import logging
import re
from datetime import date

from datasets import load_dataset

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

DATASET_PATH = "openlegaldata/court-decisions-germany"
DATASET_NAME = 'dump-20221018'
# OpenLegalData shifts the `date` field for anonymity. Real year is encoded in
# file_number as the trailing /YY slash-suffix, for example "XII ZR 17/18" to 2018.
# Civil BGH senates are numbered with Roman numerals followed by ZR/ZB/ZA.
_RE_YEAR = re.compile(r"/(\d{2,4})\s*$")
_RE_CIVIL = re.compile(r"^([IVXLCDM]+)\s+(ZR|ZB|ZA)\b")

log = logging.getLogger(__name__)


class DEScraper(BaseScraper):
    country = "Deutschland"

    def scrape(
        self,
        start_date: date | None = None,
        end_date: date | None = None,
    ) -> list[Case]:
        log.info(f"Loading {DATASET_PATH} (gated; requires HF_TOKEN) …")
        dataset = load_dataset(path=DATASET_PATH, name=DATASET_NAME, split="train", token=settings.hf_token or None)
        cases = [
            self._row_to_case(row) for row in dataset
            if (row.get("court") or {}).get("name") == "Bundesgerichtshof"
        ]
        cases = [c for c in cases if c is not None]

        if start_date or end_date:
            start_year = start_date.year if start_date else 0
            end_year = end_date.year if end_date else 9999
            cases = [
                c for c in cases
                if start_year <= (c.decision_date.year if c.decision_date else 0) <= end_year
            ]
        cases.sort(key=lambda c: c.decision_date or date.min, reverse=True)
        log.info(f"{len(cases)} BGH cases after year filter")
        return cases

    @staticmethod
    def _row_to_case(row: dict) -> Case | None:
        file_number = row.get("file_number") or ""
        m = _RE_YEAR.search(file_number)
        if not m:
            return None
        year = int(m.group(1))
        if year < 50:
            year += 2000
        elif year < 100:
            year += 1900
        # Use January 1 of the inferred year, the real day/month is shifted.
        decision_date = date(year, 1, 1)
        content = row.get("markdown_content") or row.get("content") or ""
        return Case(
            case_id=file_number,
            link=f"https://de.openlegaldata.io/case/{row.get('id')}",
            decision_date=decision_date,
            jurisdiction="de",
            language="de",
            full_text=content,
            metadata={
                "ecli": row.get("ecli"),
                "type": row.get("type"),
                "slug": row.get("slug"),
            },
        )

    @staticmethod
    def civil_filter(cases: list[Case]) -> list[Case]:
        return [c for c in cases if _RE_CIVIL.match(c.case_id or "")]