Improve docs management and add invoices repo (#51)

* Create a repository app for documents, first step

* Step two (broken)

* Complete the implementation of document repository and add invoices

* Add support for invoices

* Update submodules

ram/repository/models.py

@@ -0,0 +1,90 @@
+from django.db import models
+from django.core.exceptions import ValidationError
+
+from tinymce import models as tinymce
+
+from ram.models import PrivateDocument
+from metadata.models import Decoder, Shop, Tag
+from roster.models import RollingStock
+from bookshelf.models import Book, Catalog
+
+
+class GenericDocument(PrivateDocument):
+    notes = tinymce.HTMLField(blank=True)
+    tags = models.ManyToManyField(Tag, blank=True, related_name="document")
+
+    class Meta:
+        verbose_name_plural = "Generic documents"
+
+
+class InvoiceDocument(PrivateDocument):
+    private = models.BooleanField(default=True, editable=False)
+    rolling_stock = models.ManyToManyField(
+        RollingStock, related_name="invoice", blank=True
+    )
+    book = models.ManyToManyField(Book, related_name="invoice", blank=True)
+    catalog = models.ManyToManyField(
+        Catalog, related_name="invoice", blank=True
+    )
+    date = models.DateField()
+    shop = models.ForeignKey(
+        Shop, on_delete=models.SET_NULL, null=True, blank=True
+    )
+    file = models.FileField(
+        upload_to="files/invoices/",
+    )
+    notes = tinymce.HTMLField(blank=True)
+
+
+class DecoderDocument(PrivateDocument):
+    decoder = models.ForeignKey(
+        Decoder, on_delete=models.CASCADE, related_name="document"
+    )
+
+    class Meta:
+        constraints = [
+            models.UniqueConstraint(
+                fields=["decoder", "file"], name="unique_decoder_file"
+            )
+        ]
+
+
+class BookDocument(PrivateDocument):
+    book = models.ForeignKey(
+        Book, on_delete=models.CASCADE, related_name="document"
+    )
+
+    class Meta:
+        verbose_name_plural = "Book documents"
+        constraints = [
+            models.UniqueConstraint(
+                fields=["book", "file"], name="unique_book_file"
+            )
+        ]
+
+
+class CatalogDocument(PrivateDocument):
+    catalog = models.ForeignKey(
+        Catalog, on_delete=models.CASCADE, related_name="document"
+    )
+
+    class Meta:
+        verbose_name_plural = "Catalog documents"
+        constraints = [
+            models.UniqueConstraint(
+                fields=["catalog", "file"], name="unique_catalog_file"
+            )
+        ]
+
+
+class RollingStockDocument(PrivateDocument):
+    rolling_stock = models.ForeignKey(
+        RollingStock, on_delete=models.CASCADE, related_name="document"
+    )
+
+    class Meta:
+        constraints = [
+            models.UniqueConstraint(
+                fields=["rolling_stock", "file"], name="unique_stock_file"
+            )
+        ]