"""Render a session-summary SVG from a content JSON and the session's transcripts.jsonl.

Usage: uv run python render.py <session_dir> <content.json> <out.svg> [--no-png]

Also exports <out>.png next to the SVG (Inkscape + ImageMagick, 64-color quantized); pass
--no-png to skip. A missing tool or failed export exits non-zero.

Layout: header, main-point band, a fixed left sidebar (session focus, participants and roles,
transcription quality), then any number of topic cards. Topic cards fill the main column next
to the sidebar, then continue below it in two-column rows. A full-width signals block follows
(opportunities and blockers/risks always, open questions when any), then an optional next-steps
table and the footer. Text is wrapped and the canvas height is computed, so nothing is clipped.
Transcription-quality metrics are computed from the JSONL, never typed in by hand.
"""

import json
import shutil
import statistics
import subprocess
import sys
import tempfile
from collections import Counter
from datetime import datetime, timedelta
from pathlib import Path
from xml.dom import minidom
from xml.sax.saxutils import escape

W      = 1680
M      = 48
GAP    = 24
PAD    = 28
SIDE_W = 468
MAIN_X = M + SIDE_W + 32
MAIN_W = W - M - MAIN_X
FULL_W = W - 2 * M
HALF_W = (FULL_W - GAP) // 2
FONT   = "'Inter','Segoe UI',Roboto,'Helvetica Neue',Arial,sans-serif"
RED    = "#B91C1C"

ACCENTS = {
    "amber": "#B45309", "teal": "#0D9488", "red": "#B91C1C", "violet": "#7C3AED",
    "green": "#15803D", "blue": "#2563EB", "rose": "#BE123C", "slate": "#475569",
}
PEOPLE_COLORS = ["#7C3AED", "#2563EB", "#B45309", "#0F766E", "#15803D", "#BE123C", "#0369A1"]
BAR_COLORS    = ["#2563EB", "#60A5FA", "#93C5FD"]

L = {
    "en": {
        "eyebrow": "SESSION RECONSTRUCTION", "segments": "transcribed segments",
        "length": "session length", "rt": "faster than real time", "main": "MAIN POINT",
        "focus": "SESSION FOCUS", "people": "PARTICIPANTS AND ROLES",
        "quality": "TRANSCRIPTION QUALITY", "next": "NEXT STEPS", "action": "ACTION",
        "owner": "OWNER", "when": "WHEN", "q_length": "Session length",
        "q_voiced": "Reconstructed speech", "q_pause": "Pause cuts",
        "q_low": "Low-confidence segments (p < 0.8)", "q_spk": "Speaker identified by the model",
        "q_unc": "Uncertain / unknown speaker", "q_mis": "Mis-detected languages",
        "q_lat": "Median latency per segment", "corr": "Names and terms corrected",
        "others": "Others", "none": "none",
        "opps": "OPPORTUNITIES", "risks": "BLOCKERS / RISKS", "qs": "OPEN QUESTIONS",
        "none_id": "None identified in this session",
        "langs": {"es": "Spanish", "en": "English"},
        "months": "Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec",
    },
    "es": {
        "eyebrow": "RECONSTRUCCIÓN DE SESIÓN", "segments": "segmentos transcritos",
        "length": "de sesión", "rt": "más rápido que tiempo real", "main": "PUNTO PRINCIPAL",
        "focus": "ENFOQUE DE LA SESIÓN", "people": "PARTICIPANTES Y ROLES",
        "quality": "CALIDAD DE LA TRANSCRIPCIÓN", "next": "PRÓXIMOS PASOS",
        "action": "ACCIÓN", "owner": "RESPONSABLE", "when": "CUÁNDO",
        "q_length": "Duración de la sesión", "q_voiced": "Voz reconstruida",
        "q_pause": "Cortes por pausa", "q_low": "Segmentos con confianza baja (p < 0.8)",
        "q_spk": "Voz identificada por el modelo", "q_unc": "Hablante dudoso / desconocido",
        "q_mis": "Idiomas mal detectados", "q_lat": "Latencia mediana por segmento",
        "corr": "Nombres y términos corregidos", "others": "Otros", "none": "ninguno",
        "opps": "OPORTUNIDADES", "risks": "BLOQUEOS / RIESGOS", "qs": "PREGUNTAS ABIERTAS",
        "none_id": "Ninguno identificado en esta sesión",
        "langs": {"es": "Español", "en": "Inglés"},
        "months": "ene feb mar abr may jun jul ago sep oct nov dic",
    },
}


