text: """Translation layer between pyproject config and setuptools distribution and
  metadata objects.
  
  The distribution and metadata objects are modeled after (an old version of)
  core metadata, therefore configs in the format specified for ``pyproject.toml``
  need to be processed before being applied.
  """
  import logging
  import os
  import warnings
  from collections.abc import Mapping
  from email.headerregistry import Address
  from functools import partial, reduce
  from itertools import chain
  from types import MappingProxyType
  from typing import (TYPE_CHECKING, Any, Callable, Dict, List, Optional, Set, Tuple,
                      Type, Union)
  
  from setuptools._deprecation_warning import SetuptoolsDeprecationWarning
  
  if TYPE_CHECKING:
      from setuptools._importlib import metadata  # noqa
      from setuptools.dist import Distribution  # noqa
  
  EMPTY: Mapping = MappingProxyType({})  # Immutable dict-like
  _Path = Union[os.PathLike, str]
  _DictOrStr = Union[dict, str]
  _CorrespFn = Callable[["Distribution", Any, _Path], None]
  _Correspondence = Union[str, _CorrespFn]
  
  _logger = logging.getLogger(__name__)
  
  
  def apply(dist: "Distribution", config: dict, filename: _Path) -> "Distribution":
      """Apply configuration dict read with :func:`read_configuration`"""
  
      if not config:
          return dist  # short-circuit unrelated pyproject.toml file
  
      root_dir = os.path.dirname(filename) or "."
  
      _apply_project_table(dist, config, root_dir)
      _apply_tool_table(dist, config, filename)
  
      current_directory = os.getcwd()
      os.chdir(root_dir)
      try:
          dist._finalize_requires()
          dist._finalize_license_files()
      finally:
          os.chdir(current_directory)
  
      return dist
  
  
  def _apply_project_table(dist: "Distribution", config: dict, root_dir: _Path):
      project_table = config.get("project", {}).copy()
      if not project_table:
          return  # short-circuit
  
      _handle_missing_dynamic(dist, project_table)
      _unify_entry_points(project_table)
  
      for field, value in project_table.items():
          norm_key = json_compatible_key(field)
          corresp = PYPROJECT_CORRESPONDENCE.get(norm_key, norm_key)
          if callable(corresp):
              corresp(dist, value, root_dir)
          else:
              _set_config(dist, corresp, value)
  
  
  def _apply_tool_table(dist: "Distribution", config: dict, filename: _Path):
      tool_table = config.get("tool", {}).get("setuptools", {})
      if not tool_table:
          return  # short-circuit
  
      for field, value in tool_table.items():
          norm_key = json_compatible_key(field)
  
          if norm_key in TOOL_TABLE_DEPRECATIONS:
              suggestion = TOOL_TABLE_DEPRECATIONS[norm_key]
              msg = f"The parameter `{norm_key}` is deprecated, {suggestion}"
              warnings.warn(msg, SetuptoolsDeprecationWarning)
  
          norm_key = TOOL_TABLE_RENAMES.get(norm_key, norm_key)
          _set_config(dist, norm_key, value)
  
      _copy_command_options(config, dist, filename)
  
  
  def _handle_missing_dynamic(dist: "Distribution", project_table: dict):
      """Be temporarily forgiving with ``dynamic`` fields not listed in ``dynamic``"""
      # TODO: Set fields back to `None` once the feature stabilizes
      dynamic = set(project_table.get("dynamic", []))
      for field, getter in _PREVIOUSLY_DEFINED.items():
          if not (field in project_table or field in dynamic):
              value = getter(dist)
              if value:
                  msg = _WouldIgnoreField.message(field, value)
                  warnings.warn(msg, _WouldIgnoreField)
  
  
  def json_compatible_key(key: str) -> str:
      """As defined in :pep:`566#json-compatible-metadata`"""
      return key.lower().replace("-", "_")
  
  
  def _set_config(dist: "Distribution", field: str, value: Any):
      setter = getattr(dist.metadata, f"set_{field}", None)
      if setter:
          setter(value)
      elif hasattr(dist.metadata, field) or field in SETUPTOOLS_PATCHES:
          setattr(dist.metadata, field, value)
      else:
          setattr(dist, field, value)
  
