Add invoice tracking model

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/billing/admin.py

@@ -22,7 +22,7 @@ from __future__ import unicode_literals
 from django.contrib import admin
 from django.utils.translation import ugettext_lazy as _
 
-from weblate.billing.models import Plan, Billing
+from weblate.billing.models import Plan, Billing, Invoice
 
 
 class PlanAdmin(admin.ModelAdmin):
@@ -51,5 +51,18 @@ class BillingAdmin(admin.ModelAdmin):
     list_projects.short_description = _('Projects')
 
 
+class InvoiceAdmin(admin.ModelAdmin):
+    list_display = (
+        'billing', 'start', 'end', 'payment', 'currency', 'ref'
+    )
+    list_filter = ('currency',)
+    search_fields = (
+        'billing__user__username', 'billing__projects__name',
+        'ref', 'note',
+    )
+    date_hierarchy = 'end'
+
+
 admin.site.register(Plan, PlanAdmin)
 admin.site.register(Billing, BillingAdmin)
+admin.site.register(Invoice, InvoiceAdmin)

weblate/billing/migrations/0007_invoice.py

+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.2 on 2016-02-10 12:53
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('billing', '0006_auto_20160106_1834'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Invoice',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('start', models.DateField()),
+                ('end', models.DateField()),
+                ('payment', models.IntegerField()),
+                ('currency', models.IntegerField(choices=[(0, 'EUR'), (1, 'BTC')], default=1)),
+                ('ref', models.CharField(blank=True, max_length=50)),
+                ('note', models.TextField(blank=True)),
+                ('billing', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='billing.Billing')),
+            ],
+        ),
+    ]

weblate/billing/models.py

@@ -127,3 +127,26 @@ class Billing(models.Model):
             )
         )
     in_limits.boolean = True
+
+
+@python_2_unicode_compatible
+class Invoice(models.Model):
+    CURRENCY_EUR = 0
+    CURRENCY_BTC = 1
+
+    billing = models.ForeignKey(Billing)
+    start = models.DateField()
+    end = models.DateField()
+    payment = models.IntegerField()
+    currency = models.IntegerField(
+        choices=(
+            (CURRENCY_EUR, 'EUR'),
+            (CURRENCY_BTC, 'BTC'),
+        ),
+        default=CURRENCY_BTC
+    )
+    ref = models.CharField(blank=True, max_length=50)
+    note = models.TextField(blank=True)
+
+    def __str__(self):
+        return '{0} - {1}: {2}'.format(self.start, self.end, self.billing)