 42 Z" fill="${P.boat}"/>`
  + `<path d="M-70 0 L0 -88 L70 0 Z" fill="#e0624c"/><path d="M0 -88 L0 0" stroke="#a83322" `
  + 'stroke-width="4"/></g>';
const girl = (x, y, s = 1) => `<g transform="translate(${x} ${y}) scale(${s})">`
  + '<path d="M-14 120 L-14 170 M14 120 L14 170" stroke="#2e2a26" stroke-width="9" '
  + 'stroke-linecap="round"/><path d="M0 40 L-55 130 L55 130 Z" fill="#e7a83c"/>'
  + '<circle cx="0" cy="0" r="40" fill="#f6d8c2"/><path d="M-42 4 Q-44 -46 0 -46 Q44 -46 42 4 '
  + 'L30 -12 Q0 -30 -30 -12 Z" fill="#2e2a26"/><circle cx="-14" cy="6" r="4" fill="#2e2a26"/>'
  + '<circle cx="14" cy="6" r="4" fill="#2e2a26"/></g>';
const frog = (x, y, s = 1) => `<g transform="translate(${x} ${y}) scale(${s})">`
  + '<ellipse cx="0" cy="40" rx="130" ry="44" fill="#a9a39a"/>'
  + '<ellipse cx="0" cy="0" rx="62" ry="42" fill="#5f9e47"/><circle cx="-34" cy="-38" r="20" '
  + 'fill="#5f9e47"/><circle cx="34" cy="-38" r="20" fill="#5f9e47"/><circle cx="-34" cy="-40" '
  + 'r="9" fill="#2e2a26"/><circle cx="34" cy="-40" r="9" fill="#2e2a26"/>'
  + '<path d="M-26 6 Q0 22 26 6" fill="none" stroke="#2e2a26" stroke-width="5"/></g>';
const fish = (x, y, s = 1) => `<g transform="translate(${x} ${y}) scale(${s})">`
  + '<ellipse cx="0" cy="0" rx="42" ry="20" fill="#e8893a"/><path d="M38 0 L72 -22 L72 22 Z" '
  + 'fill="#e8893a"/><circle cx="-22" cy="-4" r="5" fill="#2e2a26"/></g>';
const heron = (x, y, s = 1) => `<g transform="translate(${x} ${y}) scale(${s})">`
  + '<path d="M0 60 L0 230" stroke="#6e675f" stroke-width="8"/>'
  + '<ellipse cx="10" cy="40" rx="70" ry="38" fill="#ffffff" stroke="#c9c2b8" stroke-width="4"/>'
  + '<path d="M-48 30 Q-80 -40 -40 -110" fill="none" stroke="#ffffff" stroke-width="20" '
  + 'stroke-linecap="round"/><circle cx="-40" cy="-114" r="20" fill="#ffffff"/>'
  + '<path d="M-58 -116 L-118 -104 L-58 -104 Z" fill="#e3b33c"/><circle cx="-44" cy="-118" '
  + 'r="4" fill="#2e2a26"/></g>';
const gull = (x, y, s = 1) => `<path d="M${x - 50 * s} ${y} q${25 * s} ${-30 * s} ${50 * s} 0 `
  + `q${25 * s} ${-30 * s} ${50 * s} 0" fill="none" stroke="#2e2a26" stroke-width="7" `
  + 'stroke-linecap="round"/>';
const disc = (x, y, r, fill) => `<circle cx="${x}" cy="${y}" r="${r}" fill="${fill}"/>`;
const stars = (n, seed) => {
  const r = mulberry32(seed);
  return Array.from({ length: n }, () => disc(r() * W, r() * 420, 3 + r() * 5, '#f7e7a8')).join('');
};
const hills = (y, fill, seed) => wave(y, 60, fill, seed);
const SCENES = {
  // The cover is the whole page, 260 × 200 mm: 2186 × 1682 units. The sky on the right
