from __future__ import annotations

import logging
import re
import time
from datetime import date
from html import unescape
from urllib.parse import urljoin

import requests
from dateutil import parser as dateutil_parser

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

# Data source: https://juportal.be/zoekmachine/zoekformulier
# We submit the official search form with civil case-number prefix "C." and
# page through server-side "next_page" form actions.

log = logging.getLogger(__name__)

BASE_URL = "https://juportal.be"
SEARCH_FORM_URL = f"{BASE_URL}/zoekmachine/zoekformulier"
SEARCH_RESULTS_URL = f"{BASE_URL}/zoekmachine/zoekresultaten"
DELAY_SECONDS = 3
RETRY_DELAY_SECONDS = 30
MAX_PAGES_PER_QUERY = 300

_RE_FORM_TOKEN = re.compile(r'name=["\']TOKEN["\'][^>]*value=["\']([^"\']*)', re.IGNORECASE)
_RE_ACTION_VALUE = re.compile(
    r'<button[^>]*name=["\']action["\'][^>]*value=["\']([^"\']*)',
    re.IGNORECASE,
)
_RE_NEXT_VALUE = re.compile(
    r'<button[^>]*name=["\']next_page["\'][^>]*value=["\']([^"\']*)',
    re.IGNORECASE,
)
_RE_CONTENT_LINK = re.compile(r'href=["\'](/content/ECLI:BE:CASS:[^"\']+)["\']', re.IGNORECASE)
_RE_ROLE = re.compile(r"Rolnummer:\s*([A-Z]\.[0-9]{2}\.[0-9]{4}\.[A-Z])", re.IGNORECASE)
_RE_DATE = re.compile(r"Vonnis/arrest van\s+([0-9]{1,2}\s+[A-Za-z]+\s+[0-9]{4})", re.IGNORECASE)
_RE_ECLI = re.compile(r"(ECLI:BE:CASS:[A-Z0-9:.]+)")
_RE_RESULT_ROW_META = re.compile(
    r"Hof van Cassatie\s*-\s*([0-9]{1,2}\s+[A-Za-z]+\s+[0-9]{4})\s*-\s*([A-Z]\.[0-9]{2}\.[0-9]{4}\.[A-Z])",
    re.IGNORECASE,
)


def _parse_date(text: str | None) -> date | None:
    if not text:
        return None
    cleaned = text.strip()
    try:
        return date.fromisoformat(cleaned)
    except ValueError:
        pass
    try:
        return dateutil_parser.parse(cleaned, dayfirst=True).date()
    except (ValueError, OverflowError, dateutil_parser.ParserError):
        return None


def _extract_token(html: str) -> str | None:
    match = _RE_FORM_TOKEN.search(html)
    return match.group(1) if match else None


def _extract_action_value(html: str) -> str | None:
    match = _RE_ACTION_VALUE.search(html)
    return match.group(1) if match else None


def _extract_next_value(html: str) -> str | None:
    match = _RE_NEXT_VALUE.search(html)
    return match.group(1) if match else None


def _extract_result_links(html: str) -> list[str]:
    links = []
    seen: set[str] = set()
    for raw_link in _RE_CONTENT_LINK.findall(html):
        clean = raw_link.split("#", 1)[0]
        if ":ARR." not in clean:
            continue
        if clean in seen:
            continue
        seen.add(clean)
        links.append(urljoin(BASE_URL, clean))
    return links


def _extract_result_cases(html: str) -> list[Case]:
    cases: list[Case] = []
    seen: set[str] = set()
    chunks = html.split("<tr>")
    for chunk in chunks:
        link_match = _RE_CONTENT_LINK.search(chunk)
        if not link_match:
            continue
        rel = link_match.group(1).split("#", 1)[0]
        if ":ARR." not in rel:
            continue
        link = urljoin(BASE_URL, rel)
        if link in seen:
            continue
        seen.add(link)

        ecli_match = _RE_ECLI.search(chunk)
        meta_match = _RE_RESULT_ROW_META.search(unescape(re.sub(r"<[^>]+>", " ", chunk)))
        if not meta_match:
            continue
        decision_date = _parse_date(meta_match.group(1))
        case_id = meta_match.group(2).upper()
        if not case_id.startswith("C."):
            continue

        cases.append(
            Case(
                case_id=case_id,
                link=link,
                decision_date=decision_date,
                jurisdiction="be",
                language="nl",
                full_text=None,
                metadata={
                    "ecli": (ecli_match.group(1).upper() if ecli_match else None),
                    "source": "juportal.be",
                },
            )
        )
    return cases


def _extract_case_id(page_text: str) -> str | None:
    match = _RE_ROLE.search(page_text)
    return match.group(1).upper() if match else None


