Extension to Python Markdown for Embedded Gists

mdx_gist.py

# -*- coding: utf-8 -*-
#
# Copyright (c) 2013 Michael Rabbitt.
#
# 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 Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the 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 OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
# Warning: URL formats of "raw" gists are undocummented and subject to change.
# See also:  http://developer.github.com/v3/gists/
#
# Inspired by "[Python] reStructuredText GitHub Gist directive"
# (https://gist.github.com/brianhsu/1407759), public domain by Brian Hsu
'''
Extension to Python Markdown for Embedded Gists (gist.github.com)

Basic Example:

    >>> import markdown
    >>> text = """
    ... Text of the gist:
    ... [:gist: 4747847]
    ... """
    >>> html = markdown.markdown(text, ['gist'])
    >>> print(html)
    <p>Text of the gist:
    <div class="gist">
    <script src="https://gist.github.com/4747847.js"></script>
    <noscript>
    <pre>import this</pre>
    </noscript>
    </div>
    </p>

Example with filename:

    >>> import markdown
    >>> text = """
    ... Text of the gist:
    ... [:gist: 4747847 zen.py]
    ... """
    >>> html = markdown.markdown(text, ['gist'])
    >>> print(html)
    <p>Text of the gist:
    <div class="gist">
    <script src="https://gist.github.com/4747847.js?file=zen.py"></script>
    <noscript>
    <pre>import this</pre>
    </noscript>
    </div>
    </p>

Basic Example with hexidecimal id:

    >>> import markdown
    >>> text = """
    ... Text of the gist:
    ... [:gist: c4a43d6fdce612284ac0]
    ... """
    >>> html = markdown.markdown(text, ['gist'])
    >>> print(html)
    <p>Text of the gist:
    <div class="gist">
    <script src="https://gist.github.com/c4a43d6fdce612284ac0.js"></script>
    <noscript>
    <pre>Moo</pre>
    </noscript>
    </div>
    </p>

Example with hexidecimal id filename:

    >>> import markdown
    >>> text = """
    ... Text of the gist:
    ... [:gist: c4a43d6fdce612284ac0 cow.txt]
    ... """
    >>> html = markdown.markdown(text, ['gist'])
    >>> print(html)
    <p>Text of the gist:
    <div class="gist">
    <script src="https://gist.github.com/c4a43d6fdce612284ac0.js?file=cow.txt"></script>
    <noscript>
    <pre>Moo</pre>
    </noscript>
    </div>
    </p>

Example using reStructuredText syntax:

    >>> import markdown
    >>> text = """
    ... Text of the gist:
    ... .. gist:: 4747847 zen.py
    ... """
    >>> html = markdown.markdown(text, ['gist'])
    >>> print(html)
    <p>Text of the gist:
    <div class="gist">
    <script src="https://gist.github.com/4747847.js?file=zen.py"></script>
    <noscript>
    <pre>import this</pre>
    </noscript>
    </div>
    </p>

Example using hexidecimal ID and reStructuredText syntax:

    >>> import markdown
    >>> text = """
    ... Text of the gist:
    ... .. gist:: c4a43d6fdce612284ac0 cow.txt
    ... """
    >>> html = markdown.markdown(text, ['gist'])
    >>> print(html)
    <p>Text of the gist:
    <div class="gist">
    <script src="https://gist.github.com/c4a43d6fdce612284ac0.js?file=cow.txt"></script>
    <noscript>
    <pre>Moo</pre>
    </noscript>
    </div>
    </p>

Error Case: non-existent Gist ID:

    >>> import markdown
    >>> text = """
    ... Text of the gist:
    ... [:gist: 0]
    ... """
    >>> html = markdown.markdown(text, ['gist'])
    >>> print(html)
    <p>Text of the gist:
    <div class="gist">
    <script src="https://gist.github.com/0.js"></script>
    <noscript><!-- WARNING: Received a 404 response from Gist URL: \
    https://gist.githubusercontent.com/raw/0 --></noscript>
    </div>
    </p>

Error Case:  non-existent file:

    >>> import markdown
    >>> text = """
    ... Text of the gist:
    ... [:gist: 4747847 doesntexist.py]
    ... """
    >>> html = markdown.markdown(text, ['gist'])
    >>> print(html)
    <p>Text of the gist:
    <div class="gist">
    <script src="https://gist.github.com/4747847.js?file=doesntexist.py"></script>
    <noscript><!-- WARNING: Received a 404 response from Gist URL: \
    https://gist.githubusercontent.com/raw/4747847/doesntexist.py --></noscript>
    </div>
    </p>

