#!/usr/bin/env python3
#
#  source.py
"""
Add hyperlinks to source files, either on GitHub or in the documentation itself.

.. extensions:: sphinx_toolbox.source

If you're looking for a ``[source]`` button to go at the end of your class and
function signatures, checkout :mod:`sphinx.ext.linkcode` and :mod:`sphinx.ext.viewcode`.


Usage
-------

.. confval:: source_link_target
	:type: :class:`str`
	:required: False
	:default: ``'Sphinx'``

	The target of the source link, either ``'GitHub'`` or ``'Sphinx'``.
	Case insensitive.


.. rst:role:: source

	Role which shows a link to the given source file, either on GitHub or within the Sphinx documentation.

	By default, the link points to the code within the documentation,
	but can be configured to point to GitHub by setting :confval:`source_link_target` to ``'GitHub'``.


	:bold-title:`Example`

	.. rest-example::

		:source:`sphinx_toolbox/config.py`

		Here is the :source:`source code <sphinx_toolbox/config.py>`


API Reference
--------------
"""
#
#  Copyright © 2020-2021 Dominic Davis-Foster <dominic@davis-foster.co.uk>
#
#  Permission is hereby granted, free of charge, to any person obtaining a copy
#  of this software and associated documentation files (the "Software"), to deal
#  in the Software without restriction, including without limitation the rights
#  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#  copies of the Software, and to permit persons to whom the Software is
#  furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included in all
#  copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
#  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
#  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
#  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
#  DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
#  OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
#  OR OTHER DEALINGS IN THE SOFTWARE.
#
#  Based on pyspecific.py from the Python documentation.
#  Copyright 2008-2014 by Georg Brandl.
#  Licensed under the PSF License 2.0
#
#  Parts of the docstrings based on https://docutils.sourceforge.io/docs/howto/rst-roles.html
#

# stdlib
from typing import TYPE_CHECKING, Dict, List, Sequence, Tuple

# 3rd party
import sphinx
from docutils import nodes
from docutils.nodes import system_message
from docutils.parsers.rst.states import Inliner
from sphinx import addnodes
from sphinx.application import Sphinx
from sphinx.environment import BuildEnvironment
from sphinx.errors import NoUri
from sphinx.util import split_explicit_title

# this package
from sphinx_toolbox.utils import SphinxExtMetadata, metadata_add_version

if TYPE_CHECKING:
	# this package
	from sphinx_toolbox.utils import Config

__all__ = ("source_role", "setup")

# TODO: rawstring: Return it as a problematic node linked to a system message if a problem is encountered.

_sphinx_version = sphinx.version_info[:3]


def _make_viewcode_node(
		title: str,
		pagename: str,
		env: BuildEnvironment,
		) -> nodes.Node:
	"""
	Construct a node for the :mod:`sphinx.ext.viewcode` link.

	Handles Sphinx 3.5+ compatibility.
	"""

	if _sphinx_version < (3, 5, 0):
		return addnodes.pending_xref(
				title,
				nodes.inline(title, title),
				reftype="viewcode",
				refdomain="std",
				refexplicit=False,
				reftarget=pagename,
				refid=title,
				refdoc=env.docname,
				)
	else:
		# 3rd party
		from sphinx.util.nodes import make_refnode

		assert env.app.builder is not None

		try:
			return make_refnode(
					env.app.builder,
					fromdocname=env.docname,
					todocname=pagename,
					targetid=title,
					child=nodes.inline(title, title),
					)
		except NoUri:
			return nodes.inline(title, title)


def source_role(
		name: str,
		rawtext: str,
		text: str,
		lineno: int,
		inliner: Inliner,
		options: Dict = {},
		content: List[str] = []
		) -> Tuple[Sequence[nodes.Node], List[system_message]]:
	"""
	Adds a link to the given Python source file in the documentation or on GitHub.

	:param name: The local name of the interpreted role, the role name actually used in the document.
	:param rawtext: A string containing the entire interpreted text input, including the role and markup.
	:param text: The interpreted text content.
	:param lineno: The line number where the interpreted text begins.
	:param inliner: The :class:`docutils.parsers.rst.states.Inliner` object that called :func:`~.source_role`.
		It contains the several attributes useful for error reporting and document tree access.
	:param options: A dictionary of directive options for customization (from the ``role`` directive),
		to be interpreted by the function.
		Used for additional attributes for the generated elements and other functionality.
	:param content: A list of strings, the directive content for customization (from the ``role`` directive).
		To be interpreted by the function.

	:return: A list containing the created node, and a list containing any messages generated during the function.

	.. versionchanged:: 2.8.0

		Now returns a sequence of :class:`nodes.reference <docutils.nodes.reference>` and
		:class:`addnodes.pending_xref <sphinx.addnodes.pending_xref>` as the first tuple element,
		rather than :class:`nodes.reference <docutils.nodes.reference>` and
		:class:`addnodes.pending_xref <sphinx.addnodes.only>` as in previous versions.
	"""

	has_t, title, target = split_explicit_title(text)
	title = nodes.unescape(title)
	target = nodes.unescape(target)

	env = inliner.document.settings.env
	config = env.app.config

	nodes_: List[nodes.Node] = []
	messages: List[system_message] = []
	refnode: nodes.Node

	if config.source_link_target == "sphinx":
		if target.endswith("/__init__.py"):
			pagename = "_modules/" + target.rsplit('/', 1)[0]
		else:
			pagename = "_modules/" + target.replace(".py", '')

		# refnode = addnodes.only(expr="html")
		# refnode += addnodes.pending_xref(

		refnode = _make_viewcode_node(
				title,
				pagename,
				env,
				)

		# refnode = addnodes.pending_xref(
		# 		title,
		# 		nodes.inline(title, title),
		# 		reftype="viewcode",
		# 		refdomain="std",
		# 		refexplicit=False,
		# 		reftarget=pagename,
		# 		refid=title,
		# 		refdoc=env.docname,
		# 		)

		nodes_.append(refnode)

	elif config.source_link_target == "github":
		refnode = nodes.reference(
				title,
				title,
				refuri=str(config.github_source_url / target),
				)

		nodes_.append(refnode)

	else:
		message = inliner.document.reporter.error(f"Unsupported source link target '{config.source_link_target}'.")
		messages.append(message)

	return nodes_, messages


def _configure(app: Sphinx, config: "Config") -> None:
	"""
	Validate the provided configuration values.

	:param app: The Sphinx application.
	:param config:
	"""

	config.source_link_target = str(config.source_link_target).lower().strip()  # type: ignore[attr-defined]

	if config.source_link_target not in {"sphinx", "github"}:
		# this package
		from sphinx_toolbox.config import InvalidOptionError

		raise InvalidOptionError("Invalid value for 'source_link_target'.")


@metadata_add_version
def setup(app: Sphinx) -> SphinxExtMetadata:
	"""
	Setup :mod:`sphinx_toolbox.source`.

	:param app: The Sphinx application.
	"""

	# Link to source code
	app.add_role("source", source_role)

	# The target for the source link. One of GitHub or Sphinx (GitLab coming soon™)
	app.add_config_value("source_link_target", "Sphinx", "env", types=[str])
	app.connect("config-inited", _configure)

	app.setup_extension("sphinx_toolbox.github")

	return {"parallel_read_safe": True}