"""Line items nested under quotes. Editable only while the quote is offered."""
from fastapi import APIRouter, Depends, Query
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.db.engine import get_db
from app.models.catalog import Material, Unit
from app.models.procurement import ItemDecision, LineItem, Quote
from app.schemas.procurement import LineItemCreate, LineItemUpdate
from app.services.expand_service import parse_expand, serialize_line_items
from app.services.material_service import ensure_brand_material_belong
from app.services.supplier_material_service import link_supplier_material
from app.utils.errors import ConflictError, NotFoundError
from app.utils.pagination import paginate, sort_query

router = APIRouter(prefix="/quotes/{quote_id}/line-items", tags=["line-items"])


async def _quote_or_404(db: AsyncSession, quote_id) -> Quote:
    quote = await db.get(Quote, quote_id)
    if quote is None:
        raise NotFoundError("پیشنهاد (استعلام) یافت نشد")
    return quote


async def _line_item_or_404(db: AsyncSession, quote_id, line_item_id) -> LineItem:
    li = await db.scalar(
        select(LineItem).where(LineItem.id == line_item_id, LineItem.quote_id == quote_id)
    )
    if li is None:
        raise NotFoundError("خط آیتم یافت نشد")
    return li


@router.get("")
async def list_line_items(
    quote_id,
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    sort: str | None = None,
    expand: str | None = None,
    db: AsyncSession = Depends(get_db),
):
    await _quote_or_404(db, quote_id)
    stmt = select(LineItem).where(LineItem.quote_id == quote_id)
    stmt = sort_query(stmt, LineItem, sort, default="created_at")
    items, meta = await paginate(stmt, page, page_size, db)
    data = await serialize_line_items(db, items, parse_expand(expand))
    return {"data": data, "meta": meta}


@router.post("", status_code=201)
async def create_line_item(quote_id, payload: LineItemCreate, db: AsyncSession = Depends(get_db)):
    async with db.begin():
        quote = await _quote_or_404(db, quote_id)
        if quote.status != "offered":
            raise ConflictError("خط آیتم فقط در پیشنهادهای offered قابل افزودن است")

        if await db.get(Material, payload.material_id) is None:
            raise NotFoundError("متریال یافت نشد", field="material_id")
        if await db.get(Unit, payload.unit_id) is None:
            raise NotFoundError("واحد یافت نشد", field="unit_id")
        await ensure_brand_material_belong(db, payload.brand_material_id, payload.material_id)

        li = LineItem(
            quote_id=quote.id,
            material_id=payload.material_id,
            brand_material_id=payload.brand_material_id,
            unit_id=payload.unit_id,
            quantity=payload.quantity,
            notes=payload.notes,
        )
        db.add(li)
        await db.flush()
        # v2.5: auto-link the material to the quote's supplier (catalog edge).
        await link_supplier_material(db, quote.supplier_id, payload.material_id)
        # auto-create the 1:1 pending decision (contract P0-22)
        db.add(ItemDecision(line_item_id=li.id, status="pending"))
    return {"data": (await serialize_line_items(db, [li], set()))[0]}


@router.get("/{line_item_id}")
async def get_line_item(
    quote_id, line_item_id, expand: str | None = None, db: AsyncSession = Depends(get_db)
):
    li = await _line_item_or_404(db, quote_id, line_item_id)
    return {"data": (await serialize_line_items(db, [li], parse_expand(expand)))[0]}


@router.patch("/{line_item_id}")
async def update_line_item(
    quote_id, line_item_id, payload: LineItemUpdate, db: AsyncSession = Depends(get_db)
):
    li = await _line_item_or_404(db, quote_id, line_item_id)
    quote = await _quote_or_404(db, quote_id)
    if quote.status != "offered":
        raise ConflictError("خط آیتم فقط در پیشنهادهای offered قابل ویرایش است")

    new_material_id = payload.material_id if payload.material_id is not None else li.material_id
    if payload.material_id is not None:
        if await db.get(Material, payload.material_id) is None:
            raise NotFoundError("متریال یافت نشد", field="material_id")
    if payload.unit_id is not None:
        if await db.get(Unit, payload.unit_id) is None:
            raise NotFoundError("واحد یافت نشد", field="unit_id")
    if payload.brand_material_id is not None or payload.material_id is not None:
        # If only the material changed, re-validate the EXISTING brand link against it.
        effective_bm = payload.brand_material_id if payload.brand_material_id is not None else li.brand_material_id
        await ensure_brand_material_belong(db, effective_bm, new_material_id)

    old_material_id = li.material_id
    if payload.material_id is not None:
        li.material_id = payload.material_id
        # v2.5: keep the supplier<->material catalog edge in sync.
        await link_supplier_material(db, quote.supplier_id, payload.material_id)
    if payload.brand_material_id is not None:
        li.brand_material_id = payload.brand_material_id
    if payload.unit_id is not None:
        li.unit_id = payload.unit_id
    if payload.quantity is not None:
        li.quantity = payload.quantity
    if payload.notes is not None:
        li.notes = payload.notes
    await db.flush()

    if payload.material_id is not None and payload.material_id != old_material_id:
        from app.services.quote_service import cleanup_orphan_materials
        await cleanup_orphan_materials(db, [old_material_id])

    return {"data": (await serialize_line_items(db, [li], set()))[0]}


@router.delete("/{line_item_id}")
async def delete_line_item(quote_id, line_item_id, db: AsyncSession = Depends(get_db)):
    li = await _line_item_or_404(db, quote_id, line_item_id)
    quote = await _quote_or_404(db, quote_id)
    if quote.status != "offered":
        raise ConflictError("خط آیتم فقط در پیشنهادهای offered قابل حذف است")
    decision = await db.scalar(select(ItemDecision).where(ItemDecision.line_item_id == li.id))
    if decision is not None and decision.status == "chosen":
        raise ConflictError("خط آیتم انتخاب‌شده قابل حذف نیست")
    old_material_id = li.material_id
    await db.delete(li)  # specs / links / decision / receipt cascade via DDL
    await db.flush()

    if old_material_id:
        from app.services.quote_service import cleanup_orphan_materials
        await cleanup_orphan_materials(db, [old_material_id])

    return {"data": {"id": str(line_item_id), "deleted": True}}