  // takes the title.
  cover: svgDoc(rect('#d9ecf2', 0, COVER) + disc(560, 260, 110, '#f6d27a')
    + wave(980, 70, P.grass, 3, COVER) + wave(1180, 24, P.river, 4, COVER)
    + ripples(1250, 1640, 22, 5) + boat(1000, 1330, 2.2), COVER),
  rain: svgDoc(rect('#e6eef0') + ripples(60, 360, 10, 7, '#9fb9c4') + rect('#f1e3c8', 640, 360)
    + `<rect x="760" y="560" width="660" height="90" rx="12" fill="#b07d53"/>`
    + girl(1260, 380, 1.4) + boat(880, 520, 0.9)),
  stream: svgDoc(rect('#e3f0f4') + hills(420, P.grass, 11) + wave(600, 22, P.river, 12)
    + ripples(650, 960, 14, 13) + girl(1800, 300, 1.5) + boat(1300, 700, 1)),
  frog: svgDoc(rect('#e3f0f4') + hills(380, P.grass, 21) + wave(560, 22, P.river, 22)
    + ripples(620, 960, 14, 23) + frog(1480, 600, 1.6) + boat(820, 760, 1)),
  bridge: svgDoc(rect('#e3f0f4') + hills(400, P.grass, 31) + wave(540, 20, P.river, 32)
    + '<path d="M300 560 Q1093 120 1886 560" fill="none" stroke="#9a6b45" stroke-width="60"/>'
    + ripples(600, 960, 12, 33) + boat(1093, 720, 1) + fish(1450, 860, 1.1) + fish(1680, 800, 0.9)
    + fish(1300, 930, 0.8)),
  heron: svgDoc(rect('#e3f0f4') + hills(300, '#a7cc8a', 41) + wave(420, 16, '#7aaec4', 42)
    + ripples(480, 960, 18, 43) + heron(1700, 230, 1.3) + boat(700, 700, 0.8)),
  dusk: svgDoc(rect('#f4c9b5') + disc(500, 520, 110, '#f29a5c') + hills(470, '#c79c87', 51)
    + wave(560, 18, '#c98f8a', 52) + ripples(600, 960, 14, 53, '#f6ddd0') + boat(1300, 760, 0.9)),
  night: svgDoc(rect('#2f3e5c') + stars(40, 61) + disc(1500, 200, 80, '#f7e7a8')
    + hills(470, '#253247', 62) + wave(560, 14, '#3f5878', 63)
    + '<path d="M1460 600 L1540 600 L1580 980 L1420 980 Z" fill="#f7e7a8" opacity=".35"/>'
    + ripples(600, 960, 12, 64, '#8aa3c2') + boat(900, 760, 0.9)),
  sea: svgDoc(rect('#d6ecf4') + disc(1700, 200, 70, '#f6d27a') + wave(420, 8, '#4f88a6', 71)
    + ripples(470, 960, 22, 72) + gull(900, 200, 1.2) + gull(1150, 140, 0.9) + boat(700, 650, 0.8)),
  window: svgDoc(rect('#efe2c8') + rect('#d6ecf4', 90, 640, 420, 1100)
    + rect('#4f88a6', 470, 260, 420, 1100) + boat(1250, 500, 0.4) + `<rect x="420" y="90" `
    + 'width="1100" height="640" fill="none" stroke="#b07d53" stroke-width="40"/><path '
    + 'd="M970 90 L970 730" stroke="#b07d53" stroke-width="24"/>' + rect('#b07d53', 730, 60)
    + girl(1750, 470, 1.6)),
};
// #endregion
const pictures = Object.keys(SCENES).map((id) => ({ id, typeId: 'picture', kind: 'svg',
  createdAt: 0, updatedAt: 0, placement: { span: 'side' },
  svg: { fileId: `${id}.svg`, width: W, height: id === 'cover' ? COVER : 1000 } }));

