"""Base class of epub2/epub3 builders."""

from __future__ import annotations

import html
import os
import os.path
import re
import time
from pathlib import Path
from typing import TYPE_CHECKING, NamedTuple
from urllib.parse import quote
from zipfile import ZIP_DEFLATED, ZIP_STORED, ZipFile

from docutils import nodes
from docutils.utils import smartquotes

from sphinx import addnodes
from sphinx.builders.html import StandaloneHTMLBuilder
from sphinx.builders.html._build_info import BuildInfo
from sphinx.locale import __
from sphinx.util import logging
from sphinx.util._pathlib import _StrPath
from sphinx.util.display import status_iterator
from sphinx.util.fileutil import copy_asset_file
from sphinx.util.osutil import copyfile, ensuredir, relpath

if TYPE_CHECKING:
    from typing import Any

    from docutils.nodes import Element, Node

try:
    from PIL import Image

    PILLOW_AVAILABLE = True
except ImportError:
    PILLOW_AVAILABLE = False


logger = logging.getLogger(__name__)


# (Fragment) templates from which the metainfo files content.opf and
# toc.ncx are created.
# This template section also defines strings that are embedded in the html
# output but that may be customized by (re-)setting module attributes,
# e.g. from conf.py.

COVERPAGE_NAME = 'epub-cover.xhtml'

TOCTREE_TEMPLATE = 'toctree-l%d'

LINK_TARGET_TEMPLATE = ' [%(uri)s]'

FOOTNOTE_LABEL_TEMPLATE = '#%d'

FOOTNOTES_RUBRIC_NAME = 'Footnotes'

CSS_LINK_TARGET_CLASS = 'link-target'

# XXX These strings should be localized according to epub_language
GUIDE_TITLES = {
    'toc': 'Table of Contents',
    'cover': 'Cover',
}

MEDIA_TYPES = {
    '.xhtml': 'application/xhtml+xml',
    '.css': 'text/css',
    '.png': 'image/png',
    '.webp': 'image/webp',
    '.gif': 'image/gif',
    '.svg': 'image/svg+xml',
    '.jpg': 'image/jpeg',
    '.jpeg': 'image/jpeg',
    '.otf': 'font/otf',
    '.ttf': 'font/ttf',
    '.woff': 'font/woff',
}

VECTOR_GRAPHICS_EXTENSIONS = ('.svg',)

# Regular expression to match colons only in local fragment identifiers.
# If the URI contains a colon before the #,
# it is an external link that should not change.
REFURI_RE = re.compile('([^#:]*#)(.*)')


class ManifestItem(NamedTuple):
    href: str
    id: str
    media_type: str


class Spine(NamedTuple):
    idref: str
    linear: bool


class Guide(NamedTuple):
    type: str
    title: str
    uri: str


class NavPoint(NamedTuple):
    navpoint: str
    playorder: int
    text: str
    refuri: str
    children: list[NavPoint]


def sphinx_smarty_pants(t: str, language: str = 'en') -> str:
    t = t.replace('&quot;', '"')
    t = smartquotes.educateDashesOldSchool(t)
    t = smartquotes.educateQuotes(t, language)
    t = t.replace('"', '&quot;')
    return t


ssp = sphinx_smarty_pants


# The epub publisher


class EpubBuilder(StandaloneHTMLBuilder):
    """Builder that outputs epub files.

    It creates the metainfo files container.opf, toc.ncx, mimetype, and
    META-INF/container.xml.  Afterwards, all necessary files are zipped to an
    epub file.
    """

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

    # don't add links
    add_permalinks = False
    # don't use # as current path. ePub check reject it.
    allow_sharp_as_current_path = False
    # don't add sidebar etc.
    embedded = True
    # disable download role
    download_support = False
    # don't create links to original images from images
    html_scaled_image_link = False
    # don't generate search index or include search page
    search = False

    coverpage_name = COVERPAGE_NAME
    toctree_template = TOCTREE_TEMPLATE
    link_target_template = LINK_TARGET_TEMPLATE
    css_link_target_class = CSS_LINK_TARGET_CLASS
    guide_titles = GUIDE_TITLES
    media_types = MEDIA_TYPES
    refuri_re = REFURI_RE
    template_dir: _StrPath = _StrPath()
    doctype = ''

    def init(self) -> None:
        super().init()
        # the output files for epub must be .html only
        self.out_suffix = '.xhtml'
        self.link_suffix = '.xhtml'
        self.playorder = 0
        self.tocid = 0
        self.id_cache: dict[str, str] = {}
        self.use_index = self.get_builder_config('use_index', 'epub')
        self.refnodes: list[dict[str, Any]] = []

    def create_build_info(self) -> BuildInfo:
        return BuildInfo(self.config, self.tags, frozenset({'html', 'epub'}))

    def get_theme_config(self) -> tuple[str, dict[str, str | int | bool]]:
        return self.config.epub_theme, self.config.epub_theme_options

