#!/usr/bin/env python3
"""
Baut data/normen_index.json: Gesetz/Paragraph → Liste von Entscheidungen (doknr).

Liest YAML-Köpfe aus ge_md/, mappt Abkürzungen auf Lawgit-Slugs und prüft,
ob laws_md/<slug>/§N.md existiert.
"""

from __future__ import annotations

import argparse
import json
import os
import re
import sys
from collections import defaultdict
from pathlib import Path

# Häufige RII-Abkürzungen → Ordnername unter laws_md/
GESETZ_ALIASE: dict[str, str] = {
    "bgb": "bgb",
    "gg": "gg",
    "stgb": "stgb",
    "stpo": "stpo",
    "zpo": "zpo",
    "inso": "inso",
    "hgb": "hgb",
    "gmbhg": "gmbhg",
    "aktg": "aktg",
    "sgb": "sgb",  # oft mit Bandnummer — unmapped oft
    "bverfgg": "bverfgg",
    "vwgo": "vwgo",
    "fgo": "fgo",
    "sgg": "sgg",
    "arbgg": "arbgg",
    "gvg": "gvg",
    "egbgb": "egbgb",
    "agg": "agg",
    "urhg": "urhg",
    "tmg": "tmg",
    "bdsg": "bdsg",
    "ao": "ao",
    "ustg": "ustg",
    "estg": "estg",
    "vvg": "vvg",
    "vob": "vob",
    "baugb": "baugb",
    "whg": "whg",
    "bnatschg": "bnatschg",
}


def map_gesetz_slug(abbrev: str) -> str:
    key = (abbrev or "").strip().lower()
    key = (
        key.replace("ä", "ae")
        .replace("ö", "oe")
        .replace("ü", "ue")
        .replace("ß", "ss")
        .replace(".", "")
    )
    return GESETZ_ALIASE.get(key, key)


def lawgit_path_for(
    lawgit_root: Path, gesetz_slug: str, paragraph: str
) -> tuple[Path | None, bool]:
    """Pfad zu laws_md/<slug>/§N.md (oder Art. N.md) und ob die Datei existiert."""
    if not gesetz_slug:
        return None, False
    slug = map_gesetz_slug(gesetz_slug)
    base = lawgit_root / "laws_md" / slug
    if not paragraph:
        readme = base / "README.md"
        return readme, readme.is_file()

    candidates = [
        base / f"§{paragraph}.md",
        base / f"§{paragraph.lower()}.md",
        base / f"Art. {paragraph}.md",
        base / f"Art. {paragraph.lower()}.md",
        base / f"Art {paragraph}.md",
        base / f"Artikel {paragraph}.md",
    ]
    for path in candidates:
        if path.is_file():
            return path, True
    return candidates[0], False


def parse_frontmatter(md: str) -> dict:
    """Einfacher YAML-Kopf-Parser für unsere festgelegten Felder."""
    if not md.startswith("---"):
        return {}
    end = md.find("\n---", 3)
    if end < 0:
        return {}
    block = md[3:end].strip()
    meta: dict = {"normen": [], "vorinstanz": []}
    current_list: str | None = None
    for line in block.splitlines():
        if line.startswith("normen:"):
            current_list = "normen"
            if line.strip() == "normen: []":
                current_list = None
            continue
        if line.startswith("vorinstanz:"):
            current_list = "vorinstanz"
            if line.strip() == "vorinstanz: []":
                current_list = None
            continue
        if line.startswith("  - ") and current_list == "normen":
            # { gesetz: "...", paragraph: "...", roh: "..." }
            m = re.search(
                r'gesetz:\s*"([^"]*)".*?paragraph:\s*"([^"]*)".*?roh:\s*"([^"]*)"',
                line,
            )
            if m:
                meta["normen"].append(
                    {"gesetz": m.group(1), "paragraph": m.group(2), "roh": m.group(3)}
                )
            continue
        if line.startswith("  - ") and current_list == "vorinstanz":
            continue
        if re.match(r"^[a-z_]+:", line) and not line.startswith(" "):
            current_list = None
            key, _, val = line.partition(":")
            val = val.strip()
            if val.startswith('"') and val.endswith('"'):
                val = json.loads(val)
            meta[key.strip()] = val
    return meta


