'''

Abbreviation Extension for Python-Markdown

==========================================

This extension adds abbreviation handling to Python-Markdown.

Simple Usage:

    >>> import markdown

    >>> text = """

    ... Some text with an ABBR and a REF. Ignore REFERENCE and ref.

    ...

    ... *[ABBR]: Abbreviation

    ... *[REF]: Abbreviation Reference

    ... """

    >>> markdown.markdown(text, ['abbr'])

    u'<p>Some text with an <abbr title="Abbreviation">ABBR</abbr> and a <abbr title="Abbreviation Reference">REF</abbr>. Ignore REFERENCE and ref.</p>'

Copyright 2007-2008

* [Waylan Limberg](http://achinghead.com/)

* [Seemant Kulleen](http://www.kulleen.org/)

'''

import re

import markdown

from markdown.util import etree

# Global Vars

ABBR_REF_RE = re.compile(r'[*]\[(?P<abbr>[^\]]*)\][ ]?:\s*(?P<title>.*)')

class AbbrExtension(markdown.Extension):

    """ Abbreviation Extension for Python-Markdown. """

    def extendMarkdown(self, md, md_globals):

        """ Insert AbbrPreprocessor before ReferencePreprocessor. """

        md.preprocessors.add('abbr', AbbrPreprocessor(md), '<reference')

class AbbrPreprocessor(markdown.preprocessors.Preprocessor):

    """ Abbreviation Preprocessor - parse text for abbr references. """

    def run(self, lines):

        '''

        Find and remove all Abbreviation references from the text.

        Each reference is set as a new AbbrPattern in the markdown instance.

        '''

        new_text = []

        for line in lines:

            m = ABBR_REF_RE.match(line)

            if m:

                abbr = m.group('abbr').strip()

                title = m.group('title').strip()

                self.markdown.inlinePatterns['abbr-%s'%abbr] = \

                    AbbrPattern(self._generate_pattern(abbr), title)

            else:

                new_text.append(line)

        return new_text

    def _generate_pattern(self, text):

        '''

        Given a string, returns an regex pattern to match that string. 

        'HTML' -> r'(?P<abbr>[H][T][M][L])' 

        Note: we force each char as a literal match (in brackets) as we don't 

        know what they will be beforehand.

        '''

        chars = list(text)

        for i in range(len(chars)):

            chars[i] = r'[%s]' % chars[i]

        return r'(?P<abbr>\b%s\b)' % (r''.join(chars))

class AbbrPattern(markdown.inlinepatterns.Pattern):

    """ Abbreviation inline pattern. """

    def __init__(self, pattern, title):

        markdown.inlinepatterns.Pattern.__init__(self, pattern)

        self.title = title

    def handleMatch(self, m):

        abbr = etree.Element('abbr')

        abbr.text = m.group('abbr')

        abbr.set('title', self.title)

        return abbr

def makeExtension(configs=None):

    return AbbrExtension(configs=configs)

if __name__ == "__main__":

    import doctest

    doctest.testmod()