1 files changed, 89 insertions, 0 deletions
diff --git a/server/szurubooru/func/snapshots.py b/server/szurubooru/func/snapshots.py
new file mode 100644
index 0000000..5d366ab
--- /dev/null
+++ b/server/szurubooru/func/snapshots.py
@@ -0,0 +1,89 @@
+import datetime
+from sqlalchemy.inspection import inspect
+from szurubooru import db
+
+def get_tag_snapshot(tag):
+    ret = {
+        'names': [tag_name.name for tag_name in tag.names],
+        'category': tag.category.name,
+        'suggestions': sorted(rel.first_name for rel in tag.suggestions),
+        'implications': sorted(rel.first_name for rel in tag.implications),
+    }
+    return ret
+
+def get_tag_category_snapshot(category):
+    return {
+        'name': category.name,
+        'color': category.color,
+    }
+
+# pylint: disable=invalid-name
+serializers = {
+    'tag': get_tag_snapshot,
+    'tag_category': get_tag_category_snapshot,
+}
+
+def get_resource_info(entity):
+    table_name = entity.__table__.name
+    primary_key = inspect(entity).identity
+    assert table_name in serializers
+    assert primary_key is not None
+    assert len(primary_key) == 1
+    primary_key = primary_key[0]
+    return (table_name, primary_key)
+
+def get_snapshots(entity):
+    table_name, primary_key = get_resource_info(entity)
+    return db.session \
+        .query(db.Snapshot) \
+        .filter(db.Snapshot.resource_type == table_name) \
+        .filter(db.Snapshot.resource_id == primary_key) \
+        .order_by(db.Snapshot.creation_time.desc()) \
+        .all()
+
+def get_data(entity):
+    ret = []
+    for snapshot in get_snapshots(entity):
+        ret.append({'data': snapshot.data, 'time': snapshot.creation_time})
+    return ret
+
+def save(operation, entity, auth_user):
+    table_name, primary_key = get_resource_info(entity)
+    now = datetime.datetime.now()
+
+    snapshot = db.Snapshot()
+    snapshot.creation_time = now
+    snapshot.operation = operation
+    snapshot.resource_type = table_name
+    snapshot.resource_id = primary_key
+    snapshot.data = serializers[table_name](entity)
+    snapshot.user = auth_user
+
+    earlier_snapshots = get_snapshots(entity)
+
+    delta = datetime.timedelta(minutes=10)
+    snapshots_left = len(earlier_snapshots)
+    while earlier_snapshots:
+        last_snapshot = earlier_snapshots.pop(0)
+        is_fresh = now - last_snapshot.creation_time <= delta
+        if snapshot.data != last_snapshot.data:
+            if not is_fresh or last_snapshot.user != auth_user:
+                break
+        db.session.delete(last_snapshot)
+        if snapshot.operation != db.Snapshot.OPERATION_DELETED:
+            snapshot.operation = last_snapshot.operation
+        snapshots_left -= 1
+
+    if not snapshots_left and operation == db.Snapshot.OPERATION_DELETED:
+        pass
+    else:
+        db.session.add(snapshot)
+
+def create(entity, auth_user):
+    save(db.Snapshot.OPERATION_CREATED, entity, auth_user)
+
+def modify(entity, auth_user):
+    save(db.Snapshot.OPERATION_MODIFIED, entity, auth_user)
+
+def delete(entity, auth_user):
+    save(db.Snapshot.OPERATION_DELETED, entity, auth_user)