# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2026 Bryan Joshua Pedini
"""
Signal receivers for the proxmox_power_button plugin.

Enforce that a VMID is unique *within its cluster*. This runs on post_clean —
fired during full_clean() — so it surfaces as a normal validation error in both
the UI forms and the REST API, covering VM creation, VMID edits, and moving a VM
to a different cluster.

(The custom fields themselves are provisioned by migrations/0001_initial.py.)
"""
from django.core.exceptions import ValidationError
from django.dispatch import receiver

from netbox.signals import post_clean
from virtualization.models import VirtualMachine

VMID_FIELD = "vmid"


@receiver(post_clean, sender=VirtualMachine)
def enforce_vmid_unique_per_cluster(sender, instance, **kwargs):
    data = instance.custom_field_data or {}
    vmid = data.get(VMID_FIELD)
    # Nothing to check until both a VMID and a cluster are set.
    if vmid is None or instance.cluster_id is None:
        return

    duplicate = (
        VirtualMachine.objects
        .filter(cluster_id=instance.cluster_id, custom_field_data__vmid=vmid)
        .exclude(pk=instance.pk or 0)
        .first()
    )
    if duplicate is not None:
        raise ValidationError(
            f"VMID {vmid} is already assigned to VM '{duplicate.name}' in "
            f"cluster '{instance.cluster}'. VMIDs must be unique within a cluster."
        )