text: # Copyright 2017 The TensorFlow Authors. All Rights Reserved.
  #
  # 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.
  # ==============================================================================
  """TensorBoard WSGI Application Logic.
  
  Provides TensorBoardWSGIApp for building a TensorBoard WSGI app.
  """
  
  import base64
  import collections
  import hashlib
  import io
  import json
  import re
  import textwrap
  import time
  from urllib import parse as urlparse
  import zipfile
  
  from werkzeug import wrappers
  
  from tensorboard import errors
  from tensorboard import plugin_util
  from tensorboard import auth
  from tensorboard import context
  from tensorboard.backend import empty_path_redirect
  from tensorboard.backend import experiment_id
  from tensorboard.backend import experimental_plugin
  from tensorboard.backend import http_util
  from tensorboard.backend import path_prefix
  from tensorboard.backend import security_validator
  from tensorboard.plugins import base_plugin
  from tensorboard.plugins.core import core_plugin
  from tensorboard.util import tb_logging
  
  
  DATA_PREFIX = "/data"
  PLUGIN_PREFIX = "/plugin"
  PLUGINS_LISTING_ROUTE = "/plugins_listing"
  PLUGIN_ENTRY_ROUTE = "/plugin_entry.html"
  
  EXPERIMENTAL_PLUGINS_QUERY_PARAM = "experimentalPlugin"
  
  # Slashes in a plugin name could throw the router for a loop. An empty
  # name would be confusing, too. To be safe, let's restrict the valid
  # names as follows.
  _VALID_PLUGIN_RE = re.compile(r"^[A-Za-z0-9_-]+$")
  
  logger = tb_logging.get_logger()
  
  
  def TensorBoardWSGIApp(
      flags,
      plugins,
      data_provider=None,
      assets_zip_provider=None,
      deprecated_multiplexer=None,
      auth_providers=None,
      experimental_middlewares=None,
  ):
      """Constructs a TensorBoard WSGI app from plugins and data providers.
  
      Args:
        flags: An argparse.Namespace containing TensorBoard CLI flags.
        plugins: A list of plugins, which can be provided as TBPlugin subclasses
            or TBLoader instances or subclasses.
        data_provider: Instance of `tensorboard.data.provider.DataProvider`. May
            be `None` if `flags.generic_data` is set to `"false"` in which case
            `deprecated_multiplexer` must be passed instead.
        assets_zip_provider: See TBContext documentation for more information. If
            `None` a placeholder assets zipfile will be used containing only a
            default `index.html` file, and the actual frontend assets must be
            supplied by middleware wrapping this WSGI app.
        deprecated_multiplexer: Optional `plugin_event_multiplexer.EventMultiplexer`
            to use for any plugins not yet enabled for the DataProvider API.
            Required if the data_provider argument is not passed.
        auth_providers: Optional mapping whose values are `AuthProvider` values
          and whose keys are used by (e.g.) data providers to specify
          `AuthProvider`s via the `AuthContext.get` interface. Defaults to `{}`.
        experimental_middlewares: Optional list of WSGI middlewares (i.e.,
          callables that take a WSGI application and return a WSGI application)
          to apply directly around the core TensorBoard app itself, "inside" the
          request redirection machinery for `--path_prefix`, experiment IDs, etc.
          You can use this to add handlers for additional routes. Middlewares are
          applied in listed order, so the first element of this list is the
          innermost application. Defaults to `[]`. This parameter is experimental
          and may be reworked or removed.
  
      Returns:
        A WSGI application that implements the TensorBoard backend.
  
