#!/usr/bin/env python3

"""
Pandoc filter to process code blocks with class "plantuml" into
plant-generated images.
Needs `plantuml.jar` from http://plantuml.com/.
"""

import os
import sys
import subprocess

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


kinds = {
    'plantuml': {
        'tag': 'plantuml',
        'argv': lambda src, dest: [
            'plantuml', '-tsvg', '-o', '.', src,
        ],
        'ext': '.uml',
        'prefix': b'@startuml\n',
        'suffix': b'\n@enduml\n',
    },
    'dot': {
        'tag': 'dot',
        'argv': lambda src, dest: [
            'dot', '-Tsvg', '-o', dest, src, '-Nfontname=Bitstream Charter',
            '-Nfontsize=10',
        ],
        'ext': '.dot',
        'prefix': b'digraph foo {\n',
        'suffix': b'}\n',
    },
}


def process_to_svg(kind, ident, classes, keyvals, code, format_):
    caption, typef, keyvals = get_caption(keyvals)

    filename = get_filename4code(kind['tag'], code)
    filetype = get_extension(format_, "png", html="svg", latex="svg")

    src = filename + kind['ext']
    dest = filename + '.' + filetype

    if not os.path.isfile(dest):
        txt = code.encode(sys.getfilesystemencoding())
        txt = kind['prefix'] + txt + kind['suffix']
        with open(src, "wb") as f:
            f.write(txt)

        func = kind['argv']
        argv = func(src, dest)
        subprocess.check_call(argv)
        sys.stderr.write('Created image ' + dest + '\n')

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


def combo(key, value, format_, _):
    if key == 'CodeBlock':
        [[ident, classes, keyvals], code] = value

        for tag, kind in kinds.items():
            if tag in classes:
                return process_to_svg(
                    kind, ident, classes, keyvals, code, format_)


def main():
    toJSONFilter(combo)


if __name__ == "__main__":
    main()