def char_w(c):
    if c in "ilI.,:;'|!·":
        return 0.26
    if c in "fjrt()[]-":
        return 0.34
    if c == " ":
        return 0.28
    if c in "mwMW—":
        return 0.86
    if c.isdigit():
        return 0.56
    if c.isupper():
        return 0.68
    return 0.53


def text_w(s, size, bold=False, spacing=0.0):
    w = sum(char_w(c) for c in s) * size * 1.05
    return (w * 1.07 if bold else w) + spacing * len(s)


def wrap(s, size, width, bold=False, spacing=0.0):
    lines, cur = [], ""
    for word in str(s).split():
        trial = f"{cur} {word}" if cur else word
        if not cur or text_w(trial, size, bold, spacing) <= width:
            cur = trial
        else:
            lines.append(cur)
            cur = word
    return lines + [cur] if cur else lines or [""]


def txt(x, y, s, size, fill, bold=False, anchor=None, spacing=None, italic=False):
    attrs = f'x="{x:.0f}" y="{y:.0f}" font-size="{size}" fill="{fill}"'
    if bold:
        attrs += ' font-weight="700"'
    if anchor:
        attrs += f' text-anchor="{anchor}"'
    if spacing:
        attrs += f' letter-spacing="{spacing}"'
    if italic:
        attrs += ' font-style="italic"'
    return f"<text {attrs}>{escape(str(s))}</text>"


def para(out, x, y, s, size, width, lh, fill, **style):
    """Draw wrapped text with the first baseline at y; return the last baseline."""
    lines = wrap(s, size, width, style.get("bold", False), style.get("spacing") or 0.0)
    for i, line in enumerate(lines):
        out.append(txt(x, y + i * lh, line, size, fill, **style))
    return y + (len(lines) - 1) * lh


def box(x, y, w, h, fill="#FFFFFF", stroke="#DCE2EC", rx=12):
    return (f'<rect x="{x:.0f}" y="{y:.0f}" width="{w:.0f}" height="{h:.0f}" rx="{rx}" '
            f'fill="{fill}" stroke="{stroke}"/>')


def hline(x1, y, x2, color="#EDF1F7"):
    return f'<line x1="{x1:.0f}" y1="{y:.0f}" x2="{x2:.0f}" y2="{y:.0f}" stroke="{color}"/>'


def fmt_dur(sec):
    sec = int(round(sec))
    h, rem = divmod(sec, 3600)
    m, s = divmod(rem, 60)
    return f"{h} h {m:02d} min {s:02d} s" if h else f"{m} min {s:02d} s"


def metrics(session_dir, expected):
    path = Path(session_dir) / "transcripts.jsonl"
    segs = [json.loads(line) for line in path.open(encoding="utf-8") if line.strip()]
    t0 = datetime.fromisoformat(segs[0]["ts"])
    t1 = datetime.fromisoformat(segs[-1]["ts"]) + timedelta(seconds=segs[-1].get("duration_s") or 0)
    voiced = sum(s.get("duration_s") or 0 for s in segs)
    tx = [s["transcribe_s"] for s in segs if s.get("transcribe_s")]
    status = Counter(s.get("speaker_status") for s in segs)
    langs = Counter(s.get("lang") or "?" for s in segs)
    return {
        "n": len(segs), "t0": t0, "t1": t1, "length": (t1 - t0).total_seconds(),
        "voiced": voiced, "pause": sum(1 for s in segs if s.get("end_reason") == "pause"),
        "low": sum(1 for s in segs if (s.get("lang_prob") or 0) < 0.8),
        "matched": status["matched"], "uncertain": status["uncertain"],
        "unknown": status["unknown"], "langs": langs,
        "misdetected": [code for code, _ in langs.most_common() if code not in expected],
        "latency": statistics.median(tx) if tx else 0.0,
        "rt": voiced / sum(tx) if tx else 0.0,
    }


