"""B - 攻防数据切片: 进球/射门/控球/xG 聚合(stats)。"""
from __future__ import annotations

from typing import TYPE_CHECKING

from src.db.base import AsyncSessionLocal
from src.llm.slices.common import MatchHeader, SliceResult, _is_stats_available
from src.llm.slices.form import _get_form

if TYPE_CHECKING:
    from sqlalchemy.ext.asyncio import AsyncSession


async def stats_slice(header: MatchHeader, *, limit: int = 10, before=None, db: AsyncSession | None = None) -> SliceResult:
    """B - 攻防数据切片: 进球、射门、控球,评估攻防强度。before=match_date 用于回测。

    db: 可选共享 session,避免每个切片独立建连(见 context_builder 模块 docstring)。
    """
    if db is not None:
        home_form = await _get_form(db, header.home_team_id, before=before, limit=limit)
        away_form = await _get_form(db, header.away_team_id, before=before, limit=limit)
    else:
        async with AsyncSessionLocal() as new_db:
            home_form = await _get_form(new_db, header.home_team_id, before=before, limit=limit)
            away_form = await _get_form(new_db, header.away_team_id, before=before, limit=limit)
    lines = [f"── 攻防数据(近 {limit} 场) ──"]
    n_total = 0
    # P0-1 修复:每场历史比赛必须根据「该队当时是主是客」判断 side,
    # 不能用本场 side 硬套 —— 否则进球/失球/xG 全部算反。
    for label, name, form, team_id in (
        ("主队", header.home_name, home_form, header.home_team_id),
        ("客队", header.away_name, away_form, header.away_team_id),
    ):
        if form:
            gf = ga = shots = sot = poss = xg = xga = 0
            n = n_shots = n_poss = n_xg = 0
            for fm in form:
                if fm.home_goals is None: continue
                is_home = (fm.home_team_id == team_id)
                gf += fm.home_goals if is_home else fm.away_goals
                ga += fm.away_goals if is_home else fm.home_goals
                n += 1
                # 只使用 cutoff 之前已可用的统计数据
                if fm.stats and _is_stats_available(fm.stats, before):
                    if fm.stats.home_shots is not None:
                        shots += fm.stats.home_shots if is_home else fm.stats.away_shots
                        sot += fm.stats.home_shots_on_target if is_home else fm.stats.away_shots_on_target
                        n_shots += 1
                    if fm.stats.home_possession is not None:
                        poss += fm.stats.home_possession if is_home else (100 - fm.stats.home_possession)
                        n_poss += 1
                    if fm.stats.home_xg is not None:
                        xg += fm.stats.home_xg if is_home else fm.stats.away_xg
                        xga += fm.stats.away_xg if is_home else fm.stats.home_xg
                        n_xg += 1
            n_total += n
            if n > 0:
                lines.append(f"  {label} {name}:")
                lines.append(f"    场均进球 {gf/n:.2f}, 场均失球 {ga/n:.2f}")
                if n_shots: lines.append(f"    场均射门 {shots/n_shots:.1f}, 射正 {sot/n_shots:.1f}")
                if n_poss: lines.append(f"    平均控球 {poss/n_poss:.1f}%")
                if n_xg: lines.append(f"    场均 xG {xg/n_xg:.2f}, 场均被 xG {xga/n_xg:.2f}")
            else:
                lines.append(f"  {label} {name}: 无比分数据")
        else:
            lines.append(f"  {label} {name}: 无数据")
    return SliceResult(text="\n".join(lines), has_data=n_total > 0, n_records=n_total)