# Data migration: legacy `users_user` row shape -> `businesses` + `users` (MySQL-oriented).

import django.db.models.deletion
from django.db import migrations, models


def set_businesses_autoincrement_mysql(apps, schema_editor):
    if schema_editor.connection.vendor != "mysql":
        return
    with schema_editor.connection.cursor() as cursor:
        cursor.execute("ALTER TABLE businesses AUTO_INCREMENT = 2000")


def backfill_users_for_business_schema(apps, schema_editor):
    Business = apps.get_model("users", "Business")
    User = apps.get_model("users", "User")
    if not Business.objects.exists():
        Business.objects.create(name="Default")
    default_b = Business.objects.order_by("pk").first()
    for u in User.objects.all():
        if u.business_id is None:
            u.business_id = default_b.pk
        ident = getattr(u, "identifier", None) or f"user_{u.pk}"
        if not u.username:
            u.username = str(ident)[:150]
        if not u.password_hash:
            u.password_hash = ""
        u.save()


class Migration(migrations.Migration):

    dependencies = [
        ("users", "0001_initial"),
    ]

    operations = [
        migrations.CreateModel(
            name="Business",
            fields=[
                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
                ("name", models.CharField(max_length=255)),
                ("created_at", models.DateTimeField(auto_now_add=True)),
            ],
            options={
                "db_table": "businesses",
            },
        ),
        migrations.RunPython(set_businesses_autoincrement_mysql, migrations.RunPython.noop),
        migrations.AddField(
            model_name="user",
            name="business",
            field=models.ForeignKey(
                db_column="business_id",
                null=True,
                on_delete=django.db.models.deletion.CASCADE,
                related_name="users",
                to="users.business",
            ),
        ),
        migrations.AddField(
            model_name="user",
            name="username",
            field=models.CharField(max_length=150, null=True),
        ),
        migrations.AddField(
            model_name="user",
            name="password_hash",
            field=models.CharField(max_length=255, null=True),
        ),
        migrations.AddField(
            model_name="user",
            name="role",
            field=models.CharField(
                choices=[("user", "User"), ("admin", "Admin")],
                default="user",
                max_length=50,
            ),
        ),
        migrations.RunPython(backfill_users_for_business_schema, migrations.RunPython.noop),
        migrations.RemoveField(
            model_name="user",
            name="identifier",
        ),
        migrations.RemoveField(
            model_name="user",
            name="language_preference",
        ),
        migrations.RemoveField(
            model_name="user",
            name="updated_at",
        ),
        migrations.AlterField(
            model_name="user",
            name="business",
            field=models.ForeignKey(
                db_column="business_id",
                on_delete=django.db.models.deletion.CASCADE,
                related_name="users",
                to="users.business",
            ),
        ),
        migrations.AlterField(
            model_name="user",
            name="username",
            field=models.CharField(max_length=150),
        ),
        migrations.AlterField(
            model_name="user",
            name="password_hash",
            field=models.CharField(max_length=255),
        ),
        migrations.AlterModelTable(
            name="user",
            table="users",
        ),
        migrations.AddConstraint(
            model_name="user",
            constraint=models.UniqueConstraint(
                fields=("business", "username"),
                name="uq_users_business_username",
            ),
        ),
    ]