"""Build HTML documentation and Devhelp_ support files.

.. _Devhelp: https://wiki.gnome.org/Apps/Devhelp
"""

from __future__ import annotations

import gzip
import os
import re
from os import path
from typing import TYPE_CHECKING, Any

from docutils import nodes
from sphinx import addnodes
from sphinx.builders.html import StandaloneHTMLBuilder
from sphinx.environment.adapters.indexentries import IndexEntries
from sphinx.locale import get_translation
from sphinx.util import logging
from sphinx.util.nodes import NodeMatcher
from sphinx.util.osutil import make_filename

if TYPE_CHECKING:
    from sphinx.application import Sphinx

import xml.etree.ElementTree as etree

__version__ = '2.0.0'
__version_info__ = (2, 0, 0)

logger = logging.getLogger(__name__)
__ = get_translation(__name__, 'console')

package_dir = path.abspath(path.dirname(__file__))


class DevhelpBuilder(StandaloneHTMLBuilder):
    """
    Builder that also outputs GNOME Devhelp file.
    """
    name = 'devhelp'
    epilog = __('To view the help file:\n'
                '$ mkdir -p $HOME/.local/share/devhelp/books\n'
                '$ ln -s $PWD/%(outdir)s $HOME/.local/share/devhelp/books/%(project)s\n'
                '$ devhelp')

    # don't copy the reST source
    copysource = False
    supported_image_types = ['image/png', 'image/gif', 'image/jpeg']

    # don't add links
    add_permalinks = False
    # don't add sidebar etc.
    embedded = True

    def init(self) -> None:
        super().init()
        self.out_suffix = '.html'
        self.link_suffix = '.html'

    def handle_finish(self) -> None:
        self.build_devhelp(self.outdir, self.config.devhelp_basename)

    def build_devhelp(self, outdir: str | os.PathLike[str], outname: str) -> None:
        logger.info(__('dumping devhelp index...'))

        # Basic info
        root = etree.Element('book',
                             title=self.config.html_title,
                             name=self.config.project,
                             link="index.html",
                             version=self.config.version)
        tree = etree.ElementTree(root)

        # TOC
        chapters = etree.SubElement(root, 'chapters')

        tocdoc = self.env.get_and_resolve_doctree(
            self.config.master_doc, self, prune_toctrees=False)

        def write_toc(node: nodes.Node, parent: etree.Element) -> None:
            if isinstance(node, (addnodes.compact_paragraph, nodes.bullet_list)):
                for subnode in node:
                    write_toc(subnode, parent)
            elif isinstance(node, nodes.list_item):
                item = etree.SubElement(parent, 'sub')
                for subnode in node:
                    write_toc(subnode, item)
            elif isinstance(node, nodes.reference):
                parent.attrib['link'] = node['refuri']
                parent.attrib['name'] = node.astext()

        matcher = NodeMatcher(addnodes.compact_paragraph, toctree=Any)
        for node in tocdoc.findall(matcher):
            write_toc(node, chapters)

        # Index
        functions = etree.SubElement(root, 'functions')
        index = IndexEntries(self.env).create_index(self)

        def write_index(title: str, refs: list[Any], subitems: Any) -> None:
            if len(refs) == 0:
                pass
            elif len(refs) == 1:
                etree.SubElement(functions, 'function',
                                 name=title, link=refs[0][1])
            else:
                for i, ref in enumerate(refs):
                    etree.SubElement(functions, 'function',
                                     name="[%d] %s" % (i, title),
                                     link=ref[1])

            if subitems:
                parent_title = re.sub(r'\s*\(.*\)\s*$', '', title)
                for subitem in subitems:
                    write_index(f'{parent_title} {subitem[0]}',
                                subitem[1], [])

        for (_group_key, group) in index:
            for title, (refs, subitems, _category_key) in group:
                write_index(title, refs, subitems)

        # Dump the XML file
        xmlfile = path.join(outdir, outname + '.devhelp.gz')
        with gzip.GzipFile(filename=xmlfile, mode='w', mtime=0) as f:
            tree.write(f, 'utf-8')


def setup(app: Sphinx) -> dict[str, Any]:
    app.require_sphinx('5.0')
    app.setup_extension('sphinx.builders.html')
    app.add_builder(DevhelpBuilder)
    app.add_message_catalog(__name__, path.join(package_dir, 'locales'))

    app.add_config_value('devhelp_basename',
                         lambda self: make_filename(self.project),
                         'devhelp')

    return {
        'version': __version__,
        'parallel_read_safe': True,
        'parallel_write_safe': True,
    }