Allow to import orders (#1516)

* Allow to import orders

* seats, subevents

* Plugin support

* Add docs

* Warn about lack of quota handling

* Control interface test

* Test skeleton

* First tests for the impotr columns

* Add tests for all columns

* Fix question validation

src/pretix/control/forms/orderimport.py

@@ -0,0 +1,53 @@
+from django import forms
+from django.utils.translation import gettext_lazy as _
+
+from pretix.base.services.orderimport import get_all_columns
+
+
+class ProcessForm(forms.Form):
+    orders = forms.ChoiceField(
+        label=_('Import mode'),
+        choices=(
+            ('many', _('Create a separate order for each line')),
+            ('one', _('Create one order with one position per line')),
+        )
+    )
+    status = forms.ChoiceField(
+        label=_('Order status'),
+        choices=(
+            ('paid', _('Create orders as fully paid')),
+            ('pending', _('Create orders as pending and still require payment')),
+        )
+    )
+    testmode = forms.BooleanField(
+        label=_('Create orders as test mode orders'),
+        required=False
+    )
+
+    def __init__(self, *args, **kwargs):
+        headers = kwargs.pop('headers')
+        initital = kwargs.pop('initial', {})
+        self.event = kwargs.pop('event')
+        initital['testmode'] = self.event.testmode
+        kwargs['initial'] = initital
+        super().__init__(*args, **kwargs)
+
+        header_choices = [
+            ('csv:{}'.format(h), _('CSV column: "{name}"').format(name=h)) for h in headers
+        ]
+
+        for c in get_all_columns(self.event):
+            choices = []
+            if c.default_value:
+                choices.append((c.default_value, c.default_label))
+            choices += header_choices
+            for k, v in c.static_choices():
+                choices.append(('static:{}'.format(k), v))
+
+            self.fields[c.identifier] = forms.ChoiceField(
+                label=str(c.verbose_name),
+                choices=choices,
+                widget=forms.Select(
+                    attrs={'data-static': 'true'}
+                )
+            )