content: import collections
  import importlib
  import importlib.util  # to make the type checker happy
  import os
  import re
  import sys
  from fnmatch import fnmatch
  from os.path import isfile, join
  from pathlib import Path
  from urllib.parse import parse_qs
  
  import flask
  
  from . import _validate
  from ._callback_context import context_value
  from ._get_app import get_app
  from ._get_paths import get_relative_path
  from ._utils import AttributeDict
  
  CONFIG = AttributeDict()
  PAGE_REGISTRY = collections.OrderedDict()
  
  
  def _infer_image(module):
      """
      Return:
      - A page specific image: `assets/<module>.<extension>` is used, e.g. `assets/weekly_analytics.png`
      - A generic app image at `assets/app.<extension>`
      - A logo at `assets/logo.<extension>`
      """
      assets_folder = CONFIG.assets_folder
      valid_extensions = ["apng", "avif", "gif", "jpeg", "jpg", "png", "svg", "webp"]
      page_id = module.split(".")[-1]
      files_in_assets = []
  
      if os.path.exists(assets_folder):
          files_in_assets = [
              f for f in os.listdir(assets_folder) if isfile(join(assets_folder, f))
          ]
      app_file = None
      logo_file = None
      for fn in files_in_assets:
          fn_without_extension, _, extension = fn.partition(".")
          if extension.lower() in valid_extensions:
              if (
                  fn_without_extension == page_id
                  or fn_without_extension == page_id.replace("_", "-")
              ):
                  return fn
  
              if fn_without_extension == "app":
                  app_file = fn
  
              if fn_without_extension == "logo":
                  logo_file = fn
  
      if app_file:
          return app_file
  
      return logo_file
  
  
  def _module_name_to_page_name(module_name):
      return module_name.split(".")[-1].replace("_", " ").capitalize()
  
  
  def _infer_path(module_name, template):
      if template is None:
          if CONFIG.pages_folder:
              pages_module = str(Path(CONFIG.pages_folder).name)
              path = (
                  module_name.split(pages_module)[-1]
                  .replace("_", "-")
                  .replace(".", "/")
                  .lower()
              )
          else:
              path = module_name.replace("_", "-").replace(".", "/").lower()
      else:
          # replace the variables in the template with "none" to create a default path if
          # no path is supplied
          path = re.sub("<.*?>", "none", template)
      path = "/" + path if not path.startswith("/") else path
      return path
  
  
  def _module_name_is_package(module_name):
      if module_name not in sys.modules:
          return False
      file = sys.modules[module_name].__file__
      return file and file.endswith("__init__.py")
  
  
  def _path_to_module_name(path):
      return str(path).replace(".py", "").strip(os.sep).replace(os.sep, ".")
  
  
  def _infer_module_name(page_path):
      relative_path = page_path.split(CONFIG.pages_folder)[-1]
      module = _path_to_module_name(relative_path)
      proj_root = flask.helpers.get_root_path(CONFIG.name)
      if CONFIG.pages_folder.startswith(proj_root):
          parent_path = CONFIG.pages_folder[len(proj_root) :]
      else:
          parent_path = CONFIG.pages_folder
      parent_module = _path_to_module_name(parent_path)
  
      module_name = f"{parent_module}.{module}"
      if _module_name_is_package(CONFIG.name):
          # Only prefix with CONFIG.name when it's an imported package name
          module_name = f"{CONFIG.name}.{module_name}"
      return module_name
  
  
  def _parse_query_string(search):
      if not search or not search.startswith("?"):
          return {}
  
      query_string = search[1:]
  
      parsed_qs = parse_qs(query_string, keep_blank_values=True)
  
      return {k: v[0] if len(v) == 1 else v for k, v in parsed_qs.items()}
  
  
  def _parse_path_variables(pathname, path_template):
      """
      creates the dict of path variables passed to the layout
      e.g. path_template= "/asset/<asset_id>"
           if pathname provided by the browser is "/assets/a100"
           returns **{"asset_id": "a100"}
      """
  
      # parse variable definitions e.g. <var_name> from template
      # and create pattern to match
      wildcard_pattern = re.sub("<.*?>", "*", path_template)
      var_pattern = re.sub("<.*?>", "(.*)", path_template)
  
      # check that static sections of the pathname match the template
      if not fnmatch(pathname, wildcard_pattern):
          return None
  
