from functools import partial
from optparse import Values
from typing import Any, Tuple
from unittest.mock import patch

import sphinx.domains.python
import sphinx.ext.autodoc
from docutils.parsers.rst import Parser as RstParser
from docutils.utils import new_document
from sphinx.addnodes import desc_signature
from sphinx.application import Sphinx
from sphinx.domains.python import PyAttribute
from sphinx.ext.autodoc import AttributeDocumenter

# Defensively check for the things we want to patch
_parse_annotation = getattr(sphinx.domains.python, "_parse_annotation", None)

# We want to patch:
# * sphinx.ext.autodoc.stringify_typehint (in sphinx < 6.1)
# * sphinx.ext.autodoc.stringify_annotation (in sphinx >= 6.1)
STRINGIFY_PATCH_TARGET = ""
for target in ["stringify_typehint", "stringify_annotation"]:
    if hasattr(sphinx.ext.autodoc, target):
        STRINGIFY_PATCH_TARGET = f"sphinx.ext.autodoc.{target}"
        break

# If we didn't locate both patch targets, we will just do nothing.
OKAY_TO_PATCH = bool(_parse_annotation and STRINGIFY_PATCH_TARGET)

# A label we inject to the type string so we know not to try to treat it as a
# type annotation
TYPE_IS_RST_LABEL = "--is-rst--"


orig_add_directive_header = AttributeDocumenter.add_directive_header
orig_handle_signature = PyAttribute.handle_signature


def stringify_annotation(app: Sphinx, annotation: Any, mode: str = "") -> str:  # noqa: U100
    """Format the annotation with sphinx-autodoc-typehints and inject our
    magic prefix to tell our patched PyAttribute.handle_signature to treat
    it as rst."""
    from . import format_annotation

    return TYPE_IS_RST_LABEL + format_annotation(annotation, app.config)


def patch_attribute_documenter(app: Sphinx) -> None:
    """Instead of using stringify_typehint in
    `AttributeDocumenter.add_directive_header`, use `format_annotation`
    """

    def add_directive_header(*args: Any, **kwargs: Any) -> Any:
        with patch(STRINGIFY_PATCH_TARGET, partial(stringify_annotation, app)):
            return orig_add_directive_header(*args, **kwargs)

    AttributeDocumenter.add_directive_header = add_directive_header  # type:ignore[assignment]


def rst_to_docutils(settings: Values, rst: str) -> Any:
    """Convert rst to a sequence of docutils nodes"""
    doc = new_document("", settings)
    RstParser().parse(rst, doc)
    # Remove top level paragraph node so that there is no line break.
    return doc.children[0].children


def patched_parse_annotation(settings: Values, typ: str, env: Any) -> Any:
    # if typ doesn't start with our label, use original function
    if not typ.startswith(TYPE_IS_RST_LABEL):
        return _parse_annotation(typ, env)  # type: ignore
    # Otherwise handle as rst
    typ = typ[len(TYPE_IS_RST_LABEL) :]
    return rst_to_docutils(settings, typ)


def patched_handle_signature(self: PyAttribute, sig: str, signode: desc_signature) -> Tuple[str, str]:
    target = "sphinx.domains.python._parse_annotation"
    new_func = partial(patched_parse_annotation, self.state.document.settings)
    with patch(target, new_func):
        return orig_handle_signature(self, sig, signode)


def patch_attribute_handling(app: Sphinx) -> None:
    """Use format_signature to format class attribute type annotations"""
    if not OKAY_TO_PATCH:
        return
    PyAttribute.handle_signature = patched_handle_signature  # type:ignore[assignment]
    patch_attribute_documenter(app)


__all__ = ["patch_attribute_handling"]