// ─── 4 · Build & show ───────────────────────────────────────────────────────
await loadFonts(FONTS, markdown);
await loadCjkFonts({ [HAND]: FONTS[HAND] }, markdown, { vertical: true });
await loadCjkFonts({ [ROUND]: FONTS[ROUND] }, 'かみのふねおしまい', { vertical: true });
await Promise.all(Object.entries(SCENES).map(([id, svg]) => loadSvg(`${id}.svg`, svg)));
const doc = await buildWithFonts(
  () => buildDocument({ markdown, resources: pictures }, config()), markdown);
showBook(doc, { title: t({ en: 'A hiragana picture book',
  es: 'Un libro ilustrado en hiragana' }) });
offerPdf(() => renderToPdf(doc, { fontProvider: cjkPdfProvider, resourceBytes: imageBytes }),
  `${RECIPE}.pdf`);

Kit · core, fonts, viewer, pdf, images, cjk: the same in every recipe · 488 lines
// ─── 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 · pdf v1 ── the same in every recipe that exports a PDF ──────────────
/** postext-pdf embeds TrueType bytes. Fetch the Fontsource file the screen
 *  used, snapping to a weight the family ships and falling back to upright
 *  when it has no italic: the PDF asks for every face a block could use. */
async function fontsourceProvider(family, weight, style) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  const weights = meta?.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && meta && !meta.styles.includes('italic') ? 'normal' : style;
  const res = await fetch(`https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-latin-${w}-${s}.woff2`);
  if (!res.ok) throw new Error(`Fontsource has no ${family} ${w} ${s} (${res.status})`);
  return decompressWoff2(new Uint8Array(await res.arrayBuffer()));
}

/** A "Build the PDF" button in the bar. Once built: "Open the PDF" (a new
 *  tab, since CodePen's preview frame cannot show PDFs) and a download link. */
function offerPdf(makePdf, filename) {
  viewer();
  const button = Object.assign(document.createElement('button'), { type: 'button', textContent: 'Build the PDF' });
  button.dataset.postextPdf = filename;
  button.addEventListener('click', async () => {
    button.disabled = true;
    button.textContent = 'Building the PDF…';
    try {
      const bytes = await makePdf();
      const url = URL.createObjectURL(new Blob([bytes], { type: 'application/pdf' }));
      const size = `${Math.max(1, Math.round(bytes.length / 1024))} KB`;
      button.replaceWith(
        Object.assign(document.createElement('a'), { href: url, target: '_blank', rel: 'noopener', textContent: 'Open the PDF ↗' }),
        Object.assign(document.createElement('a'), { href: url, download: filename, textContent: `Download ${filename} · ${size}` }));
    } catch (error) {
      button.disabled = false;
      button.textContent = 'Build the PDF';
      kitFail(error);
    }
  });
  document.getElementById('pt-actions').append(button);
}

// ─── Kit · images v1 ── recipes with pictures · postext.dev/cookbook ──────────
/** Registers a photo or PNG for the canvas and keeps its bytes for the PDF.
 *  fetch → ImageBitmap never taints the canvas (a plain cross-origin <img> would). */
async function loadImage(fileId, url) {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`Image not found (${res.status}): ${url}`);
  const bytes = new Uint8Array(await res.arrayBuffer());
  registerResourceImage(fileId, await createImageBitmap(new Blob([bytes])));
  (loadImage.bytes ??= new Map()).set(fileId, bytes);
}

/** Registers SVG markup (drawn in code, or fetched) as a vector image. */
async function loadSvg(fileId, svg) {
  const img = new Image();
  img.src = `data:image/svg+xml;charset=utf-8,${encodeURIComponent(svg)}`;
  await img.decode();
  registerResourceImage(fileId, img);
  (loadImage.bytes ??= new Map()).set(fileId, new TextEncoder().encode(svg));
}

/** renderToPdf({ resourceBytes: imageBytes }) */
function imageBytes(fileId) { return loadImage.bytes?.get(fileId); }

/** renderToHtml({ resourceImageUrl: imageUrl }) */
function imageUrl(fileId) {
  const bytes = imageBytes(fileId);
  if (!bytes) return undefined;
  imageUrl.urls ??= new Map();
  if (!imageUrl.urls.has(fileId)) {
    const type = /\.svg$/i.test(fileId) ? 'image/svg+xml' : /\.png$/i.test(fileId) ? 'image/png' : 'image/jpeg';
    imageUrl.urls.set(fileId, URL.createObjectURL(new Blob([bytes], { type })));
  }
  return imageUrl.urls.get(fileId);
}

// ─── Kit · cjk v1 ── Chinese, Japanese and Korean books · postext.dev/cookbook ─
// Fontsource ships a CJK family as about a hundred files per weight, each
// declared in its stylesheet with the unicode-range it covers. The screen
// loads the files the sample touches; the PDF gets the same files for the
// characters its pages set in each face, and embeds each as a subset.
// A book bound on the right (vertical text) is shown with its spreads
// mirrored: page 1 alone on the left of the spine, then [3 | 2].

