"""A simple HTML to BBcode converter. Aimed to be used to convert WordPress
HTML into `forum.hardware.fr` BBcode. Currently missing support for colours,
and everything else might explode anytime.
"""

import html.parser
from collections import namedtuple
import types

TRtuple = namedtuple('TRtuple',
                     ['tags', 'txt_action'],
                     defaults=[('', ''), None])


class HTMLtoBBcode(html.parser.HTMLParser):
    """Subclass of `html.parser.HTMLParser` that does the format conversion."""

    def __init__(self):
        super().__init__()
        self.tree = []
        self.output = ''

        self.tag_translate = {
                'h2':         TRtuple(('[b][u]', '[/u][/b]\n'),
                                      txt_action='capitalise'),
                'h3':         TRtuple(('[b][u]', '[/u][/b]\n'),
                                      txt_action='capitalise'),
                'h4':         TRtuple(('[b][u]', '[/u][/b]\n'),
                                      txt_action='capitalise'),
                'p':          TRtuple(('\n', '')),
                'strong':     TRtuple(('[b]', '[/b]')),
                'em':         TRtuple(('[i]', '[/i]')),
                's':          TRtuple(('[strike]', '[/strike]')),
                'blockquote': TRtuple(('[quote]', '[/quote]')),
                'code':       TRtuple(('[cpp]', '[/cpp]')),
                'ul':         TRtuple(('\n', '')),
                'ol':         TRtuple(('\n', '')),
                'li':         TRtuple(('[*]', '\n')),
                'a':          TRtuple(('[url={href}]', '[/url]')),
                # `img` tags are not always closed, leading to issues,
                # therefore using a single tag for images is simpler
                'img':        TRtuple(('[img]{src}[/img]', '')),
                # `span` is here for underlines to be processed
                'span':       TRtuple(('', ''))
        }

        self.attr_translate = {
                'style': {'text-decoration': {'underline': ('[u]', '[/u]')},
                          'color': {}}
        }

        self.text_translate = {
                'capitalise': str.upper
        }

    def handle_starttag(self, tag, attrs):
        # Nothing to do here?
        if not self.tag_translate.get(tag):
            return

        # As some tags are part of tag properties instead of being direct tags,
        # if they need to be closed, they cannot be collected easily by
        # `handle_endtag`. Therefore, all BBcode closing tags are added to the
        # `self.tree` list, and they will just be popped by `handle_endtag`.
        self.output += (self.tag_translate[tag].tags[0].
                        format(**dict(attrs)))
        self.tree.append(self.tag_translate[tag].tags[1])

        # Keeping this commented just in case this is after all the right
        # way to exclude those...
        # # Do we have a link? In that case we skip this entire bit
        # if tag == 'a' and any('href' in _attr for _attr in attrs):
        #     return
        # # Do we have an image? Already handled
        # if tag == 'img':
        #     return
        # Should be a lot easier with the `if` block, but we might exclude some
        # tags...
        if not tag in self.tag_translate:
            for attr, val in attrs:
                # e.g. attrs = [('style', 'text-decoration:underline;'),
                #               (...), (...)]
                # e.g. attrs = [('style', 'color:#4ac456;'),
                #               ('class', 'has-text-color')]
                #
                # e.g. attr = 'style'
                #
                # e.g. val = 'text-decoration:underline;'
                # e.g. val = 'color:#4ac456;'
                #
                # e.g. property_ = 'text-decoration'
                # e.g. property_ = 'color'
                #
                # e.g. value = 'underline'
                # e.g. value = '#4ac456'
                #
                _parse_attr = val.strip(';').split(':')
                # Not everything can be stripped/split, hence the try block
                try:
                    property_ = _parse_attr[0]
                    value = _parse_attr[1]

                    # Are we dealing with a color? Insert it to the translation
                    # dict `self.attr_translate`
                    if property_ == 'color':
                        self.attr_translate['style']['color'].setdefault(
                                value,
                                ('[{}]'.format(value), '[/{}]'.format(value))
                        )

                    self.output += (self.attr_translate
                                    [attr][property_][value][0])
                    self.tree.append(self.attr_translate
                                    [attr][property_][value][1])
                # Any other error to catch here?
                except IndexError:
                    pass
        # If the data that follows the tag needs to be modified, we need to
        # pass the info somehow to `handle_data`. `self.text_translate`
        # will likely only contain methods as values, as opposed to strings
        # for normal tags, so it's easy to just add a method to `self.tree`
        # and look for methods in `handle_data`.
        if self.tag_translate[tag].txt_action:
            self.tree.append(self.text_translate
                                [self.tag_translate[tag].txt_action])

    def handle_endtag(self, tag):
        if self.tag_translate.get(tag):
            self.output += self.tree.pop()

    def handle_data(self, data):
        # TODO: check: reconversion to handle webhook input? that seems to
        # completely mess up text... why did I have that in the first place?!
        # _data = bytes(data, 'utf8').decode('unicode_escape')
        _data = data
        #
        # Otherwise this works fine for debugging with the webhook as a `str`
        # _data = data
        # In case the incoming data is just a series of new lines, discard them
        if set(_data) == {'\n'}:
            return

        # Check if last element from `self.tree` is a method. If yes, it means
        # we have a `txt_action` to perform against the `data`.
        # Currently the only method type is `types.MethodDescriptorType` but
        # possibly there will be more later.
        try:
            if isinstance(self.tree[-1], types.MethodDescriptorType):
                # self.tree.pop() is a method!
                _data = self.tree.pop()(_data)
        except IndexError:
            pass
        self.output += _data

    def feed(self, data):
        # Resets `output` to an empty string before calling `feed`
        self.output = ''
        super().feed(data)