legex/scrapers/ch.py

import logging
import re
from datetime import date
from typing import Any
from urllib.parse import unquote

from datasets import load_dataset

from legex.models.base import Case
from legex.scrapers.base import BaseScraper

DATASET_NAME = "voilaj/swiss-caselaw"
log = logging.getLogger(__name__)

_RE_JUMPCGI = re.compile(r"JumpCGI\?id=\d{2}\.\d{2}\.\d{4}_([0-9][A-Z])_(\d+)/(\d{4})")
_RE_AZA = re.compile(r"aza://\d{2}-\d{2}-\d{4}-([0-9][A-Z])_(\d+)-(\d{4})")


class CHScraper(BaseScraper):
    country = "Schweiz"

    def scrape(
        self,
        start_date: date | None = None,
        end_date: date | None = None,
    ) -> list[Case]:
        log.info(f"Loading bger shard from {DATASET_NAME} …")
        dataset = load_dataset(DATASET_NAME, data_files="data/bger.parquet", split="train")
        cases = self._to_cases(dataset)

        if start_date or end_date:
            cases = [
                c for c in cases
                if c.decision_date is not None
                and (start_date is None or c.decision_date >= start_date)
                and (end_date is None or c.decision_date <= end_date)
            ]
        cases.sort(key=lambda c: c.decision_date or date.min, reverse=True)
        log.info(f"{len(cases)} cases after filtering")
        return cases

    def _to_cases(self, dataset: Any) -> list[Case]:
        results: list[Case] = []
        seen: set[str] = set()
        for row in dataset:
            link = (row.get("source_url") or "").strip()
            if not link or link in seen:
                continue
            seen.add(link)

            raw_date = row.get("decision_date")
            decision_date = date.fromisoformat(raw_date) if raw_date else None
            case_id, chamber, division = self.parse_case_id(link)

            metadata: dict[str, Any] = {
                k: v for k, v in row.items()
                if k not in ("source_url", "decision_date", "language", "full_text") and v is not None
            }
            if chamber is not None:
                metadata["chamber"] = chamber
                metadata["division"] = division

            results.append(Case(
                case_id=case_id,
                link=link,
                decision_date=decision_date,
                jurisdiction="ch",
                language=(row.get("language") or "").strip().lower() or None,
                full_text=row.get("full_text"),
                metadata=metadata,
            ))
        return results

    @staticmethod
    def parse_case_id(link: str | None) -> tuple[str | None, str | None, str | None]:
        if not link:
            return None, None, None
        m = _RE_JUMPCGI.search(unquote(link)) or _RE_AZA.search(unquote(link))
        if not m:
            return None, None, None
        chamber, num, year = m.group(1), m.group(2), m.group(3)
        return f"{chamber}_{num}/{year}", chamber, chamber[0]

    @staticmethod
    def civil_filter(cases: list[Case]) -> list[Case]:
        return [c for c in cases if (c.metadata or {}).get("division") in {"4", "5"}]