import os
import pkg_resources
from django.conf import settings
from django.core.management.base import BaseCommand, CommandError

from dav_base.config.modules import DJANGO_MAIN_MODULE, ModuleMeta


class Command(BaseCommand):
    help = 'Enable a modular app in django-dav installation.'

    def add_arguments(self, parser):
        parser.add_argument('module', help='the name of the module')

    def handle(self, *args, **options):
        django_base_dir = settings.BASE_DIR
        django_main_module = DJANGO_MAIN_MODULE
        module_name = options['module']

        config = settings.MODULE_CONFIG

        if module_name in config.modules.keys():
            raise CommandError('Module \'{}\' is already enabled'.format(module_name))

        settings_file_name = 'settings-{}.py'.format(module_name)
        input_file = os.path.join('django_project_config', settings_file_name)
        if pkg_resources.resource_exists(module_name, input_file):
            output_file = os.path.join(django_base_dir, django_main_module, settings_file_name)
            if not os.path.exists(output_file):
                with open(output_file, 'w') as f:
                    f.write(pkg_resources.resource_string(module_name, input_file))

        module_meta_obj = ModuleMeta(module_name)
        config.modules[module_name] = module_meta_obj
        config.save()

        self.stdout.write(self.style.SUCCESS('Module \'{}\' enabled.'.format(module_name)))