"""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, TaskRecordResponse


def _task_to_response(task: Task) -> TaskResponse:
    """将 Task ORM 对象递归转为 TaskResponse（含子任务树）"""
    product_sn = ""
    product_material = ""
    try:
        if task.product:
            product_sn = task.product.serial_number or ""
            product_material = (task.product.material_name or task.product.material_id or "")
    except Exception:
        pass
    return TaskResponse(
        id=task.id,
        product_id=task.product_id,
        product_sn=product_sn,
        product_material=product_material,
        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,
        remark=task.remark,
        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],
        records=[TaskRecordResponse.model_validate(r) for r in (task.records or [])],
    )


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), selectinload(Task.records))
        .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), selectinload(Task.records))
                .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,
        external_serial=product.external_serial,
        order_id=product.order_id,
        order_no=product.order.order_no if product.order else "",
        material_id=product.material_id,
        material_name=product.material_name,
        spec_model=product.spec_model,
        category=product.category,
        material_type=product.material_type,
        parent_product_id=product.parent_product_id,
        current_location_id=product.current_location_id,
        overall_status=product.overall_status,
        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 — 自动生成 16 位 HEX 序列号"""
    from app.services.counter_service import ensure_sequence, next_hex_id
    from app.models.production_order import ProductionOrder

    await ensure_sequence(db)
    hex_id = await next_hex_id(db)

    # 处理订单: 如果传了 order_no 但没传 order_id，查找或创建
    order_id = data.order_id
    if not order_id and data.order_no:
        result = await db.execute(
            select(ProductionOrder).where(ProductionOrder.order_no == data.order_no.strip())
        )
        existing = result.scalar_one_or_none()
        if existing:
            order_id = existing.id
        else:
            new_order = ProductionOrder(order_no=data.order_no.strip())
            db.add(new_order)
            await db.flush()
            order_id = new_order.id

    product = Product(
        serial_number=hex_id,
        order_id=order_id,
        material_id=data.material_id,
        material_name=data.material_name or None,
        spec_model=data.spec_model or None,
        category=data.category or None,
        material_type=data.material_type or None,
        external_serial=data.external_serial,
        parent_product_id=data.parent_product_id,
    )
    db.add(product)
    await db.commit()
    await db.refresh(product, ["order"])
    return ProductResponse(
        id=product.id,
        serial_number=product.serial_number,
        external_serial=product.external_serial,
        order_id=product.order_id,
        order_no=product.order.order_no if product.order else (data.order_no or ""),
        material_id=product.material_id,
        material_name=product.material_name,
        spec_model=product.spec_model,
        category=product.category,
        material_type=product.material_type,
        parent_product_id=product.parent_product_id,
        current_location_id=product.current_location_id,
        overall_status=product.overall_status,
        status=product.status,
        created_at=product.created_at,
    )


async def update_product(db: AsyncSession, product_id: uuid.UUID, data: ProductUpdate) -> ProductResponse:
    """更新产品"""
    from app.models.production_order import ProductionOrder

    product = await get_product(db, product_id)
    update_data = data.model_dump(exclude_unset=True)

    # 处理 order_no → order_id 映射
    if "order_no" in update_data:
        order_no_val = update_data.pop("order_no")
        if order_no_val and order_no_val.strip():
            result = await db.execute(
                select(ProductionOrder).where(ProductionOrder.order_no == order_no_val.strip())
            )
            existing = result.scalar_one_or_none()
            if existing:
                product.order_id = existing.id
            else:
                new_order = ProductionOrder(order_no=order_no_val.strip())
                db.add(new_order)
                await db.flush()
                product.order_id = new_order.id
        else:
            product.order_id = None

    for field, value in update_data.items():
        setattr(product, field, value)
    await db.commit()
    await db.refresh(product, ["order"])
    return ProductResponse(
        id=product.id,
        serial_number=product.serial_number,
        external_serial=product.external_serial,
        order_id=product.order_id,
        order_no=product.order.order_no if product.order else "",
        material_id=product.material_id,
        material_name=product.material_name,
        spec_model=product.spec_model,
        category=product.category,
        material_type=product.material_type,
        parent_product_id=product.parent_product_id,
        current_location_id=product.current_location_id,
        overall_status=product.overall_status,
        status=product.status,
        created_at=product.created_at,
    )


VALID_OVERALL_STATUS = {"备货", "生产", "测试", "维修", "在库"}


async def update_overall_status(db: AsyncSession, serial_number: str, status_value: str) -> ProductScanResponse:
    """更新产品宏观状态"""
    if status_value not in VALID_OVERALL_STATUS:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"无效状态: {status_value}，合法值: {', '.join(sorted(VALID_OVERALL_STATUS))}",
        )

    result = await db.execute(
        select(Product)
        .options(selectinload(Product.order))
        .where(Product.serial_number == serial_number)
    )
    product = result.scalar_one_or_none()
    if not product:
        raise HTTPException(status_code=404, detail=f"未找到序列号 {serial_number} 的产品")

    product.overall_status = status_value
    await db.commit()
    await db.refresh(product)

    return await get_product_by_serial(db, serial_number)


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(
            id=p.id,
            serial_number=p.serial_number,
            external_serial=p.external_serial,
            order_id=p.order_id,
            order_no=p.order.order_no if p.order else "",
            material_id=p.material_id,
            material_name=p.material_name,
            spec_model=p.spec_model,
            category=p.category,
            material_type=p.material_type,
            parent_product_id=p.parent_product_id,
            current_location_id=p.current_location_id,
            overall_status=p.overall_status,
            status=p.status,
            created_at=p.created_at,
        )
        for p in products
    ]