// packet-render.js — THE prayer packet renderer, shared by both callers.
//
// ★ ONE RENDERER, TWO CALLERS. The packet is produced in two places:
//   - library/scripts/posters/packet.mjs   (build time, Node, writes files)
//   - the UPG-100 legend's Export > Prayer packet action (click time, browser)
// Both import THIS module, so a change to a page lands in both. The backlog card
// asked for exactly this: "reuse the existing print actions rather than growing a
// fourth implementation."
//
// It is pure: no fs, no process, no DOM. Everything it needs is passed in —
// strings, language, the zone, its groups, photos, and the map SVG. That is what
// lets the same code run under Node and in a browser tab.
//
// PAGE ORDER IS THE PRODUCT SPEC, do not reorder:
//   1        the map one-pager
//   2..n     the people groups, 20 per page, with photos
//   n+1      the 12 prayer points
//   n+2      the prayer wheel
//
// I18N: every human-readable string comes from packet-strings.json. A new language
// is a NEW BLOCK there, never a code change, and fallback is PER KEY so a
// half-finished translation renders its finished keys instead of blanking.

// Right-to-left locales. Kept as data rather than a per-language flag in the
// catalog: script direction is a property of the LANGUAGE, not of a translation,
// so a new Arabic-script locale is one entry here and not a schema change.
const RTL = new Set(['ar', 'he', 'fa', 'ur', 'ps', 'sd', 'yi']);

// Scripts with no coverage in the packet's Georgia/Palatino/serif stack, mapped to
// the vendored face that does cover them. MEASURED by rendering each script at 48px
// and reading the PIXELS: Latin, Cyrillic, Arabic and CJK all shape correctly with
// system fonts; DEVANAGARI renders as tofu boxes.
// ⚠ A width heuristic got this exactly backwards — it reported Arabic and Chinese
// broken and Hindi fine, because Devanagari tofu boxes happen to match real glyph
// advance. Never infer glyph coverage from measurements; look at the pixels.
const SCRIPT_FONT = {
  hi: { family: 'Noto Serif Devanagari', dir: 'noto-serif-devanagari',
        file: 'noto-serif-devanagari-400-devanagari.woff2' },
  mr: { family: 'Noto Serif Devanagari', dir: 'noto-serif-devanagari',
        file: 'noto-serif-devanagari-400-devanagari.woff2' },   // Marathi, same script
  ne: { family: 'Noto Serif Devanagari', dir: 'noto-serif-devanagari',
        file: 'noto-serif-devanagari-400-devanagari.woff2' },   // Nepali, same script
};

export function createPacketRenderer({ strings, lang = 'en', fontData = null }) {
  const EN = strings.en;
  const L = strings[lang] || {};
  const t = (k) => (L[k] !== undefined ? L[k] : EN[k]);
  const tr = (k) => ((L.rhythms || {})[k] !== undefined ? L.rhythms[k] : EN.rhythms[k]);
  // ⚠ PER-POINT, PER-FIELD — never `L.points || EN.points`. That expression reads as a
  // whole-block fallback and behaves as one only when the key is ABSENT; when a translator
  // has done SOME of the 12 it is TRUNCATING, because a 3-element array is truthy. Measured
  // 2026-09-24 with a partial block: the packet rendered a page headed "12 Prayer Points"
  // containing THREE — points 4..12 silently gone, including the Mark 5 passage point 4
  // prints in full. Nothing was blank and no error was raised, so it looked translated.
  // A half-finished translation is the NORMAL state of a language in progress, and
  // "a new language is a NEW BLOCK, never a code change" only holds if a partial block
  // degrades per key. English fixes the LENGTH (12) and supplies every missing field.
  const LP = Array.isArray(L.points) ? L.points : [];
  const POINTS = EN.points.map((en, i) => {
    const loc = LP[i];
    if (!loc || typeof loc !== 'object') return en;
    // Field-level merge: a point translated for `text` but not `sub` keeps the English
    // `sub` rather than losing it. refs/n/print_passage stay authoritative from English —
    // they are structure and scripture addresses, not prose.
    return { ...en, ...Object.fromEntries(Object.entries(loc).filter(([, v]) => v !== undefined && v !== '')) };
  });
  const fill = (s, vars) => String(s).replace(/\{(\w+)\}/g, (_, k) => (vars[k] ?? ''));
  const flat = (v) => (v && typeof v === 'object' ? (v.label ?? v.value ?? '') : (v ?? ''));