  
  _CONTENT_TYPES = {
      ".md": "text/markdown",
      ".rst": "text/x-rst",
      ".txt": "text/plain",
  }
  
  
  def _guess_content_type(file: str) -> Optional[str]:
      _, ext = os.path.splitext(file.lower())
      if not ext:
          return None
  
      if ext in _CONTENT_TYPES:
          return _CONTENT_TYPES[ext]
  
      valid = ", ".join(f"{k} ({v})" for k, v in _CONTENT_TYPES.items())
      msg = f"only the following file extensions are recognized: {valid}."
      raise ValueError(f"Undefined content type for {file}, {msg}")
  
  
  def _long_description(dist: "Distribution", val: _DictOrStr, root_dir: _Path):
      from setuptools.config import expand
  
      if isinstance(val, str):
          text = expand.read_files(val, root_dir)
          ctype = _guess_content_type(val)
      else:
          text = val.get("text") or expand.read_files(val.get("file", []), root_dir)
          ctype = val["content-type"]
  
      _set_config(dist, "long_description", text)
      if ctype:
          _set_config(dist, "long_description_content_type", ctype)
  
  
  def _license(dist: "Distribution", val: dict, root_dir: _Path):
      from setuptools.config import expand
  
      if "file" in val:
          _set_config(dist, "license", expand.read_files([val["file"]], root_dir))
      else:
          _set_config(dist, "license", val["text"])
  
  
  def _people(dist: "Distribution", val: List[dict], _root_dir: _Path, kind: str):
      field = []
      email_field = []
      for person in val:
          if "name" not in person:
              email_field.append(person["email"])
          elif "email" not in person:
              field.append(person["name"])
          else:
              addr = Address(display_name=person["name"], addr_spec=person["email"])
              email_field.append(str(addr))
  
      if field:
          _set_config(dist, kind, ", ".join(field))
      if email_field:
          _set_config(dist, f"{kind}_email", ", ".join(email_field))
  
  
  def _project_urls(dist: "Distribution", val: dict, _root_dir):
      _set_config(dist, "project_urls", val)
  
  
  def _python_requires(dist: "Distribution", val: dict, _root_dir):
      from setuptools.extern.packaging.specifiers import SpecifierSet
  
      _set_config(dist, "python_requires", SpecifierSet(val))
  
  
  def _dependencies(dist: "Distribution", val: list, _root_dir):
      if getattr(dist, "install_requires", []):
          msg = "`install_requires` overwritten in `pyproject.toml` (dependencies)"
          warnings.warn(msg)
      _set_config(dist, "install_requires", val)
  
  
  def _optional_dependencies(dist: "Distribution", val: dict, _root_dir):
      existing = getattr(dist, "extras_require", {})
      _set_config(dist, "extras_require", {**existing, **val})
  
  
  def _unify_entry_points(project_table: dict):
      project = project_table
      entry_points = project.pop("entry-points", project.pop("entry_points", {}))
      renaming = {"scripts": "console_scripts", "gui_scripts": "gui_scripts"}
      for key, value in list(project.items()):  # eager to allow modifications
          norm_key = json_compatible_key(key)
          if norm_key in renaming and value:
              entry_points[renaming[norm_key]] = project.pop(key)
  
      if entry_points:
          project["entry-points"] = {
              name: [f"{k} = {v}" for k, v in group.items()]
              for name, group in entry_points.items()
          }
  
  
  def _copy_command_options(pyproject: dict, dist: "Distribution", filename: _Path):
      tool_table = pyproject.get("tool", {})
      cmdclass = tool_table.get("setuptools", {}).get("cmdclass", {})
      valid_options = _valid_command_options(cmdclass)
  
      cmd_opts = dist.command_options
      for cmd, config in pyproject.get("tool", {}).get("distutils", {}).items():
          cmd = json_compatible_key(cmd)
          valid = valid_options.get(cmd, set())
          cmd_opts.setdefault(cmd, {})
          for key, value in config.items():
              key = json_compatible_key(key)
              cmd_opts[cmd][key] = (str(filename), value)
              if key not in valid:
                  # To avoid removing options that are specified dynamically we
                  # just log a warn...
                  _logger.warning(f"Command option {cmd}.{key} is not defined")
  
  
  def _valid_command_options(cmdclass: Mapping = EMPTY) -> Dict[str, Set[str]]:
      from .._importlib import metadata
      from setuptools.dist import Distribution
  
      valid_options = {"global": _normalise_cmd_options(Distribution.global_options)}
  
      unloaded_entry_points = metadata.entry_points(group='distutils.commands')
      loaded_entry_points = (_load_ep(ep) for ep in unloaded_entry_points)
      entry_points = (ep for ep in loaded_entry_points if ep)
      for cmd, cmd_class in chain(entry_points, cmdclass.items()):
          opts = valid_options.get(cmd, set())
          opts = opts | _normalise_cmd_options(getattr(cmd_class, "user_options", []))
          valid_options[cmd] = opts
  