'''
from __future__ import unicode_literals, print_function
import warnings
from markdown.extensions import Extension
from markdown.inlinepatterns import Pattern
from markdown.util import AtomicString
from markdown.util import etree

try:
    import requests
except ImportError:
    requests = None  # NOQA

GIST_JS_URL = "https://gist.github.com/{0}.js"
GIST_FILE_JS_URL = "https://gist.github.com/{0}.js?file={1}"
GIST_RAW_URL = "https://gist.githubusercontent.com/raw/{0}"
GIST_FILE_RAW_URL = "https://gist.githubusercontent.com/raw/{0}/{1}"

GIST_MD_RE = r'\[:gist:\s*(?P<gist_id>\S+)(?:\s*(?P<filename>.+?))?\s*\]'
GIST_RST_RE = r'(?m)^\.\.\s*gist::\s*(?P<gist_id>[^\]\s]+)(?:\s*(?P<filename>.+))\s*$'


class GistFetchException(Exception):
    '''Raised when attempt to fetch content of a Gist from github.com fails.'''
    def __init__(self, url, status_code):
        Exception.__init__(self)
        self.message = 'Received a {0} response from Gist URL: {1}'.format(
            status_code, url)


class GistPattern(Pattern):
    """ InlinePattern for footnote markers in a document's body text. """

    def __init__(self, pattern, configs):
        Pattern.__init__(self, pattern)

    def get_raw_gist_with_filename(self, gist_id, filename):
        url = GIST_FILE_RAW_URL.format(gist_id, filename)
        resp = requests.get(url)

        if not resp.ok:
            raise GistFetchException(url, resp.status_code)

        return resp.text

    def get_raw_gist(self, gist_id):
        url = GIST_RAW_URL.format(gist_id)
        resp = requests.get(url)

        if not resp.ok:
            raise GistFetchException(url, resp.status_code)

        return resp.text

    def handleMatch(self, m):
        gist_id = m.group('gist_id')
        gist_file = m.group('filename')

        gist_elem = etree.Element('div')
        gist_elem.set('class', 'gist')
        script_elem = etree.SubElement(gist_elem, 'script')

        if requests:
            noscript_elem = etree.SubElement(gist_elem, 'noscript')

            try:
                if gist_file:
                    script_elem.set('src', GIST_FILE_JS_URL.format(
                        gist_id, gist_file))
                    raw_gist = (self.get_raw_gist_with_filename(
                        gist_id, gist_file))

                else:
                    script_elem.set('src', GIST_JS_URL.format(
                        gist_id))
                    raw_gist = (self.get_raw_gist(gist_id))

                # Insert source as <pre/> within <noscript>
                pre_elem = etree.SubElement(noscript_elem, 'pre')
                pre_elem.text = AtomicString(raw_gist)

            except GistFetchException as e:
                warnings.warn(e.message)
                warning_comment = etree.Comment(' WARNING: {0} '.format(e.message))
                noscript_elem.append(warning_comment)

        else:
            warnings.warn('"requests" package not installed.  '
                          'Please install to add inline gist source.')

        return gist_elem


class GistExtension(Extension):
    def __init__(self, configs={}):
        # set extension defaults
        self.config = {}

        # Override defaults with user settings
        for key, value in configs:
            self.setConfig(key, value)

    def extendMarkdown(self, md, md_globals):
        gist_md_pattern = GistPattern(GIST_MD_RE, self.getConfigs())
        gist_md_pattern.md = md
        md.inlinePatterns.add('gist', gist_md_pattern, "<not_strong")

        gist_rst_pattern = GistPattern(GIST_RST_RE, self.getConfigs())
        gist_rst_pattern.md = md
        md.inlinePatterns.add('gist-rst', gist_rst_pattern, ">gist")

        md.registerExtension(self)


def makeExtension(configs=None):
    return GistExtension(configs)

if __name__ == '__main__':
    import doctest

    # Silence user warnings thrown by tests:
    with warnings.catch_warnings(record=True):
        doctest.testmod(optionflags=(doctest.NORMALIZE_WHITESPACE +
                                     doctest.REPORT_NDIFF))