def _extract_ecli(page_text: str) -> str | None:
    match = _RE_ECLI.search(page_text)
    return match.group(1).upper() if match else None


def _extract_decision_date(page_text: str) -> date | None:
    match = _RE_DATE.search(page_text)
    return _parse_date(match.group(1) if match else None)


def _extract_text(page_html: str) -> str | None:
    text = unescape(re.sub(r"<[^>]+>", "\n", page_html))
    lines = [line.strip() for line in text.splitlines()]
    cleaned = [line for line in lines if line]
    return "\n".join(cleaned) if cleaned else None


class BEScraper(BaseScraper):
    country = "Belgium"

    def scrape(
        self,
        start_date: date | None = None,
        end_date: date | None = None,
    ) -> list[Case]:
        start = start_date or date(2015, 1, 1)
        end = end_date or date.today()
        cases: list[Case] = []
        seen: set[str] = set()
        session = requests.Session()

        for year in range(start.year, end.year + 1):
            year_start = max(start, date(year, 1, 1))
            year_end = min(end, date(year, 12, 31))
            if year_start > year_end:
                continue
            year_cases = self._scrape_year(session, year_start, year_end)
            for case in year_cases:
                if not case.link or case.link in seen:
                    continue
                seen.add(case.link)
                cases.append(case)

        return cases

    def _scrape_year(
        self,
        session: requests.Session,
        start_date: date,
        end_date: date,
    ) -> list[Case]:
        log.info("Belgium %s to %s", start_date.isoformat(), end_date.isoformat())
        form_html = self._fetch_text(session, SEARCH_FORM_URL)
        if form_html is None:
            return []
        token = _extract_token(form_html)
        action_value = _extract_action_value(form_html)
        if not token or not action_value:
            return []

        payload = {
            "TOKEN": token,
            "action": action_value,
            "TRECHNOROLE": "C.",
            "TRECHDECISIONDE": start_date.isoformat(),
            "TRECHDECISIONA": end_date.isoformat(),
            "TRECHNPPAGE": "50",
            "TRECHORDER": "DATEDEC",
            "TRECHDESCASC": "DESC",
            "TRECHOPER": "AND",
            "TRECHLIMIT": "25000",
            "TRECHMODE": "SIMPLE",
            "TRECHSCORE": "1",
            "TRECHSHOWFICHES": "fiches",
        }
        page_html = self._post_text(session, SEARCH_FORM_URL, payload)
        if page_html is None:
            return []

        results: list[Case] = []
        seen_links: set[str] = set()
        for page_idx in range(1, MAX_PAGES_PER_QUERY + 1):
            links = _extract_result_links(page_html)
            if not links:
                break
            log.info("Belgium page %d: %d decision links", page_idx, len(links))
            page_cases = _extract_result_cases(page_html)
            for case in page_cases:
                if not case.link or case.link in seen_links:
                    continue
                seen_links.add(case.link)
                results.append(case)

            next_value = _extract_next_value(page_html)
            next_token = _extract_token(page_html)
            if not next_value or not next_token:
                break
            time.sleep(DELAY_SECONDS)
            page_html = self._post_text(
                session,
                SEARCH_RESULTS_URL,
                {"TOKEN": next_token, "next_page": next_value},
            )
            if page_html is None:
                break

        return [
            c for c in results
            if c.decision_date is not None
            and start_date <= c.decision_date <= end_date
        ]

    def _fetch_case(self, link: str) -> Case | None:
        html = self._fetch_url_text(link)
        if html is None:
            return None
        text = _extract_text(html)
        if text is None:
            return None

        case_id = _extract_case_id(text)
        if not case_id or not case_id.startswith("C."):
            return None

        decision_date = _extract_decision_date(text)
        ecli = _extract_ecli(text)
        return Case(
            case_id=case_id,
            link=link,
            decision_date=decision_date,
            jurisdiction="be",
            language="nl",
            full_text=text,
            metadata={"ecli": ecli, "source": "juportal.be"} if ecli else {"source": "juportal.be"},
        )

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

    def _fetch_text(self, session: requests.Session, url: str) -> str | None:
        try:
            response = session.get(url, timeout=30)
            if response.status_code == 429:
                time.sleep(RETRY_DELAY_SECONDS)
                response = session.get(url, timeout=30)
            if not response.ok:
                return None
            return response.text
        except requests.RequestException:
            return None

    def _post_text(self, session: requests.Session, url: str, data: dict[str, str]) -> str | None:
        try:
            response = session.post(url, data=data, timeout=30)
            if response.status_code == 429:
                time.sleep(RETRY_DELAY_SECONDS)
                response = session.post(url, data=data, timeout=30)
            if not response.ok:
                return None
            return response.text
        except requests.RequestException:
            return None