def panel_title(out, x, y, w, title):
    out.append(txt(x + PAD, y + 34, title, 13, "#5A6878", bold=True, spacing=2.2))
    out.append(hline(x + PAD, y + 50, x + w - PAD))
    return y + 50


def render_focus(x, y, w, items, lang):
    out = []
    cur = panel_title(out, x, y, w, L[lang]["focus"])
    inner = w - 2 * PAD
    for i, item in enumerate(items):
        base = cur + (28 if i == 0 else 30)
        color = ACCENTS["amber"] if item.get("tone") == "warn" else ACCENTS["blue"]
        out.append(f'<rect x="{x + PAD}" y="{base - 9:.0f}" width="8" height="8" rx="2" '
                   f'fill="{color}"/>')
        cur = para(out, x + PAD + 20, base, item["label"], 14.5, inner - 20, 19, "#0F172A",
                   bold=True)
        if item.get("detail"):
            cur = para(out, x + PAD + 20, cur + 20, item["detail"], 12, inner - 20, 16,
                       "#5A6878", italic=item.get("tone") == "warn")
    h = cur + 26 - y
    return [box(x, y, w, h)] + out, h


def render_people(x, y, w, people, note, lang):
    out = []
    cur = panel_title(out, x, y, w, L[lang]["people"])
    inner = w - 2 * PAD
    for i, p in enumerate(people):
        base = cur + (32 if i == 0 else 30)
        speaks = p.get("status", "speaks") == "speaks"
        color = PEOPLE_COLORS[i % len(PEOPLE_COLORS)] if speaks else "#94A3B8"
        initial = p.get("initial") or p["name"][:1].upper()
        out.append(f'<circle cx="{x + PAD + 14}" cy="{base - 5:.0f}" r="14" fill="{color}"/>')
        out.append(txt(x + PAD + 14, base - 1, initial, 12, "#FFFFFF", bold=True,
                       anchor="middle"))
        cur = para(out, x + PAD + 40, base, p["name"], 14.5, inner - 40, 18, "#0F172A",
                   bold=True)
        if p.get("role"):
            cur = para(out, x + PAD + 40, cur + 18, p["role"], 12, inner - 40, 16, "#5A6878")
    if note:
        out.append(hline(x + PAD, cur + 16, x + w - PAD, "#F3F6FA"))
        cur = para(out, x + PAD, cur + 38, note, 12, inner, 16, "#5A6878", italic=True)
    h = cur + 26 - y
    return [box(x, y, w, h)] + out, h


