# Copyright 2023 DeepMind Technologies Limited. 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.
# ==============================================================================
"""Asserts all public symbols are covered in the docs."""

import inspect
import types
from typing import Any, Mapping, Sequence, Tuple

from sphinx import application
from sphinx import builders
from sphinx import errors
import tsuite as _module


def find_internal_python_modules(
    root_module: types.ModuleType,) -> Sequence[Tuple[str, types.ModuleType]]:
  """Returns `(name, module)` for all submodules under `root_module`."""
  modules = set([(root_module.__name__, root_module)])
  visited = set()
  to_visit = [root_module]

  while to_visit:
    mod = to_visit.pop()
    visited.add(mod)

    for name in dir(mod):
      obj = getattr(mod, name)
      if inspect.ismodule(obj) and obj not in visited:
        if obj.__name__.startswith(_module.__name__):
          if '_src' not in obj.__name__:
            to_visit.append(obj)
            modules.add((obj.__name__, obj))

  return sorted(modules)


def get_public_symbols() -> Sequence[Tuple[str, types.ModuleType]]:
  names = set()
  for module_name, module in find_internal_python_modules(_module):
    for name in module.__all__:
      names.add(module_name + '.' + name)
  return tuple(names)


class CoverageCheck(builders.Builder):
  """Builder that checks all public symbols are included."""

  name = 'coverage_check'

  def get_outdated_docs(self) -> str:
    return 'coverage_check'

  def write(self, *ignored: Any) -> None:
    pass

  def finish(self) -> None:
    documented_objects = frozenset(self.env.domaindata['py']['objects'])
    undocumented_objects = set(get_public_symbols()) - documented_objects

    # Exclude deprecated API symbols.
    assertion_exceptions = ()
    undocumented_objects -= {'tsuite.' + s for s in assertion_exceptions}

    # Exclude pytypes.
    pytypes_exceptions = ()

    undocumented_objects -= {'tsuite.' + s for s in pytypes_exceptions}

    if undocumented_objects:
      undocumented_objects = tuple(sorted(undocumented_objects))
      raise errors.SphinxError(
          'All public symbols must be included in our documentation, did you '
          'forget to add an entry to `api.rst`?\n'
          f'Undocumented symbols: {undocumented_objects}')


def setup(app: application.Sphinx) -> Mapping[str, Any]:
  app.add_builder(CoverageCheck)
  return dict(version=_module.__version__, parallel_read_safe=True)
