"""Link HQ Site rows to ActiveSite registry entries (Pengaturan view list)."""

from __future__ import annotations

from django.db import transaction
from django.utils.text import slugify

from apps.farms.models import Kandang, Site
from apps.sync.models import ActiveSite


def desired_hq_site_id(active_site: ActiveSite) -> str:
    """HQ Site PK should match the farm site slug when known."""
    source = str(active_site.source_site_id or "").strip()
    if source:
        return source[:64]
    code = slugify(str(active_site.code or "").strip())[:64]
    if code:
        return code
    raise ValueError("ActiveSite needs source_site_id or code to create an HQ site.")


@transaction.atomic
def ensure_hq_site_for_active_site(active_site: ActiveSite) -> Site:
    """
    Ensure the active-site registry entry has an HQ Site for farm visibility.

    Site.site_id matches ActiveSite.source_site_id (farm Site.site_id) when set.
    Prefers an existing linked site, then a site already keyed by that id, then an
    unlinked site owned by the registrar with a matching name (re-keyed if needed),
    otherwise creates a new Site.
    """
    owner = active_site.managed_by
    if owner is None:
        raise ValueError("ActiveSite.managed_by is required to create an HQ site.")

    desired_id = desired_hq_site_id(active_site)
    site_name = (active_site.name or active_site.code or "Site")[:30]

    existing = Site.objects.filter(active_site=active_site).first()
    if existing is not None:
        if existing.pk == desired_id:
            return existing
        return _rekey_site(existing, desired_id=desired_id, site_name=site_name, owner=owner)

    by_pk = Site.objects.filter(pk=desired_id).first()
    if by_pk is not None:
        by_pk.active_site = active_site
        by_pk.user = owner
        if by_pk.site_name != site_name:
            by_pk.site_name = site_name
        by_pk.save(update_fields=["active_site", "user", "site_name", "updated_at"])
        return by_pk

    orphan = (
        Site.objects.filter(
            user=owner, active_site__isnull=True, site_name__iexact=site_name
        )
        .order_by("pk")
        .first()
    )
    if orphan is None and active_site.code:
        orphan = (
            Site.objects.filter(
                user=owner, active_site__isnull=True, site_name__iexact=active_site.code
            )
            .order_by("pk")
            .first()
        )
    if orphan is not None:
        if orphan.pk == desired_id:
            orphan.active_site = active_site
            orphan.save(update_fields=["active_site", "updated_at"])
            return orphan
        return _rekey_site(
            orphan,
            desired_id=desired_id,
            site_name=site_name,
            owner=owner,
            active_site=active_site,
        )

    return Site.objects.create(
        site_id=desired_id,
        site_name=site_name,
        user=owner,
        active_site=active_site,
    )


def _rekey_site(
    old: Site,
    *,
    desired_id: str,
    site_name: str,
    owner,
    active_site: ActiveSite | None = None,
) -> Site:
    """Move an HQ site (and its kandangs) onto the farm slug primary key."""
    link = active_site if active_site is not None else old.active_site
    new_site = Site.objects.create(
        site_id=desired_id,
        site_name=site_name or old.site_name,
        user=owner,
        active_site=None,
    )
    Kandang.objects.filter(site=old).update(site=new_site)
    old_active = old.active_site
    old.delete()
    new_site.active_site = link or old_active
    new_site.save(update_fields=["active_site", "updated_at"])
    return new_site