New concept for fee handling (#610)

* New concept for fee handling

* More usages

* Remove all usages, make all tests pass

* API changes

* Small fixes

* Fix order of invoice lines

* Rebase migration

src/pretix/base/migrations/0076_orderfee.py

@@ -0,0 +1,72 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.4 on 2017-08-28 14:35
+from __future__ import unicode_literals
+
+from decimal import Decimal
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+def fee_converter(app, schema_editor):
+    OrderFee = app.get_model('pretixbase', 'OrderFee')
+    Order = app.get_model('pretixbase', 'Order')
+
+    of = []
+    for o in Order.objects.exclude(payment_fee=Decimal('0.00')).iterator():
+        of.append(OrderFee(
+            order=o,
+            value=o.payment_fee,
+            fee_type='payment',
+            tax_rate=o.payment_fee_tax_rate,
+            tax_rule=o.payment_fee_tax_rule,
+            tax_value=o.payment_fee_tax_value,
+            internal_type=o.payment_provider
+        ))
+        if len(of) > 900:
+            OrderFee.objects.bulk_create(of)
+            of = []
+    OrderFee.objects.bulk_create(of)
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0075_auto_20170828_0901'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='OrderFee',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('value', models.DecimalField(decimal_places=2, max_digits=10, verbose_name='Value')),
+                ('description', models.CharField(blank=True, max_length=190)),
+                ('internal_type', models.CharField(blank=True, max_length=255)),
+                ('fee_type', models.CharField(choices=[('payment', 'Payment method fee'), ('shipping', 'Shipping fee')], max_length=100)),
+                ('tax_rate', models.DecimalField(decimal_places=2, max_digits=7, verbose_name='Tax rate')),
+                ('tax_value', models.DecimalField(decimal_places=2, max_digits=10, verbose_name='Tax value')),
+                ('order', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='fees', to='pretixbase.Order', verbose_name='Order')),
+                ('tax_rule', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, to='pretixbase.TaxRule')),
+            ],
+        ),
+        migrations.RunPython(
+            fee_converter, migrations.RunPython.noop
+        ),
+        migrations.RemoveField(
+            model_name='order',
+            name='payment_fee',
+        ),
+        migrations.RemoveField(
+            model_name='order',
+            name='payment_fee_tax_rate',
+        ),
+        migrations.RemoveField(
+            model_name='order',
+            name='payment_fee_tax_rule',
+        ),
+        migrations.RemoveField(
+            model_name='order',
+            name='payment_fee_tax_value',
+        ),
+    ]

src/pretix/base/migrations/0077_auto_20170829_1126.py

@@ -0,0 +1,41 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.4 on 2017-08-29 11:26
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+def assign_positions(app, schema_editor):
+    Invoice = app.get_model('pretixbase', 'Invoice')
+
+    for i in Invoice.objects.iterator():
+        for j, l in enumerate(i.lines.all()):
+            l.position = j
+            l.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0076_orderfee'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='invoiceline',
+            name='position',
+            field=models.PositiveIntegerField(default=0),
+        ),
+        migrations.AlterField(
+            model_name='orderfee',
+            name='fee_type',
+            field=models.CharField(choices=[('payment', 'Payment fee'), ('shipping', 'Shipping fee'), ('other', 'Other fees')], max_length=100),
+        ),
+        migrations.RunPython(
+            assign_positions, migrations.RunPython.noop
+        ),
+        migrations.AlterModelOptions(
+            name='invoiceline',
+            options={'ordering': ('position', 'pk')},
+        ),
+    ]