"""产品服务 — 业务逻辑层：扫码查询、CRUD"""
from __future__ import annotations
import uuid
from fastapi import HTTPException, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from app.models.product import Product
from app.models.production_order import ProductionOrder
from app.models.task import Task
from app.schemas.product import ProductCreate, ProductUpdate, ProductResponse, ProductScanResponse
from app.schemas.task import TaskSummaryResponse, TaskResponse


def _task_to_response(task: Task) -> TaskResponse:
    """将 Task ORM 对象递归转为 TaskResponse（含子任务树）"""
    return TaskResponse(
        id=task.id,
        product_id=task.product_id,
        parent_task_id=task.parent_task_id,
        task_name=task.task_name,
        assignee_id=task.assignee_id,
        status=task.status,
        notify_parent_on_complete=task.notify_parent_on_complete,
        is_rework=task.is_rework,
        reject_reason=task.reject_reason,
        received_at=task.received_at,
        completed_at=task.completed_at,
        created_at=task.created_at,
        child_tasks=[_task_to_response(c) for c in task.child_tasks],
    )


async def _load_task_tree(db: AsyncSession, product_id: uuid.UUID) -> list[TaskResponse]:
    """递归加载产品下的完整任务树"""
    # 先取顶层任务
    result = await db.execute(
        select(Task)
        .options(selectinload(Task.child_tasks))
        .where(
            Task.product_id == product_id,
            Task.parent_task_id.is_(None),
        )
        .order_by(Task.created_at)
    )
    top_tasks = result.scalars().all()

    # 递归加载每层子任务
    async def _load_children(t: Task):
        for child in t.child_tasks:
            child_result = await db.execute(
                select(Task)
                .options(selectinload(Task.child_tasks))
                .where(Task.id == child.id)
            )
            refreshed = child_result.scalar_one()
            t.child_tasks[t.child_tasks.index(child)] = refreshed
            await _load_children(refreshed)

    for task in top_tasks:
        await _load_children(task)

    return [_task_to_response(t) for t in top_tasks]


async def get_product_by_serial(db: AsyncSession, serial_number: str) -> ProductScanResponse:
    """扫码查询：根据 16 位序列号查出产品 + 所属订单 + 完整任务树"""
    result = await db.execute(
        select(Product)
        .options(
            selectinload(Product.order),
            selectinload(Product.parent_product),
        )
        .where(Product.serial_number == serial_number)
    )
    product = result.scalar_one_or_none()
    if not product:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"未找到序列号为 {serial_number} 的产品",
        )

    # 获取顶层任务摘要（兼容旧接口）
    top_tasks_result = await db.execute(
        select(Task)
        .where(
            Task.product_id == product.id,
            Task.parent_task_id.is_(None),
        )
        .order_by(Task.created_at)
    )
    top_tasks = top_tasks_result.scalars().all()

    # 获取完整任务树（递归嵌套，供前端渲染十字矩阵树状图）
    task_tree = await _load_task_tree(db, product.id)

    return ProductScanResponse(
        id=product.id,
        serial_number=product.serial_number,
        order_id=product.order_id,
        order_no=product.order.order_no if product.order else "",
        material_id=product.material_id,
        parent_product_id=product.parent_product_id,
        current_location_id=product.current_location_id,
        status=product.status,
        created_at=product.created_at,
        top_level_tasks=[
            TaskSummaryResponse.model_validate(t) for t in top_tasks
        ],
        task_tree=task_tree,
    )


async def get_product(db: AsyncSession, product_id: uuid.UUID) -> Product:
    """获取产品，不存在则 404"""
    result = await db.execute(
        select(Product)
        .options(selectinload(Product.order))
        .where(Product.id == product_id)
    )
    product = result.scalar_one_or_none()
    if not product:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"产品不存在: {product_id}",
        )
    return product


async def create_product(db: AsyncSession, data: ProductCreate) -> ProductResponse:
    """创建产品"""
    product = Product(**data.model_dump())
    db.add(product)
    await db.commit()
    await db.refresh(product)
    return ProductResponse.model_validate(product)


async def update_product(db: AsyncSession, product_id: uuid.UUID, data: ProductUpdate) -> ProductResponse:
    """更新产品"""
    product = await get_product(db, product_id)
    update_data = data.model_dump(exclude_unset=True)
    for field, value in update_data.items():
        setattr(product, field, value)
    await db.commit()
    await db.refresh(product)
    return ProductResponse.model_validate(product)


async def get_all_products(db: AsyncSession, skip: int = 0, limit: int = 50) -> list[ProductResponse]:
    """获取产品列表"""
    result = await db.execute(
        select(Product)
        .options(selectinload(Product.order))
        .offset(skip)
        .limit(limit)
        .order_by(Product.created_at.desc())
    )
    products = result.scalars().all()
    return [ProductResponse.model_validate(p) for p in products]