      :type plugins: list[base_plugin.TBLoader]
      """
      if assets_zip_provider is None:
          assets_zip_provider = _placeholder_assets_zip_provider
      plugin_name_to_instance = {}
      context = base_plugin.TBContext(
          data_provider=data_provider,
          flags=flags,
          logdir=flags.logdir,
          multiplexer=deprecated_multiplexer,
          assets_zip_provider=assets_zip_provider,
          plugin_name_to_instance=plugin_name_to_instance,
          sampling_hints=flags.samples_per_plugin,
          window_title=flags.window_title,
      )
      tbplugins = []
      experimental_plugins = []
      for plugin_spec in plugins:
          loader = make_plugin_loader(plugin_spec)
          try:
              plugin = loader.load(context)
          except Exception:
              logger.error(
                  "Failed to load plugin %s; ignoring it.",
                  getattr(loader.load, "__qualname__", loader.load),
                  exc_info=True,
              )
              plugin = None
          if plugin is None:
              continue
          tbplugins.append(plugin)
          if isinstance(
              loader, experimental_plugin.ExperimentalPlugin
          ) or isinstance(plugin, experimental_plugin.ExperimentalPlugin):
              experimental_plugins.append(plugin.plugin_name)
          plugin_name_to_instance[plugin.plugin_name] = plugin
      return TensorBoardWSGI(
          tbplugins,
          flags.path_prefix,
          data_provider,
          experimental_plugins,
          auth_providers,
          experimental_middlewares,
      )
  
  
  def make_plugin_loader(plugin_spec):
      """Returns a plugin loader for the given plugin.
  
      Args:
        plugin_spec: A TBPlugin subclass, or a TBLoader instance or subclass.
  
      Returns:
        A TBLoader for the given plugin.
  
      :type plugin_spec:
        Type[base_plugin.TBPlugin] | Type[base_plugin.TBLoader] |
        base_plugin.TBLoader
      :rtype: base_plugin.TBLoader
      """
      if isinstance(plugin_spec, base_plugin.TBLoader):
          return plugin_spec
      if isinstance(plugin_spec, type):
          if issubclass(plugin_spec, base_plugin.TBLoader):
              return plugin_spec()
          if issubclass(plugin_spec, base_plugin.TBPlugin):
              return base_plugin.BasicLoader(plugin_spec)
      raise TypeError("Not a TBLoader or TBPlugin subclass: %r" % (plugin_spec,))
  
  
  class TensorBoardWSGI(object):
      """The TensorBoard WSGI app that delegates to a set of TBPlugin."""
  
      def __init__(
          self,
          plugins,
          path_prefix="",
          data_provider=None,
          experimental_plugins=None,
          auth_providers=None,
          experimental_middlewares=None,
      ):
          """Constructs TensorBoardWSGI instance.
  
          Args:
            plugins: A list of base_plugin.TBPlugin subclass instances.
            path_prefix: A prefix of the path when app isn't served from root.
            data_provider: `tensorboard.data.provider.DataProvider` or
              `None`; if present, will inform the "active" state of
              `/plugins_listing`.
            experimental_plugins: A list of plugin names that are only provided
                experimentally. The corresponding plugins will only be activated for
                a user if the user has specified the plugin with the experimentalPlugin
                query parameter in the URL.
            auth_providers: Optional mapping whose values are `AuthProvider`
              values and whose keys are used by (e.g.) data providers to specify
              `AuthProvider`s via the `AuthContext.get` interface.
              Defaults to `{}`.
            experimental_middlewares: Optional list of WSGI middlewares to apply
              directly around the core TensorBoard app itself. Defaults to `[]`.
              This parameter is experimental and may be reworked or removed.
  
          Returns:
            A WSGI application for the set of all TBPlugin instances.
  
          Raises:
            ValueError: If some plugin has no plugin_name
            ValueError: If some plugin has an invalid plugin_name (plugin
                names must only contain [A-Za-z0-9_.-])
            ValueError: If two plugins have the same plugin_name
            ValueError: If some plugin handles a route that does not start
                with a slash
  
          :type plugins: list[base_plugin.TBPlugin]
          """
          self._plugins = plugins
          self._path_prefix = path_prefix
          self._data_provider = data_provider
          self._experimental_plugins = frozenset(experimental_plugins or ())
          self._auth_providers = auth_providers or {}
          self._extra_middlewares = list(experimental_middlewares or [])
          if self._path_prefix.endswith("/"):
              # Should have been fixed by `fix_flags`.
              raise ValueError(
                  "Trailing slash in path prefix: %r" % self._path_prefix
              )
  
          self.exact_routes = {
              # TODO(@chihuahua): Delete this RPC once we have skylark rules that
              # obviate the need for the frontend to determine which plugins are
              # active.
              DATA_PREFIX + PLUGINS_LISTING_ROUTE: self._serve_plugins_listing,
              DATA_PREFIX + PLUGIN_ENTRY_ROUTE: self._serve_plugin_entry,
          }
          unordered_prefix_routes = {}
  
