from sqlalchemy import insert, select, update
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.imported_part import ImportedPart

_FIELDS = frozenset({
    "InventoryID", "Description", "TBXColour",
    "ProductMaxThreadDepthmm", "ProductMaxThreadDepthin",
    "ProductODmm", "ProductODin", "TBXThreadAttribute",
})


async def get(db: AsyncSession, inventory_id: str) -> ImportedPart | None:
    return await db.get(ImportedPart, inventory_id)


async def list_all(
    db: AsyncSession, skip: int = 0, limit: int = 500
) -> list[ImportedPart]:
    result = await db.execute(
        select(ImportedPart).order_by(ImportedPart.InventoryID).offset(skip).limit(limit)
    )
    return list(result.scalars().all())


async def count(db: AsyncSession) -> int:
    from sqlalchemy import func
    result = await db.execute(select(func.count()).select_from(ImportedPart))
    return result.scalar_one()


async def delete(db: AsyncSession, part: ImportedPart) -> None:
    await db.delete(part)
    await db.commit()


async def upsert_bulk(db: AsyncSession, records: list[dict]) -> tuple[int, int]:
    """Insert-or-update records keyed on InventoryID. Returns (created, updated)."""
    if not records:
        return 0, 0

    clean = [
        {k: str(v) if v is not None else None for k, v in r.items() if k in _FIELDS}
        for r in records
        if r.get("InventoryID")
    ]
    if not clean:
        return 0, 0

    incoming_ids = {r["InventoryID"] for r in clean}

    result = await db.execute(
        select(ImportedPart.InventoryID).where(ImportedPart.InventoryID.in_(incoming_ids))
    )
    existing_ids = {row[0] for row in result.all()}

    to_insert = [r for r in clean if r["InventoryID"] not in existing_ids]
    to_update = [r for r in clean if r["InventoryID"] in existing_ids]

    if to_insert:
        await db.execute(insert(ImportedPart), to_insert)

    for record in to_update:
        inv_id = record["InventoryID"]
        vals = {k: v for k, v in record.items() if k != "InventoryID"}
        if vals:
            await db.execute(
                update(ImportedPart)
                .where(ImportedPart.InventoryID == inv_id)
                .values(vals)
            )

    await db.commit()
    return len(to_insert), len(to_update)