def render_quality(x, y, w, mt, expected, corrections, lang):
    t = L[lang]
    out = []
    cur = panel_title(out, x, y, w, t["quality"])
    inner = w - 2 * PAD
    n = mt["n"]
    parts = [(t["langs"].get(c, c.upper()), mt["langs"][c]) for c in expected if mt["langs"][c]]
    other = n - sum(v for _, v in parts)
    if other:
        parts.append((t["others"], other))
    bar_y, bx = cur + 20, x + PAD
    out.append(f'<clipPath id="langbar"><rect x="{bx}" y="{bar_y:.0f}" width="{inner}" '
               f'height="18" rx="9"/></clipPath><g clip-path="url(#langbar)">')
    legend = []
    for i, (name, count) in enumerate(parts):
        color = "#CBD5E1" if name == t["others"] else BAR_COLORS[min(i, len(BAR_COLORS) - 1)]
        seg_w = inner * count / n
        out.append(f'<rect x="{bx:.1f}" y="{bar_y:.0f}" width="{seg_w + 0.5:.1f}" height="18" '
                   f'fill="{color}"/>')
        bx += seg_w
        legend.append((f"{name} {count} ({round(100 * count / n)} %)", color))
    out.append("</g>")
    lx, ly = x + PAD, bar_y + 42
    for label, color in legend:
        lw = text_w(label, 12) + 30
        if lx + lw > x + w - PAD:
            lx, ly = x + PAD, ly + 20
        out.append(f'<circle cx="{lx + 4:.0f}" cy="{ly - 4:.0f}" r="4" fill="{color}"/>')
        out.append(txt(lx + 14, ly, label, 12, "#5A6878"))
        lx += lw
    cur = ly + 14
    out.append(hline(x + PAD, cur, x + w - PAD))
    pct = lambda k: f"{mt[k]} ({round(100 * mt[k] / n)} %)"  # noqa: E731
    rows = [
        (t["q_length"], fmt_dur(mt["length"])),
        (t["q_voiced"], fmt_dur(mt["voiced"])),
        (t["q_pause"], f"{mt['pause']} / {n}"),
        (t["q_low"], pct("low")),
        (t["q_spk"], f"{round(100 * mt['matched'] / n)} % ({mt['matched']} / {n})"),
        (t["q_unc"], f"{mt['uncertain']} / {mt['unknown']}"),
        (t["q_mis"], " · ".join(mt["misdetected"][:8]) or t["none"]),
        (t["q_lat"], f"{mt['latency']:.2f} s"),
    ]
    for i, (label, value) in enumerate(rows):
        base = cur + 26
        out.append(txt(x + PAD, base, label, 12, "#5A6878"))
        out.append(txt(x + w - PAD, base, value, 14.5, "#0F172A", bold=True, anchor="end"))
        cur = base + 10
        if i < len(rows) - 1:
            out.append(hline(x + PAD, cur, x + w - PAD, "#F3F6FA"))
    if corrections:
        top, body = cur + 18, []
        last = para(body, x + PAD + 16, top + 22, t["corr"], 12, inner - 32, 16, "#334155",
                    bold=True)
        for line in corrections:
            last = para(body, x + PAD + 16, last + 18, line, 12, inner - 32, 16, "#5A6878")
        bh = last + 16 - top
        out.append(box(x + PAD, top, inner, bh, fill="#F8FAFC", stroke="none", rx=8))
        out.append(f'<rect x="{x + PAD}" y="{top:.0f}" width="3" height="{bh:.0f}" rx="1.5" '
                   f'fill="#94A3B8"/>')
        out.extend(body)
        cur = top + bh
    h = cur + 26 - y
    return [box(x, y, w, h)] + out, h


def render_card(x, y, w, c, min_h=0):
    acc = ACCENTS.get(c.get("accent", "blue"), ACCENTS["blue"])
    px, inner, out = x + PAD, w - 2 * PAD, []
    cur = para(out, px, y + 32, c["eyebrow"].upper(), 10, inner, 14, acc, bold=True,
               spacing=1.7)
    cur = para(out, px, cur + 27, c["title"], 19, inner, 24, "#0F172A", bold=True)
    if c.get("subtitle"):
        cur = para(out, px, cur + 22, c["subtitle"], 12, inner, 16, "#64748B")
    cur += 14
    out.append(hline(px, cur, px + inner, "#EEF2F6"))
    for section in c.get("sections", []):
        cur = para(out, px, cur + 22, section["label"].upper(), 9.5, inner, 13, "#94A3B8",
                   bold=True, spacing=1.3)
        dot = RED if section.get("tone") == "limit" else acc
        for bullet in section.get("bullets", []):
            base = cur + 21
            out.append(f'<circle cx="{px + 5}" cy="{base - 5:.0f}" r="2.4" fill="{dot}"/>')
            cur = para(out, px + 16, base, bullet, 12.5, inner - 16, 17, "#334155")
        cur += 4
    if c.get("chips"):
        cx, top = px, cur + 12
        for chip in c["chips"]:
            cw = text_w(chip, 11, bold=True) + 28
            if cx + cw > px + inner:
                cx, top = px, top + 36
            out.append(box(cx, top, cw, 28, fill="#F5F3FF", stroke="#DDD6FE", rx=6))
            out.append(txt(cx + cw / 2, top + 18, chip, 11, acc, bold=True, anchor="middle"))
            cx += cw + 10
        cur = top + 28
    for i, note in enumerate(c.get("notes", [])):
        cur = para(out, px, cur + (26 if i == 0 else 17), note, 11.5, inner, 16, "#64748B")
    h = max(cur + 24 - y, min_h)
    head = [box(x, y, w, h, stroke="#E2E8F0"),
            f'<rect x="{x}" y="{y:.0f}" width="{w}" height="4" rx="2" fill="{acc}"/>']
    return head + out, h


