import re

import markdown
from markdown.blockprocessors import BlockProcessor, HRProcessor
from markdown.extensions.fenced_code import FencedBlockPreprocessor
from markdown.preprocessors import Preprocessor
from markdown.util import etree

from django.utils.crypto import get_random_string


QUOTE_START = get_random_string(32)
QUOTE_END = get_random_string(32)


class BBCodeHRProcessor(HRProcessor):
    RE = r'^\[hr\]*'

    # Detect hr on any line of a block.
    SEARCH_RE = re.compile(RE, re.MULTILINE | re.IGNORECASE)


class QuoteExtension(markdown.Extension):
    def extendMarkdown(self, md):
        md.registerExtension(self)

        md.preprocessors.add('misago_bbcode_quote', QuotePreprocessor(md), '_end')
        md.parser.blockprocessors.add(
            'misago_bbcode_quote', QuoteBlockProcessor(md.parser), '>code'
        )


class QuotePreprocessor(Preprocessor):
    QUOTE_BLOCK_RE = re.compile(
        r'''
\[quote\](?P<text>.*?)\[/quote\]
'''.strip(), re.IGNORECASE | re.MULTILINE | re.DOTALL
    )
    QUOTE_BLOCK_TITLE_RE = re.compile(
        r'''
\[quote=("?)(?P<title>.*?)("?)](?P<text>.*?)\[/quote\]
'''.strip(), re.IGNORECASE | re.MULTILINE | re.DOTALL
    )

    def run(self, lines):
        text = '\n'.join(lines)
        while self.QUOTE_BLOCK_RE.search(text):
            text = self.QUOTE_BLOCK_RE.sub(self.replace, text)
        while self.QUOTE_BLOCK_TITLE_RE.search(text):
            text = self.QUOTE_BLOCK_TITLE_RE.sub(self.replace_titled, text)
        return text.split('\n')

    def replace(self, matchobj):
        text = matchobj.group('text')
        return '\n\n%s\n\n%s\n\n%s\n\n' % (QUOTE_START, text, QUOTE_END)

    def replace_titled(self, matchobj):
        title = matchobj.group('title').strip()
        text = matchobj.group('text')

        if title:
            return '\n\n%s%s\n\n%s\n\n%s\n\n' % (QUOTE_START, title, text, QUOTE_END)
        else:
            return '\n\n%s\n\n%s\n\n%s\n\n' % (QUOTE_START, text, QUOTE_END)


class QuoteBlockProcessor(BlockProcessor):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._title = None
        self._quote = 0
        self._children = []

    def test(self, parent, block):
        return block.strip().startswith(QUOTE_START) or self._quote

    def run(self, parent, blocks):
        block = blocks.pop(0)
        if block.strip().startswith(QUOTE_START):
            self._quote += 1
            if self._quote == 1:
                self._title = block[len(QUOTE_START):].strip() or None

        self._children.append(block)

        if block.strip() == QUOTE_END:
            self._quote -= 1

        if not self._quote:
            children, self._children = self._children[1:-1], []
            title, self._title = self._title, None

            aside = etree.SubElement(parent, 'aside')
            aside.set('class', 'quote-block')

            heading = etree.SubElement(aside, 'div')
            heading.set('class', 'quote-heading')

            blockquote = etree.SubElement(aside, 'blockquote')
            blockquote.set('class', 'quote-body')

            if title:
                heading.text = title

            self.parser.parseBlocks(blockquote, children)


class CodeBlockExtension(markdown.Extension):
    def extendMarkdown(self, md):
        md.registerExtension(self)

        md.preprocessors.add(
            'misago_code_bbcode', CodeBlockPreprocessor(md), ">normalize_whitespace"
        )


class CodeBlockPreprocessor(FencedBlockPreprocessor):
    FENCED_BLOCK_RE = re.compile(
        r'''
\[code(=("?)(?P<lang>.*?)("?))?](([ ]*\n)+)?(?P<code>.*?)((\s|\n)+)?\[/code\]
''', re.IGNORECASE | re.MULTILINE | re.DOTALL | re.VERBOSE
    )