[owners] Implement GetChangeApprovalStatus for Depot Tools

Change-Id: I2d24e4e02e099381e10b29c7e9a09d530cde4a40
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2536817
Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

owners_client.py

@@ -2,7 +2,15 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import os
+
 import owners
+import scm
+
+
+APPROVED = 'APPROVED'
+PENDING = 'PENDING'
+INSUFFICIENT_REVIEWERS = 'INSUFFICIENT_REVIEWERS'
 
 
 class OwnersClient(object):
@@ -26,8 +34,15 @@ class OwnersClient(object):
     """List all owners for a file."""
     raise Exception('Not implemented')
 
-  def IsChangeApproved(self, change_id):
-    """Check if the latest patch set for a change has been approved."""
+  def GetChangeApprovalStatus(self, change_id):
+    """Check the approval status for the latest patch in a change.
+
+    Returns a map of path to approval status, where the status can be one of:
+    - APPROVED: An owner of the file has reviewed the change.
+    - PENDING:  An owner of the file has been added as a reviewer, but no owner
+      has approved.
+    - INSUFFICIENT_REVIEWERS: No owner of the file has been added as a reviewer.
+    """
     raise Exception('Not implemented')
 
   def IsOwnerConfigurationValid(self, change_id, patch):
@@ -37,10 +52,43 @@ class OwnersClient(object):
 
 class DepotToolsClient(OwnersClient):
   """Implement OwnersClient using owners.py Database."""
-  def __init__(self, host, root):
+  def __init__(self, host, root, branch):
     super(DepotToolsClient, self).__init__(host)
     self._root = root
+    self._branch = branch
     self._db = owners.Database(root, open, os.path)
+    self._db.override_files({
+      f: scm.GIT.GetOldContents(self._root, f, self._branch)
+      for _, f in scm.GIT.CaptureStatus(self._root, self._branch)
+      if os.path.basename(f) == 'OWNERS'
+    })
 
   def ListOwnersForFile(self, _project, _branch, path):
-    return sorted(self._db.all_possible_owners([arg], None))
+    return sorted(self._db.all_possible_owners([path], None))
+
+  def GetChangeApprovalStatus(self, change_id):
+    data = gerrit_util.GetChange(
+        self._host, change_id,
+        ['DETAILED_ACCOUNTS', 'DETAILED_LABELS', 'CURRENT_FILES',
+         'CURRENT_REVISION'])
+
+    reviewers = [r['email'] for r in data['reviewers']['REVIEWER']]
+
+    # Get reviewers that have approved this change
+    label = change['labels']['Code-Review']
+    max_value = max(int(v) for v in label['values'])
+    approvers = [v['email'] for v in label['all'] if v['value'] == max_value]
+
+    files = data['revisions'][data['current_revision']]['files']
+
+    self._db.load_data_needed_for(files)
+
+    status = {}
+    for f in files:
+      if self._db.is_covered_by(f, approvers):
+        status[f] = APPROVED
+      elif self._db.is_covered_by(f, reviewers):
+        status[f] = PENDING
+      else:
+        status[f] = INSUFFICIENT_REVIEWERS
+    return status