def render_signals(x, y, w, content, lang):
    """Opportunities, blockers/risks and (when any) open questions as side-by-side panels."""
    t = L[lang]
    cols = [("opps", content.get("opportunities") or [], ACCENTS["green"]),
            ("risks", content.get("blockers") or [], RED)]
    if content.get("open_questions"):
        cols.append(("qs", content["open_questions"], ACCENTS["violet"]))
    col_w = (w - GAP * (len(cols) - 1)) // len(cols)
    panels, bottom = [], 0
    for i, (key, items, acc) in enumerate(cols):
        cx, out = x + i * (col_w + GAP), []
        px, inner = cx + PAD, col_w - 2 * PAD
        out.append(txt(px, y + 34, t[key], 13, acc, bold=True, spacing=2.2))
        out.append(hline(px, y + 50, px + inner, "#EEF2F6"))
        cur = y + 50
        if not items:
            cur = para(out, px, cur + 26, t["none_id"], 12.5, inner, 17, "#94A3B8", italic=True)
        for item in items:
            base = cur + (26 if cur == y + 50 else 21)
            out.append(f'<circle cx="{px + 5}" cy="{base - 5:.0f}" r="2.4" fill="{acc}"/>')
            cur = para(out, px + 16, base, item, 12.5, inner - 16, 17, "#334155")
        panels.append((cx, col_w, acc, out))
        bottom = max(bottom, cur)
    h = bottom + 24 - y
    elems = []
    for cx, cw, acc, out in panels:
        elems += [box(cx, y, cw, h, stroke="#E2E8F0"),
                  f'<rect x="{cx}" y="{y:.0f}" width="{cw}" height="4" rx="2" fill="{acc}"/>']
        elems += out
    return elems, h


def render_next(x, y, w, nxt, lang):
    t = L[lang]
    px, inner, out = x + PAD, w - 2 * PAD, []
    out.append(txt(px, y + 34, t["next"], 13, "#5A6878", bold=True, spacing=2.2))
    c_owner, c_when = px + inner * 0.60, px + inner * 0.80
    for label, cx in ((t["action"], px), (t["owner"], c_owner), (t["when"], c_when)):
        out.append(txt(cx, y + 66, label, 11.5, "#64748B", bold=True, spacing=1.6))
    cur = y + 76
    out.append(hline(px, cur, px + inner, "#DCE2EC"))
    for row in nxt.get("rows", []):
        base = cur + 26
        last = para(out, px, base, row["action"], 13.5, inner * 0.58, 18, "#1E293B")
        last = max(last, para(out, c_owner, base, row.get("owner", ""), 13.5, inner * 0.19,
                              18, "#1E293B"))
        last = max(last, para(out, c_when, base, row.get("when", ""), 12.5, inner * 0.20,
                              18, "#2563EB", bold=True))
        cur = last + 14
        out.append(hline(px, cur, px + inner, "#F3F6FA"))
    if nxt.get("note"):
        cur = para(out, px, cur + 24, nxt["note"], 12, inner, 16, "#5A6878", italic=True)
    h = cur + 24 - y
    return [box(x, y, w, h)] + out, h


def render(session_dir, content):
    lang = content.get("lang", "en")
    t = L[lang]
    expected = content.get("expected_langs", ["es", "en"])
    mt = metrics(session_dir, expected)
    body = []

