"""Pré-rend les diagrammes Mermaid du guide intégré en PNG (#105).

Scanne les blocs ``<pre class="mermaid-code">`` de frontend/index.html,
extrait leur code, et appelle scripts/render_guide_diagram.mjs (Chromium +
mermaid v11) pour produire ``backend/assets/guide_diagrams/<sha1>.png``.
Ces PNG sont commités : le PDF du guide les embarque comme vraies images
(WeasyPrint ne sait pas exécuter Mermaid).

Usage : python scripts/build_guide_diagrams.py
"""
import hashlib
import html
import json
import re
import subprocess
import sys
import tempfile
from pathlib import Path

ROOT = Path(__file__).resolve().parent.parent
ASSETS = ROOT / "backend" / "assets" / "guide_diagrams"


def extract_mermaid() -> dict[str, str]:
    page_html = (ROOT / "frontend" / "index.html").read_text(encoding="utf-8")
    out: dict[str, str] = {}
    for m in re.finditer(
        r'<pre class="mermaid-code"><code class="language-mermaid">(.*?)</code></pre>',
        page_html,
        re.DOTALL,
    ):
        code = m.group(1)
        code = html.unescape(code).strip()
        sha = hashlib.sha1(code.encode("utf-8")).hexdigest()[:16]
        out[sha] = code
    return out


def main() -> int:
    jobs = extract_mermaid()
    if not jobs:
        print("aucun bloc mermaid dans index.html")
        return 1
    todo = {k: v for k, v in jobs.items() if not (ASSETS / f"{k}.png").exists()}
    print("diagrammes:", len(jobs), "| à rendre:", len(todo))
    if not todo:
        return 0
    with tempfile.NamedTemporaryFile("w", suffix=".json", delete=False, encoding="utf-8") as f:
        json.dump(todo, f)
        path = f.name
    r = subprocess.run(
        ["node", str(ROOT / "scripts" / "render_guide_diagram.mjs"), path],
        cwd=ROOT,
        capture_output=True,
        check=False,
        text=True,
        timeout=300,
    )
    print(r.stdout[-2000:])
    if r.returncode != 0:
        print(r.stderr[-2000:])
    return r.returncode


if __name__ == "__main__":
    sys.exit(main())