    # generic support functions
    def make_id(self, name: str) -> str:
        # id_cache is intentionally mutable
        """Return a unique id for name."""
        id = self.id_cache.get(name)
        if not id:
            id = 'epub-%d' % self.env.new_serialno('epub')
            self.id_cache[name] = id
        return id

    def get_refnodes(
        self,
        doctree: Node,
        result: list[dict[str, Any]],
    ) -> list[dict[str, Any]]:
        """Collect section titles, their depth in the toc and the refuri."""
        # XXX: is there a better way than checking the attribute
        # toctree-l[1-8] on the parent node?
        if isinstance(doctree, nodes.reference) and doctree.get('refuri'):
            refuri = doctree['refuri']
            if refuri.startswith(('http://', 'https://', 'irc:', 'mailto:')):
                return result
            classes = doctree.parent.attributes['classes']
            for level in range(8, 0, -1):  # or range(1, 8)?
                if (self.toctree_template % level) in classes:
                    result.append({
                        'level': level,
                        'refuri': html.escape(refuri),
                        'text': ssp(html.escape(doctree.astext())),
                    })
                    break
        elif isinstance(doctree, nodes.Element):
            for elem in doctree:
                result = self.get_refnodes(elem, result)
        return result

    def check_refnodes(self, nodes: list[dict[str, Any]]) -> None:
        appeared: set[str] = set()
        for node in nodes:
            if node['refuri'] in appeared:
                logger.warning(
                    __('duplicated ToC entry found: %s'),
                    node['refuri'],
                    type='epub',
                    subtype='duplicated_toc_entry',
                )
            else:
                appeared.add(node['refuri'])

    def get_toc(self) -> None:
        """Get the total table of contents, containing the master_doc
        and pre and post files not managed by Sphinx.
        """
        doctree = self.env.get_and_resolve_doctree(
            self.config.master_doc,
            self,
            tags=self.tags,
            prune_toctrees=False,
            includehidden=True,
        )
        self.refnodes = self.get_refnodes(doctree, [])
        master_dir = Path(self.config.master_doc).parent
        for item in self.refnodes:
            item['refuri'] = str(master_dir / item['refuri'])
        self.toc_add_files(self.refnodes)

    def toc_add_files(self, refnodes: list[dict[str, Any]]) -> None:
        """Add the root_doc, pre and post files to a list of refnodes."""
        refnodes.insert(
            0,
            {
                'level': 1,
                'refuri': html.escape(self.config.root_doc + self.out_suffix),
                'text': ssp(
                    html.escape(self.env.titles[self.config.root_doc].astext())
                ),
            },
        )
        for file, text in reversed(self.config.epub_pre_files):
            refnodes.insert(
                0,
                {
                    'level': 1,
                    'refuri': html.escape(file),
                    'text': ssp(html.escape(text)),
                },
            )
        for file, text in self.config.epub_post_files:
            refnodes.append({
                'level': 1,
                'refuri': html.escape(file),
                'text': ssp(html.escape(text)),
            })

    def fix_fragment(self, prefix: str, fragment: str) -> str:
        """Return a href/id attribute with colons replaced by hyphens."""
        return prefix + fragment.replace(':', '-')

    def fix_ids(self, tree: nodes.document) -> None:
        """Replace colons with hyphens in href and id attributes.