          # Serve the routes from the registered plugins using their name as the route
          # prefix. For example if plugin z has two routes /a and /b, they will be
          # served as /data/plugin/z/a and /data/plugin/z/b.
          plugin_names_encountered = set()
          for plugin in self._plugins:
              if plugin.plugin_name is None:
                  raise ValueError("Plugin %s has no plugin_name" % plugin)
              if not _VALID_PLUGIN_RE.match(plugin.plugin_name):
                  raise ValueError(
                      "Plugin %s has invalid name %r"
                      % (plugin, plugin.plugin_name)
                  )
              if plugin.plugin_name in plugin_names_encountered:
                  raise ValueError(
                      "Duplicate plugins for name %s" % plugin.plugin_name
                  )
              plugin_names_encountered.add(plugin.plugin_name)
  
              try:
                  plugin_apps = plugin.get_plugin_apps()
              except Exception as e:  # pylint: disable=broad-except
                  if (
                      type(plugin) is core_plugin.CorePlugin
                  ):  # pylint: disable=unidiomatic-typecheck
                      raise
                  logger.warning(
                      "Plugin %s failed. Exception: %s",
                      plugin.plugin_name,
                      str(e),
                  )
                  continue
              for route, app in plugin_apps.items():
                  if not route.startswith("/"):
                      raise ValueError(
                          "Plugin named %r handles invalid route %r: "
                          "route does not start with a slash"
                          % (plugin.plugin_name, route)
                      )
                  if (
                      type(plugin) is core_plugin.CorePlugin
                  ):  # pylint: disable=unidiomatic-typecheck
                      path = route
                  else:
                      path = (
                          DATA_PREFIX
                          + PLUGIN_PREFIX
                          + "/"
                          + plugin.plugin_name
                          + route
                      )
  
                  if path.endswith("/*"):
                      # Note we remove the '*' but leave the slash in place.
                      path = path[:-1]
                      if "*" in path:
                          # note we re-add the removed * in the format string
                          raise ValueError(
                              "Plugin %r handles invalid route '%s*': Only "
                              "trailing wildcards are supported "
                              "(i.e., `/.../*`)" % (plugin.plugin_name, path)
                          )
                      unordered_prefix_routes[path] = app
                  else:
                      if "*" in path:
                          raise ValueError(
                              "Plugin %r handles invalid route %r: Only "
                              "trailing wildcards are supported "
                              "(i.e., `/.../*`)" % (plugin.plugin_name, path)
                          )
                      self.exact_routes[path] = app
  
          # Wildcard routes will be checked in the given order, so we sort them
          # longest to shortest so that a more specific route will take precedence
          # over a more general one (e.g., a catchall route `/*` should come last).
          self.prefix_routes = collections.OrderedDict(
              sorted(
                  unordered_prefix_routes.items(),
                  key=lambda x: len(x[0]),
                  reverse=True,
              )
          )
  
          self._app = self._create_wsgi_app()
  
      def _create_wsgi_app(self):
          """Apply middleware to create the final WSGI app."""
          app = self._route_request
          for middleware in self._extra_middlewares:
              app = middleware(app)
          app = _auth_context_middleware(app, self._auth_providers)
          app = empty_path_redirect.EmptyPathRedirectMiddleware(app)
          app = experiment_id.ExperimentIdMiddleware(app)
          app = path_prefix.PathPrefixMiddleware(app, self._path_prefix)
          app = security_validator.SecurityValidatorMiddleware(app)
          app = _handling_errors(app)
          return app
  
      @wrappers.Request.application
      def _serve_plugin_entry(self, request):
          """Serves a HTML for iframed plugin entry point.
  
          Args:
            request: The werkzeug.Request object.
  
