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from optparse import make_option
from django.core.management.base import BaseCommand, CommandError
from synnefo.management.common import get_backend, check_backend_credentials


class Command(BaseCommand):
    output_transaction = True
    args = "<backend ID>"
    help = "Modify a backend"

    option_list = BaseCommand.option_list + (
        make_option('--clustername',
            dest='clustername',
            help="Set backend's clustername"),
        make_option('--port',
            dest='port',
            help="Set backend's port"),
        make_option('--username',
            dest='username',
            help="Set backend'username"),
        make_option('--password',
            dest='password',
            help="Set backend's password"),
        make_option('--drained',
            dest='drained',
            action='store_true',
            default=False,
            help="Set the backend as drained to exclude from allocation "\
                 "operations"),
        make_option('--no-drained',
            dest='drained',
            action='store_false'),
        make_option('--offline',
            dest='offline',
            action='store_true',
            default=False,
            help="Set the backend as offline to not communicate in order "\
                 "to avoid delays"),
        make_option('--no-offline',
            dest='offline',
            action='store_false')
        )

    def handle(self, *args, **options):
        if len(args) != 1:
            raise CommandError("Please provide a backend ID")

        backend = get_backend(args[0])

        # Ensure fields correspondence with options and Backend model
        fields = ('clustername', 'port', 'username', 'password', 'drained',
                  'offline')
        for field in fields:
            value = options.get(field)
            if value is not None:
                backend.__setattr__(field, value)

        credentials = ('clustername', 'port', 'username', 'password')
        for field in credentials:
            if options.get(field):
                # check credentials, if any of them changed!
                check_backend_credentials(backend.clustername, backend.port,
                                          backend.username, backend.password)
                return

        backend.save()