from django.db import migrations, models


def canonical_mobile(value):
    if value is None:
        return None
    text = str(value)
    if len(text) == 12 and text.startswith('98'):
        return int(text[2:])
    return value


def normalized_rows(model, alias, per_workspace=False):
    seen = {}
    updates = []
    fields = ('pk', 'mobile', 'sys_ws_id') if per_workspace else ('pk', 'mobile')
    for row in model.objects.using(alias).only(*fields).iterator():
        mobile = canonical_mobile(row.mobile)
        key = (row.sys_ws_id, mobile) if per_workspace else mobile
        if mobile is not None and key in seen:
            raise RuntimeError(
                f'Duplicate mobiles in {model._meta.label}: record IDs {seen[key]} and {row.pk}. '
                'Resolve these records before migration. No records were deleted.'
            )
        if mobile is not None:
            seen[key] = row.pk
        if mobile != row.mobile:
            row.mobile = mobile
            updates.append(row)
    return updates


def check_and_normalize_mobiles(apps, schema_editor):
    alias = schema_editor.connection.alias
    customer = apps.get_model('customer', 'Customer')
    user = apps.get_model('cuser', 'CUser')
    role = apps.get_model('cuser', 'CuserRole')
    # Audit both tables before writing. A collision never silently merges people.
    customer_updates = normalized_rows(customer, alias, per_workspace=True)
    user_updates = normalized_rows(user, alias)
    role_updates = []
    for row in role.objects.using(alias).only('pk', 'mobile').iterator():
        normalized = canonical_mobile(row.mobile)
        if normalized != row.mobile:
            row.mobile = normalized
            role_updates.append(row)
    customer.objects.using(alias).bulk_update(customer_updates, ['mobile'], batch_size=500)
    user.objects.using(alias).bulk_update(user_updates, ['mobile'], batch_size=500)
    role.objects.using(alias).bulk_update(role_updates, ['mobile'], batch_size=500)


class Migration(migrations.Migration):
    dependencies = [('customer', '0007_alter_customer_name_family'), ('cuser', '0013_alter_cuser_name_family')]
    operations = [
        migrations.RunPython(check_and_normalize_mobiles, migrations.RunPython.noop),
        migrations.AddConstraint(
            model_name='customer',
            constraint=models.UniqueConstraint(fields=('sys_ws', 'mobile'), name='customer_workspace_mobile_unique'),
        ),
    ]