"""Understat xG 数据源。

迁移自旧项目 app/data/sources/understat.py,改成 async。
使用 Repository 模式进行数据访问,不直接控制事务。
"""
from __future__ import annotations

import asyncio
import json
import logging
import random
import re
from datetime import datetime, timedelta, timezone

from sqlalchemy import select
from sqlalchemy.orm import selectinload

from src.core.http_client import get_client
from src.data.config import FDCO_TO_UNDERSTAT, LEAGUE_NAMES
from src.data.normalize import normalize_understat
from src.data.sources import register
from src.db.models import League, Match, MatchStats, Team

logger = logging.getLogger(__name__)

UNDERSTAT_BASE = "https://understat.com/getLeagueData/{league}/{season}"


async def fetch_understat(league_code: str, season: int) -> list[dict]:
    """抓取 understat 单赛季 xG 数据。

    Args:
        league_code: fdco 风格代码,如 'E0'
        season: 赛季起始年,如 2025 表示 2025-2026 赛季

    Returns:
        比赛数组,每项含 datetime/h/a/xG
    """
    understat_league = FDCO_TO_UNDERSTAT.get(league_code)
    if understat_league is None:
        raise ValueError(f"未知联赛代码: {league_code}")

    url = UNDERSTAT_BASE.format(league=understat_league, season=season)
    headers = {
        "User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36",
        "X-Requested-With": "XMLHttpRequest",
        "Referer": f"https://understat.com/league/{understat_league}/{season}",
    }

    # 重试:网络错误 / 5xx / 429
    last_exc: Exception | None = None
    for attempt in range(3):
        try:
            client = get_client()
            resp = await client.get(url, headers=headers, timeout=30)
            resp.raise_for_status()
            break
        except Exception as e:
            last_exc = e
            if attempt == 2:
                raise
            delay = min(2 ** attempt, 8) + random.uniform(0, 1)
            logger.warning("understat fetch failed, retry %d in %.1fs: %s", attempt + 1, delay, e)
            await asyncio.sleep(delay)
    else:
        raise RuntimeError(f"understat fetch failed: {last_exc}")

    # understat 返回 JS 对象,需要提取 JSON
    text = resp.text
    # 匹配 var datesData = JSON.parse('...');
    match = re.search(r"var\s+datesData\s*=\s*JSON\.parse\('([^']+)'\)", text)
    if not match:
        logger.warning("understat 响应格式不符: %s...", text[:200])
        return []
    decoded = match.group(1).encode().decode("unicode_escape")
    data = json.loads(decoded)
    return data


def _match_key(home_team_id: int, away_team_id: int, match_date) -> tuple[int, int, str]:
    """比赛去重键:(主队, 客队, 天级日期 ISO 字符串)。

    统一在这里构造,避免"预加载时用 str(date)、写入时用 isoformat()"这类
    隐式格式依赖 —— 两者当前恰好相等,但一旦有人改动其一就会静默失配,
    导致所有比赛被判为不存在而重复插入。
    """
    if hasattr(match_date, "date") and callable(match_date.date):
        match_date = match_date.date()
    return (home_team_id, away_team_id, match_date.isoformat() if match_date is not None else "")


@register
class UnderstatSource:
    """understat xG 数据源(实现 DataSource 协议)。"""

    name = "understat"

    async def ingest(self, db, *, league: str, season: int) -> dict:
        """采集 understat xG → 回填到现有 Match。只回填 xG 字段,不创建新 Match。

        注意: 本方法不控制事务(commit/rollback),由调用方通过 UnitOfWork 控制。

        P1-3: 批量查询优化,将单赛季 380 场 × 3 次 DB 往返降为 3 次查询。
        """
        from src.db.repositories import LeagueRepository, TeamRepository

        result = {"updated": 0, "skipped": 0, "unmatched": 0, "errors": []}

        try:
            raw_matches = await fetch_understat(league, season)
        except Exception as e:
            logger.exception("understat fetch failed for %s %s", league, season)
            result["errors"].append(f"fetch failed: {e}")
            return result

        # 使用 Repository
        league_repo = LeagueRepository(db)
        team_repo = TeamRepository(db)

        # 查联赛
        league_obj = await league_repo.get_by_code(league)
        if league_obj is None:
            result["errors"].append(f"league {league} not found in DB")
            return result

        # === 批量优化: 一次规范化,收集球队名和日期 ===
        normalized_matches: list = []
        all_team_names: set[str] = set()
        for raw in raw_matches:
            if not raw.get("isResult"):
                continue
            try:
                nm = normalize_understat(raw, league)
                if nm is None:
                    result["skipped"] += 1
                    continue
            except Exception as e:
                result["errors"].append(f"normalize: {e}")
                continue
            normalized_matches.append((nm, raw))
            all_team_names.add(nm.home_team)
            all_team_names.add(nm.away_team)

        if not normalized_matches:
            return result

        # === 批量查询球队(1 次 DB 往返) ===
        team_name_to_id = {}
        if all_team_names:
            teams = await team_repo.get_all_by_names(list(all_team_names))
            team_name_to_id = {name: team.id for name, team in teams.items()}

        # === 批量查询已有比赛(1 次 DB 往返,按日期范围) ===
        match_dict: dict[tuple, Match] = {}
        dates = [nm.date for nm, _ in normalized_matches if nm.date is not None]
        if dates:
            min_dt = min(dates) - timedelta(days=30)
            max_dt = max(dates) + timedelta(days=30)
            stmt = (
                select(Match)
                .options(selectinload(Match.stats))
                .where(Match.league_id == league_obj.id)
                .where(Match.match_date >= min_dt)
                .where(Match.match_date <= max_dt)
            )
            for m in (await db.execute(stmt)).scalars():
                key = _match_key(m.home_team_id, m.away_team_id, m.match_date_date)
                match_dict[key] = m

        # === 内存匹配 + 回填 xG ===
        for nm, raw in normalized_matches:
            home_team_id = team_name_to_id.get(nm.home_team)
            away_team_id = team_name_to_id.get(nm.away_team)
            if home_team_id is None or away_team_id is None:
                result["unmatched"] += 1
                continue

            match_key = _match_key(home_team_id, away_team_id, nm.date)
            existing = match_dict.get(match_key)
            if existing is None:
                result["unmatched"] += 1
                continue

            # 回填 xG
            if existing.stats is None and (nm.home_xg is not None or nm.away_xg is not None):
                now = datetime.now(timezone.utc)
                existing.stats = MatchStats(
                    match_id=existing.id,
                    source="understat",
                    source_event_id=str(raw.get("id", "")),
                    retrieved_at=now,
                    available_at=now,
                )
                db.add(existing.stats)
                await db.flush()
            if existing.stats is not None:
                if existing.stats.home_xg is None and nm.home_xg is not None:
                    existing.stats.home_xg = nm.home_xg
                    result["updated"] += 1
                if existing.stats.away_xg is None and nm.away_xg is not None:
                    existing.stats.away_xg = nm.away_xg

        # 注意: 不在此处 commit,由调用方 UnitOfWork 控制事务
        return result