  // ── SHEET GEOMETRY — the letter-portrait sheet, same as the poster format ───
  const W = 1500, H = 1941;         // CSS px; 8.5x11 at width 1500
  const PAGE_W_IN = 8.5;
  const SCALE = (PAGE_W_IN * 96 / W).toFixed(6);   // print scale: one sheet = one page
  const M = 60, HEAD = 90;                          // margins + running header
  const COLS = 2, ROWS = 10, PER_PAGE = COLS * ROWS;
  const GUT = 14;
  const CW = (W - 2 * M - GUT * (COLS - 1)) / COLS;
  const CH = (H - 2 * M - HEAD - GUT * (ROWS - 1)) / ROWS;
  const PHOTO = Math.min(CH - 8, CW * 0.34);

  const esc = (s) => String(s ?? '').replace(/&/g, '&amp;').replace(/</g, '&lt;')
    .replace(/>/g, '&gt;').replace(/"/g, '&quot;');
  // ⚠ `lang` (the factory parameter), never a module-level LANG — and never
  // process.env.LANG, which is the SHELL's POSIX locale ("en_US.UTF-8"): not a valid
  // BCP-47 tag, and it throws inside toLocaleString.
  const num = (n) => (Number.isFinite(Number(n)) ? Number(n).toLocaleString(lang) : '—');

  const sheet = (inner, cls = '') =>
    `<div class="sheet ${cls}">${inner}</div>`;

  // The script font for THIS language, if it needs one. `fontData` is a base64
  // woff2 the caller supplies: the packet must stay a SELF-CONTAINED file that
  // prints offline (the Node generator writes standalone HTML with no server, and
  // photos are already inlined for the same reason), so a URL would break exactly
  // where the packet is most used. Absent fontData, the rule is simply omitted and
  // the stack falls back to serif — a legible wrong font beats a broken document.
  const SF = SCRIPT_FONT[lang] || null;
  const fontFace = (SF && fontData)
    ? `@font-face{font-family:'${SF.family}';font-style:normal;font-weight:400;`
      + `font-display:swap;src:url(data:font/woff2;base64,${fontData}) format('woff2')}`
    : '';
  // Prepend the script face to EVERY element's stack in one rule rather than
  // editing 22 hardcoded Georgia declarations. The browser falls through per
  // CHARACTER, so Latin text in a Hindi packet still renders in Georgia.
  const scriptStack = SF
    ? `.sheet,.sheet *{font-family:'${SF.family}',Georgia,'Palatino Linotype',serif !important}`
    : '';

  function css() {
    return `
    ${fontFace}
    ${scriptStack}
    @page{size:letter portrait;margin:0}
    html,body{margin:0;background:#fff;-webkit-print-color-adjust:exact;print-color-adjust:exact}
    .sheet{position:relative;width:${W}px;height:${H}px;background:#f7f4ec;overflow:hidden;
           page-break-after:always;break-after:page}
    .sheet:last-child{page-break-after:auto;break-after:auto}
    .hd{position:absolute;left:${M}px;top:46px;font:700 30px Georgia,'Palatino Linotype',serif;color:#1b1a17}
    .hd-r{position:absolute;right:${M}px;top:54px;font:400 19px Georgia,serif;color:#8c8170}
    .card{position:absolute;display:flex;gap:12px;align-items:center;
          border-bottom:1px solid #e2ddd0;padding-bottom:6px}
    .card img,.card .nophoto{width:${PHOTO.toFixed(0)}px;height:${PHOTO.toFixed(0)}px;flex:0 0 auto;border-radius:3px}
    .card img{object-fit:cover}
    .card .nophoto{border:1px solid #d6d0c0;background:#f2efe6;display:flex;align-items:center;
                   justify-content:center;font:italic 13px Georgia,serif;color:#a89f8c;text-align:center;padding:6px}
    .nm{font:700 25px Georgia,serif;color:#1b1a17;line-height:1.1}
    .mt{font:400 17px Georgia,serif;color:#6d766e}
    /* FINE PRINT — the agent: "attribution minimal, fine print small". */
    .fine{position:absolute;left:0;right:0;bottom:22px;text-align:center;
          font:400 13px Georgia,serif;color:#a89f8c}
    /* PRINT. The sheet is authored at ${W}px wide while @page is physical, so without
       a rescale the browser maps ${W}px -> 15.6in and TILES one sheet over many pages.