/** The files of a Fontsource face, read from its stylesheet: { url, range,
 *  ranges }, the last declared first (the order the browser tries them in). */
function cjkSlices(family, weight, style) {
  cjkSlices.cache ??= new Map();
  const id = fontsourceId(family);
  const css = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/${weight}${style === 'italic' ? '-italic' : ''}.css`;
  if (!cjkSlices.cache.has(css)) {
    cjkSlices.cache.set(css, fetch(css)
      .then((res) => {
        if (!res.ok) throw new Error(`Fontsource has no ${family} ${weight} ${style} (${res.status})`);
        return res.text();
      })
      .then((text) => [...text.matchAll(/@font-face\s*{([^}]*)}/g)].map(([, rule]) => {
        const range = /unicode-range:\s*([^;]+);/.exec(rule)?.[1].trim() ?? 'U+0-10FFFF';
        const ranges = range.split(',').map((part) => {
          const [lo, hi = lo] = part.trim().slice(2).split('-');
          return [parseInt(lo, 16), parseInt(hi, 16)];
        });
        return { url: new URL(/url\(([^)]+?\.woff2)\)/.exec(rule)[1], css).href, range, ranges };
      }).reverse()));
  }
  return cjkSlices.cache.get(css);
}

/** The file of `slices` that holds code point `cp`, if any. */
function cjkSliceFor(slices, cp) {
  return slices.find((slice) => slice.ranges.some(([lo, hi]) => cp >= lo && cp <= hi));
}

/** Whether Fontsource serves `family` as a Chinese, Japanese or Korean
 *  family (its subsets name the script). Fails when the API does not
 *  answer: a CJK face taken for a Latin one would paint in a system face. */
async function isCjkFamily(family) {
  const meta = await fontsourceMeta(family);
  if (!meta) throw new Error(`api.fontsource.org did not describe ${family}: reload to try again`);
  return !!meta.subsets?.some((subset) => /^(chinese|japanese|korean)/.test(subset));
}

/** faces = { 'Noto Serif TC': ['400', '700'] }, as for loadFonts: the
 *  whole FONTS object may be passed, its other families are left to
 *  loadFonts. Adds one FontFace per file of each CJK face with its
 *  unicodeRange, then loads the files `text` touches. `text` is what the
 *  faces set: the sample for the text face; a book in several voices calls
 *  it once per voice (loadCjkFonts({ 'LXGW WenKai TC': ['400'] }, quotes)),
 *  so the heading and quotation faces fetch and check only their own
 *  characters. Fails when a character of `text` is in no file of a face.
 *  List every weight the pages use: a weight left to buildWithFonts gets
 *  the latin file only. With { vertical: true } it also loads each
 *  family's vertical forms (brackets, quotes, pause marks) for the canvas,
 *  which needs loadVerticalAlternates imported from postext. Resolves to
 *  the number of files loaded. */
async function loadCjkFonts(faces, text, { vertical = false } = {}) {
  kitStatus('Loading fonts…');
  let loaded = 0;
  try {
    if (vertical && typeof loadVerticalAlternates !== 'function') {
      throw new Error('loadCjkFonts(…, { vertical: true }) needs loadVerticalAlternates imported from postext');
    }
    for (const [family, specs] of Object.entries(faces)) {
      if (!(await isCjkFamily(family))) continue;
      const twin = [];
      for (const spec of new Set(specs)) {
        const weight = parseInt(spec, 10);
        const style = spec.endsWith('i') ? 'italic' : 'normal';
        const slices = await cjkSlices(family, weight, style);
        const missing = [...new Set(text)].filter((ch) => /\S/.test(ch) && !cjkSliceFor(slices, ch.codePointAt(0)));
        if (missing.length) {
          throw new Error(`${family} ${spec} has no file for ${missing.slice(0, 12).join(' ')}: `
            + `give each face the text it sets (loadCjkFonts({ '${family}': ['${spec}'] }, text))`);
        }
        for (const slice of slices) {
          document.fonts.add(new FontFace(family, `url(${slice.url}) format('woff2')`,
            { weight: String(weight), style, unicodeRange: slice.range }));
          twin.push({ source: slice.url, weight: String(weight), style, unicodeRange: slice.range });
        }
        const font = `${style === 'italic' ? 'italic ' : ''}${weight} 16px "${family}"`;
        loaded += (await document.fonts.load(font, text)).length;
        if (!document.fonts.check(font, text)) throw new Error(`${family} ${spec} did not load for the sample`);
      }
      // The same files under a twin name with the `vert` feature on: the
      // canvas paints the punctuation of vertical lines with it.
      if (vertical && twin.length) await loadVerticalAlternates(family, twin);
    }
  } catch (error) {
    kitFail(error);
    throw error;
  }
  return loaded;
}