def parse_frontmatter_normen(md: str) -> list[dict]:
    return parse_frontmatter(md).get("normen") or []


def build_index(
    ge_md: Path,
    lawgit_root: Path,
) -> dict:
    by_norm: dict[str, list[dict]] = defaultdict(list)
    unmapped: list[dict] = []
    decisions = 0

    for path in sorted(ge_md.rglob("*.md")):
        try:
            text = path.read_text(encoding="utf-8", errors="replace")
        except OSError:
            continue
        meta = parse_frontmatter(text)
        if not meta.get("doknr"):
            continue
        decisions += 1
        entry_base = {
            "doknr": meta.get("doknr"),
            "gericht": meta.get("gericht"),
            "ebene": meta.get("ebene"),
            "aktenzeichen": meta.get("aktenzeichen"),
            "datum": meta.get("datum"),
            "path": str(path.relative_to(ge_md)),
            "doktyp": meta.get("doktyp"),
            "hat_leitsatz": bool(
                        re.search(r"^## Leitsatz\s*$", text, re.M)
                        and re.search(
                            r"^## Leitsatz\s*\n\n.+\n", text, re.M | re.S
                        )
                    ),
        }
        norms = meta.get("normen") or []
        if not norms:
            unmapped.append({**entry_base, "grund": "keine_normen"})
            continue
        for n in norms:
            slug = map_gesetz_slug(n.get("gesetz", ""))
            para = n.get("paragraph", "")
            key = f"{slug}/§{para}" if para else slug
            lg_path, ok = lawgit_path_for(lawgit_root, slug, para)
            item = {
                **entry_base,
                "roh": n.get("roh"),
                "gesetz": slug,
                "paragraph": para,
                "lawgit": str(lg_path.relative_to(lawgit_root)) if lg_path and ok else None,
                "mapped": ok,
            }
            if ok:
                by_norm[key].append(item)
            else:
                unmapped.append({**item, "grund": "kein_lawgit_pfad"})

    return {
        "lawgit_root": str(lawgit_root.resolve()),
        "ge_md": str(ge_md.resolve()),
        "entscheidungen": decisions,
        "normen": {k: v for k, v in sorted(by_norm.items())},
        "unmapped": unmapped,
    }


def main() -> int:
    parser = argparse.ArgumentParser(description="Normen-Index aus ge_md/ bauen")
    parser.add_argument(
        "--lawgit",
        default=os.environ.get("LAWGIT_ROOT", "../lawgit"),
        help="Pfad zu lawgit (Default: ../lawgit oder LAWGIT_ROOT)",
    )
    parser.add_argument("--ge-md", default="ge_md", help="Verzeichnis der Entscheidungen")
    parser.add_argument(
        "--out",
        default="data/normen_index.json",
        help="Ausgabedatei",
    )
    args = parser.parse_args()

    lawgit = Path(args.lawgit).resolve()
    ge_md = Path(args.ge_md).resolve()
    if not ge_md.is_dir():
        print(f"ge_md fehlt: {ge_md}", file=sys.stderr)
        return 1
    if not (lawgit / "laws_md").is_dir():
        print(
            f"Warnung: {lawgit}/laws_md fehlt — Mapping wird überwiegend unmapped.",
            file=sys.stderr,
        )

    index = build_index(ge_md, lawgit)
    out = Path(args.out)
    out.parent.mkdir(parents=True, exist_ok=True)
    out.write_text(
        json.dumps(index, indent=2, ensure_ascii=False) + "\n",
        encoding="utf-8",
    )
    mapped_norms = len(index["normen"])
    print(
        f"Index: {index['entscheidungen']} Entscheidungen, "
        f"{mapped_norms} Norm-Schlüssel, "
        f"{len(index['unmapped'])} unmapped → {out}"
    )
    return 0


if __name__ == "__main__":
    raise SystemExit(main())