"""Attribute definitions (global attribute dictionary) CRUD — P2 set."""
from fastapi import APIRouter, Depends, Query
from sqlalchemy import func, or_, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.auth import require_role
from app.db.engine import get_db
from app.models.catalog import AttributeDefinition, MaterialAttributeValue, Unit
from app.models.procurement import LineItemSpec
from app.schemas.catalog import AttributeDefinitionCreate, AttributeDefinitionUpdate
from app.services.expand_service import unit_to_dict
from app.utils.errors import ConflictError, NotFoundError, ValidationError
from app.utils.pagination import paginate, sort_query
from app.utils.serialization import to_iso

router = APIRouter(prefix="/attribute-definitions", tags=["attribute-definitions"])
_procurement_writer = require_role("admin", "procurement_manager")


def attr_def_to_dict(ad: AttributeDefinition, unit: Unit | None = None) -> dict:
    d = {
        "id": str(ad.id),
        "attribute_key": ad.attribute_key,
        "label": ad.label,
        "data_type": ad.data_type,
        "unit_id": ad.unit_id,
        "enum_values": ad.enum_values,
        "created_at": to_iso(ad.created_at),
    }
    if unit is not None:
        d["unit"] = unit_to_dict(unit)
    return d


@router.get("")
async def list_attribute_definitions(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    q: str | None = None,
    data_type: str | None = None,
    unit_id: int | None = None,
    sort: str | None = None,
    expand: str | None = None,
    db: AsyncSession = Depends(get_db),
):
    stmt = select(AttributeDefinition)
    if q:
        stmt = stmt.where(
            or_(
                AttributeDefinition.attribute_key.ilike(f"%{q}%"),
                AttributeDefinition.label.ilike(f"%{q}%"),
            )
        )
    if data_type:
        stmt = stmt.where(AttributeDefinition.data_type == data_type)
    if unit_id is not None:
        stmt = stmt.where(AttributeDefinition.unit_id == unit_id)
    stmt = sort_query(stmt, AttributeDefinition, sort)
    items, meta = await paginate(stmt, page, page_size, db)

    units = {}
    if expand and "unit" in {t.strip() for t in expand.split(",")}:
        unit_ids = {ad.unit_id for ad in items if ad.unit_id is not None}
        if unit_ids:
            rows = (await db.execute(select(Unit).where(Unit.id.in_(unit_ids)))).scalars().all()
            units = {u.id: u for u in rows}
    return {
        "data": [attr_def_to_dict(ad, units.get(ad.unit_id)) for ad in items],
        "meta": meta,
    }


@router.post("", status_code=201)
async def create_attribute_definition(
    payload: AttributeDefinitionCreate,
    db: AsyncSession = Depends(get_db),
    _auth=Depends(_procurement_writer),
):
    duplicate = await db.scalar(select(AttributeDefinition.id).where(AttributeDefinition.attribute_key == payload.attribute_key))
    if duplicate is not None:
        raise ConflictError("ویژگی با این attribute_key قبلاً ثبت شده است", field="attribute_key")
    if payload.data_type == "enum" and not payload.enum_values:
        raise ValidationError("برای data_type=enum باید enum_values مشخص شود", field="enum_values")
    ad = AttributeDefinition(
        attribute_key=payload.attribute_key,
        label=payload.label,
        data_type=payload.data_type,
        unit_id=payload.unit_id,
        enum_values=payload.enum_values,
    )
    db.add(ad)
    await db.flush()
    return {"data": attr_def_to_dict(ad)}


@router.get("/{definition_id}")
async def get_attribute_definition(
    definition_id, expand: str | None = None, db: AsyncSession = Depends(get_db)
):
    ad = await db.get(AttributeDefinition, definition_id)
    if ad is None:
        raise NotFoundError("تعریف ویژگی یافت نشد")
    unit = None
    if expand and "unit" in {t.strip() for t in expand.split(",")} and ad.unit_id is not None:
        unit = await db.get(Unit, ad.unit_id)
    return {"data": attr_def_to_dict(ad, unit)}


@router.patch("/{definition_id}")
async def update_attribute_definition(
    definition_id,
    payload: AttributeDefinitionUpdate,
    db: AsyncSession = Depends(get_db),
    _auth=Depends(_procurement_writer),
):
    ad = await db.get(AttributeDefinition, definition_id)
    if ad is None:
        raise NotFoundError("تعریف ویژگی یافت نشد")

    if payload.data_type is not None and payload.data_type != ad.data_type:
        # Changing data_type with existing values is a hard block (P2-9).
        values = await db.scalar(
            select(func.count()).select_from(MaterialAttributeValue).where(
                MaterialAttributeValue.attribute_definition_id == definition_id
            )
        )
        specs = await db.scalar(
            select(func.count()).select_from(LineItemSpec).where(
                LineItemSpec.attribute_definition_id == definition_id
            )
        )
        if values or specs:
            raise ConflictError("به دلیل وجود مقادیر ثبت‌شده، تغییر data_type امکان‌پذیر نیست", field="data_type")
        ad.data_type = payload.data_type
        if payload.data_type == "enum" and not payload.enum_values:
            raise ValidationError("برای data_type=enum باید enum_values مشخص شود", field="enum_values")
    if payload.label is not None:
        ad.label = payload.label
    if payload.unit_id is not None:
        ad.unit_id = payload.unit_id
    if payload.enum_values is not None:
        ad.enum_values = payload.enum_values
    await db.flush()
    return {"data": attr_def_to_dict(ad)}


@router.delete("/{definition_id}")
async def delete_attribute_definition(
    definition_id,
    db: AsyncSession = Depends(get_db),
    _auth=Depends(_procurement_writer),
):
    ad = await db.get(AttributeDefinition, definition_id)
    if ad is None:
        raise NotFoundError("تعریف ویژگی یافت نشد")
    # ON DELETE RESTRICT from material_attribute_values / line_item_specs — block if values exist.
    values = await db.scalar(
        select(func.count()).select_from(MaterialAttributeValue).where(
            MaterialAttributeValue.attribute_definition_id == definition_id
        )
    )
    specs = await db.scalar(
        select(func.count()).select_from(LineItemSpec).where(
            LineItemSpec.attribute_definition_id == definition_id
        )
    )
    if values or specs:
        raise ConflictError("این ویژگی دارای مقادیر ثبت‌شده است و قابل حذف نیست")
    await db.delete(ad)  # category_attributes cascade via DDL
    await db.flush()
    return {"data": {"id": str(definition_id), "deleted": True}}