"""Module containing a preprocessor that converts outputs in the notebook from
one format to another.
"""

# Copyright (c) Jupyter Development Team.
# Distributed under the terms of the Modified BSD License.

import base64
import io
import os
import sys
import subprocess

from testpath.tempdir import TemporaryDirectory
from traitlets import Unicode, default

from .convertfigures import ConvertFiguresPreprocessor

from shutil import which


# inkscape path for darwin (macOS)
INKSCAPE_APP = '/Applications/Inkscape.app/Contents/Resources/bin/inkscape'
# Recent versions of Inkscape (v1.0) moved the executable from 
# Resources/bin/inkscape to MacOS/inkscape
INKSCAPE_APP_v1 = '/Applications/Inkscape.app/Contents/MacOS/inkscape'

if sys.platform == "win32":
    try:
        import winreg
    except ImportError:
        import _winreg as winreg


class SVG2PDFPreprocessor(ConvertFiguresPreprocessor):
    """
    Converts all of the outputs in a notebook from SVG to PDF.
    """

    @default('from_format')
    def _from_format_default(self):
        return 'image/svg+xml'

    @default('to_format')
    def _to_format_default(self):
        return 'application/pdf'

    inkscape_version = Unicode(
        help="""The version of inkscape being used.

        This affects how the conversion command is run.
        """
    ).tag(config=True)

    @default('inkscape_version')
    def _inkscape_version_default(self):
        p = subprocess.Popen([self.inkscape, '--version'],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE)
        output, _ = p.communicate()
        if p.returncode != 0:
            raise RuntimeError("Unable to find inkscape executable --version")
        return output.decode('utf-8').split(' ')[1]

    command = Unicode(
        help="""The command to use for converting SVG to PDF

        This string is a template, which will be formatted with the keys
        to_filename and from_filename.

        The conversion call must read the SVG from {from_filename},
        and write a PDF to {to_filename}.
        """).tag(config=True)

    @default('command')
    def _command_default(self):
        major_verison = self.inkscape_version.split('.')[0]
        export_option = ' --export-filename' if int(major_verison) > 0 else ' --export-pdf'
        gui_option = '' if int(major_verison) > 0 else ' --without-gui'

        return '{inkscape}{gui_option}{export_option}='.format(
            inkscape=self.inkscape, export_option=export_option, gui_option=gui_option
        ) + '"{to_filename}" "{from_filename}"'

    inkscape = Unicode(help="The path to Inkscape, if necessary").tag(config=True)
    @default('inkscape')
    def _inkscape_default(self):
        inkscape_path = which('inkscape')
        if inkscape_path is not None:
            return inkscape_path
        if sys.platform == "darwin":
            if os.path.isfile(INKSCAPE_APP_v1):
                return INKSCAPE_APP_v1
            # Order is important. If INKSCAPE_APP exists, prefer it over
            # the executable in the MacOS directory.
            if os.path.isfile(INKSCAPE_APP):
                return INKSCAPE_APP
        if sys.platform == "win32":
            wr_handle = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
            try:
                rkey = winreg.OpenKey(wr_handle, "SOFTWARE\\Classes\\inkscape.svg\\DefaultIcon")
                inkscape = winreg.QueryValueEx(rkey, "")[0]
            except FileNotFoundError:
                raise FileNotFoundError("Inkscape executable not found")
            return inkscape
        return "inkscape"


    def convert_figure(self, data_format, data):
        """
        Convert a single SVG figure to PDF.  Returns converted data.
        """

        # Work in a temporary directory
        with TemporaryDirectory() as tmpdir:

            # Write fig to temp file
            input_filename = os.path.join(tmpdir, 'figure.svg')
            # SVG data is unicode text
            with io.open(input_filename, 'w', encoding='utf8') as f:
                f.write(data)

            # Call conversion application
            output_filename = os.path.join(tmpdir, 'figure.pdf')
            shell = self.command.format(from_filename=input_filename,
                                   to_filename=output_filename)
            subprocess.call(shell, shell=True) # Shell=True okay since input is trusted.

            # Read output from drive
            # return value expects a filename
            if os.path.isfile(output_filename):
                with open(output_filename, 'rb') as f:
                    # PDF is a nb supported binary, data type, so base64 encode.
                    return base64.encodebytes(f.read())
            else:
                raise TypeError("Inkscape svg to pdf conversion failed")
