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

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