1 files changed, 76 insertions, 0 deletions
diff --git a/archivist/virtual_prefixes.py b/archivist/virtual_prefixes.py
new file mode 100644
index 0000000..632e3cf
--- /dev/null
+++ b/archivist/virtual_prefixes.py
@@ -0,0 +1,76 @@
+prefixes = {}
+registered = False
+
+def register_prefixes():
+    global registered
+    if registered: return
+
+    if not prefixes:
+        _create_prefixes()
+
+    for prefix in prefixes.values():
+        prefix.get_or_create()
+
+    registered = True
+
+def _create_prefixes():
+    from .model import Document
+
+    FieldVirtualPrefix('direction', 'In- or outgoing', Document.direction)
+    FieldVirtualPrefix('date', 'Date of creation', Document.created)
+    FieldVirtualPrefix('mime', 'Mime Type', Document.mimetype)
+    ContainsFieldVirtualPrefix('name', 'Name/description of document', Document.name)
+
+    for part in ('day', 'month', 'year'):
+        FieldPartVirtualPrefix(part, part.capitalize() + ' of creation', Document.created, part)
+
+def query(prefix, value):
+    register_prefixes()
+
+    if prefix in prefixes:
+        return prefixes[prefix].as_query(value)
+    return None
+
+def is_virtual(prefix):
+    register_prefixes()
+    return prefix in prefixes
+
+class VirtualPrefix:
+    def __init__(self, name, description, accessor):
+        self.name = name
+        self.accessor = accessor
+        self.description = description
+        prefixes[name] = self
+
+    def get_or_create(self):
+        from .model import Prefix
+        return Prefix.get_or_create(name = self.name, defaults={
+            'description' : self.description,
+            'virtual' : True})
+
+    def check_for(self, document, value):
+        return self.accessor(document) == value
+
+    def as_query(self, value):
+        raise NotImplementedError
+
+class FieldVirtualPrefix(VirtualPrefix):
+    def __init__(self, name, description, field):
+        self._field = field
+        super().__init__(name, description, lambda doc: getattr(doc, field.name))
+
+    def as_query(self, value):
+        return self._field == value
+
+class ContainsFieldVirtualPrefix(FieldVirtualPrefix):
+    def as_query(self, value):
+        return self._field.contains(value)
+
+class FieldPartVirtualPrefix(VirtualPrefix):
+    def __init__(self, name, description, field, part):
+        self._field = field
+        self._field_part = getattr(field, part)
+        super().__init__(name, description, lambda doc: getattr(getattr(doc, field.name), part))
+
+    def as_query(self, value):
+        return self._field_part == int(value)