    # Header
    t0, t1 = mt["t0"], mt["t1"]
    month = t["months"].split()[t0.month - 1]
    date_line = (f"{t0.day} {month} {t0.year} · {t0:%H:%M} – {t1:%H:%M} · "
                 f"{mt['n']} {t['segments']}")
    title_size = 32
    while text_w(content["title"], title_size, bold=True) > 1030 and title_size > 22:
        title_size -= 1
    hours, minutes = divmod(int(mt["length"] // 60), 60)
    stats = [(str(mt["n"]), t["segments"]),
             (f"{hours}h {minutes:02d}m" if hours else f"{minutes}m", t["length"]),
             (f"{mt['rt']:.1f}×", t["rt"])]
    body += ['<rect x="0" y="0" width="1680" height="160" fill="#0B1220"/>',
             '<rect x="0" y="158" width="1680" height="4" fill="#2563EB"/>',
             '<rect x="48" y="40" width="6" height="24" rx="3" fill="#3B82F6"/>',
             txt(68, 58, content.get("eyebrow", t["eyebrow"]).upper(), 13, "#94A3B8",
                 bold=True, spacing=2.2),
             txt(48, 110, content["title"], title_size, "#F8FAFC", bold=True),
             txt(48, 140, date_line, 15, "#A8B6CA"),
             hline(1120, 48, 1632, "#22304A")]
    for i, (value, label) in enumerate(stats):
        body.append(txt(1120 + 180 * i, 94, value, 30, "#F8FAFC", bold=True))
        body.append(txt(1120 + 180 * i, 116, label, 12, "#8FA0B6"))

    # Main point band
    y = 184
    mp = content["main_point"]
    pill = mp.get("pill", "")
    pill_w = text_w(pill, 9.5, True, 1.1) + 32 if pill else 0
    status_w = text_w(mp.get("status", ""), 11, True)
    head_w = FULL_W - 2 * PAD - 154 - status_w - pill_w - 48
    band = []
    cur = para(band, M + PAD + 154, y + 38, mp["headline"], 21, head_w, 26, "#1F2937",
               bold=True)
    right = M + FULL_W - PAD
    if pill:
        band.append(box(right - pill_w, y + 22, pill_w, 26, stroke="#EFD6A4", rx=13))
        band.append(txt(right - pill_w / 2, y + 39, pill, 9.5, "#B45309", bold=True,
                        anchor="middle", spacing=1.1))
    if mp.get("status"):
        band.append(txt(right - pill_w - 20, y + 38, mp["status"], 11, "#B45309", bold=True,
                        anchor="end"))
    cur = para(band, M + PAD, cur + 32, mp.get("body", ""), 12.5, FULL_W - 2 * PAD, 20,
               "#475569")
    band_h = cur + 22 - y
    body += [box(M, y, FULL_W, band_h, fill="#FDF6E9", stroke="#EFD6A4"),
             f'<rect x="{M}" y="{y}" width="5" height="{band_h:.0f}" rx="2.5" fill="#B45309"/>',
             f'<rect x="{M + PAD}" y="{y + 20}" width="140" height="24" rx="12" '
             f'fill="#B45309"/>',
             txt(M + PAD + 70, y + 36, t["main"], 9.5, "#FFFFFF", bold=True, anchor="middle",
                 spacing=1.2)] + band
    y += band_h + GAP

    # Sidebar
    side_y = y
    blocks = [
        lambda yy: render_focus(M, yy, SIDE_W, content.get("focus", []), lang),
        lambda yy: render_people(M, yy, SIDE_W, content.get("participants", []),
                                 content.get("participants_note"), lang),
        lambda yy: render_quality(M, yy, SIDE_W, mt, expected,
                                  content.get("corrections", []), lang),
    ]
    for block in blocks:
        elems, h = block(side_y)
        body += elems
        side_y += h + GAP

