# HG changeset patch
# User Boris Feld <boris.feld@octobus.net>
# Date 1505308431 -7200
# Node ID 6275808e89ef2de9a66a3fb1ac72fbea35f46418
# Parent  01cf426bd4582d76c1b79eeb0af3d9167a558adb
topic: setup 'topic' value for working ctx

The way amend work in core change in e8a7c1a0565a. The intermediate commit
disappear and we can no longer rely on it to carry the topic value to amend. To
fix this, we ensure the current topic value can be retrieved through the
`workingctx.extra()` value. Since there is no way to carry a "missing" key
information in a way that survives and "dict.update" call. We also has to
introduce hacking behavior about a special empty value for topic.

diff -r 01cf426bd458 -r 6275808e89ef hgext3rd/topic/__init__.py
--- a/hgext3rd/topic/__init__.py	Thu Sep 14 20:33:03 2017 +0200
+++ b/hgext3rd/topic/__init__.py	Wed Sep 13 15:13:51 2017 +0200
@@ -58,6 +58,7 @@
 from mercurial.i18n import _
 from mercurial import (
     bookmarks,
+    changelog,
     cmdutil,
     commands,
     context,
@@ -307,6 +308,26 @@
         repo.names.addnamespace(namespaces.namespace(
             'topics', 'topic', namemap=_namemap, nodemap=_nodemap,
             listnames=lambda repo: repo.topics))
+    # Wrap workingctx extra to return the topic name
+    extensions.wrapfunction(context.workingctx, '__init__', wrapinit)
+    # Wrap changelog.add to drop empty topic
+    extensions.wrapfunction(changelog.changelog, 'add', wrapadd)
+
+def wrapinit(orig, self, repo, *args, **kwargs):
+    orig(self, repo, *args, **kwargs)
+    if repo.currenttopic:
+        self._extra[constants.extrakey] = repo.currenttopic
+    else:
+        # Empty key will be dropped from extra by another hack at the changegroup level
+        self._extra[constants.extrakey] = ''
+
+def wrapadd(orig, cl, manifest, files, desc, transaction, p1, p2, user,
+            date=None, extra=None):
+    if constants.extrakey in extra and not extra[constants.extrakey]:
+        extra = extra.copy()
+        del extra[constants.extrakey]
+    return orig(cl, manifest, files, desc, transaction, p1, p2, user,
+                date=date, extra=extra)
 
 # revset predicates are automatically registered at loading via this symbol
 revsetpredicate = topicrevset.revsetpredicate