        Some readers crash because they interpret the part as a
        transport protocol specification.
        """
        for reference in tree.findall(nodes.reference):
            if 'refuri' in reference:
                m = self.refuri_re.match(reference['refuri'])
                if m:
                    reference['refuri'] = self.fix_fragment(m.group(1), m.group(2))
            if 'refid' in reference:
                reference['refid'] = self.fix_fragment('', reference['refid'])

        for target in tree.findall(nodes.target):
            self._update_node_id(target)

            next_node: Node = target.next_node(ascend=True)
            if isinstance(next_node, nodes.Element):
                self._update_node_id(next_node)

        for desc_signature in tree.findall(addnodes.desc_signature):
            self._update_node_id(desc_signature)

    def _update_node_id(self, node: Element, /) -> None:
        """Update IDs of given *node*."""
        new_ids: list[str] = []
        for node_id in node['ids']:
            new_id = self.fix_fragment('', node_id)
            if new_id not in new_ids:
                new_ids.append(new_id)
        node['ids'] = new_ids

    @staticmethod
    def _make_footnote_ref(doc: nodes.document, label: str) -> nodes.footnote_reference:
        """Create a footnote_reference node with children"""
        footnote_ref = nodes.footnote_reference('[#]_')
        footnote_ref.append(nodes.Text(label))
        doc.note_autofootnote_ref(footnote_ref)
        return footnote_ref

    @staticmethod
    def _make_footnote(doc: nodes.document, label: str, uri: str) -> nodes.footnote:
        """Create a footnote node with children"""
        footnote = nodes.footnote(uri)
        para = nodes.paragraph()
        para.append(nodes.Text(uri))
        footnote.append(para)
        footnote.insert(0, nodes.label('', label))
        doc.note_autofootnote(footnote)
        return footnote

    @staticmethod
    def _footnote_spot(tree: nodes.document) -> tuple[Element, int]:
        """Find or create a spot to place footnotes.

        The function returns the tuple (parent, index).
        """
        # The code uses the following heuristic:
        # a) place them after the last existing footnote
        # b) place them after an (empty) Footnotes rubric
        # c) create an empty Footnotes rubric at the end of the document
        fns = list(tree.findall(nodes.footnote))
        if fns:
            fn = fns[-1]
            return fn.parent, fn.parent.index(fn) + 1
        for node in tree.findall(nodes.rubric):
            if len(node) == 1 and node.astext() == FOOTNOTES_RUBRIC_NAME:
                return node.parent, node.parent.index(node) + 1
        doc = next(tree.findall(nodes.document))
        rub = nodes.rubric()
        rub.append(nodes.Text(FOOTNOTES_RUBRIC_NAME))
        doc.append(rub)
        return doc, doc.index(rub) + 1

    def add_visible_links(
        self, tree: nodes.document, show_urls: str = 'inline'
    ) -> None:
        """Add visible link targets for external links"""
        if show_urls == 'no':
            return
        if show_urls == 'footnote':
            doc = next(tree.findall(nodes.document))
            fn_spot, fn_idx = self._footnote_spot(tree)
            nr = 1
        for node in list(tree.findall(nodes.reference)):
            uri = node.get('refuri', '')
            if uri.startswith(('http:', 'https:', 'ftp:')) and uri not in node.astext():
                idx = node.parent.index(node) + 1
                if show_urls == 'inline':
                    uri = self.link_target_template % {'uri': uri}
                    link = nodes.inline(uri, uri)
                    link['classes'].append(self.css_link_target_class)
                    node.parent.insert(idx, link)
                elif show_urls == 'footnote':
                    label = FOOTNOTE_LABEL_TEMPLATE % nr
                    nr += 1
                    footnote_ref = self._make_footnote_ref(doc, label)
                    node.parent.insert(idx, footnote_ref)
                    footnote = self._make_footnote(doc, label, uri)
                    fn_spot.insert(fn_idx, footnote)
                    footnote_ref['refid'] = footnote['ids'][0]
                    footnote.add_backref(footnote_ref['ids'][0])
                    fn_idx += 1

    def write_doc(self, docname: str, doctree: nodes.document) -> None:
        """Write one document file.

        This method is overwritten in order to fix fragment identifiers
        and to add visible external links.
        """
        self.fix_ids(doctree)
        self.add_visible_links(doctree, self.config.epub_show_urls)
        super().write_doc(docname, doctree)

    def fix_genindex(self, tree: list[tuple[str, list[tuple[str, Any]]]]) -> None:
        """Fix href attributes for genindex pages."""
        # XXX: modifies tree inline
        # Logic modeled from themes/basic/genindex.html
        for _key, columns in tree:
            for _entryname, (links, subitems, _key) in columns:
                for i, (ismain, link) in enumerate(links):
                    if m := self.refuri_re.match(link):
                        links[i] = ismain, self.fix_fragment(m.group(1), m.group(2))
                for _subentryname, subentrylinks in subitems:
                    for i, (ismain, link) in enumerate(subentrylinks):
                        if m := self.refuri_re.match(link):
                            subentrylinks[i] = (
                                ismain,
                                self.fix_fragment(m.group(1), m.group(2)),
                            )