/** The PDF font provider for recipes with CJK faces: a family whose
 *  Fontsource subsets are Chinese, Japanese or Korean gets the files that
 *  hold the characters its pages set (`request.codePoints`); any other
 *  family gets the latin file fontsourceProvider fetches (the "pdf" block)
 *  and, when the face sets letters only latin-ext has, that file too. */
async function cjkPdfProvider(family, weight, style, request) {
  if (!(await isCjkFamily(family))) return cjkLatinPdfFiles(family, weight, style, request);
  const meta = await fontsourceMeta(family);
  const weights = meta.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && !meta.styles.includes('italic') ? 'normal' : style;
  const slices = await cjkSlices(family, w, s);
  const picked = new Set();
  for (const cp of request?.codePoints ?? []) {
    const slice = cjkSliceFor(slices, cp);
    if (slice) picked.add(slice);
  }
  if (!picked.size) picked.add(slices[0]);
  return Promise.all(slices.filter((slice) => picked.has(slice)).map(async (slice) => {
    const res = await fetch(slice.url);
    if (!res.ok) throw new Error(`Fontsource file ${slice.url} (${res.status})`);
    return decompressWoff2(new Uint8Array(await res.arrayBuffer()));
  }));
}

/** A Latin family set next to the CJK faces: its latin file, then its
 *  latin-ext file when the face sets letters only latin-ext has (ō ū in
 *  Hepburn rōmaji, ǎ in pinyin), the file loadFonts adds on screen for
 *  them. Latin comes first: postext-pdf draws a character from the first
 *  file that has it, as the browser takes a character both files hold from
 *  latin. A face Fontsource ships without latin-ext, or whose file does
 *  not come, gets latin alone, and the PDF names the letters it lacks. */
async function cjkLatinPdfFiles(family, weight, style, request) {
  const meta = await fontsourceMeta(family);
  const beyond = [...(request?.codePoints ?? [])].some(cjkLatinExtOnly);
  if (!beyond || !meta?.subsets?.includes('latin-ext')) return fontsourceProvider(family, weight, style);
  const weights = meta.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && !meta.styles.includes('italic') ? 'normal' : style;
  const id = fontsourceId(family);
  const url = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-latin-ext-${w}-${s}.woff2`;
  const [latin, ext] = await Promise.all([fontsourceProvider(family, weight, style), fetch(url)
    .then(async (res) => (res.ok ? decompressWoff2(new Uint8Array(await res.arrayBuffer())) : null), () => null)]);
  return ext ? [latin, ext] : latin;
}

/** Whether code point `cp` is in Fontsource's latin-ext file and not in
 *  its latin file: Latin Extended-A and -B, IPA, the spacing modifiers and
 *  Latin Extended Additional (loadFonts's test for latin-ext), less the
 *  few latin holds too (ı Œ œ ʻ ʼ ˆ ˚ ˜). */
function cjkLatinExtOnly(cp) {
  if (!((cp >= 0x100 && cp <= 0x2ff) || (cp >= 0x1e00 && cp <= 0x1eff))) return false;
  return ![0x131, 0x152, 0x153, 0x2bb, 0x2bc, 0x2c6, 0x2da, 0x2dc].includes(cp);
}

/** showPages for a book bound on either edge. A right-bound book (the
 *  document says so: doc.binding is 'right' for page.binding 'right' and
 *  for vertical text) lies on the desk as it opens: page 1 alone on the
 *  left of the spine, then [3 | 2], the spine shade on each page's inner
 *  edge. `binding` ('left' | 'right') overrides the document's. */
function showBook(docs, { binding, ...options } = {}) {
  const count = showPages(docs, options);
  const right = (binding ?? [docs].flat()[0]?.binding) === 'right';
  if (!document.getElementById('pt-kit-cjk')) {
    // The pages keep direction ltr: a canvas draws text in the direction its
    // element inherits, and under rtl each run would end where the engine
    // starts it, its brackets mirrored.
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit-cjk">
      .pt-spread[dir="rtl"] canvas { direction: ltr; }
      .pt-spread[dir="rtl"] 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); }
    </style>`);
  }
  // Each pair stays [verso, recto] in the page; right to left, the verso
  // sits on the right. Phones stack the pages in reading order either way.
  for (const spread of document.querySelectorAll('#pages > .pt-spread')) spread.dir = right ? 'rtl' : 'ltr';
  document.getElementById('pages').dataset.binding = right ? 'right' : 'left';
  return count;
}

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