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

# Copyright (C) 2011-2017 RhodeCode GmbH
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License, version 3
# (only), as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# This program is dual-licensed. If you wish to learn more about the
# RhodeCode Enterprise Edition, including its added features, Support services,
# and proprietary license terms, please see https://rhodecode.com/licenses/


"""
Renderer for markup languages with ability to parse using rst or markdown
"""

import re
import os
import logging
import itertools

from mako.lookup import TemplateLookup
from mako.template import Template as MakoTemplate

from docutils.core import publish_parts
from docutils.parsers.rst import directives
import markdown

from rhodecode.lib.markdown_ext import (
    UrlizeExtension, GithubFlavoredMarkdownExtension)
from rhodecode.lib.utils2 import safe_unicode, md5_safe, MENTIONS_REGEX

log = logging.getLogger(__name__)

# default renderer used to generate automated comments
DEFAULT_COMMENTS_RENDERER = 'rst'


class MarkupRenderer(object):
    RESTRUCTUREDTEXT_DISALLOWED_DIRECTIVES = ['include', 'meta', 'raw']

    MARKDOWN_PAT = re.compile(r'\.(md|mkdn?|mdown|markdown)$', re.IGNORECASE)
    RST_PAT = re.compile(r'\.re?st$', re.IGNORECASE)
    JUPYTER_PAT = re.compile(r'\.(ipynb)$', re.IGNORECASE)
    PLAIN_PAT = re.compile(r'^readme$', re.IGNORECASE)

    extensions = ['codehilite', 'extra', 'def_list', 'sane_lists']
    markdown_renderer = markdown.Markdown(
        extensions, safe_mode=True, enable_attributes=False)

    markdown_renderer_flavored = markdown.Markdown(
        extensions + [GithubFlavoredMarkdownExtension()], safe_mode=True,
        enable_attributes=False)

    # extension together with weights. Lower is first means we control how
    # extensions are attached to readme names with those.
    PLAIN_EXTS = [
        # prefer no extension
        ('', 0),  # special case that renders READMES names without extension
        ('.text', 2), ('.TEXT', 2),
        ('.txt', 3), ('.TXT', 3)
    ]

    RST_EXTS = [
        ('.rst', 1), ('.rest', 1),
        ('.RST', 2), ('.REST', 2)
    ]

    MARKDOWN_EXTS = [
        ('.md', 1), ('.MD', 1),
        ('.mkdn', 2), ('.MKDN', 2),
        ('.mdown', 3), ('.MDOWN', 3),
        ('.markdown', 4), ('.MARKDOWN', 4)
    ]

    def _detect_renderer(self, source, filename=None):
        """
        runs detection of what renderer should be used for generating html
        from a markup language

        filename can be also explicitly a renderer name

        :param source:
        :param filename:
        """

        if MarkupRenderer.MARKDOWN_PAT.findall(filename):
            detected_renderer = 'markdown'
        elif MarkupRenderer.RST_PAT.findall(filename):
            detected_renderer = 'rst'
        elif MarkupRenderer.JUPYTER_PAT.findall(filename):
            detected_renderer = 'jupyter'
        elif MarkupRenderer.PLAIN_PAT.findall(filename):
            detected_renderer = 'plain'
        else:
            detected_renderer = 'plain'

        return getattr(MarkupRenderer, detected_renderer)

    @classmethod
    def renderer_from_filename(cls, filename, exclude):
        """
        Detect renderer markdown/rst from filename and optionally use exclude
        list to remove some options. This is mostly used in helpers.
        Returns None when no renderer can be detected.
        """
        def _filter(elements):
            if isinstance(exclude, (list, tuple)):
                return [x for x in elements if x not in exclude]
            return elements

        if filename.endswith(
                tuple(_filter([x[0] for x in cls.MARKDOWN_EXTS if x[0]]))):
            return 'markdown'
        if filename.endswith(tuple(_filter([x[0] for x in cls.RST_EXTS if x[0]]))):
            return 'rst'

        return None

    def render(self, source, filename=None):
        """
        Renders a given filename using detected renderer
        it detects renderers based on file extension or mimetype.
        At last it will just do a simple html replacing new lines with <br/>