    def is_vector_graphics(self, filename: str) -> bool:
        """Does the filename extension indicate a vector graphic format?"""
        ext = os.path.splitext(filename)[-1]
        return ext in VECTOR_GRAPHICS_EXTENSIONS

    def copy_image_files_pil(self) -> None:
        """Copy images using Pillow, the Python Imaging Library.
        The method tries to read and write the files with Pillow, converting
        the format and resizing the image if necessary/possible.
        """
        ensuredir(self.outdir / self.imagedir)
        for src in status_iterator(
            self.images,
            __('copying images... '),
            'brown',
            len(self.images),
            self.config.verbosity,
        ):
            dest = self.images[src]
            try:
                img = Image.open(self.srcdir / src)
            except OSError:
                if not self.is_vector_graphics(src):
                    logger.warning(
                        __('cannot read image file %r: copying it instead'),
                        self.srcdir / src,
                    )
                try:
                    copyfile(
                        self.srcdir / src,
                        self.outdir / self.imagedir / dest,
                        force=True,
                    )
                except OSError as err:
                    logger.warning(
                        __('cannot copy image file %r: %s'),
                        self.srcdir / src,
                        err,
                    )
                continue
            if self.config.epub_fix_images:
                if img.mode == 'P':
                    # See the Pillow documentation for Image.convert()
                    # https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.convert
                    img = img.convert()
            if self.config.epub_max_image_width > 0:
                (width, height) = img.size
                nw = self.config.epub_max_image_width
                if width > nw:
                    nh = round((height * nw) / width)
                    img = img.resize((nw, nh), Image.BICUBIC)
            try:
                img.save(self.outdir / self.imagedir / dest)
            except OSError as err:
                logger.warning(
                    __('cannot write image file %r: %s'),
                    self.srcdir / src,
                    err,
                )

    def copy_image_files(self) -> None:
        """Copy image files to destination directory.
        This overwritten method can use Pillow to convert image files.
        """
        if self.images:
            if self.config.epub_fix_images or self.config.epub_max_image_width:
                if not PILLOW_AVAILABLE:
                    logger.warning(__('Pillow not found - copying image files'))
                    super().copy_image_files()
                else:
                    self.copy_image_files_pil()
            else:
                super().copy_image_files()

    def copy_download_files(self) -> None:
        pass

    def handle_page(
        self,
        pagename: str,
        addctx: dict[str, Any],
        templatename: str = 'page.html',
        *,
        outfilename: Path | None = None,
        event_arg: Any = None,
    ) -> None:
        """Create a rendered page.

        This method is overwritten for genindex pages in order to fix href link
        attributes.
        """
        if pagename.startswith('genindex') and 'genindexentries' in addctx:
            if not self.use_index:
                return
            self.fix_genindex(addctx['genindexentries'])
        addctx['doctype'] = self.doctype
        super().handle_page(
            pagename, addctx, templatename, outfilename=outfilename, event_arg=event_arg
        )

    def build_mimetype(self) -> None:
        """Write the metainfo file mimetype."""
        logger.info(__('writing mimetype file...'))
        copyfile(
            self.template_dir / 'mimetype',
            self.outdir / 'mimetype',
            force=True,
        )

    def build_container(self, outname: str = 'META-INF/container.xml') -> None:
        """Write the metainfo file META-INF/container.xml."""
        logger.info(__('writing META-INF/container.xml file...'))
        outdir = self.outdir / 'META-INF'
        ensuredir(outdir)
        copyfile(
            self.template_dir / 'container.xml',
            outdir / 'container.xml',
            force=True,
        )

    def content_metadata(self) -> dict[str, Any]:
        """Create a dictionary with all metadata for the content.opf
        file properly escaped.
        """
        if (source_date_epoch := os.getenv('SOURCE_DATE_EPOCH')) is not None:
            time_tuple = time.gmtime(int(source_date_epoch))
        else:
            time_tuple = time.gmtime()

        metadata: dict[str, Any] = {
            'title': html.escape(self.config.epub_title),
            'author': html.escape(self.config.epub_author),
            'uid': html.escape(self.config.epub_uid),
            'lang': html.escape(self.config.epub_language),
            'publisher': html.escape(self.config.epub_publisher),
            'copyright': html.escape(self.config.epub_copyright),
            'scheme': html.escape(self.config.epub_scheme),
            'id': html.escape(self.config.epub_identifier),
            'date': html.escape(time.strftime('%Y-%m-%d', time_tuple)),
            'manifest_items': [],
            'spines': [],
            'guides': [],
        }
        return metadata

    def build_content(self) -> None:
        """Write the metainfo file content.opf It contains bibliographic data,
        a file list and the spine (the reading order).
        """
        logger.info(__('writing content.opf file...'))
        metadata = self.content_metadata()

