from django import template
from django.conf import settings

from docutils import nodes
from docutils.parsers.rst import directives
from pygments import highlight
from pygments.lexers import get_lexer_by_name
from pygments.formatters import HtmlFormatter


pygments_formatter = HtmlFormatter()

def pygments_directive(name, arguments, options, content, lineno,
                       content_offset, block_text, state, state_machine):
    try:
        lexer = get_lexer_by_name(arguments[0])
    except ValueError:
        # no lexer found - use the text one instead of an exception
        lexer = get_lexer_by_name('text')
    parsed = highlight(u'\n'.join(content), lexer, pygments_formatter)
    return [nodes.raw('', parsed, format='html')]
pygments_directive.arguments = (1, 0, 1) 
pygments_directive.content = 1
directives.register_directive('code', pygments_directive)


register = template.Library()

@register.filter
def rest ( value, headerlevel=2 ): 
    try:
        from docutils.core import publish_parts
    except ImportError:
        if settings.DEBUG:
            raise template.TemplateSyntaxError, "Error in {% rest %} filter: The Python docutils library isn't installed."
        return value
    else:
        docutils_settings = getattr(settings, "REST_FILTER_SETTINGS", {'initial_header_level': int(headerlevel)})
        parts = publish_parts(source=value, writer_name="html4css1", settings_overrides=docutils_settings)
        return parts["html_body"]