Custom ditaa extension for Nikola

ditaa.py

# Copyright © 2021 Luke Plant

# Permission is hereby granted, free of charge, to any
# person obtaining a copy of this software and associated
# documentation files (the "Software"), to deal in the
# Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish,
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# Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice
# shall be included in all copies or substantial portions of
# the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
# PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
# OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

"""Custom reST_ directive for ditaa_ integration.
.. _reST: http://docutils.sourceforge.net/rst.html
.. _ditaa: https://github.com/stathissideris/ditaa/
"""

import hashlib
import os
import subprocess
import tempfile

from docutils.nodes import image, literal_block
from docutils.parsers.rst import Directive, directives
from nikola.plugin_categories import RestExtension

OUTPUT_DIR = None  # Set below
OUTPUT_URL_PATH = None  # Set below


class Ditaa(Directive):
    required_arguments = 0
    optional_arguments = 0
    has_content = True

    option_spec = {
        "filename": directives.path,
        "class": directives.class_option,
        "alt": directives.unchanged,
        "cmdline": directives.unchanged,
    }

    def run(self):
        if not os.path.exists(OUTPUT_DIR):
            os.makedirs(OUTPUT_DIR)

        nodes = []

        body = "\n".join(self.content)
        tf = tempfile.NamedTemporaryFile(delete=False)
        tf.write(body.encode("utf8"))
        tf.flush()

        # make a filename
        filename_template = self.options.pop("filename", "{checksum}.png")
        filename = filename_template.format(
            {
                "checksum": hashlib.sha256(body.encode("utf-8")).hexdigest()[0:12],
            }
        )

        alt = self.options.get("alt", "ditaa diagram")
        classes = self.options.pop("class", ["ditaa"])
        cmdline_opts = self.options.pop("cmdline", "").split(" ")

        cmdline = [
            "ditaa",
            tf.name,
            os.path.join(OUTPUT_DIR, filename),
            "--overwrite",
            "--encoding",
            "utf8",
        ] + cmdline_opts

        try:
            p = subprocess.run(cmdline, capture_output=True)
        except Exception as exc:
            error = self.state_machine.reporter.error(
                f"Failed to run ditaa: {exc}", literal_block(self.block_text, self.block_text), line=self.lineno
            )
            nodes.append(error)
        else:
            if p.returncode == 0:
                url = OUTPUT_URL_PATH + "/" + filename
                imgnode = image(uri=url, classes=classes, alt=alt)
                nodes.append(imgnode)
            else:
                error = self.state_machine.reporter.error(
                    f'Error in "{self.name}" directive: {p.stderr}',
                    literal_block(self.block_text, self.block_text),
                    line=self.lineno,
                )
                nodes.append(error)
        finally:
            os.unlink(tf.name)

        self.state.document.settings.record_dependencies.add("####MAGIC####CONFIG:DITAA_OUTPUT_URL_PATH")
        return nodes


class Plugin(RestExtension):
    name = "ditaa"

    def set_site(self, site):
        global OUTPUT_DIR, OUTPUT_URL_PATH
        directives.register_directive("ditaa", Ditaa)
        OUTPUT_DIR = site.config["DITAA_OUTPUT_FOLDER"]
        OUTPUT_URL_PATH = site.config["DITAA_OUTPUT_URL_PATH"]
        return super().set_site(site)