       ⚠ Use zoom, NOT transform:scale(). They look identical on screen and behave
       completely differently under pagination:
         transform  is paint-time  — the element still RESERVES its full ${H}px layout
                    box, so the paginator walks ${H}px of content and breaks it across
                    two sheets, inking only the top of the first. Measured: 8 sheets
                    came out as 16 PDF pages. Negative margins do NOT fix this — they
                    collapse the outer space, not the fragmentation box.
         zoom       is layout-time — the box itself becomes ${(PAGE_W_IN*96).toFixed(0)}px
                    wide, so pagination sees the scaled size. Measured: 1 page/sheet.
       Verified by _probe-pagecount.mjs (transform 2, transform+margins 2, zoom 1). */
    @media print{
      html,body{width:${(PAGE_W_IN * 96).toFixed(0)}px;margin:0;padding:0}
      .sheet{width:${W}px;height:${H}px;zoom:${SCALE};
             page-break-after:always;break-after:page}
      .sheet:last-child{page-break-after:auto;break-after:auto}
    }`;
  }

  // Lift the poster's stylesheet so the inlined map keeps its palette and map rules,
  // dropping only the rules that would fight the packet's own page shell.
  //
  // Comments are stripped FIRST and deliberately: generate.mjs's CSS comments are long
  // prose that contains braces and selector-like text, so any brace-counting or
  // selector regex run over the raw source mis-parses them as rules. Strip, then split.
  function mapCss(posterHtml) {
    const block = posterHtml.match(/<style>([\s\S]*?)<\/style>/);
    if (!block) return '';
    const css = block[1].replace(/\/\*[\s\S]*?\*\//g, '');

    // Drop @media (the poster's own print-scaling rules, which do not apply here).
    // Depth-aware because @media bodies nest a further level of braces.
    let out = '', depth = 0, i = 0;
    while (i < css.length) {
      if (css.startsWith('@media', i)) {
        let d = 0, started = false;
        while (i < css.length) {
          if (css[i] === '{') { d++; started = true; }
          else if (css[i] === '}') { d--; if (started && d === 0) { i++; break; } }
          i++;
        }
        continue;
      }
      out += css[i++];
    }

    // Drop document-level rules: these style the POSTER page, not the map, and would
    // override the packet's background, box-sizing and stage geometry.
    const DOC = /(^|,)\s*(html|body|\*|\.stage)\s*$/;
    return out.split('}')
      .map((r) => {
        const at = r.indexOf('{');
        if (at < 0) return '';
        const sel = r.slice(0, at).trim();
        if (!sel) return '';
        // :root must be KEPT — it carries the palette the map's var()s resolve against.
        if (sel !== ':root' && sel.split(',').some((s) => DOC.test(s.trim()) || /^(html|body|\*|\.stage)$/.test(s.trim()))) return '';
        return `${sel}{${r.slice(at + 1).trim()}}`;
      })
      .filter(Boolean).join('\n');
  }

  // ── PAGE 1: the map one-pager ───────────────────────────────────────────────
  // Lightweight by design — the agent asked for "a lightweight one pager that shows
  // the geography with all the pins", explicitly NOT the poster. The poster remains
  // its own artefact (generate.mjs); this is the packet's cover.
  function mapPage(zone, groups, mapSvg) {
    const count = groups.length;
    return sheet(`
      <div style="position:absolute;left:${M}px;top:${M}px;right:${M}px;text-align:center">
        <div style="font:600 21px Georgia,serif;letter-spacing:3px;color:#8c8170">${esc(t('map_page_kicker'))}</div>
        <div style="font:700 56px Georgia,serif;color:#1b1a17;margin-top:8px">${esc(zone.label || zone.id)}</div>
        <div style="font:italic 24px Georgia,serif;color:#6d766e;margin-top:10px">
          ${esc(fill(t('map_page_sub'), { count: num(count) }))}</div>
      </div>
      ${mapSvg}
      <div class="fine">${esc(t('privacy_note'))}</div>`);
  }

