"""Suppliers CRUD — v2.6: 1 supplier → exactly 1 category (category_id FK)."""
from fastapi import APIRouter, Depends, Query
from sqlalchemy import func, or_, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.auth import require_procurement_writer, require_role
from app.db.engine import get_db
from app.models.catalog import MaterialCategory
from app.models.procurement import Quote, Supplier
from app.schemas.procurement import SupplierCreate, SupplierUpdate
from app.utils.errors import ConflictError, NotFoundError
from app.utils.pagination import paginate, sort_query
from app.utils.serialization import to_iso

router = APIRouter(prefix="/suppliers", tags=["suppliers"])
_procurement_writer = require_procurement_writer()


def supplier_to_dict(supplier: Supplier, category: MaterialCategory | None = None) -> dict:
    return {
        "id": str(supplier.id),
        "name": supplier.name,
        "category_id": str(supplier.category_id),
        "category": {
            "id": str(category.id),
            "slug": category.slug,
            "name": category.name,
        } if category else None,
        "location": supplier.location,
        "phone": supplier.phone,
        "contact_person": supplier.contact_person,
        "tax_id": supplier.tax_id,
        "created_at": to_iso(supplier.created_at),
    }


async def _category_or_404(db: AsyncSession, category_id) -> MaterialCategory:
    category = await db.get(MaterialCategory, category_id)
    if category is None:
        raise NotFoundError("دسته‌بندی یافت نشد", field="category_id")
    return category


@router.get("")
async def list_suppliers(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    q: str | None = None,
    category_id=None,
    sort: str | None = None,
    db: AsyncSession = Depends(get_db),
):
    stmt = select(Supplier)
    if q:
        stmt = stmt.where(
            or_(
                Supplier.name.ilike(f"%{q}%"),
                Supplier.location.ilike(f"%{q}%"),
                Supplier.phone.ilike(f"%{q}%"),
            )
        )
    if category_id:
        stmt = stmt.where(Supplier.category_id == category_id)
    stmt = sort_query(stmt, Supplier, sort)
    items, meta = await paginate(stmt, page, page_size, db)
    cat_ids = {s.category_id for s in items}
    cats = {}
    if cat_ids:
        cats = {
            c.id: c for c in (await db.execute(select(MaterialCategory).where(MaterialCategory.id.in_(cat_ids)))).scalars()
        }
    return {"data": [supplier_to_dict(s, cats.get(s.category_id)) for s in items], "meta": meta}


@router.post("", status_code=201)
async def create_supplier(
    payload: SupplierCreate,
    db: AsyncSession = Depends(get_db),
    _auth=Depends(_procurement_writer),
):
    category = await _category_or_404(db, payload.category_id)
    supplier = Supplier(
        name=payload.name,
        category_id=payload.category_id,
        location=payload.location,
        phone=payload.phone,
        contact_person=payload.contact_person,
        tax_id=payload.tax_id,
    )
    db.add(supplier)
    await db.flush()
    return {"data": supplier_to_dict(supplier, category)}


@router.get("/{supplier_id}")
async def get_supplier(supplier_id, db: AsyncSession = Depends(get_db)):
    supplier = await db.get(Supplier, supplier_id)
    if supplier is None:
        raise NotFoundError("تأمین‌کننده یافت نشد")
    category = await db.get(MaterialCategory, supplier.category_id)
    return {"data": supplier_to_dict(supplier, category)}


@router.patch("/{supplier_id}")
async def update_supplier(
    supplier_id,
    payload: SupplierUpdate,
    db: AsyncSession = Depends(get_db),
    _auth=Depends(_procurement_writer),
):
    supplier = await db.get(Supplier, supplier_id)
    if supplier is None:
        raise NotFoundError("تأمین‌کننده یافت نشد")
    if payload.name is not None:
        supplier.name = payload.name
    if payload.category_id is not None:
        if payload.category_id != supplier.category_id:
            await _category_or_404(db, payload.category_id)
        supplier.category_id = payload.category_id
    if payload.location is not None:
        supplier.location = payload.location
    if payload.phone is not None:
        supplier.phone = payload.phone
    if payload.contact_person is not None:
        supplier.contact_person = payload.contact_person
    if payload.tax_id is not None:
        supplier.tax_id = payload.tax_id
    await db.flush()
    category = await db.get(MaterialCategory, supplier.category_id)
    return {"data": supplier_to_dict(supplier, category)}


@router.delete("/{supplier_id}")
async def delete_supplier(
    supplier_id,
    db: AsyncSession = Depends(get_db),
    _auth=Depends(_procurement_writer),
):
    supplier = await db.get(Supplier, supplier_id)
    if supplier is None:
        raise NotFoundError("تأمین‌کننده یافت نشد")
    # quotes.supplier_id is NOT NULL RESTRICT — block if any quote exists.
    linked = await db.scalar(select(func.count()).select_from(Quote).where(Quote.supplier_id == supplier_id))
    if linked:
        raise ConflictError("این تأمین‌کننده دارای پیشنهاد است و قابل حذف نیست")
    await db.delete(supplier)  # supplier_materials cascade via DDL
    await db.flush()
    return {"data": {"id": str(supplier_id), "deleted": True}}