# Append a 4-digit suffix to site ids that are still name-only slugs.

import re
import secrets

from django.db import migrations, models
import django.db.models.deletion
from django.utils.text import slugify

_HAS_SUFFIX = re.compile(r"-\d{4}$")


def forwards_add_numeric_suffix(apps, schema_editor):
    Site = apps.get_model("farms", "Site")
    Kandang = apps.get_model("farms", "Kandang")
    PusatRegistration = apps.get_model("farms", "PusatRegistration")

    used = set(Site.objects.values_list("site_id", flat=True))
    mapping: dict[str, str] = {}

    for site in Site.objects.all().order_by("site_id"):
        old = str(site.site_id)
        if _HAS_SUFFIX.search(old):
            continue
        base = slugify(str(site.site_name or "").strip())[:55] or old[:55]
        for _ in range(32):
            candidate = f"{base}-{secrets.randbelow(10_000):04d}"
            if candidate not in used:
                used.add(candidate)
                mapping[old] = candidate
                break
        else:
            raise RuntimeError(f"Could not allocate numeric site id for {old}")

    for old_id, new_id in mapping.items():
        Kandang.objects.filter(site_id=old_id).update(site_id=new_id)
        PusatRegistration.objects.filter(site_id=old_id).update(site_id=new_id)
        Site.objects.filter(site_id=old_id).update(site_id=new_id)


def noop_reverse(apps, schema_editor):
    raise RuntimeError("Cannot reverse site id numeric suffix migration.")


class Migration(migrations.Migration):

    atomic = False

    dependencies = [
        ("farms", "0017_site_slug_pk"),
    ]

    operations = [
        migrations.AlterField(
            model_name="kandang",
            name="site",
            field=models.ForeignKey(
                db_constraint=False,
                on_delete=django.db.models.deletion.CASCADE,
                related_name="kandangs",
                to="farms.site",
            ),
        ),
        migrations.AlterField(
            model_name="pusatregistration",
            name="site",
            field=models.OneToOneField(
                db_constraint=False,
                on_delete=django.db.models.deletion.CASCADE,
                related_name="pusat_registration",
                to="farms.site",
            ),
        ),
        migrations.RunPython(forwards_add_numeric_suffix, noop_reverse),
        migrations.AlterField(
            model_name="kandang",
            name="site",
            field=models.ForeignKey(
                on_delete=django.db.models.deletion.CASCADE,
                related_name="kandangs",
                to="farms.site",
            ),
        ),
        migrations.AlterField(
            model_name="pusatregistration",
            name="site",
            field=models.OneToOneField(
                on_delete=django.db.models.deletion.CASCADE,
                related_name="pusat_registration",
                to="farms.site",
            ),
        ),
    ]