from docutils import nodes

from docutils.parsers.rst import Directive, directives
from sphinx.util.docutils import SphinxDirective

from shutil import which
from pathlib import Path
import shlex
import subprocess
import tempfile

class D2langDirective(SphinxDirective):
    required_arguments = 0
    has_content = True
    optional_arguments = 3
    option_spec = {
        'layout': directives.unchanged_required,
        'filename': directives.unchanged_required,
    }
    def run(self):
        d2_bin = which('d2')
        srcdir = self.state.document.settings.env.srcdir
        diag_source = self.content
        if 'filename' in self.options:
            output_fname = self.options.get('filename')
        else:
            output_fname = 'test.svg'
        if 'layout' in self.options:
            layout = self.options.get('layout')
        else:
            layout = 'dagre'
        if self.arguments:
            path = Path(srcdir + self.arguments[0])
            if path.is_file():
                build_svg(self.arguments[0], srcdir, output_fname, layout)
            else:
                raise
        else:
            with tempfile.NamedTemporaryFile() as fp:
                for line in self.content.data:
                    fp.write(bytes(line,'utf-8'))
                    fp.write(bytes('\n','utf-8'))
                fp.seek(0)
                build_svg(fp.name, srcdir, output_fname, layout)
        image_node = nodes.image(uri=output_fname)
        return [image_node]

def build_svg(diag_src, out_dir, filename, layout):
    d2_bin = which('d2')
    cmd_line = '%s -l %s %s %s' % (d2_bin, layout, diag_src, out_dir + "/" + filename)
    args = shlex.split(cmd_line)
    subprocess.run(args)
    return True