'''
toc
===================================
Generates Table of Contents for markdown.
Only generates a ToC for the headers FOLLOWING the [TOC] tag,
so you can insert it after a specific section that need not be
included in the ToC.

The default container format (which includes a 'Table of Contents' heading )
can be overridden by providing something like the following entry in pelicanconf.py:
ASF_TOC = {
    'CONTAINER_FORMAT': "<div id='toc'>{}</div>"
}
'''

from __future__ import unicode_literals

import logging
import re

from bs4 import BeautifulSoup, Comment

from pelican import contents, signals
from pelican.utils import slugify


logger = logging.getLogger(__name__)

'''
https://github.com/waylan/Python-Markdown/blob/master/markdown/extensions/headerid.py
'''
IDCOUNT_RE = re.compile(r'^(.*)_([0-9]+)$')


def unique(id_, ids):
    """ Ensure id is unique in set of ids. Append '_1', '_2'... if not """
    while id_ in ids or not id_:
        m = IDCOUNT_RE.match(id_)
        if m:
            id_ = '%s_%d' % (m.group(1), int(m.group(2)) + 1)
        else:
            id_ = '%s_%d' % (id_, 1)
    ids.add(id_)
    return id_
'''
end
'''


class HtmlTreeNode(object):
    def __init__(self, parent, header, level, id_, content):
        self.children = []
        self.parent = parent
        self.header = header
        self.level = level
        self.id = id_
        self.content = content

    def add(self, new_header, ids):
        new_level = new_header.name
        new_string = new_header.string
        new_id = new_header.attrs.get('id')

        if not new_string:
            new_string = new_header.find_all(
                text=lambda t: not isinstance(t, Comment),
                recursive=True)
            new_string = "".join(new_string)

        if not new_id:
            new_id = slugify(new_string, ())

        new_id = unique(new_id, ids)  # make sure id is unique
        new_header.attrs['id'] = new_id
        if(self.level < new_level):
            new_node = HtmlTreeNode(self, new_string, new_level, new_id, self.content)
            self.children += [new_node]
            return new_node, new_header
        elif(self.level == new_level):
            new_node = HtmlTreeNode(self.parent, new_string, new_level, new_id, self.content)
            self.parent.children += [new_node]
            return new_node, new_header
        elif(self.level > new_level):
            return self.parent.add(new_header, ids)

    def __str__(self):
        ret = ""
        if self.parent:
            ret = "<a class='toc-href' href='#{0}' title='{1}'>{1}</a>".format(
                self.id, self.header)

        if self.children:
            ret += "<ul>{}</ul>".format('{}' * len(self.children)).format(
                *self.children)

        if self.parent:
            ret = "<li>{}</li>".format(ret)

        if not self.parent:
            fmt = self.content.settings.get('ASF_TOC',{}).get('CONTAINER_FORMAT')
            if fmt:
                print(f"Overriding TOC CONTAINER_FORMAT: {fmt}")
            else:
                fmt = "<div id='toc' style='border-radius: 3px; border: 1px solid #999; background-color: #EEE; padding: 4px;'><h4>Table of Contents:</h4><ul>{}</ul></div>"
            ret = fmt.format(ret)

        return ret


def init_default_config(pel_ob):
    from pelican.settings import DEFAULT_CONFIG

    TOC_DEFAULT = {
        'TOC_HEADERS': '^h[1-6]',
        'TOC_RUN': 'true'
    }

    DEFAULT_CONFIG.setdefault('TOC', TOC_DEFAULT)
    if(pel_ob):
        pel_ob.settings.setdefault('TOC', TOC_DEFAULT)


def generate_toc(content):
    if isinstance(content, contents.Static):
        return

    all_ids = set()
    title = content.metadata.get('title', 'Title')
    tree = node = HtmlTreeNode(None, title, 'h0', '', content)
    soup = BeautifulSoup(content._content, 'html.parser') # pylint: disable=protected-access
    settoc = False

    try:
        header_re = re.compile(content.metadata.get(
            'toc_headers', content.settings['TOC']['TOC_HEADERS']))
    except re.error as e:
        logger.error("TOC_HEADERS '%s' is not a valid re\n",
                     content.settings['TOC']['TOC_HEADERS'])
        raise e

    # Find TOC tag
    tocTag = soup.find('p', text='[TOC]')
    if tocTag:
        for header in tocTag.findAllNext(header_re):
            settoc = True
            node, new_header = node.add(header, all_ids)
            header.replaceWith(new_header)  # to get our ids back into soup

        if settoc:
            print("Generating ToC for %s" % content.slug)
            tree_string = '{}'.format(tree)
            tree_soup = BeautifulSoup(tree_string, 'html.parser')
            content.toc = tree_soup.decode(formatter='html')
            itoc = soup.find('p', text='[TOC]')
            if itoc:
                itoc.replaceWith(tree_soup)

        content._content = soup.decode(formatter='html')  # pylint: disable=protected-access


def register():
    signals.initialized.connect(init_default_config)
    signals.content_object_init.connect(generate_toc)