          Returns:
            A werkzeug.Response object.
          """
          name = request.args.get("name")
          plugins = [
              plugin for plugin in self._plugins if plugin.plugin_name == name
          ]
  
          if not plugins:
              raise errors.NotFoundError(name)
  
          if len(plugins) > 1:
              # Technically is not possible as plugin names are unique and is checked
              # by the check on __init__.
              reason = (
                  "Plugin invariant error: multiple plugins with name "
                  "{name} found: {list}"
              ).format(name=name, list=plugins)
              raise AssertionError(reason)
  
          plugin = plugins[0]
          module_path = plugin.frontend_metadata().es_module_path
          if not module_path:
              return http_util.Respond(
                  request, "Plugin is not module loadable", "text/plain", code=400
              )
  
          # non-self origin is blocked by CSP but this is a good invariant checking.
          if urlparse.urlparse(module_path).netloc:
              raise ValueError("Expected es_module_path to be non-absolute path")
  
          module_json = json.dumps("." + module_path)
          script_content = "import({}).then((m) => void m.render());".format(
              module_json
          )
          digest = hashlib.sha256(script_content.encode("utf-8")).digest()
          script_sha = base64.b64encode(digest).decode("ascii")
  
          html = textwrap.dedent(
              """
              <!DOCTYPE html>
              <head><base href="plugin/{name}/" /></head>
              <body><script type="module">{script_content}</script></body>
              """
          ).format(name=name, script_content=script_content)
          return http_util.Respond(
              request,
              html,
              "text/html",
              csp_scripts_sha256s=[script_sha],
          )
  
      @wrappers.Request.application
      def _serve_plugins_listing(self, request):
          """Serves an object mapping plugin name to whether it is enabled.
  
          Args:
            request: The werkzeug.Request object.
  
          Returns:
            A werkzeug.Response object.
          """
          response = collections.OrderedDict()
          ctx = plugin_util.context(request.environ)
          eid = plugin_util.experiment_id(request.environ)
          plugins_with_data = frozenset(
              self._data_provider.list_plugins(ctx, experiment_id=eid)
              or frozenset()
              if self._data_provider is not None
              else frozenset()
          )
          plugins_to_skip = self._experimental_plugins - frozenset(
              request.args.getlist(EXPERIMENTAL_PLUGINS_QUERY_PARAM)
          )
          for plugin in self._plugins:
              if plugin.plugin_name in plugins_to_skip:
                  continue
  
              if (
                  type(plugin) is core_plugin.CorePlugin
              ):  # pylint: disable=unidiomatic-typecheck
                  # This plugin's existence is a backend implementation detail.
                  continue
  
              is_active = bool(
                  frozenset(plugin.data_plugin_names()) & plugins_with_data
              )
              if not is_active:
                  try:
                      start = time.time()
                      is_active = plugin.is_active()
                      elapsed = time.time() - start
                      logger.info(
                          "Plugin listing: is_active() for %s took %0.3f seconds",
                          plugin.plugin_name,
                          elapsed,
                      )
                  except Exception:
                      is_active = False
                      logger.error(
                          "Plugin listing: is_active() for %s failed (marking inactive)",
                          plugin.plugin_name,
                          exc_info=True,
                      )
  
              plugin_metadata = plugin.frontend_metadata()
              output_metadata = {
                  "disable_reload": plugin_metadata.disable_reload,
                  "enabled": is_active,
                  # loading_mechanism set below
                  "remove_dom": plugin_metadata.remove_dom,
                  # tab_name set below
              }
  
              if plugin_metadata.tab_name is not None:
                  output_metadata["tab_name"] = plugin_metadata.tab_name
              else:
                  output_metadata["tab_name"] = plugin.plugin_name
  
