From 6bd5bf74225a314dcfe4d68b3695a237dd0b8a5e Mon Sep 17 00:00:00 2001
From: Markus Unterwaditzer <markus@unterwaditzer.net>
Date: Mon, 20 Oct 2014 17:37:19 +0200
Subject: [PATCH] Simplify sync code

Before deletion, vdirsyncer will now check if the item changed on the
other side, and induce a re-upload if the item did change.

Because of this behavior it is now possible to remove the special-casing
if no status is available.

Fix #128
---
 tests/test_sync.py | 15 +++++++++++++
 vdirsyncer/sync.py | 54 ++++++++++++++++++++++++++++++----------------
 2 files changed, 50 insertions(+), 19 deletions(-)

diff --git a/tests/test_sync.py b/tests/test_sync.py
index aed544d..0a6b24d 100644
--- a/tests/test_sync.py
+++ b/tests/test_sync.py
@@ -148,6 +148,21 @@ def test_conflict_resolution_both_etags_new(winning_storage):
     assert u'item {}'.format(winning_storage) in n
 
 
+def test_updated_and_deleted():
+    a = MemoryStorage()
+    b = MemoryStorage()
+    href_a, etag_a = a.upload(Item(u'UID:1'))
+    status = {}
+    sync(a, b, status, force_delete=True)
+
+    (href_b, etag_b), = b.list()
+    b.delete(href_b, etag_b)
+    a.update(href_a, Item(u'UID:1\nupdated'), etag_a)
+    sync(a, b, status, force_delete=True)
+
+    assert len(list(a.list())) == len(list(b.list())) == 1
+
+
 def test_conflict_resolution_invalid_mode():
     a = MemoryStorage()
     b = MemoryStorage()
diff --git a/vdirsyncer/sync.py b/vdirsyncer/sync.py
index abb92ca..fc29f14 100644
--- a/vdirsyncer/sync.py
+++ b/vdirsyncer/sync.py
@@ -273,25 +273,41 @@ def _get_actions(storages, status):
 
         a = a_idents.get(ident, None)
         b = b_idents.get(ident, None)
-        if ident not in status:
-            if a and b:  # missing status
-                yield _action_conflict_resolve(ident)
-            elif a and not b:  # new item was created in a
-                yield _action_upload(ident, 'b')
-            elif not a and b:  # new item was created in b
-                yield _action_upload(ident, 'a')
-        else:
+        assert not a or a['etag'] is not None
+        assert not b or b['etag'] is not None
+
+        try:
             _, status_etag_a, _, status_etag_b = status[ident]
-            if a and b:
-                if a['etag'] != status_etag_a and b['etag'] != status_etag_b:
-                    yield _action_conflict_resolve(ident)
-                elif a['etag'] != status_etag_a:  # item was updated in a
-                    yield _action_update(ident, 'b')
-                elif b['etag'] != status_etag_b:  # item was updated in b
-                    yield _action_update(ident, 'a')
-            elif a and not b:  # was deleted from b
+        except KeyError:
+            status_etag_a = status_etag_b = None
+
+        if a and b:
+            if a['etag'] != status_etag_a and b['etag'] != status_etag_b:
+                # item was modified on both sides
+                # OR: missing status
+                yield _action_conflict_resolve(ident)
+            elif a['etag'] != status_etag_a:
+                # item was only modified in a
+                yield _action_update(ident, 'b')
+            elif b['etag'] != status_etag_b:
+                # item was only modified in b
+                yield _action_update(ident, 'a')
+        elif a and not b:
+            if a['etag'] != status_etag_a:
+                # was deleted from b but modified on a
+                # OR: new item was created in a
+                yield _action_upload(ident, 'b')
+            else:
+                # was deleted from b and not modified on a
                 yield _action_delete(ident, 'a')
-            elif not a and b:  # was deleted from a
+        elif not a and b:
+            if b['etag'] != status_etag_b:
+                # was deleted from a but modified on b
+                # OR: new item was created in b
+                yield _action_upload(ident, 'a')
+            else:
+                # was deleted from a and not changed on b
                 yield _action_delete(ident, 'b')
-            elif not a and not b:  # was deleted from a and b
-                yield _action_delete(ident, None)
+        elif not a and not b:
+            # was deleted from a and b, clean up status
+            yield _action_delete(ident, None)