"""统计 API(Phase 2 Task 9,spec §7.6): /api/platform/stats(超管,可
?tenant= 单租户下钻)与 /api/platform/tenants/{slug}/stats(本租户管理员)。

聚合逻辑全在 app/platform/stats.py(纯查询函数);本层只做鉴权、日期解析
(复用 data_routes 的 _parse_dt——ISO 日期/日期时间,日期-only 的 to 含
当日全天,边界含,naive UTC)与 runtime 获取。

多租户合并纪律(**禁 ATTACH**,spec §7.6: 默认上限 10 个附加库):
逐租户库查询 → merge_stats 应用层合并。合并范围:
- 含停用租户——Task 8 偏差 4 语义(后台可见停用租户数据)在统计同样
  适用: 停用只是聊天面 503,历史数据仍属后台可见资产;
- 跳过库文件不存在的未懒建租户——零数据等价,且不为一次统计主动建
  空库(保持 engine 懒建纪律;与 main.lifespan 启动清扫同一 db_path.
  exists() 判据,差异是清扫只扫 active、统计含停用,口径在此声明)。
显式单租户(?tenant= 与 /tenants/{slug}/stats)沿用 data_routes 的
_runtime_by_slug 语义: 未懒建租户首次查询触发建库(Task 8 语义,空
统计 200 不炸)。
"""
from fastapi import APIRouter, Depends, Query, Request

from app.platform.auth import require_super
from app.platform.registry import TenantRuntime
from app.platform.routes.data_routes import _parse_dt, _runtime_by_slug
from app.platform.routes.tenant_routes import _tenant_guard
from app.platform.stats import collect_stats, merge_stats

router = APIRouter(prefix="/api/platform", tags=["platform-stats"])


def _bounds(from_raw: str | None, to_raw: str | None) -> tuple:
    """?from/&to= → (from_dt, to_dt) naive UTC 闭区间(解析/报错同 data_routes)。"""
    bound_from = _parse_dt(from_raw, "from") if from_raw else None
    bound_to = _parse_dt(to_raw, "to", end_of_day=True) if to_raw else None
    return bound_from, bound_to


async def _stats_for(
        rt: TenantRuntime, bound_from, bound_to) -> dict:
    """单个就绪 runtime 的统计(租户库 session 上跑全部聚合)。"""
    async with rt.session_factory() as db:
        return await collect_stats(db, from_dt=bound_from, to_dt=bound_to)


@router.get("/stats")
async def platform_stats(
        request: Request,
        tenant: str | None = None,
        from_dt: str | None = Query(default=None, alias="from"),
        to_dt: str | None = Query(default=None, alias="to"),
        user=Depends(require_super)):
    """平台统计(超管): 缺省全部租户合并(逐库查询应用层合并,禁 ATTACH),
    ?tenant=slug 单租户下钻(未知 slug 404)。?from/&to= 闭区间筛选。"""
    bound_from, bound_to = _bounds(from_dt, to_dt)
    if tenant is not None:
        rt = await _runtime_by_slug(request, tenant)
        return await _stats_for(rt, bound_from, bound_to)

    registry = request.app.state.registry
    parts = []
    for rt in registry.runtimes():
        # 合并范围口径见模块 docstring: 含停用、跳过无库文件(不建空库)
        if not rt.db_path.exists():
            continue
        ready = await registry.ensure_ready(rt)
        parts.append(await _stats_for(ready, bound_from, bound_to))
    return merge_stats(parts)


@router.get("/tenants/{slug}/stats")
async def tenant_stats(
        slug: str, request: Request,
        from_dt: str | None = Query(default=None, alias="from"),
        to_dt: str | None = Query(default=None, alias="to"),
        user=Depends(_tenant_guard)):
    """单租户统计(本租户管理员或超管): 查询/懒建语义同 data_routes。"""
    bound_from, bound_to = _bounds(from_dt, to_dt)
    rt = await _runtime_by_slug(request, slug)
    return await _stats_for(rt, bound_from, bound_to)