"""Department sections within an organization."""

from __future__ import annotations

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models import OrgSection
from app.schemas import OrgSectionCreate, OrgSectionRead

DEFAULT_SECTIONS = ["Admin", "HR", "Engineering", "Finance"]


async def ensure_default_sections(
    session: AsyncSession,
    company_domain: str,
) -> None:
    existing = await session.scalar(
        select(OrgSection.id)
        .where(OrgSection.company_domain == company_domain)
        .limit(1)
    )
    if existing:
        return
    for name in DEFAULT_SECTIONS:
        session.add(OrgSection(company_domain=company_domain, name=name))
    await session.flush()


async def list_org_sections(
    session: AsyncSession,
    company_domain: str,
) -> list[OrgSectionRead]:
    await ensure_default_sections(session, company_domain)
    result = await session.scalars(
        select(OrgSection)
        .where(OrgSection.company_domain == company_domain)
        .order_by(OrgSection.name.asc())
    )
    return [OrgSectionRead.model_validate(section) for section in result.all()]


async def create_org_section(
    session: AsyncSession,
    company_domain: str,
    payload: OrgSectionCreate,
) -> OrgSectionRead:
    name = payload.name.strip()
    if not name:
        raise ValueError("Section name is required.")

    existing = await session.scalar(
        select(OrgSection).where(
            OrgSection.company_domain == company_domain,
            OrgSection.name.ilike(name),
        )
    )
    if existing:
        raise ValueError("That section already exists.")

    section = OrgSection(company_domain=company_domain, name=name)
    session.add(section)
    await session.flush()
    return OrgSectionRead.model_validate(section)


async def get_org_section(
    session: AsyncSession,
    company_domain: str,
    section_id,
) -> OrgSection | None:
    return await session.scalar(
        select(OrgSection).where(
            OrgSection.id == section_id,
            OrgSection.company_domain == company_domain,
        )
    )