# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.apps import apps
from django.core import checks
from django.core.checks.registry import registry
from django.core.management.base import BaseCommand, CommandError


class Command(BaseCommand):
    help = "Checks the entire Django project for potential problems."

    requires_system_checks = False

    def add_arguments(self, parser):
        parser.add_argument('args', metavar='app_label', nargs='*')
        parser.add_argument('--tag', '-t', action='append', dest='tags',
            help='Run only checks labeled with given tag.')
        parser.add_argument('--list-tags', action='store_true', dest='list_tags',
            help='List available tags.')
        parser.add_argument('--deploy', action='store_true', dest='deploy',
            help='Check deployment settings.')

    def handle(self, *app_labels, **options):
        include_deployment_checks = options['deploy']
        if options.get('list_tags'):
            self.stdout.write('\n'.join(sorted(registry.tags_available(include_deployment_checks))))
            return

        if app_labels:
            app_configs = [apps.get_app_config(app_label) for app_label in app_labels]
        else:
            app_configs = None

        tags = options.get('tags')
        if tags:
            try:
                invalid_tag = next(
                    tag for tag in tags if not checks.tag_exists(tag, include_deployment_checks)
                )
            except StopIteration:
                # no invalid tags
                pass
            else:
                raise CommandError('There is no system check with the "%s" tag.' % invalid_tag)

        self.check(
            app_configs=app_configs,
            tags=tags,
            display_num_errors=True,
            include_deployment_checks=include_deployment_checks,
        )