        # files
        self.files: list[str] = []
        self.ignored_files = [
            '.buildinfo',
            'mimetype',
            'content.opf',
            'toc.ncx',
            'META-INF/container.xml',
            'Thumbs.db',
            'ehthumbs.db',
            '.DS_Store',
            'nav.xhtml',
            self.config.epub_basename + '.epub',
            *self.config.epub_exclude_files,
        ]
        if not self.use_index:
            self.ignored_files.append('genindex' + self.out_suffix)
        for root, dirs, files in os.walk(self.outdir):
            root_path = Path(root)
            dirs.sort()
            for fn in sorted(files):
                filename = relpath(root_path / fn, self.outdir)
                if filename in self.ignored_files:
                    continue
                ext = os.path.splitext(filename)[-1]
                if ext not in self.media_types:
                    # we always have JS and potentially OpenSearch files, don't
                    # always warn about them
                    if ext not in {'.js', '.xml'}:
                        logger.warning(
                            __('unknown mimetype for %s, ignoring'),
                            filename,
                            type='epub',
                            subtype='unknown_project_files',
                        )
                    continue
                filename = filename.replace(os.sep, '/')
                item = ManifestItem(
                    html.escape(quote(filename)),
                    html.escape(self.make_id(filename)),
                    html.escape(self.media_types[ext]),
                )
                metadata['manifest_items'].append(item)
                self.files.append(filename)

        # spine
        spinefiles = set()
        for refnode in self.refnodes:
            if '#' in refnode['refuri']:
                continue
            if refnode['refuri'] in self.ignored_files:
                continue
            refuri = refnode['refuri'].replace(os.sep, '/')
            spine = Spine(html.escape(self.make_id(refuri)), True)
            metadata['spines'].append(spine)
            spinefiles.add(refuri)
        for info in self.domain_indices:
            spine = Spine(html.escape(self.make_id(info[0] + self.out_suffix)), True)
            metadata['spines'].append(spine)
            spinefiles.add(info[0] + self.out_suffix)
        if self.use_index:
            spine = Spine(html.escape(self.make_id('genindex' + self.out_suffix)), True)
            metadata['spines'].append(spine)
            spinefiles.add('genindex' + self.out_suffix)
        # add auto generated files
        for name in self.files:
            if name not in spinefiles and name.endswith(self.out_suffix):
                spine = Spine(html.escape(self.make_id(name)), False)
                metadata['spines'].append(spine)

        # add the optional cover
        html_tmpl = None
        if self.config.epub_cover:
            image, html_tmpl = self.config.epub_cover
            image = image.replace(os.sep, '/')
            metadata['cover'] = html.escape(self.make_id(image))
            if html_tmpl:
                spine = Spine(html.escape(self.make_id(self.coverpage_name)), True)
                metadata['spines'].insert(0, spine)
                if self.coverpage_name not in self.files:
                    ext = os.path.splitext(self.coverpage_name)[-1]
                    self.files.append(self.coverpage_name)
                    item = ManifestItem(
                        html.escape(self.coverpage_name),
                        html.escape(self.make_id(self.coverpage_name)),
                        html.escape(self.media_types[ext]),
                    )
                    metadata['manifest_items'].append(item)
                ctx = {'image': html.escape(image), 'title': self.config.project}
                self.handle_page(
                    os.path.splitext(self.coverpage_name)[0], ctx, html_tmpl
                )
                spinefiles.add(self.coverpage_name)

        auto_add_cover = True
        auto_add_toc = True
        if self.config.epub_guide:
            for type, uri, title in self.config.epub_guide:
                file = uri.split('#')[0]
                if file not in self.files:
                    self.files.append(file)
                if type == 'cover':
                    auto_add_cover = False
                if type == 'toc':
                    auto_add_toc = False
                metadata['guides'].append(
                    Guide(html.escape(type), html.escape(title), html.escape(uri))
                )
        if auto_add_cover and html_tmpl:
            metadata['guides'].append(
                Guide(
                    'cover',
                    self.guide_titles['cover'],
                    html.escape(self.coverpage_name),
                )
            )
        if auto_add_toc and self.refnodes:
            metadata['guides'].append(
                Guide(
                    'toc',
                    self.guide_titles['toc'],
                    html.escape(self.refnodes[0]['refuri']),
                )
            )