              es_module_handler = plugin_metadata.es_module_path
              element_name = plugin_metadata.element_name
              is_ng_component = plugin_metadata.is_ng_component
              if is_ng_component:
                  if element_name is not None:
                      raise ValueError(
                          "Plugin %r declared as both Angular built-in and legacy"
                          % plugin.plugin_name
                      )
                  if es_module_handler is not None:
                      raise ValueError(
                          "Plugin %r declared as both Angular built-in and iframed"
                          % plugin.plugin_name
                      )
                  loading_mechanism = {
                      "type": "NG_COMPONENT",
                  }
              elif element_name is not None and es_module_handler is not None:
                  logger.error(
                      "Plugin %r declared as both legacy and iframed; skipping",
                      plugin.plugin_name,
                  )
                  continue
              elif element_name is not None and es_module_handler is None:
                  loading_mechanism = {
                      "type": "CUSTOM_ELEMENT",
                      "element_name": element_name,
                  }
              elif element_name is None and es_module_handler is not None:
                  loading_mechanism = {
                      "type": "IFRAME",
                      "module_path": "".join(
                          [
                              request.script_root,
                              DATA_PREFIX,
                              PLUGIN_PREFIX,
                              "/",
                              plugin.plugin_name,
                              es_module_handler,
                          ]
                      ),
                  }
              else:
                  # As a compatibility measure (for plugins that we don't
                  # control), we'll pull it from the frontend registry for now.
                  loading_mechanism = {
                      "type": "NONE",
                  }
              output_metadata["loading_mechanism"] = loading_mechanism
  
              response[plugin.plugin_name] = output_metadata
          return http_util.Respond(request, response, "application/json")
  
      def __call__(self, environ, start_response):
          """Central entry point for the TensorBoard application.
  
          This __call__ method conforms to the WSGI spec, so that instances of this
          class are WSGI applications.
  
          Args:
            environ: See WSGI spec (PEP 3333).
            start_response: See WSGI spec (PEP 3333).
          """
          return self._app(environ, start_response)
  
      def _route_request(self, environ, start_response):
          """Delegate an incoming request to sub-applications.
  
          This method supports strict string matching and wildcard routes of a
          single path component, such as `/foo/*`. Other routing patterns,
          like regular expressions, are not supported.
  
          This is the main TensorBoard entry point before middleware is
          applied. (See `_create_wsgi_app`.)
  
          Args:
            environ: See WSGI spec (PEP 3333).
            start_response: See WSGI spec (PEP 3333).
          """
  
          request = wrappers.Request(environ)
          parsed_url = urlparse.urlparse(request.path)
          clean_path = _clean_path(parsed_url.path)
  
          # pylint: disable=too-many-function-args
          if clean_path in self.exact_routes:
              return self.exact_routes[clean_path](environ, start_response)
          else:
              for path_prefix in self.prefix_routes:
                  if clean_path.startswith(path_prefix):
                      return self.prefix_routes[path_prefix](
                          environ, start_response
                      )
  
              logger.warning("path %s not found, sending 404", clean_path)
              return http_util.Respond(
                  request, "Not found", "text/plain", code=404
              )(environ, start_response)
          # pylint: enable=too-many-function-args
  
  
  def _handling_errors(wsgi_app):
      def wrapper(environ, start_response):
          try:
              return wsgi_app(environ, start_response)
          except errors.PublicError as e:
              request = wrappers.Request(environ)
              error_app = http_util.Respond(
                  request,
                  str(e),
                  "text/plain",
                  code=e.http_code,
                  headers=e.headers,
              )
              return error_app(environ, start_response)
          # Let other exceptions be handled by the server, as an opaque
          # internal server error.
  
      return wrapper
  
  
  def _auth_context_middleware(wsgi_app, auth_providers):
      def wrapper(environ, start_response):
          environ = dict(environ)
          auth_ctx = auth.AuthContext(auth_providers, environ)
          ctx = context.from_environ(environ).replace(auth=auth_ctx)
          context.set_in_environ(environ, ctx)
          return wsgi_app(environ, start_response)
  
      return wrapper
  
  
  def _clean_path(path):
      """Removes a trailing slash from a non-root path.
  
      Arguments:
        path: The path of a request.
  
      Returns:
        The route to use to serve the request.
      """
      if path != "/" and path.endswith("/"):
          return path[:-1]
      return path
  
  
  def _placeholder_assets_zip_provider():
      """Defines a default assets zip provider containing a dummy index.html."""
      memfile = io.BytesIO()
      with zipfile.ZipFile(memfile, mode="w") as zf:
          zf.writestr("index.html", "TensorBoard placeholder index.html")
      return memfile
  