        :param file_name:
        :param source:
        """

        renderer = self._detect_renderer(source, filename)
        readme_data = renderer(source)
        return readme_data

    @classmethod
    def _flavored_markdown(cls, text):
        """
        Github style flavored markdown

        :param text:
        """

        # Extract pre blocks.
        extractions = {}

        def pre_extraction_callback(matchobj):
            digest = md5_safe(matchobj.group(0))
            extractions[digest] = matchobj.group(0)
            return "{gfm-extraction-%s}" % digest
        pattern = re.compile(r'<pre>.*?</pre>', re.MULTILINE | re.DOTALL)
        text = re.sub(pattern, pre_extraction_callback, text)

        # Prevent foo_bar_baz from ending up with an italic word in the middle.
        def italic_callback(matchobj):
            s = matchobj.group(0)
            if list(s).count('_') >= 2:
                return s.replace('_', r'\_')
            return s
        text = re.sub(r'^(?! {4}|\t)\w+_\w+_\w[\w_]*', italic_callback, text)

        # Insert pre block extractions.
        def pre_insert_callback(matchobj):
            return '\n\n' + extractions[matchobj.group(1)]
        text = re.sub(r'\{gfm-extraction-([0-9a-f]{32})\}',
                      pre_insert_callback, text)

        return text

    @classmethod
    def urlify_text(cls, text):
        url_pat = re.compile(r'(http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]'
                             r'|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+)')

        def url_func(match_obj):
            url_full = match_obj.groups()[0]
            return '<a href="%(url)s">%(url)s</a>' % ({'url': url_full})

        return url_pat.sub(url_func, text)

    @classmethod
    def plain(cls, source, universal_newline=True):
        source = safe_unicode(source)
        if universal_newline:
            newline = '\n'
            source = newline.join(source.splitlines())

        source = cls.urlify_text(source)
        return '<br />' + source.replace("\n", '<br />')

    @classmethod
    def markdown(cls, source, safe=True, flavored=True, mentions=False):
        # It does not allow to insert inline HTML. In presence of HTML tags, it
        # will replace them instead with [HTML_REMOVED]. This is controlled by
        # the safe_mode=True parameter of the markdown method.

        if flavored:
            markdown_renderer = cls.markdown_renderer_flavored
        else:
            markdown_renderer = cls.markdown_renderer

        if mentions:
            mention_pat = re.compile(MENTIONS_REGEX)

            def wrapp(match_obj):
                uname = match_obj.groups()[0]
                return ' **@%(uname)s** ' % {'uname': uname}
            mention_hl = mention_pat.sub(wrapp, source).strip()
            # we extracted mentions render with this using Mentions false
            return cls.markdown(mention_hl, safe=safe, flavored=flavored,
                                mentions=False)

        source = safe_unicode(source)
        try:
            if flavored:
                source = cls._flavored_markdown(source)
            return markdown_renderer.convert(source)
        except Exception:
            log.exception('Error when rendering Markdown')
            if safe:
                log.debug('Fallback to render in plain mode')
                return cls.plain(source)
            else:
                raise