      # parse variable names e.g. var_name from template
      var_names = re.findall("<(.*?)>", path_template)
  
      # parse variables from path
      variables = re.findall(var_pattern, pathname)
      variables = variables[0] if isinstance(variables[0], tuple) else variables
  
      return dict(zip(var_names, variables))
  
  
  def _create_redirect_function(redirect_to):
      def redirect():
          return flask.redirect(redirect_to, code=301)
  
      return redirect
  
  
  def _set_redirect(redirect_from, path):
      app = get_app()
      if redirect_from and len(redirect_from):
          for redirect in redirect_from:
              fullname = app.get_relative_path(redirect)
              app.server.add_url_rule(
                  fullname,
                  fullname,
                  _create_redirect_function(app.get_relative_path(path)),
              )
  
  
  def register_page(
      module,
      path=None,
      path_template=None,
      name=None,
      order=None,
      title=None,
      description=None,
      image=None,
      image_url=None,
      redirect_from=None,
      layout=None,
      **kwargs,
  ):
      """
      Assigns the variables to `dash.page_registry` as an `OrderedDict`
      (ordered by `order`).
  
      `dash.page_registry` is used by `pages_plugin` to set up the layouts as
      a multi-page Dash app. This includes the URL routing callbacks
      (using `dcc.Location`) and the HTML templates to include title,
      meta description, and the meta description image.
  
      `dash.page_registry` can also be used by Dash developers to create the
      page navigation links or by template authors.
  
      - `module`:
         The module path where this page's `layout` is defined. Often `__name__`.
  
      - `path`:
         URL Path, e.g. `/` or `/home-page`.
         If not supplied, will be inferred from the `path_template` or `module`,
         e.g. based on path_template: `/asset/<asset_id` to `/asset/none`
         e.g. based on module: `pages.weekly_analytics` to `/weekly-analytics`
  
      - `relative_path`:
          The path with `requests_pathname_prefix` prefixed before it.
          Use this path when specifying local URL paths that will work
          in environments regardless of what `requests_pathname_prefix` is.
          In some deployment environments, like Dash Enterprise,
          `requests_pathname_prefix` is set to the application name,
          e.g. `my-dash-app`.
          When working locally, `requests_pathname_prefix` might be unset and
          so a relative URL like `/page-2` can just be `/page-2`.
          However, when the app is deployed to a URL like `/my-dash-app`, then
          `relative_path` will be `/my-dash-app/page-2`.
  
      - `path_template`:
         Add variables to a URL by marking sections with <variable_name>. The layout function
         then receives the <variable_name> as a keyword argument.
         e.g. path_template= "/asset/<asset_id>"
              then if pathname in browser is "/assets/a100" then layout will receive **{"asset_id":"a100"}
  
      - `name`:
         The name of the link.
         If not supplied, will be inferred from `module`,
         e.g. `pages.weekly_analytics` to `Weekly analytics`
  
      - `order`:
         The order of the pages in `page_registry`.
         If not supplied, then the filename is used and the page with path `/` has
         order `0`
  
      - `title`:
         (string or function) Specifies the page title displayed in the browser tab.
          If not supplied, the app's title is used if different from the default "Dash".
          Otherwise, the title is the given `name` or inferred from the module name.
          For example, `pages.weekly_analytics` is inferred as "Weekly Analytics".
  
      - `description`:
         (string or function) The <meta type="description"></meta>.
         If not defined, the application description will be used if available.
  
      - `image`:
         The meta description image used by social media platforms.
         If not supplied, then it looks for the following images in `assets/`:
          - A page specific image: `assets/<module>.<extension>` is used, e.g. `assets/weekly_analytics.png`
          - A generic app image at `assets/app.<extension>`
          - A logo at `assets/logo.<extension>`
          When inferring the image file, it will look for the following extensions:
          APNG, AVIF, GIF, JPEG, JPG, PNG, SVG, WebP.
  
      -  `image_url`:
         Overrides the image property and sets the `<image>` meta tag to the provided image URL.
  
      - `redirect_from`:
         A list of paths that should redirect to this page.
         For example: `redirect_from=['/v2', '/v3']`
  
      - `layout`:
         The layout function or component for this page.
         If not supplied, then looks for `layout` from within the supplied `module`.
  
      - `**kwargs`:
         Arbitrary keyword arguments that can be stored
  
      ***
  
      `page_registry` stores the original property that was passed in under
      `supplied_<property>` and the coerced property under `<property>`.
      For example, if this was called:
      ```
      register_page(
          'pages.historical_outlook',
          name='Our historical view',
          custom_key='custom value'
      )
      ```
      Then this will appear in `page_registry`:
      ```
      OrderedDict([
          (
              'pages.historical_outlook',
              dict(
                  module='pages.historical_outlook',
  
                  supplied_path=None,
                  path='/historical-outlook',
  
                  supplied_name='Our historical view',
                  name='Our historical view',
  
                  supplied_title=None,
                  title='Our historical view'
  
                  supplied_layout=None,
                  layout=<function pages.historical_outlook.layout>,
  
                  custom_key='custom value'
              )
          ),
      ])
      ```
      """
      if context_value.get().get("ignore_register_page"):
          return
  
