[Rietveld] Add support for patchset dependencies

appengine/chromium_rietveld/codereview/dependency_utils.py

Index: appengine/chromium_rietveld/codereview/dependency_utils.py
diff --git a/appengine/chromium_rietveld/codereview/dependency_utils.py b/appengine/chromium_rietveld/codereview/dependency_utils.py
new file mode 100644
index 0000000000000000000000000000000000000000..991d3454707c11ec691d17cec35eaea057b3dbdf
--- /dev/null
+++ b/appengine/chromium_rietveld/codereview/dependency_utils.py
@@ -0,0 +1,153 @@
+# Copyright 2015 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Contains utilities to help deal with the dependencies of a patchset."""
+
+from codereview import models
+
+
+DEPENDENCY_DELIMITER = ':'
+
+
+def remove_dependencies_from_all_patchsets(issue):
+  """Remove all dependencies from all patchsets of this issue.
+
+  This method should be called when a CL is closed or deleted.
+
+  Args:
+    issue: (models.Issue) The issue we to remove dependencies to.
+  """
+  for patchset in issue.patchsets:
+    remove_dependencies(patchset)
+
+
+def remove_all_patchsets_as_dependents(issue):
+  """Remove all patchsets of this issue as dependents.
+
+  This method should be called when a CL is deleted.
+
+  Args:
+    issue: (models.Issue) The issue whose dependencies we want to update.
+  """
+  for patchset in issue.patchsets:
+    remove_as_dependent(patchset)
+
+
+def remove_dependencies(patchset):
+  """Remove all dependencies on this patchset.
+
+  This method should be called when a patchset is deleted.
+
+  Args:
+    patchset: (models.PatchSet) The patchset we want to remove dependencies to.
+  """
+  _update_dependents(patchset, remove_dependency=True)
+
+
+def remove_as_dependent(patchset):
+  """Remove the specified patchset as a dependent.
+
+  This method should be called when a patchset is deleted.
+
+  Args:
+    patchset: (models.PatchSet) The patchset we want to remove as a dependent.
+  """
+  dependency_str = patchset.depends_on_patchset
+  if not dependency_str:
+    return
+  depends_on_tokens = get_dependency_tokens(dependency_str)
+  depends_on_issue = models.Issue.get_by_id(int(depends_on_tokens[0]))
+  if not depends_on_issue:
+    return
+  depends_on_patchset = models.PatchSet.get_by_id(
+        int(depends_on_tokens[1]), parent=depends_on_issue.key)
+  if not depends_on_patchset:
+    return
+  if depends_on_patchset.dependent_patchsets:
+    target_str = _get_dependency_str(patchset.issue_key.id(),
+                                     patchset.key.id())
+    if target_str in depends_on_patchset.dependent_patchsets:
+      depends_on_patchset.dependent_patchsets.remove(target_str)
+      depends_on_patchset.put()
+
+
+def get_dependency_tokens(dependency_str):
+  return dependency_str.split(DEPENDENCY_DELIMITER)
+
+
+def _get_dependency_str(issue_key, patchset_key):
+  return '%s%s%s' % (issue_key, DEPENDENCY_DELIMITER, patchset_key)
+
+
+def _update_dependents(patchset, remove_dependency):
+  if not patchset:
+    return
+  for dependency_str in patchset.dependent_patchsets:
+    depends_on_tokens = get_dependency_tokens(dependency_str)
+    dependent_issue = models.Issue.get_by_id(int(depends_on_tokens[0]))
+    if not dependent_issue:
+      continue
+    dependent_patchset = models.PatchSet.get_by_id(
+        int(depends_on_tokens[1]), parent=dependent_issue.key)
+    if not dependent_patchset:
+      continue
+    dependent_str = _get_dependency_str(patchset.issue_key.id(),
+                                        patchset.key.id())
+    if remove_dependency:
+      # Sanity check that the dependency_str of this patchset is what we expect
+      # before we delete it.
+      if dependent_patchset.depends_on_patchset == dependent_str:
+        dependent_patchset.depends_on_patchset = ""
+        dependent_patchset.put()
+    else:
+      # Sanity check that this patchset has no existing dependency before we add
+      # a new one.
+      if dependent_patchset.depends_on_patchset == "":
+        dependent_patchset.depends_on_patchset = dependent_str
+        dependent_patchset.put()
+
+
+def mark_as_dependent_and_get_dependency_str(
+    dependency_str, dependent_issue_key, dependent_patchset_key):
+  """Marks the specified patchset as a dependent and returns its dependency str.
+
+  Args:
+    dependency_str: (str) The issue and patchset the specified patchset depends
+                     on.
+    dependent_issue_key: (str) The issue key of the patchset we want to mark as
+                         dependent.
+    dependent_patchset_key: (str) The key of the patchset we want to mark as
+                            dependent.
+  """
+  if not dependency_str:
+    return None
+  depends_on_tokens = get_dependency_tokens(dependency_str)
+  depends_on_issue = models.Issue.get_by_id(int(depends_on_tokens[0]))
+  if not depends_on_issue:
+    return None
+  depends_on_patchset = models.PatchSet.get_by_id(
+      int(depends_on_tokens[1]), parent=depends_on_issue.key)
+  if not depends_on_patchset:
+    return None
+
+  if not depends_on_patchset.dependent_patchsets:
+    depends_on_patchset.dependent_patchsets = []
+  dependent_str = _get_dependency_str(dependent_issue_key,
+                                      dependent_patchset_key)
+  if dependent_str not in depends_on_patchset.dependent_patchsets:
+    depends_on_patchset.dependent_patchsets.append(dependent_str)
+  depends_on_patchset.put()
+
+  return dependency_str
+