    @classmethod
    def rst(cls, source, safe=True, mentions=False):
        if mentions:
            mention_pat = re.compile(MENTIONS_REGEX)

            def wrapp(match_obj):
                uname = match_obj.groups()[0]
                return ' **@%(uname)s** ' % {'uname': uname}
            mention_hl = mention_pat.sub(wrapp, source).strip()
            # we extracted mentions render with this using Mentions false
            return cls.rst(mention_hl, safe=safe, mentions=False)

        source = safe_unicode(source)
        try:
            docutils_settings = dict(
                [(alias, None) for alias in
                 cls.RESTRUCTUREDTEXT_DISALLOWED_DIRECTIVES])

            docutils_settings.update({'input_encoding': 'unicode',
                                      'report_level': 4})

            for k, v in docutils_settings.iteritems():
                directives.register_directive(k, v)

            parts = publish_parts(source=source,
                                  writer_name="html4css1",
                                  settings_overrides=docutils_settings)

            return parts['html_title'] + parts["fragment"]
        except Exception:
            log.exception('Error when rendering RST')
            if safe:
                log.debug('Fallbacking to render in plain mode')
                return cls.plain(source)
            else:
                raise

    @classmethod
    def jupyter(cls, source):
        from rhodecode.lib import helpers
        import nbformat
        from nbconvert import HTMLExporter
        from traitlets.config import Config

        class CustomHTMLExporter(HTMLExporter):
            def _template_file_default(self):
                return 'basic'

        def _sanitize_resources(resources):
            """
            Skip/sanitize some of the CSS generated and included in jupyter
            so it doesn't messes up UI so much
            """

            # TODO(marcink): probably we should replace this with whole custom
            # CSS set that doesn't screw up, but jupyter generated html has some
            # special markers, so it requires Custom HTML exporter template with
            # _default_template_path_default, to achieve that

            # strip the reset CSS
            resources[0] = resources[0][resources[0].find('/*! Source'):]
            return resources

        def as_html(notebook):
            conf = Config()
            html_exporter = CustomHTMLExporter(config=conf)

            (body, resources) = html_exporter.from_notebook_node(notebook)
            header = '<!-- ## IPYTHON NOTEBOOK RENDERING ## -->'
            js = MakoTemplate(r'''
            <!-- Load mathjax -->
                <!-- MathJax configuration -->
                <script type="text/x-mathjax-config">
                MathJax.Hub.Config({
                    jax: ["input/TeX","output/HTML-CSS", "output/PreviewHTML"],
                    extensions: ["tex2jax.js","MathMenu.js","MathZoom.js", "fast-preview.js", "AssistiveMML.js", "[Contrib]/a11y/accessibility-menu.js"],
                    TeX: {
                        extensions: ["AMSmath.js","AMSsymbols.js","noErrors.js","noUndefined.js"]
                    },
                    tex2jax: {
                        inlineMath: [ ['$','$'], ["\\(","\\)"] ],
                        displayMath: [ ['$$','$$'], ["\\[","\\]"] ],
                        processEscapes: true,
                        processEnvironments: true
                    },
                    // Center justify equations in code and markdown cells. Elsewhere
                    // we use CSS to left justify single line equations in code cells.
                    displayAlign: 'center',
                    "HTML-CSS": {
                        styles: {'.MathJax_Display': {"margin": 0}},
                        linebreaks: { automatic: true }
                    },
                    showMathMenu: false
                });
                </script>
                <!-- End of mathjax configuration -->
                <script src="${h.asset('js/src/math_jax/MathJax.js')}"></script>
            ''').render(h=helpers)

            css = '<style>{}</style>'.format(
                ''.join(_sanitize_resources(resources['inlining']['css'])))

            body = '\n'.join([header, css, js, body])
            return body, resources

        notebook = nbformat.reads(source, as_version=4)
        (body, resources) = as_html(notebook)
        return body


class RstTemplateRenderer(object):

    def __init__(self):
        base = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))
        rst_template_dirs = [os.path.join(base, 'templates', 'rst_templates')]
        self.template_store = TemplateLookup(
            directories=rst_template_dirs,
            input_encoding='utf-8',
            imports=['from rhodecode.lib import helpers as h'])

    def _get_template(self, templatename):
        return self.template_store.get_template(templatename)

    def render(self, template_name, **kwargs):
        template = self._get_template(template_name)
        return template.render(**kwargs)