# HG changeset patch
# User Jun Wu <quark@fb.com>
# Date 1499211408 25200
# Node ID 266321579c68a3a315406ca9fe381b21b9bf5b35
# Parent  ed61189763ef7343659d7dc27add64c7e2c8b19e
phabricator: add node and p1 to hg:meta property

The "hg:meta" property is for extra metadata to reconstruct the patch.
Previously it does not have node or parent information since I think by
reading the patch again, the commit message will be mangled (like, added the
"Differential Revision" line) and we cannot preserve the commit hash.

However, the "parent" information could be useful. It could be helpful to
locate the "base revision" so in case of a conflict applying the patch
directly, we might be able to use 3-way merge to resolve it correctly.

Note: "local:commits" is an existing "property" used by Phabricator that has
the node and parent information. However, it lacks of timezone information
and requires "author" and "authorEmail" to be separated. So we are using a
different "property" - "hg:meta" to be distinguished from "local:commits".

diff -r ed61189763ef -r 266321579c68 contrib/phabricator.py
--- a/contrib/phabricator.py	Tue Jul 04 16:16:37 2017 -0700
+++ b/contrib/phabricator.py	Tue Jul 04 16:36:48 2017 -0700
@@ -196,6 +196,8 @@
         'data': json.dumps({
             'user': ctx.user(),
             'date': '%d %d' % ctx.date(),
+            'node': ctx.hex(),
+            'parent': ctx.p1().hex(),
         }),
     }
     callconduit(ctx.repo(), 'differential.setdiffproperty', params)
@@ -292,6 +294,11 @@
 
 _summaryre = re.compile('^Summary:\s*', re.M)
 
+# Map from "hg:meta" keys to header understood by "hg import". The order is
+# consistent with "hg export" output.
+_metanamemap = util.sortdict([(r'user', 'User'), (r'date', 'Date'),
+                              (r'node', 'Node ID'), (r'parent', 'Parent ')])
+
 def readpatch(repo, params, recursive=False):
     """generate plain-text patch readable by 'hg import'
 
@@ -316,13 +323,16 @@
     # Remove potential empty "Summary:"
     desc = _summaryre.sub('', desc)
 
-    # Try to preserve metadata (user, date) from hg:meta property
+    # Try to preserve metadata from hg:meta property. Write hg patch headers
+    # that can be read by the "import" command. See patchheadermap and extract
+    # in mercurial/patch.py for supported headers.
     diffs = callconduit(repo, 'differential.querydiffs', {'ids': [diffid]})
     props = diffs[str(diffid)][r'properties'] # could be empty list or dict
     if props and r'hg:meta' in props:
         meta = props[r'hg:meta']
-        for k, v in meta.items():
-            header += '# %s %s\n' % (k.capitalize(), v)
+        for k in _metanamemap.keys():
+            if k in meta:
+                header += '# %s %s\n' % (_metanamemap[k], meta[k])
 
     patch = ('%s%s\n%s') % (header, desc, body)