      _validate.validate_use_pages(CONFIG)
  
      page = dict(
          module=_validate.validate_module_name(module),
          supplied_path=path,
          path_template=path_template,
          path=path if path is not None else _infer_path(module, path_template),
          supplied_name=name,
          name=name if name is not None else _module_name_to_page_name(module),
      )
      page.update(
          supplied_title=title,
          title=title
          if title is not None
          else CONFIG.title
          if CONFIG.title != "Dash"
          else page["name"],
      )
      page.update(
          description=description
          if description
          else CONFIG.description
          if CONFIG.description
          else "",
          order=order,
          supplied_order=order,
          supplied_layout=layout,
          **kwargs,
      )
      page.update(
          supplied_image=image,
          image=(image if image is not None else _infer_image(module)),
          image_url=image_url,
      )
      page.update(redirect_from=_set_redirect(redirect_from, page["path"]))
  
      PAGE_REGISTRY[module] = page
  
      if page["path_template"]:
          _validate.validate_template(page["path_template"])
  
      if layout is not None:
          # Override the layout found in the file set during `plug`
          PAGE_REGISTRY[module]["layout"] = layout
  
      # set home page order
      order_supplied = any(
          p["supplied_order"] is not None for p in PAGE_REGISTRY.values()
      )
  
      for p in PAGE_REGISTRY.values():
          p["order"] = (
              0 if p["path"] == "/" and not order_supplied else p["supplied_order"]
          )
          p["relative_path"] = get_relative_path(p["path"])
  
      # Sort numeric orders first, then string orders, then no order,
      # finally by module name for matching orders
      for page in sorted(
          PAGE_REGISTRY.values(),
          key=lambda i: (
              i["order"] is None,  # False (order given) sorts before True
              i["order"] if isinstance(i["order"], (int, float)) else float("inf"),
              str(i["order"]),
              i["module"],
          ),
      ):
          PAGE_REGISTRY.move_to_end(page["module"])
  
  
  def _path_to_page(path_id):
      path_variables = None
      for page in PAGE_REGISTRY.values():
          if page["path_template"]:
              template_id = page["path_template"].strip("/")
              path_variables = _parse_path_variables(path_id, template_id)
              if path_variables:
                  return page, path_variables
          if path_id == page["path"].strip("/"):
              return page, path_variables
      return {}, None
  
  
  def _page_meta_tags(app):
      start_page, path_variables = _path_to_page(flask.request.path.strip("/"))
  
      # use the supplied image_url or create url based on image in the assets folder
      image = start_page.get("image", "")
      if image:
          image = app.get_asset_url(image)
      assets_image_url = (
          "".join([flask.request.url_root, image.lstrip("/")]) if image else None
      )
      supplied_image_url = start_page.get("image_url")
      image_url = supplied_image_url if supplied_image_url else assets_image_url
  
      title = start_page.get("title", app.title)
      if callable(title):
          title = title(**path_variables) if path_variables else title()
  
      description = start_page.get("description", "")
      if callable(description):
          description = description(**path_variables) if path_variables else description()
  
      return [
          {"name": "description", "content": description},
          {"property": "twitter:card", "content": "summary_large_image"},
          {"property": "twitter:url", "content": flask.request.url},
          {"property": "twitter:title", "content": title},
          {"property": "twitter:description", "content": description},
          {"property": "twitter:image", "content": image_url or ""},
          {"property": "og:title", "content": title},
          {"property": "og:type", "content": "website"},
          {"property": "og:description", "content": description},
          {"property": "og:image", "content": image_url or ""},
      ]
  
  
  def _import_layouts_from_pages(pages_folder):
      for root, dirs, files in os.walk(pages_folder):
          dirs[:] = [d for d in dirs if not d.startswith(".") and not d.startswith("_")]
          for file in files:
              if file.startswith("_") or file.startswith(".") or not file.endswith(".py"):
                  continue
              page_path = os.path.join(root, file)
              with open(page_path, encoding="utf-8") as f:
                  content = f.read()
                  if "register_page" not in content:
                      continue
  
              module_name = _infer_module_name(page_path)
              spec = importlib.util.spec_from_file_location(module_name, page_path)
              page_module = importlib.util.module_from_spec(spec)  # type: ignore[reportArgumentType]
              spec.loader.exec_module(page_module)  # type: ignore[reportOptionalMemberAccess]
              sys.modules[module_name] = page_module
  
              if (
                  module_name in PAGE_REGISTRY
                  and not PAGE_REGISTRY[module_name]["supplied_layout"]
              ):
                  _validate.validate_pages_layout(module_name, page_module)
                  PAGE_REGISTRY[module_name]["layout"] = getattr(page_module, "layout")
  