import importlib
import json

from django.core.management.base import BaseCommand, CommandError

from graphene_django.settings import graphene_settings

class CommandArguments(BaseCommand):

    def add_arguments(self, parser):
        parser.add_argument(
            '--schema',
            type=str,
            dest='schema',
            default=graphene_settings.SCHEMA,
            help='Django app containing schema to dump, e.g. myproject.core.schema.schema')

        parser.add_argument(
            '--out',
            type=str,
            dest='out',
            default=graphene_settings.SCHEMA_OUTPUT,
            help='Output file (default: schema.json)')

        parser.add_argument(
            '--indent',
            type=int,
            dest='indent',
            default=graphene_settings.SCHEMA_INDENT,
            help='Output file indent (default: None)')


class Command(CommandArguments):
    help = 'Dump Graphene schema JSON to file'
    can_import_settings = True

    def save_file(self, out, schema_dict, indent):
        with open(out, 'w') as outfile:
            json.dump(schema_dict, outfile, indent=indent)

    def handle(self, *args, **options):
        options_schema = options.get('schema')

        if options_schema and type(options_schema) is str:
            module_str, schema_name = options_schema.rsplit('.', 1)
            mod = importlib.import_module(module_str)
            schema = getattr(mod, schema_name)

        elif options_schema:
            schema = options_schema

        else:
            schema = graphene_settings.SCHEMA

        out = options.get('out') or graphene_settings.SCHEMA_OUTPUT

        if not schema:
            raise CommandError('Specify schema on GRAPHENE.SCHEMA setting or by using --schema')

        indent = options.get('indent')
        schema_dict = {'data': schema.introspect()}
        self.save_file(out, schema_dict, indent)

        style = getattr(self, 'style', None)
        success = getattr(style, 'SUCCESS', lambda x: x)

        self.stdout.write(success('Successfully dumped GraphQL schema to %s' % out))