"""资产业务逻辑：CRUD + 统计聚合

统一处理 Asset 主表与其一对一详情表（VPSDetail/DomainDetail/AIAccount）的联动。
"""

from datetime import date
from typing import List, Optional

from fastapi import HTTPException, status
from sqlmodel import Session, select

from app.models.asset import (
    AIAccount,
    Asset,
    AssetStatus,
    AssetType,
    DomainDetail,
    VPSDetail,
)
from app.schemas.asset import (
    AIAccountRead,
    AssetCreate,
    AssetRead,
    AssetUpdate,
    DomainDetailRead,
    VPSDetailRead,
)

# 资产类型 -> (AssetCreate/Update 中的字段名, 详情表模型)
DETAIL_MAP = {
    AssetType.VPS: ("vps_detail", VPSDetail),
    AssetType.DOMAIN: ("domain_detail", DomainDetail),
    AssetType.AI_AGENT: ("ai_detail", AIAccount),
}

# 允许排序的字段白名单
SORTABLE_FIELDS = {"expiry_date", "name", "created_at", "cost", "updated_at"}


# --------------------------------------------------------------------------- #
# 辅助函数
# --------------------------------------------------------------------------- #
def _days_to_expiry(expiry_date: Optional[date]) -> Optional[int]:
    """计算距到期天数（已过期为负数），无到期日返回 None"""
    if not expiry_date:
        return None
    return (expiry_date - date.today()).days


def _get_detail(session: Session, asset: Asset):
    """根据资产类型读取对应详情记录"""
    item = DETAIL_MAP.get(asset.asset_type)
    if not item:
        return None
    _, model = item
    return session.exec(select(model).where(model.asset_id == asset.id)).first()


def _to_read(asset: Asset, detail) -> AssetRead:
    """组装 AssetRead 输出（主表 + 详情 + 计算字段）"""
    read = AssetRead.model_validate(asset)
    read.days_to_expiry = _days_to_expiry(asset.expiry_date)
    if isinstance(detail, VPSDetail):
        read.vps_detail = VPSDetailRead.model_validate(detail)
    elif isinstance(detail, DomainDetail):
        read.domain_detail = DomainDetailRead.model_validate(detail)
    elif isinstance(detail, AIAccount):
        read.ai_detail = AIAccountRead.model_validate(detail)
    return read


# --------------------------------------------------------------------------- #
# CRUD
# --------------------------------------------------------------------------- #
def create_asset(session: Session, data: AssetCreate) -> AssetRead:
    """创建资产及其详情"""
    item = DETAIL_MAP.get(data.asset_type)
    detail_in = None
    model = None
    if item:
        field, model = item
        detail_in = getattr(data, field)
        if detail_in is None:
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail=f"asset_type={data.asset_type.value} 需要提供 {field}",
            )

    asset_data = data.model_dump(
        exclude={"vps_detail", "domain_detail", "ai_detail"}
    )
    asset = Asset(**asset_data)
    session.add(asset)
    session.commit()
    session.refresh(asset)

    detail = None
    if model is not None and detail_in is not None:
        detail = model(asset_id=asset.id, **detail_in.model_dump())
        session.add(detail)
        session.commit()
        session.refresh(detail)

    return _to_read(asset, detail)


def get_asset(session: Session, asset_id: int) -> AssetRead:
    """读取单个资产（含详情）"""
    asset = session.get(Asset, asset_id)
    if not asset:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="资产不存在")
    return _to_read(asset, _get_detail(session, asset))


def update_asset(session: Session, asset_id: int, data: AssetUpdate) -> AssetRead:
    """更新资产主表及详情（仅更新传入字段）"""
    asset = session.get(Asset, asset_id)
    if not asset:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="资产不存在")

    main_fields = data.model_dump(
        exclude_unset=True, exclude={"vps_detail", "domain_detail", "ai_detail"}
    )
    for key, value in main_fields.items():
        setattr(asset, key, value)
    session.add(asset)

