from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, func, desc
from typing import Optional
from datetime import datetime

from app.database import get_db
from app.models.plan import ProductionPlan
from app.schemas.plan import PlanCreate, PlanUpdate, PlanOut, PlanTemplate
from app.schemas.common import Response, PageResponse
from app.services.auth_service import get_current_user

router = APIRouter()


def _parse_dt(s):
    if not s:
        return None
    try:
        return datetime.fromisoformat(s.replace('Z', ''))
    except Exception:
        return None


TEMPLATE_FIELDS = (
    "steel_grade", "incoming_thickness", "product_thickness",
    "deviation_upper", "deviation_lower",
    "incoming_width", "product_width",
    "packaging_req", "trim_req", "rolling_mode",
    "coil_diameter", "split_count", "next_process",
    "incoming_weight", "incoming_od", "split_weights",
)


@router.get("/", response_model=Response[PageResponse[PlanOut]])
async def list_plans(
    page: int = 1,
    page_size: int = 20,
    status: Optional[str] = None,
    start_date: Optional[str] = Query(None),
    end_date: Optional[str] = Query(None),
    db: AsyncSession = Depends(get_db),
    _ = Depends(get_current_user),
):
    query = select(ProductionPlan).order_by(desc(ProductionPlan.plan_date))
    if status:
        query = query.where(ProductionPlan.status == status)
    _sd = _parse_dt(start_date)
    if _sd:
        query = query.where(ProductionPlan.plan_date >= _sd)
    _ed = _parse_dt(end_date)
    if _ed:
        query = query.where(ProductionPlan.plan_date <= _ed)

    total = (await db.execute(select(func.count()).select_from(query.subquery()))).scalar()
    result = await db.execute(query.offset((page - 1) * page_size).limit(page_size))
    items = [PlanOut.model_validate(p) for p in result.scalars()]
    return Response.ok(PageResponse(total=total, page=page, page_size=page_size, items=items))


@router.get("/last-template", response_model=Response[PlanTemplate])
async def get_last_template(db: AsyncSession = Depends(get_db), _ = Depends(get_current_user)):
    """最近一条计划的工艺字段（不含计划号/卷号/时间），用于新增时回填。"""
    result = await db.execute(select(ProductionPlan).order_by(desc(ProductionPlan.created_at)).limit(1))
    p = result.scalar_one_or_none()
    if not p:
        return Response.ok(PlanTemplate())
    return Response.ok(PlanTemplate(**{k: getattr(p, k, None) for k in TEMPLATE_FIELDS}))


@router.post("/", response_model=Response[PlanOut])
async def create_plan(
    body: PlanCreate,
    db: AsyncSession = Depends(get_db),
    current_user = Depends(get_current_user),
):
    existing = await db.execute(select(ProductionPlan).where(ProductionPlan.plan_no == body.plan_no))
    if existing.scalar_one_or_none():
        raise HTTPException(status_code=400, detail="计划号已存在")
    plan = ProductionPlan(**body.model_dump(), created_by=current_user.username)
    db.add(plan)
    await db.flush()
    return Response.ok(PlanOut.model_validate(plan))


@router.get("/{plan_id}", response_model=Response[PlanOut])
async def get_plan(plan_id: int, db: AsyncSession = Depends(get_db), _ = Depends(get_current_user)):
    result = await db.execute(select(ProductionPlan).where(ProductionPlan.id == plan_id))
    plan = result.scalar_one_or_none()
    if not plan:
        raise HTTPException(status_code=404, detail="计划不存在")
    return Response.ok(PlanOut.model_validate(plan))


@router.put("/{plan_id}", response_model=Response[PlanOut])
async def update_plan(
    plan_id: int,
    body: PlanUpdate,
    db: AsyncSession = Depends(get_db),
    _ = Depends(get_current_user),
):
    result = await db.execute(select(ProductionPlan).where(ProductionPlan.id == plan_id))
    plan = result.scalar_one_or_none()
    if not plan:
        raise HTTPException(status_code=404, detail="计划不存在")
    for k, v in body.model_dump(exclude_none=True).items():
        setattr(plan, k, v)
    await db.flush()
    return Response.ok(PlanOut.model_validate(plan))


@router.patch("/{plan_id}/confirm", response_model=Response[PlanOut])
async def confirm_plan(plan_id: int, db: AsyncSession = Depends(get_db), _ = Depends(get_current_user)):
    result = await db.execute(select(ProductionPlan).where(ProductionPlan.id == plan_id))
    plan = result.scalar_one_or_none()
    if not plan:
        raise HTTPException(status_code=404, detail="计划不存在")
    plan.status = "online"
    await db.flush()
    return Response.ok(PlanOut.model_validate(plan))


@router.patch("/{plan_id}/start", response_model=Response[PlanOut])
async def start_producing(plan_id: int, db: AsyncSession = Depends(get_db), _ = Depends(get_current_user)):
    """移动到入口，开始生产：本条→producing，其它 producing→online（单卷在产）。"""
    result = await db.execute(select(ProductionPlan).where(ProductionPlan.id == plan_id))
    plan = result.scalar_one_or_none()
    if not plan:
        raise HTTPException(status_code=404, detail="计划不存在")
    # 其它正在生产的全部回退为在线（强制单卷在产）
    others = await db.execute(
        select(ProductionPlan).where(
            ProductionPlan.status == "producing",
            ProductionPlan.id != plan_id,
        )
    )
    for o in others.scalars():
        o.status = "online"
    plan.status = "producing"
    await db.flush()
    return Response.ok(PlanOut.model_validate(plan))