  // ── PAGES 2..n: the people groups, 20 per sheet ─────────────────────────────
  function listPages(zone, groups, photos) {
    const pages = [];
    for (let start = 0; start < groups.length; start += PER_PAGE) {
      const slice = groups.slice(start, start + PER_PAGE);
      const cards = slice.map((g, k) => {
        const i = start + k;
        const c = k % COLS, r = Math.floor(k / COLS);
        const left = M + c * (CW + GUT), top = M + HEAD + r * (CH + GUT);
        const src = photos.get(g.slug);
        const img = src
          ? `<img src="${src}" alt="">`
          : `<div class="nophoto">${esc(t('no_photo'))}</div>`;
        return `<div class="card" style="left:${left.toFixed(0)}px;top:${top.toFixed(0)}px;
          width:${CW.toFixed(0)}px;height:${CH.toFixed(0)}px">${img}
          <div style="min-width:0">
            <div class="nm">${i + 1}. ${esc(g.name)}</div>
            <div class="mt" style="margin-top:4px">${esc(flat(g.religion))}</div>
            <div class="mt">${num(g.population)} ${esc(t('people_suffix'))} · ${esc(flat(g.country_code))}</div>
          </div></div>`;
      }).join('');
      pages.push(sheet(`
        <div class="hd">${esc(zone.label || zone.id)}</div>
        <div class="hd-r">${esc(fill(t('list_header'),
          { from: num(start + 1), to: num(Math.min(start + PER_PAGE, groups.length)), count: num(groups.length) }))}</div>
        ${cards}`));
    }
    return pages;
  }

  // ── PAGE n+1: the 12 prayer points ──────────────────────────────────────────
  function pointsPage() {
    const rows = POINTS.map((p) => {
      // ⚠ ISOLATE EACH REFERENCE FOR BIDI. Scripture references stay in English
      // (a reader looks them up in their own Bible), so on an RTL page they are
      // LTR runs inside an RTL paragraph. Without isolation the Unicode bidi
      // algorithm reorders a run that STARTS WITH A DIGIT: measured on the Arabic
      // page, "1 Peter 5:6–11" rendered as "Peter 5:6-11 1". dir="ltr" on each
      // reference pins its internal order without affecting the line's direction.
      const refs = (p.refs || [])
        .map((r) => `<span dir="ltr" style="unicode-bidi:isolate">${esc(r)}</span>`)
        .join(' · ');
      const sub = p.sub ? ` <span style="font:italic 17px Georgia,serif;color:#8c8170">— ${esc(p.sub)}</span>` : '';
      const passage = p.print_passage
        // Point 4 prints Mark 5:1-20 IN FULL. the agent: "it actually lists out the full
        // scripture, because prayer point number four is actually read the word."
        // class="p4-passage" is a TEST HOOK, not styling — the block is styled inline.
        // Without it the only way to assert the passage rendered was to search for the
        // English word "Gadarenes", which would go red the moment this key is translated.
        ? `<div class="p4-passage" style="font:400 14px Georgia,serif;color:#4a4a45;line-height:1.5;margin-top:5px;
               padding-left:10px;border-left:2px solid #d9d3c4">${esc(t('point4_passage'))}
             <div class="p4-credit" style="font:italic 12px Georgia,serif;color:#a89f8c;margin-top:3px">
               ${esc(t('point4_passage_credit'))}</div></div>`
        : '';
      return `<div style="margin-bottom:${p.print_passage ? 10 : 13}px">
        <div style="font:700 19px Georgia,serif;color:#1b1a17">
          ${p.n}. ${esc(tr(p.rhythm))}${sub}</div>
        <div style="font:400 17px Georgia,serif;color:#3b3226;line-height:1.35;margin-top:2px">${esc(p.text)}</div>
        <div style="font:600 14px Georgia,serif;color:#7a3b2e;margin-top:2px">${refs}</div>
        ${passage}
      </div>`;
    }).join('');
    return sheet(`
      <div style="position:absolute;left:${M}px;top:44px;right:${M}px">
        <div class="points-title" style="font:700 40px Georgia,serif;color:#1b1a17">${esc(t('points_title'))}</div>
        <div style="font:italic 18px Georgia,serif;color:#6d766e;margin-top:6px">${esc(t('points_intro'))}</div>
      </div>
      <div style="position:absolute;left:${M}px;top:${M + 96}px;right:${M}px;bottom:52px">${rows}</div>
      <div class="fine">${esc(t('points_attrib'))}</div>`);
  }