    # Topic cards: main column beside the sidebar, then two-column rows below it
    topics = list(content.get("topics", []))
    main_y = y
    while topics and main_y < side_y - GAP:
        elems, h = render_card(MAIN_X, main_y, MAIN_W, topics.pop(0))
        body += elems
        main_y += h + GAP
    y = max(side_y, main_y)
    while topics:
        if len(topics) == 1:
            elems, h = render_card(M, y, FULL_W, topics.pop(0))
            body += elems
        else:
            left, right_c = topics.pop(0), topics.pop(0)
            h = max(render_card(M, y, HALF_W, left)[1],
                    render_card(M + HALF_W + GAP, y, HALF_W, right_c)[1])
            body += render_card(M, y, HALF_W, left, h)[0]
            body += render_card(M + HALF_W + GAP, y, HALF_W, right_c, h)[0]
        y += h + GAP

    for key in ("opportunities", "blockers"):
        if key not in content:
            print(f"warning: content JSON has no '{key}' key; the panel will read "
                  f"'{t['none_id']}'", file=sys.stderr)
    elems, h = render_signals(M, y, FULL_W, content, lang)
    body += elems
    y += h + GAP

    if content.get("next_steps"):
        elems, h = render_next(M, y, FULL_W, content["next_steps"], lang)
        body += elems
        y += h + GAP

    # Footer
    body.append(hline(M, y, M + FULL_W, "#CBD5E1"))
    cur = y + 2
    for line in content.get("footer", []):
        cur = para(body, M, cur + 18, line, 10.5, FULL_W, 15, "#94A3B8")
    height = int(cur + 28)

    desc = content.get("description", content["main_point"]["headline"])
    head = ['<?xml version="1.0" encoding="UTF-8"?>',
            f'<svg xmlns="http://www.w3.org/2000/svg" width="{W}" height="{height}" '
            f'viewBox="0 0 {W} {height}" font-family="{FONT}" xml:lang="{lang}" role="img" '
            f'aria-labelledby="ttl dsc">',
            f'<title id="ttl">{escape(content["title"])}</title>',
            f'<desc id="dsc">{escape(desc)}</desc>',
            f'<rect width="{W}" height="{height}" fill="#EEF2F7"/>']
    return "\n".join(head + body + ["</svg>", ""])


def export_png(svg_path):
    """Export svg_path to a size-optimized PNG next to it (same stem, .png).

    Inkscape rasterizes at full width, then ImageMagick quantizes to 64 colors without
    dithering and strips metadata (~1.1 MB -> ~0.27 MB). The raw export lives in a private
    temp dir that is always deleted; only the final PNG is kept, beside the SVG.
    """
    svg = Path(svg_path)
    png = svg.with_suffix(".png")
    for tool in ("inkscape", "magick"):
        if shutil.which(tool) is None:
            sys.exit(f"error: '{tool}' not found on PATH; cannot export {png}")
    try:
        minidom.parse(str(svg))
    except Exception as exc:
        sys.exit(f"error: {svg} is not well-formed XML: {exc}")
    with tempfile.TemporaryDirectory(prefix="session-summary-") as tmp:
        raw = Path(tmp) / "full.png"
        steps = [
            ["inkscape", str(svg), "--export-type=png", f"--export-filename={raw}"],
            ["magick", str(raw), "-strip", "-colors", "64", "-dither", "None",
             "-define", "png:compression-level=9", "-define", "png:compression-strategy=1",
             str(png)],
        ]
        for cmd in steps:
            res = subprocess.run(cmd, capture_output=True, text=True)
            if res.returncode != 0:
                sys.exit(f"error: {cmd[0]} failed ({res.returncode}): {res.stderr.strip()}")
    if not png.is_file():
        sys.exit(f"error: export finished but {png} was not created")
    print(f"wrote {png} ({png.stat().st_size / 1024:.0f} KB)")


def main():
    args = [a for a in sys.argv[1:] if a != "--no-png"]
    no_png = len(args) != len(sys.argv) - 1
    if len(args) != 3:
        sys.exit("usage: render.py <session_dir> <content.json> <out.svg> [--no-png]")
    session_dir, content_path, out_path = args
    content = json.loads(Path(content_path).read_text(encoding="utf-8"))
    Path(out_path).write_text(render(session_dir, content), encoding="utf-8")
    print(f"wrote {out_path}")
    if not no_png:
        export_png(out_path)


if __name__ == "__main__":
    main()