Docserver: Add support for viewing docs with a codereview patch applied

chrome/common/extensions/docs/server2/rietveld_patcher.py

Index: chrome/common/extensions/docs/server2/rietveld_patcher.py
diff --git a/chrome/common/extensions/docs/server2/rietveld_patcher.py b/chrome/common/extensions/docs/server2/rietveld_patcher.py
new file mode 100644
index 0000000000000000000000000000000000000000..f480c0c4273601c7aab77a1e8c91da81946b3f2e
--- /dev/null
+++ b/chrome/common/extensions/docs/server2/rietveld_patcher.py
@@ -0,0 +1,176 @@
+# Copyright 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import json
+import tarfile
+from StringIO import StringIO
+
+from file_system import FileNotFoundError, ToUnicode
+from future import Future
+from patcher import Patcher
+import svn_constants
+
+_CHROMIUM_REPO_BASEURLS = [
+  'https://src.chromium.org/svn/trunk/src/',
+  'http://src.chromium.org/svn/trunk/src/',
+  'svn://svn.chromium.org/chrome/trunk/src',
+  'https://chromium.googlesource.com/chromium/src.git@master',
+  'http://git.chromium.org/chromium/src.git@master',
+]
+
+_DOCS_PATHS = [
+  svn_constants.API_PATH,
+  svn_constants.TEMPLATE_PATH,
+  svn_constants.STATIC_PATH
+]
+
+class RietveldPatcherError(Exception):
+  def __init__(self, message):
+    self.message = message
+
+class _AsyncFetchFuture(object):
+  def __init__(self,
+               base_path,
+               issue,
+               patchset,
+               files,
+               binary,
+               fetcher):
+    self._base_path = base_path
+    self._issue = issue
+    self._patchset = patchset
+    self._files = files
+    self._binary = binary
+    self._tarball = fetcher.FetchAsync('tarball/%s/%s' % (issue, patchset))
+
+  def Get(self):
+    tarball_result = self._tarball.Get()
+    if tarball_result.status_code != 200:
+      raise RietveldPatcherError(
+          'Failed to download tarball for issue %s patchset %s. Status: %s' %
+          (self._issue, self._patchset, tarball_result.status_code))
+
+    try:
+      tar = tarfile.open(fileobj=StringIO(tarball_result.content))
+    except tarfile.TarError as e:
+      raise RietveldPatcherError(
+          'Error loading tarball for issue %s patchset %s.' % (self._issue,
+                                                               self._patchset))
+
+    self._value = {}
+    for path in self._files:
+      if self._base_path:
+        tar_path = 'b/%s/%s' % (self._base_path, path)
+      else:
+        tar_path = 'b/%s' % path
+
+      patched_file = None
+      try:
+        patched_file = tar.extractfile(tar_path)
+        data = patched_file.read()
+      except tarfile.TarError as e:
+        # Show appropriate error message in the unlikely case that the tarball
+        # is corrupted.
+        raise RietveldPatcherError(
+            'Error extracting tarball for issue %s patchset %s file %s.' %
+            (self._issue, self._patchset, tar_path))
+      except KeyError as e:
+        raise FileNotFoundError(
+            'File %s not found in the tarball for issue %s patchset %s' %
+            (tar_path, self._issue, self._patchset))
+      finally:
+        if patched_file:
+          patched_file.close()
+
+      if self._binary:
+        self._value[path] = data
+      else:
+        self._value[path] = ToUnicode(data)
+
+    return self._value
+
+class RietveldPatcher(Patcher):
+  ''' Class to fetch resources from a patchset in Rietveld.
+  '''
+  def __init__(self,
+               base_path,
+               issue,
+               fetcher):
+    self._base_path = base_path
+    self._issue = issue
+    self._fetcher = fetcher
+    self._cache = None
+
+  # In RietveldPatcher, the version is the latest patchset number.
+  def GetVersion(self):
+    try:
+      issue_json = json.loads(self._fetcher.Fetch(
+          'api/%s' % self._issue).content)
+    except Exception as e:
+      raise RietveldPatcherError(
+          'Failed to fetch information for issue %s.' % self._issue)
+
+    if issue_json.get('closed'):
+      raise RietveldPatcherError('Issue %s has been closed.' % self._issue)
+
+    patchsets = issue_json.get('patchsets')
+    if not isinstance(patchsets, list) or len(patchsets) == 0:
+      raise RietveldPatcherError('Cannot parse issue %s.' % self._issue)
+
+    if not issue_json.get('base_url') in _CHROMIUM_REPO_BASEURLS:
+      raise RietveldPatcherError('Issue %s\'s base url is unknown.' %
+          self._issue)
+
+    return str(patchsets[-1])
+
+  def GetPatchedFiles(self, version=None):
+    if version is None:
+      patchset = self.GetVersion()
+    else:
+      patchset = version
+    try:
+      patchset_json = json.loads(self._fetcher.Fetch(
+          'api/%s/%s' % (self._issue, patchset)).content)
+    except Exception as e:
+      raise RietveldPatcherError(
+          'Failed to fetch details for issue %s patchset %s.' % (self._issue,
+                                                                 patchset))
+
+    files = patchset_json.get('files')
+    if files is None or not isinstance(files, dict):
+      raise RietveldPatcherError('Failed to parse issue %s patchset %s.' %
+          (self._issue, patchset))
+
+    added = []
+    deleted = []
+    modified = []
+    for key in files:
+      if not key.startswith(self._base_path + '/'):
+        continue
+
+      f = key.split(self._base_path + '/', 1)[1]
+      if any(f.startswith(path) for path in _DOCS_PATHS):
+        status = (files[key].get('status') or 'M')
+        # status can be 'A   ' or 'A + '
+        if 'A' in status:
+          added.append(f)
+        elif 'D' in status:
+          deleted.append(f)
+        elif 'M' in status:
+          modified.append(f)
+        else:
+          raise RietveldPatcherError('Unknown file status for file %s: "%s."' %
+                                                                  (key, status))
+
+    return (added, deleted, modified)
+
+  def Apply(self, paths, file_system, binary, version=None):
+    if version is None:
+      version = self.GetVersion()
+    return Future(delegate=_AsyncFetchFuture(self._base_path,
+                                             self._issue,
+                                             version,
+                                             paths,
+                                             binary,
+                                             self._fetcher))