#!/usr/bin/env python

'''
WikiLinks Extension for Python-Markdown
======================================

Converts [[WikiLinks]] to relative links.  Requires Python-Markdown 2.0+

Basic usage:

    >>> import markdown
    >>> text = "Some text with a [[WikiLink]]."
    >>> html = markdown.markdown(text, ['wikilinks'])
    >>> html
    u'<p>Some text with a <a class="wikilink" href="/WikiLink/">WikiLink</a>.</p>'

Whitespace behavior:

    >>> markdown.markdown('[[ foo bar_baz ]]', ['wikilinks'])
    u'<p><a class="wikilink" href="/foo_bar_baz/">foo bar_baz</a></p>'
    >>> markdown.markdown('foo [[ ]] bar', ['wikilinks'])
    u'<p>foo  bar</p>'

To define custom settings the simple way:

    >>> markdown.markdown(text, 
    ...     ['wikilinks(base_url=/wiki/,end_url=.html,html_class=foo)']
    ... )
    u'<p>Some text with a <a class="foo" href="/wiki/WikiLink.html">WikiLink</a>.</p>'
    
Custom settings the complex way:

    >>> md = markdown.Markdown(
    ...     extensions = ['wikilinks'], 
    ...     extension_configs = {'wikilinks': [
    ...                                 ('base_url', 'http://example.com/'), 
    ...                                 ('end_url', '.html'),
    ...                                 ('html_class', '') ]},
    ...     safe_mode = True)
    >>> md.convert(text)
    u'<p>Some text with a <a href="http://example.com/WikiLink.html">WikiLink</a>.</p>'

Use MetaData with mdx_meta.py (Note the blank html_class in MetaData):

    >>> text = """wiki_base_url: http://example.com/
    ... wiki_end_url:   .html
    ... wiki_html_class:
    ...
    ... Some text with a [[WikiLink]]."""
    >>> md = markdown.Markdown(extensions=['meta', 'wikilinks'])
    >>> md.convert(text)
    u'<p>Some text with a <a href="http://example.com/WikiLink.html">WikiLink</a>.</p>'

MetaData should not carry over to next document:

    >>> md.convert("No [[MetaData]] here.")
    u'<p>No <a class="wikilink" href="/MetaData/">MetaData</a> here.</p>'

Define a custom URL builder:

    >>> def my_url_builder(label, base, end):
    ...     return '/bar/'
    >>> md = markdown.Markdown(extensions=['wikilinks'], 
    ...         extension_configs={'wikilinks' : [('build_url', my_url_builder)]})
    >>> md.convert('[[foo]]')
    u'<p><a class="wikilink" href="/bar/">foo</a></p>'

From the command line:

    python markdown.py -x wikilinks(base_url=http://example.com/,end_url=.html,html_class=foo) src.txt

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

License: [BSD](http://www.opensource.org/licenses/bsd-license.php) 

Dependencies:
* [Python 2.3+](http://python.org)
* [Markdown 2.0+](http://www.freewisdom.org/projects/python-markdown/)
'''

import markdown
import re

def build_url(label, base, end):
    """ Build a url from the label, a base, and an end. """
    clean_label = re.sub(r'([ ]+_)|(_[ ]+)|([ ]+)', '_', label)
    return '%s%s%s'% (base, clean_label, end)


class WikiLinkExtension(markdown.Extension):
    def __init__(self, configs):
        # set extension defaults
        self.config = {
                        'base_url' : ['/', 'String to append to beginning or URL.'],
                        'end_url' : ['/', 'String to append to end of URL.'],
                        'html_class' : ['wikilink', 'CSS hook. Leave blank for none.'],
                        'build_url' : [build_url, 'Callable formats URL from label.'],
        }
        
        # Override defaults with user settings
        for key, value in configs :
            self.setConfig(key, value)
        
    def extendMarkdown(self, md, md_globals):
        self.md = md
    
        # append to end of inline patterns
        WIKILINK_RE = r'\[\[([A-Za-z0-9_ -]+)\]\]'
        wikilinkPattern = WikiLinks(WIKILINK_RE, self.config)
        wikilinkPattern.md = md
        md.inlinePatterns.add('wikilink', wikilinkPattern, "<not_strong")


class WikiLinks(markdown.inlinepatterns.Pattern):
    def __init__(self, pattern, config):
        markdown.inlinepatterns.Pattern.__init__(self, pattern)
        self.config = config
  
    def handleMatch(self, m):
        if m.group(2).strip():
            base_url, end_url, html_class = self._getMeta()
            label = m.group(2).strip()
            url = self.config['build_url'][0](label, base_url, end_url)
            a = markdown.etree.Element('a')
            a.text = label 
            a.set('href', url)
            if html_class:
                a.set('class', html_class)
        else:
            a = ''
        return a

    def _getMeta(self):
        """ Return meta data or config data. """
        base_url = self.config['base_url'][0]
        end_url = self.config['end_url'][0]
        html_class = self.config['html_class'][0]
        if hasattr(self.md, 'Meta'):
            if self.md.Meta.has_key('wiki_base_url'):
                base_url = self.md.Meta['wiki_base_url'][0]
            if self.md.Meta.has_key('wiki_end_url'):
                end_url = self.md.Meta['wiki_end_url'][0]
            if self.md.Meta.has_key('wiki_html_class'):
                html_class = self.md.Meta['wiki_html_class'][0]
        return base_url, end_url, html_class
    

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


if __name__ == "__main__":
    import doctest
    doctest.testmod()