# -*- coding: utf-8 -*-

# Copyright © 2012-2020 Roberto Alsina and others.

# Permission is hereby granted, free of charge, to any
# person obtaining a copy of this software and associated
# documentation files (the "Software"), to deal in the
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# the rights to use, copy, modify, merge, publish,
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# Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice
# shall be included in all copies or substantial portions of
# the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
# PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
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"""Markdown Extension for Nikola.

- Specific post-processing.
- Strikethrough inline patterns.
"""

import re

from nikola.plugin_categories import MarkdownExtension

try:
    from markdown.postprocessors import Postprocessor
    from markdown.inlinepatterns import SimpleTagPattern
    from markdown.extensions import Extension
except ImportError:
    # No need to catch this, if you try to use this without Markdown,
    # the markdown compiler will fail first
    Postprocessor = SimpleTagPattern = Extension = object


CODERE = re.compile('<div class="codehilite"><pre>(.*?)</pre></div>', flags=re.MULTILINE | re.DOTALL)
STRIKE_RE = r"(~{2})(.+?)(~{2})"  # ~~strike~~


class NikolaPostProcessor(Postprocessor):
    """Nikola-specific post-processing for Markdown."""

    def run(self, text):
        """Run the postprocessor."""
        output = text

        # python-markdown's highlighter uses <div class="codehilite"><pre>
        # for code.  We switch it to reST's <pre class="code">.
        # TODO: monkey-patch for CodeHilite that uses nikola.utils.NikolaPygmentsHTML
        output = CODERE.sub('<pre class="code literal-block">\\1</pre>', output)
        return output


class NikolaExtension(MarkdownExtension, Extension):
    """Nikola Markdown extensions."""

    def _add_nikola_post_processor(self, md):
        """Extend Markdown with the postprocessor."""
        pp = NikolaPostProcessor()
        md.postprocessors.register(pp, 'nikola_post_processor', 1)

    def _add_strikethrough_inline_pattern(self, md):
        """Support PHP-Markdown style strikethrough, for example: ``~~strike~~``."""
        pattern = SimpleTagPattern(STRIKE_RE, 'del')
        md.inlinePatterns.register(pattern, 'strikethrough', 175)

    def extendMarkdown(self, md, md_globals=None):
        """Extend markdown to Nikola flavours."""
        self._add_nikola_post_processor(md)
        self._add_strikethrough_inline_pattern(md)
        md.registerExtension(self)


def makeExtension(configs=None):  # pragma: no cover
    """Make extension."""
    return NikolaExtension(configs)