      return valid_options
  
  
  def _load_ep(ep: "metadata.EntryPoint") -> Optional[Tuple[str, Type]]:
      # Ignore all the errors
      try:
          return (ep.name, ep.load())
      except Exception as ex:
          msg = f"{ex.__class__.__name__} while trying to load entry-point {ep.name}"
          _logger.warning(f"{msg}: {ex}")
          return None
  
  
  def _normalise_cmd_option_key(name: str) -> str:
      return json_compatible_key(name).strip("_=")
  
  
  def _normalise_cmd_options(desc: List[Tuple[str, Optional[str], str]]) -> Set[str]:
      return {_normalise_cmd_option_key(fancy_option[0]) for fancy_option in desc}
  
  
  def _attrgetter(attr):
      """
      Similar to ``operator.attrgetter`` but returns None if ``attr`` is not found
      >>> from types import SimpleNamespace
      >>> obj = SimpleNamespace(a=42, b=SimpleNamespace(c=13))
      >>> _attrgetter("a")(obj)
      42
      >>> _attrgetter("b.c")(obj)
      13
      >>> _attrgetter("d")(obj) is None
      True
      """
      return partial(reduce, lambda acc, x: getattr(acc, x, None), attr.split("."))
  
  
  def _some_attrgetter(*items):
      """
      Return the first "truth-y" attribute or None
      >>> from types import SimpleNamespace
      >>> obj = SimpleNamespace(a=42, b=SimpleNamespace(c=13))
      >>> _some_attrgetter("d", "a", "b.c")(obj)
      42
      >>> _some_attrgetter("d", "e", "b.c", "a")(obj)
      13
      >>> _some_attrgetter("d", "e", "f")(obj) is None
      True
      """
      def _acessor(obj):
          values = (_attrgetter(i)(obj) for i in items)
          return next((i for i in values if i is not None), None)
      return _acessor
  
  
  PYPROJECT_CORRESPONDENCE: Dict[str, _Correspondence] = {
      "readme": _long_description,
      "license": _license,
      "authors": partial(_people, kind="author"),
      "maintainers": partial(_people, kind="maintainer"),
      "urls": _project_urls,
      "dependencies": _dependencies,
      "optional_dependencies": _optional_dependencies,
      "requires_python": _python_requires,
  }
  
  TOOL_TABLE_RENAMES = {"script_files": "scripts"}
  TOOL_TABLE_DEPRECATIONS = {
      "namespace_packages": "consider using implicit namespaces instead (PEP 420)."
  }
  
  SETUPTOOLS_PATCHES = {"long_description_content_type", "project_urls",
                        "provides_extras", "license_file", "license_files"}
  
  _PREVIOUSLY_DEFINED = {
      "name": _attrgetter("metadata.name"),
      "version": _attrgetter("metadata.version"),
      "description": _attrgetter("metadata.description"),
      "readme": _attrgetter("metadata.long_description"),
      "requires-python": _some_attrgetter("python_requires", "metadata.python_requires"),
      "license": _attrgetter("metadata.license"),
      "authors": _some_attrgetter("metadata.author", "metadata.author_email"),
      "maintainers": _some_attrgetter("metadata.maintainer", "metadata.maintainer_email"),
      "keywords": _attrgetter("metadata.keywords"),
      "classifiers": _attrgetter("metadata.classifiers"),
      "urls": _attrgetter("metadata.project_urls"),
      "entry-points": _attrgetter("entry_points"),
      "dependencies": _some_attrgetter("_orig_install_requires", "install_requires"),
      "optional-dependencies": _some_attrgetter("_orig_extras_require", "extras_require"),
  }
  
  
  class _WouldIgnoreField(UserWarning):
      """Inform users that ``pyproject.toml`` would overwrite previous metadata."""
  
      MESSAGE = """\
      {field!r} defined outside of `pyproject.toml` would be ignored.
      !!\n\n
      ##########################################################################
      # configuration would be ignored/result in error due to `pyproject.toml` #
      ##########################################################################
  
      The following seems to be defined outside of `pyproject.toml`:
  
      `{field} = {value!r}`
  
      According to the spec (see the link bellow), however, setuptools CANNOT
      consider this value unless {field!r} is listed as `dynamic`.
  
      https://packaging.python.org/en/latest/specifications/declaring-project-metadata/
  
      For the time being, `setuptools` will still consider the given value (as a
      **transitional** measure), but please note that future releases of setuptools will
      follow strictly the standard.
  
      To prevent this warning, you can list {field!r} under `dynamic` or alternatively
      remove the `[project]` table from your file and rely entirely on other means of
      configuration.
      \n\n!!
      """
  
      @classmethod
      def message(cls, field, value):
          from inspect import cleandoc
          return cleandoc(cls.MESSAGE.format(field=field, value=value))
  