#!/usr/bin/env python

"""

Pandoc filter to process code blocks with class "graphviz" into

graphviz-generated images.

Needs pygraphviz

"""

import os

import sys

import pygraphviz

from pandocfilters import toJSONFilter, Para, Image, get_filename4code, get_caption, get_extension, get_value

def graphviz(key, value, format, _):

    if key == 'CodeBlock':

        [[ident, classes, keyvals], file] = value

        if "graphviz-file" in classes:

            caption, typef, keyvals = get_caption(keyvals)

            prog, keyvals = get_value(keyvals, u"prog", u"dot")

            filetype = get_extension(format, "svg", html="svg", latex="pdf")

            with open(file) as f:

                code = f.read()

            dest = get_filename4code("graphviz", code, filetype)

            if not os.path.isfile(dest):

                g = pygraphviz.AGraph(string=code)

                g.layout()

                g.draw(dest, prog=prog)

                sys.stderr.write('Created image ' + dest + '\n')

            return Para([Image([ident, ['graphviz'], keyvals], caption, [dest, typef])])

if __name__ == "__main__":

    toJSONFilter(graphviz)