"""Helper functions for interacting with filament database objects."""

from typing import Optional

from sqlalchemy.exc import IntegrityError
from sqlalchemy.ext.asyncio import AsyncSession

from spoolman.database import models, vendor
from spoolman.exceptions import ItemDeleteError, ItemNotFoundError


async def create(
    *,
    db: AsyncSession,
    density: float,
    diameter: float,
    name: Optional[str] = None,
    vendor_id: Optional[int] = None,
    material: Optional[str] = None,
    price: Optional[float] = None,
    weight: Optional[float] = None,
    spool_weight: Optional[float] = None,
    article_number: Optional[str] = None,
    comment: Optional[str] = None,
) -> models.Filament:
    """Add a new filament to the database."""
    vendor_item: Optional[models.Vendor] = None
    if vendor_id is not None:
        vendor_item = await vendor.get_by_id(db, vendor_id)

    db_item = models.Filament(
        name=name,
        vendor=vendor_item,
        material=material,
        price=price,
        density=density,
        diameter=diameter,
        weight=weight,
        spool_weight=spool_weight,
        article_number=article_number,
        comment=comment,
    )
    db.add(db_item)
    await db.flush()
    return db_item


async def get_by_id(db: AsyncSession, filament_id: int) -> models.Filament:
    """Get a filament object from the database by the unique ID."""
    filament = await db.get(models.Filament, filament_id)
    if filament is None:
        raise ItemNotFoundError(f"No filament with ID {filament_id} found.")
    return filament


async def update(
    *,
    db: AsyncSession,
    filament_id: int,
    data: dict,
) -> models.Filament:
    """Update the fields of a filament object."""
    filament = await get_by_id(db, filament_id)
    for k, v in data.items():
        if k == "vendor_id":
            if v is None:
                filament.vendor = None
            else:
                filament.vendor = await vendor.get_by_id(db, v)
        else:
            setattr(filament, k, v)
    await db.flush()
    return filament


async def delete(db: AsyncSession, filament_id: int) -> None:
    """Delete a filament object."""
    filament = await get_by_id(db, filament_id)
    await db.delete(filament)
    try:
        await db.flush()  # Flush immediately so any errors are propagated in this request.
    except IntegrityError as exc:
        await db.rollback()
        raise ItemDeleteError("Failed to delete filament.") from exc