from fastapi import HTTPException
from sqlalchemy import delete, select
from sqlalchemy.orm import Session, selectinload

from .models import Product, RouteSection, RouteSectionProduct
from .serializers import model_dict


ROUTE_SECTION_DEFAULTS = [
    ("routes", "经典人文打卡线路", "黄果树、荔波小七孔、千户苗寨、镇远古城、梵净山一次串联", 0, 8),
    ("routes-outdoor", "极限山野户外野咖线路", "溶洞、峡谷、漂流、峰林骑行和山野咖啡组合", 8, 16),
    ("routes-mix", "人文+户外综合混搭线路", "非遗村寨、古城夜游、自然轻探险和精品住宿同程安排", 16, 24),
]


def route_section_error(status_code: int, message: str, code: str, details: dict | None = None) -> None:
    raise HTTPException(status_code=status_code, detail={"message": message, "code": code, "details": details or {}})


def route_section_dict(item: RouteSection, *, public: bool = False) -> dict:
    links = sorted(item.products or [], key=lambda link: (link.sortOrder, link.productId))
    if public:
        links = [link for link in links if link.product and link.product.status == "published"]

    data = {
        "id": item.id,
        "title": item.title,
        "subtitle": item.subtitle,
        "productIds": [link.productId for link in links],
        "isActive": item.isActive,
    }
    if not public:
        base = model_dict(item)
        data.update(
            {
                "sortOrder": item.sortOrder,
                "createdAt": base["createdAt"],
                "updatedAt": base["updatedAt"],
            }
        )
    return data


def route_section_query():
    return (
        select(RouteSection)
        .options(selectinload(RouteSection.products).selectinload(RouteSectionProduct.product))
        .order_by(RouteSection.sortOrder.asc())
    )




def validate_route_section_product_ids(db: Session, section_id: str, product_ids: list[str]) -> None:
    if len(set(product_ids)) != len(product_ids):
        route_section_error(422, "线路商品不能重复", "ROUTE_SECTION_PRODUCT_DUPLICATE", {"sectionId": section_id})
    if not product_ids:
        return

    products = db.scalars(select(Product).where(Product.id.in_(product_ids))).all()
    found_ids = {product.id for product in products}
    missing_ids = [product_id for product_id in product_ids if product_id not in found_ids]
    if missing_ids:
        route_section_error(422, "线路商品不存在", "ROUTE_SECTION_PRODUCT_NOT_FOUND", {"productIds": missing_ids})

    conflicts = db.scalars(
        select(RouteSectionProduct).where(
            RouteSectionProduct.productId.in_(product_ids),
            RouteSectionProduct.sectionId != section_id,
        )
    ).all()
    if conflicts:
        conflict = conflicts[0]
        route_section_error(
            409,
            "同一线路商品不能同时属于多个精选线路子分组",
            "ROUTE_SECTION_PRODUCT_CONFLICT",
            {"productId": conflict.productId, "sectionId": conflict.sectionId},
        )


def replace_route_section_products(db: Session, section: RouteSection, product_ids: list[str]) -> None:
    validate_route_section_product_ids(db, section.id, product_ids)
    db.execute(delete(RouteSectionProduct).where(RouteSectionProduct.sectionId == section.id))
    db.flush()
    section.products = []
    for index, product_id in enumerate(product_ids):
        link = RouteSectionProduct(sectionId=section.id, productId=product_id, sortOrder=index)
        section.products.append(link)
        db.add(link)