"""Prüft Pandoc-Ausgaben (HTML und EPUB) eines konvertierten Buches.

Aufruf: python tools/qa/check_pandoc.py BUCHORDNER [...]  -> JSON auf stdout
Geprüft: interne Links/Anker, Bilder, Reste von '[!TIP]', Lage des Inhaltsverzeichnisses, TeX-Reste.
"""

from __future__ import annotations

import json
import posixpath
import re
import sys
import zipfile
from pathlib import Path
from urllib.parse import unquote

from lxml import html as lhtml

ID_RE = re.compile(r"""\b(?:id|name)\s*=\s*["']([^"']+)["']""")


def _ids(text: str) -> set[str]:
    return set(ID_RE.findall(text))


def _links(doc) -> list[str]:
    return [a.get("href") for a in doc.iter("a") if a.get("href")]


def _images(doc) -> list[str]:
    srcs = [i.get("src") for i in doc.iter("img") if i.get("src")]
    srcs += [i.get("{http://www.w3.org/1999/xlink}href") or i.get("href") for i in doc.iter("image")]
    return [s for s in srcs if s and not s.startswith("data:")]


def _parse(text: str):
    return lhtml.fromstring(text.encode("utf-8"))


def _toc_position(doc) -> dict:
    """Where does the TOC (nav#TOC) stand relative to the first chapter heading?"""
    nav = doc.xpath("//*[@id='TOC']")
    if not nav:
        return {"toc": False}
    body_text = lhtml.tostring(doc, encoding="unicode")
    pos = body_text.find('id="TOC"')
    before = re.sub(r"<[^>]+>", " ", body_text[:pos])
    h1_before = len(re.findall(r"<h1\b", body_text[:pos]))
    return {"toc": True, "h1_before_toc": h1_before, "words_before_toc": len(before.split()),
            "toc_entries": len(nav[0].xpath(".//a"))}


def check_html(path: Path) -> dict:
    text = path.read_text(encoding="utf-8")
    doc = _parse(text)
    ids = _ids(text)
    broken = [h for h in _links(doc) if h.startswith("#") and unquote(h[1:]) not in ids]
    missing_img = [s for s in _images(doc) if not (path.parent / unquote(s)).exists()]
    plain = doc.text_content()
    return {
        "file": path.name, "links_internal": sum(1 for h in _links(doc) if h.startswith("#")),
        "broken_internal": len(broken), "broken_examples": broken[:5],
        "images": len(_images(doc)), "missing_images": missing_img[:5],
        "callout_residue": len(re.findall(r"\[!(?:NOTE|TIP|IMPORTANT|WARNING|CAUTION)\]", plain)),
        "tex_residue": len(re.findall(r"\\(?:frac|begin\{|mathbb|alpha|sum_)", plain)),
        "math_elements": len(doc.xpath("//*[local-name()='math']")),
        **_toc_position(doc),
    }


def check_epub(path: Path) -> dict:
    with zipfile.ZipFile(path) as z:
        names = set(z.namelist())
        docs = {n: z.read(n).decode("utf-8") for n in names if n.endswith((".xhtml", ".html"))}
    ids = {n: _ids(t) for n, t in docs.items()}
    broken: list[str] = []
    internal = 0
    missing_img: list[str] = []
    residue = tex = math = 0
    for name, text in docs.items():
        doc = _parse(text)
        base = posixpath.dirname(name)
        for h in _links(doc):
            if re.match(r"^[a-z]+:", h):
                continue
            internal += 1
            file, _, frag = h.partition("#")
            target = posixpath.normpath(posixpath.join(base, unquote(file))) if file else name
            if target not in names:
                broken.append(f"{name}: {h}")
            elif frag and unquote(frag) not in ids.get(target, set()):
                broken.append(f"{name}: {h}")
        for s in _images(doc):
            if posixpath.normpath(posixpath.join(base, unquote(s))) not in names:
                missing_img.append(f"{name}: {s}")
        plain = doc.text_content()
        residue += len(re.findall(r"\[!(?:NOTE|TIP|IMPORTANT|WARNING|CAUTION)\]", plain))
        tex += len(re.findall(r"\\(?:frac|begin\{|mathbb|alpha|sum_)", plain))
        math += len(doc.xpath("//*[local-name()='math']"))
    return {"file": path.name, "documents": len(docs), "links_internal": internal, "broken_internal": len(broken),
            "broken_examples": broken[:5], "missing_images": missing_img[:5], "callout_residue": residue,
            "tex_residue": tex, "math_elements": math, "nav": any(n.endswith("nav.xhtml") for n in names)}


def main() -> None:
    results = []
    for d in map(Path, sys.argv[1:]):
        entry = {"book": d.name}
        for f in sorted(d.glob("*.html")):
            entry["html"] = check_html(f)
        for f in sorted(d.glob("*.epub")):
            entry["epub"] = check_epub(f)
        results.append(entry)
    json.dump(results, sys.stdout, ensure_ascii=False, indent=1)


if __name__ == "__main__":
    main()