# coding=utf-8

import re
import bbcode

from urllib.parse import unquote

from django.core.exceptions import ObjectDoesNotExist
from django.core.urlresolvers import reverse

import boards


__author__ = 'neko259'


REFLINK_PATTERN = re.compile(r'^\d+$')
MULTI_NEWLINES_PATTERN = re.compile(r'(\r?\n){2,}')
ONE_NEWLINE = '\n'
REGEX_URL = re.compile(r'https?\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(/\S*)?')
LINE_BREAK_HTML = '<div class="br"></div>'


class TextFormatter():
    """
    An interface for formatter that can be used in the text format panel
    """

    def __init__(self):
        pass

    name = ''

    # Left and right tags for the button preview
    preview_left = ''
    preview_right = ''

    # Left and right characters for the textarea input
    format_left = ''
    format_right = ''


class AutolinkPattern():
    def handleMatch(self, m):
        link_element = etree.Element('a')
        href = m.group(2)
        link_element.set('href', href)
        link_element.text = href

        return link_element


class QuotePattern(TextFormatter):
    name = '>q'
    preview_left = '<span class="quote">'
    preview_right = '</span>'

    format_left = '[quote]'
    format_right = '[/quote]'


class SpoilerPattern(TextFormatter):
    name = 'spoiler'
    preview_left = '<span class="spoiler">'
    preview_right = '</span>'

    format_left = '[spoiler]'
    format_right = '[/spoiler]'

    def handleMatch(self, m):
        quote_element = etree.Element('span')
        quote_element.set('class', 'spoiler')
        quote_element.text = m.group(2)

        return quote_element


class CommentPattern(TextFormatter):
    name = ''
    preview_left = '<span class="comment">// '
    preview_right = '</span>'

    format_left = '[comment]'
    format_right = '[/comment]'


# TODO Use <s> tag here
class StrikeThroughPattern(TextFormatter):
    name = 's'
    preview_left = '<span class="strikethrough">'
    preview_right = '</span>'

    format_left = '[s]'
    format_right = '[/s]'


class ItalicPattern(TextFormatter):
    name = 'i'
    preview_left = '<i>'
    preview_right = '</i>'

    format_left = '[i]'
    format_right = '[/i]'


class BoldPattern(TextFormatter):
    name = 'b'
    preview_left = '<b>'
    preview_right = '</b>'

    format_left = '[b]'
    format_right = '[/b]'


class CodePattern(TextFormatter):
    name = 'code'
    preview_left = '<code>'
    preview_right = '</code>'

    format_left = '[code]'
    format_right = '[/code]'


def render_reflink(tag_name, value, options, parent, context):
    result = '>>%s' % value

    if REFLINK_PATTERN.match(value):
        post_id = int(value)

        try:
            post = boards.models.Post.objects.get(id=post_id)

            result = '<a href="%s">&gt;&gt;%s</a>' % (post.get_absolute_url(), post_id)
        except ObjectDoesNotExist:
            pass

    return result


def render_quote(tag_name, value, options, parent, context):
    source = ''
    if 'source' in options:
        source = options['source']

    if source:
        result = '<div class="multiquote"><div class="quote-header">%s</div><div class="quote-text">%s</div></div>' % (source, value)
    else:
        # Insert a ">" at the start of every line
        result = '<span class="quote">&gt;{}</span>'.format(
                value.replace(LINE_BREAK_HTML,
                    '{}&gt;'.format(LINE_BREAK_HTML)))

    return result


def render_notification(tag_name, value, options, parent, content):
    username = value.lower()

    return '<a href="{}" class="user-cast">@{}</a>'.format(
        reverse('notifications', kwargs={'username': username}), username)


def render_tag(tag_name, value, options, parent, context):
    tag_name = value.lower()

    try:
        url = boards.models.Tag.objects.get(name=tag_name).get_view()
    except ObjectDoesNotExist:
        url = tag_name

    return url


formatters = [
    QuotePattern,
    SpoilerPattern,
    ItalicPattern,
    BoldPattern,
    CommentPattern,
    StrikeThroughPattern,
    CodePattern,
]


PREPARSE_PATTERNS = {
    r'(?<!>)>>(\d+)': r'[post]\1[/post]',  # Reflink ">>123"
    r'^>([^>].+)': r'[quote]\1[/quote]',  # Quote ">text"
    r'^//(.+)': r'[comment]\1[/comment]',  # Comment "//text"
    r'\B@(\w+)': r'[user]\1[/user]',  # User notification "@user"
}


class Parser:
    def __init__(self):
        # The newline hack is added because br's margin does not work in all
        # browsers except firefox, when the div's does.
        self.parser = bbcode.Parser(newline=LINE_BREAK_HTML)

        self.parser.add_formatter('post', render_reflink, strip=True)
        self.parser.add_formatter('quote', render_quote, strip=True)
        self.parser.add_formatter('user', render_notification, strip=True)
        self.parser.add_formatter('tag', render_tag, strip=True)
        self.parser.add_simple_formatter(
            'comment', '<span class="comment">//%(value)s</span>')
        self.parser.add_simple_formatter(
            'spoiler', '<span class="spoiler">%(value)s</span>')
        self.parser.add_simple_formatter(
            's', '<span class="strikethrough">%(value)s</span>')
        # TODO Why not use built-in tag?
        self.parser.add_simple_formatter('code',
                                         '<pre><code>%(value)s</pre></code>',
                                         render_embedded=False)

    def preparse(self, text):
        """
        Performs manual parsing before the bbcode parser is used.
        Preparsed text is saved as raw and the text before preparsing is lost.
        """
        new_text = MULTI_NEWLINES_PATTERN.sub(ONE_NEWLINE, text)

        for key, value in PREPARSE_PATTERNS.items():
            new_text = re.sub(key, value, new_text, flags=re.MULTILINE)

        for link in REGEX_URL.findall(text):
            new_text = new_text.replace(link, unquote(link))

        return new_text

    def parse(self, text):
        return self.parser.format(text)