From b8f173b5f0445775c61e14127b23d373b5d6e554 Mon Sep 17 00:00:00 2001
From: Doug Hellmann <doug@doughellmann.com>
Date: Mon, 2 Oct 2017 11:50:20 -0400
Subject: [PATCH] add --reverse option to go from log URL to review URL

Change-Id: I9f70d954f21e96767cd5be40dd3484d1a5fa3742
Signed-off-by: Doug Hellmann <doug@doughellmann.com>
---
 git_os_job/cmd.py | 58 ++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 47 insertions(+), 11 deletions(-)

diff --git a/git_os_job/cmd.py b/git_os_job/cmd.py
index 16120bd..8d610ac 100755
--- a/git_os_job/cmd.py
+++ b/git_os_job/cmd.py
@@ -37,6 +37,13 @@ def main():
         default=False,
         help='show the URL but do not open it',
     )
+    parser.add_argument(
+        '-r', '--reverse',
+        dest='reverse',
+        action='store_true',
+        default=False,
+        help='given a log URL, show the gerrit URL',
+    )
     parser.add_argument(
         'ref',
         nargs='?',
@@ -46,22 +53,51 @@ def main():
     args = parser.parse_args()
 
     ref = args.ref
-    try:
-        ref_hash = subprocess.check_output(
-            ['git', 'show-ref', '-s', ref]
-        ).decode('utf-8').rstrip()
-    except subprocess.CalledProcessError:
-        # Maybe they gave us a commit id
+    if args.reverse:
+        # A log URL looks something like:
+        # http://logs.openstack.org/c4/c4afbe14deee6f55378cda53e624c8c6aa9a9d08/release-post/tag-releases/2ea6052/
+        try:
+            sha = ref.split('/')[4]
+        except IndexError:
+            parser.abort(
+                'Could not parse log URL {}'.format(ref)
+            )
+        try:
+            parents = subprocess.check_output(
+                ['git', 'rev-list', '--parents', '-n1', sha]
+            ).decode('utf-8').rstrip().split(' ')
+        except subprocess.CalledProcessError:
+            parser.abort(
+                'Could not determine parents of {}'.format(sha)
+            )
+        if len(parents) == 2:
+            # This commit was merged directly into the branch without
+            # a separate merge commit. We want to show it, rather than
+            # a parent.
+            commit = parents[0]
+        else:
+            # The commit is a merge commit, so we need to show the
+            # parent that has the actual patch.
+            commit = parents[-1]
+        url = 'https://review.openstack.org/#/q/commit:' + commit
+    else:
         try:
             ref_hash = subprocess.check_output(
-                ['git', 'show', '--pretty=format:%H', '--quiet', ref]
+                ['git', 'show-ref', '-s', ref]
             ).decode('utf-8').rstrip()
         except subprocess.CalledProcessError:
-            sys.stderr.write('Could not get hash for ref %r\n' % ref)
-            return 1
+            # Maybe they gave us a commit id
+            try:
+                ref_hash = subprocess.check_output(
+                    ['git', 'show', '--pretty=format:%H', '--quiet', ref]
+                ).decode('utf-8').rstrip()
+            except subprocess.CalledProcessError:
+                sys.stderr.write('Could not get hash for ref %r\n' % ref)
+                return 1
+
+        ref_hash_str = ref_hash.decode('utf8')
+        url = '%s/%s/%s/' % (args.base, ref_hash_str[:2], ref_hash_str)
 
-    ref_hash_str = ref_hash.decode('utf8')
-    url = '%s/%s/%s/' % (args.base, ref_hash_str[:2], ref_hash_str)
     if args.url:
         print(url)
     else: