"""
Export all xml courses in a diffable format.

This command loads all of the xml courses in the configured DATA_DIR.
For each of the courses, it loops through all of the modules, and dumps
each as a separate output file containing the json representation
of each of its fields (including those fields that are set as default values).
"""
import json

from django.conf import settings
from django.core.management.base import BaseCommand, CommandError
from path import Path as path

from xmodule.modulestore.xml import XMLModuleStore


class Command(BaseCommand):
    """
    Django management command to export diffable representations of all xml courses
    """
    help = '''Dump the in-memory representation of all xml courses in a diff-able format'''
    args = '<export path>'

    def handle(self, *args, **options):
        if len(args) != 1:
            raise CommandError(f'Must called with arguments: {self.args}')

        xml_module_store = XMLModuleStore(
            data_dir=settings.DATA_DIR,
            default_class='xmodule.hidden_module.HiddenDescriptor',
            load_error_modules=True,
            xblock_mixins=settings.XBLOCK_MIXINS,
            xblock_select=settings.XBLOCK_SELECT_FUNCTION,
        )

        export_dir = path(args[0])

        for course_id, course_modules in xml_module_store.modules.items():
            course_path = course_id.replace('/', '_')
            for location, descriptor in course_modules.items():
                location_path = str(location).replace('/', '_')
                data = {}
                for field_name, field in descriptor.fields.items():
                    try:
                        data[field_name] = field.read_json(descriptor)
                    except Exception as exc:  # pylint: disable=broad-except
                        data[field_name] = {
                            '$type': str(type(exc)),
                            '$value': descriptor._field_data.get(descriptor, field_name)  # pylint: disable=protected-access
                        }

                outdir = export_dir / course_path
                outdir.makedirs_p()
                with open(outdir / location_path + '.json', 'w') as outfile:
                    json.dump(data, outfile, sort_keys=True, indent=4)
                    print('', file=outfile)