        # write the project file
        copy_asset_file(
            self.template_dir / 'content.opf.jinja',
            self.outdir,
            context=metadata,
            force=True,
        )

    def new_navpoint(
        self, node: dict[str, Any], level: int, incr: bool = True
    ) -> NavPoint:
        """Create a new entry in the toc from the node at given level."""
        # XXX Modifies the node
        if incr:
            self.playorder += 1
        self.tocid += 1
        return NavPoint(
            f'navPoint{self.tocid}', self.playorder, node['text'], node['refuri'], []
        )

    def build_navpoints(self, nodes: list[dict[str, Any]]) -> list[NavPoint]:
        """Create the toc navigation structure.

        Subelements of a node are nested inside the navpoint.  For nested nodes
        the parent node is reinserted in the subnav.
        """
        navstack: list[NavPoint] = [NavPoint('dummy', 0, '', '', [])]
        level = 0
        lastnode = None
        for node in nodes:
            if not node['text']:
                continue
            file = node['refuri'].split('#')[0]
            if file in self.ignored_files:
                continue
            if node['level'] > self.config.epub_tocdepth:
                continue
            if node['level'] == level:
                navpoint = self.new_navpoint(node, level)
                navstack.pop()
                navstack[-1].children.append(navpoint)
                navstack.append(navpoint)
            elif node['level'] == level + 1:
                level += 1
                if lastnode and self.config.epub_tocdup:
                    # Insert starting point in subtoc with same playOrder
                    navstack[-1].children.append(
                        self.new_navpoint(lastnode, level, False)
                    )
                navpoint = self.new_navpoint(node, level)
                navstack[-1].children.append(navpoint)
                navstack.append(navpoint)
            elif node['level'] < level:
                while node['level'] < len(navstack):
                    navstack.pop()
                level = node['level']
                navpoint = self.new_navpoint(node, level)
                navstack[-1].children.append(navpoint)
                navstack.append(navpoint)
            else:
                msg = __('node has an invalid level')
                raise ValueError(msg)
            lastnode = node

        return navstack[0].children

    def toc_metadata(self, level: int, navpoints: list[NavPoint]) -> dict[str, Any]:
        """Create a dictionary with all metadata for the toc.ncx file
        properly escaped.
        """
        metadata: dict[str, Any] = {
            'uid': self.config.epub_uid,
            'title': html.escape(self.config.epub_title),
            'level': level,
            'navpoints': navpoints,
        }
        return metadata

    def build_toc(self) -> None:
        """Write the metainfo file toc.ncx."""
        logger.info(__('writing toc.ncx file...'))

        if self.config.epub_tocscope == 'default':
            doctree = self.env.get_and_resolve_doctree(
                self.config.root_doc,
                self,
                tags=self.tags,
                prune_toctrees=False,
                includehidden=False,
            )
            refnodes = self.get_refnodes(doctree, [])
            self.toc_add_files(refnodes)
        else:
            # 'includehidden'
            refnodes = self.refnodes
        self.check_refnodes(refnodes)
        navpoints = self.build_navpoints(refnodes)
        level = max(item['level'] for item in self.refnodes)
        level = min(level, self.config.epub_tocdepth)
        copy_asset_file(
            self.template_dir / 'toc.ncx.jinja',
            self.outdir,
            context=self.toc_metadata(level, navpoints),
            force=True,
        )

    def build_epub(self) -> None:
        """Write the epub file.

        It is a zip file with the mimetype file stored uncompressed as the first
        entry.
        """
        outname = self.config.epub_basename + '.epub'
        logger.info(__('writing %s file...'), outname)
        epub_filename = self.outdir / outname
        with ZipFile(epub_filename, 'w', ZIP_DEFLATED) as epub:
            epub.write(self.outdir / 'mimetype', 'mimetype', ZIP_STORED)
            for filename in ('META-INF/container.xml', 'content.opf', 'toc.ncx'):
                epub.write(self.outdir / filename, filename, ZIP_DEFLATED)
            for filename in self.files:
                epub.write(self.outdir / filename, filename, ZIP_DEFLATED)
