path_canonicalizer.py revision 4e180b6a0b4720a9b8e9e959a882386f690f08ff 
1# Copyright 2013 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5import logging
6import os
7import posixpath
8import traceback
9
10from branch_utility import BranchUtility
11from file_system import FileNotFoundError
12from third_party.json_schema_compiler.model import UnixName
13import svn_constants
14
15def _SimplifyFileName(file_name):
16  return (posixpath.splitext(file_name)[0]
17      .lower()
18      .replace('.', '')
19      .replace('-', '')
20      .replace('_', ''))
21
22class PathCanonicalizer(object):
23  '''Transforms paths into their canonical forms. Since the dev server has had
24  many incarnations - e.g. there didn't use to be apps/ - there may be old
25  paths lying around the webs. We try to redirect those to where they are now.
26  '''
27  def __init__(self, compiled_fs_factory, file_system):
28    # Map of simplified API names (for typo detection) to their real paths.
29    def make_public_apis(_, file_names):
30      return dict((_SimplifyFileName(name), name) for name in file_names)
31    self._public_apis = compiled_fs_factory.Create(file_system,
32                                                   make_public_apis,
33                                                   PathCanonicalizer)
34
35  def Canonicalize(self, path):
36    '''Returns the canonical path for |path|, and whether that path is a
37    permanent canonicalisation (e.g. when we redirect from a channel to a
38    channel-less URL) or temporary (e.g. when we redirect from an apps-only API
39    to an extensions one - we may at some point enable it for extensions).
40    '''
41    class ReturnType(object):
42      def __init__(self, path, permanent):
43        self.path = path
44        self.permanent = permanent
45
46      # Catch incorrect comparisons by disabling ==/!=.
47      def __eq__(self, _): raise NotImplementedError()
48      def __ne__(self, _): raise NotImplementedError()
49
50    # Strip any channel info off it. There are no channels anymore.
51    for channel_name in BranchUtility.GetAllChannelNames():
52      channel_prefix = channel_name + '/'
53      if path.startswith(channel_prefix):
54        # Redirect now so that we can set the permanent-redirect bit.  Channel
55        # redirects are the only things that should be permanent redirects;
56        # anything else *could* change, so is temporary.
57        return ReturnType(path[len(channel_prefix):], True)
58
59    # No further work needed for static.
60    if path.startswith('static/'):
61      return ReturnType(path, False)
62
63    # People go to just "extensions" or "apps". Redirect to the directory.
64    if path in ('extensions', 'apps'):
65      return ReturnType(path + '/', False)
66
67    # The rest of this function deals with trying to figure out what API page
68    # for extensions/apps to redirect to, if any. We see a few different cases
69    # here:
70    #  - Unqualified names ("browserAction.html"). These are easy to resolve;
71    #    figure out whether it's an extension or app API and redirect.
72    #     - but what if it's both? Well, assume extensions. Maybe later we can
73    #       check analytics and see which is more popular.
74    #  - Wrong names ("apps/browserAction.html"). This really does happen,
75    #    damn it, so do the above logic but record which is the default.
76    if path.startswith(('extensions/', 'apps/')):
77      default_platform, reference_path = path.split('/', 1)
78    else:
79      default_platform, reference_path = ('extensions', path)
80
81    try:
82      apps_public = self._public_apis.GetFromFileListing(
83          '/'.join((svn_constants.PUBLIC_TEMPLATE_PATH, 'apps'))).Get()
84      extensions_public = self._public_apis.GetFromFileListing(
85          '/'.join((svn_constants.PUBLIC_TEMPLATE_PATH, 'extensions'))).Get()
86    except FileNotFoundError:
87      # Probably offline.
88      logging.warning(traceback.format_exc())
89      return ReturnType(path, False)
90
91    simple_reference_path = _SimplifyFileName(reference_path)
92    apps_path = apps_public.get(simple_reference_path)
93    extensions_path = extensions_public.get(simple_reference_path)
94
95    if apps_path is None:
96      if extensions_path is None:
97        # No idea. Just return the original path. It'll probably 404.
98        pass
99      else:
100        path = 'extensions/%s' % extensions_path
101    else:
102      if extensions_path is None:
103        path = 'apps/%s' % apps_path
104      else:
105        assert apps_path == extensions_path
106        path = '%s/%s' % (default_platform, apps_path)
107
108    return ReturnType(path, False)
109