  // ── PAGE n+2: the prayer wheel ──────────────────────────────────────────────
  // REDRAWN as SVG rather than embedding the source PDF page: a raster embed cannot
  // be translated, and this packet must generate in any language. Twelve equal
  // segments, the rhythm name set along each, 5 minutes each = one hour.
  function wheelPage() {
    const cx = W / 2, cy = 1090, R = 470;
    const order = ['praise', 'wait', 'confess', 'read', 'ask', 'intercede',
      'pray_word', 'thank', 'sing', 'meditate', 'listen', 'praise_end'];
    // Hues sweep the wheel so neighbouring rhythms stay distinguishable in print.
    const seg = order.map((key, i) => {
      const a0 = (i * 30 - 90) * Math.PI / 180, a1 = ((i + 1) * 30 - 90) * Math.PI / 180;
      const x0 = cx + R * Math.cos(a0), y0 = cy + R * Math.sin(a0);
      const x1 = cx + R * Math.cos(a1), y1 = cy + R * Math.sin(a1);
      const hue = Math.round(i * 30);
      const mid = (a0 + a1) / 2;
      const tx = cx + R * 0.62 * Math.cos(mid), ty = cy + R * 0.62 * Math.sin(mid);
      let deg = mid * 180 / Math.PI;
      if (deg > 90 || deg < -90) deg += 180;            // keep every label upright
      return `<path d="M ${cx} ${cy} L ${x0.toFixed(1)} ${y0.toFixed(1)} A ${R} ${R} 0 0 1 ${x1.toFixed(1)} ${y1.toFixed(1)} Z"
                fill="hsl(${hue} 70% 72%)" stroke="#fff" stroke-width="3"/>
              <text x="${tx.toFixed(1)}" y="${ty.toFixed(1)}" transform="rotate(${deg.toFixed(1)} ${tx.toFixed(1)} ${ty.toFixed(1)})"
                text-anchor="middle" dominant-baseline="middle"
                font-family="Georgia,serif" font-weight="700" font-size="21" fill="#2b2a26">${esc(tr(key))}</text>`;
    }).join('');
    const pips = order.map((_, i) => {
      const a = ((i + 0.5) * 30 - 90) * Math.PI / 180;
      const x = cx + (R + 46) * Math.cos(a), y = cy + (R + 46) * Math.sin(a);
      return `<circle cx="${x.toFixed(1)}" cy="${y.toFixed(1)}" r="21" fill="#26251f"/>
              <text x="${x.toFixed(1)}" y="${(y + 1).toFixed(1)}" text-anchor="middle" dominant-baseline="middle"
                font-family="Georgia,serif" font-weight="700" font-size="20" fill="#fff">5</text>`;
    }).join('');
    return sheet(`
      <div style="position:absolute;left:${M}px;top:48px;right:${M}px;text-align:center">
        <div class="wheel-title" style="font:700 42px Georgia,serif;color:#1b1a17">${esc(t('wheel_title'))}</div>
        <div style="font:italic 19px Georgia,serif;color:#6d766e;margin-top:10px;
                    max-width:1000px;margin-left:auto;margin-right:auto">${esc(t('wheel_intro'))}</div>
      </div>
      <svg width="${W}" height="${H}" style="position:absolute;left:0;top:0" xmlns="http://www.w3.org/2000/svg">
        ${seg}${pips}
        <text x="${cx}" y="${cy + R + 130}" text-anchor="middle"
          font-family="Georgia,serif" font-size="20" fill="#8c8170">5 ${esc(t('wheel_minutes'))} × 12</text>
      </svg>
      <div class="fine">${esc(t('wheel_attrib'))}</div>`);
  }

  // ── BUILD ONE PACKET ────────────────────────────────────────────────────────
  // Assemble the whole document. photos is a Map(slug -> dataURL-or-URL); mapSvg is
  // the poster's <svg> plus the stylesheet its var()s resolve against (see mapCss).
  function buildPacket(zone, groups, photos, mapSvg) {
    const pages = [
      mapPage(zone, groups, mapSvg),
      ...listPages(zone, groups, photos),
      pointsPage(),
      wheelPage(),
    ];
    // ⚠ dir MUST be set for right-to-left languages or the packet renders Arabic
    // left-aligned — readable glyphs in the wrong place, which looks like a
    // styling quirk rather than the bug it is. Verified in a browser: with
    // dir="rtl" the text right-aligns, shapes correctly, and a Latin scripture
    // reference stays LTR inside the RTL line (correct bidi) with no extra work.
    return `<!DOCTYPE html><html lang="${esc(lang)}" dir="${RTL.has(lang) ? 'rtl' : 'ltr'}"><head><meta charset="utf-8">
<title>${esc(zone.label || zone.id)}</title><style>${css()}</style></head>
<body>${pages.join('\n')}</body></html>`;
  }

  return { buildPacket, mapPage, listPages, pointsPage, wheelPage, css, mapCss, PER_PAGE, W, H };
}