    # 详情表：以更新后的 asset_type 为准
    detail = None
    item = DETAIL_MAP.get(asset.asset_type)
    if item:
        field, model = item
        detail_in = getattr(data, field)
        existing = session.exec(
            select(model).where(model.asset_id == asset.id)
        ).first()
        if detail_in is not None:
            if existing:
                for key, value in detail_in.model_dump().items():
                    setattr(existing, key, value)
                session.add(existing)
                detail = existing
            else:
                detail = model(asset_id=asset.id, **detail_in.model_dump())
                session.add(detail)
        else:
            detail = existing

    session.commit()
    session.refresh(asset)
    if detail is not None:
        session.refresh(detail)
    return _to_read(asset, detail)


def delete_asset(session: Session, asset_id: int) -> None:
    """删除资产及其详情"""
    asset = session.get(Asset, asset_id)
    if not asset:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="资产不存在")
    detail = _get_detail(session, asset)
    if detail is not None:
        session.delete(detail)
    session.delete(asset)
    session.commit()


def list_assets(
    session: Session,
    asset_type: Optional[AssetType] = None,
    asset_status: Optional[AssetStatus] = None,
    is_archived: Optional[bool] = None,
    q: Optional[str] = None,
    sort: str = "expiry_date",
    order: str = "asc",
) -> List[AssetRead]:
    """资产列表（筛选 + 搜索 + 排序）"""
    stmt = select(Asset)
    if asset_type is not None:
        stmt = stmt.where(Asset.asset_type == asset_type)
    if asset_status is not None:
        stmt = stmt.where(Asset.status == asset_status)
    if is_archived is not None:
        stmt = stmt.where(Asset.is_archived == is_archived)
    if q:
        pattern = f"%{q}%"
        stmt = stmt.where(Asset.name.like(pattern) | Asset.provider.like(pattern))

    sort_col = getattr(Asset, sort if sort in SORTABLE_FIELDS else "expiry_date")
    stmt = stmt.order_by(sort_col.desc() if order == "desc" else sort_col.asc())

    assets = session.exec(stmt).all()
    return [_to_read(a, _get_detail(session, a)) for a in assets]


# --------------------------------------------------------------------------- #
# 统计
# --------------------------------------------------------------------------- #
def get_overview(session: Session) -> dict:
    """资产总览：数量分布、异常数、到期预警、支出合计"""
    assets = session.exec(select(Asset)).all()
    today = date.today()

    by_type: dict = {}
    by_status: dict = {}
    abnormal = 0
    expiring_30 = 0
    year_cost = 0.0
    month_cost = 0.0

    for a in assets:
        by_type[a.asset_type.value] = by_type.get(a.asset_type.value, 0) + 1
        by_status[a.status.value] = by_status.get(a.status.value, 0) + 1
        if a.status in (AssetStatus.STOPPED, AssetStatus.EXPIRED):
            abnormal += 1
        if a.expiry_date:
            days = (a.expiry_date - today).days
            if 0 <= days <= 30:
                expiring_30 += 1
            if a.expiry_date.year == today.year:
                year_cost += a.cost
                if a.expiry_date.month == today.month:
                    month_cost += a.cost

    return {
        "total": len(assets),
        "by_type": by_type,
        "by_status": by_status,
        "abnormal_count": abnormal,
        "expiring_30": expiring_30,
        "year_cost": round(year_cost, 2),
        "month_cost": round(month_cost, 2),
    }


def get_expiring(session: Session, days: int = 30) -> List[AssetRead]:
    """N 天内到期资产列表（按剩余天数升序）"""
    today = date.today()
    assets = session.exec(select(Asset).where(Asset.expiry_date.is_not(None))).all()
    result = []
    for a in assets:
        delta = (a.expiry_date - today).days
        if 0 <= delta <= days:
            result.append(_to_read(a, _get_detail(session, a)))
    result.sort(key=lambda x: x.days_to_expiry if x.days_to_expiry is not None else 10**9)
    return result