# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

from django.urls import reverse
from django.utils.translation import gettext_lazy as _

from horizon import exceptions
from horizon import forms
from horizon import messages

from openstack_dashboard import api


class EvacuateHostForm(forms.SelfHandlingForm):

    current_host = forms.CharField(label=_("Current Host"),
                                   widget=forms.TextInput(
                                       attrs={'readonly': 'readonly'}))
    target_host = forms.ThemableChoiceField(
        label=_("Target Host"),
        required=False,
        help_text=_("Choose a Host to evacuate servers to. If not selected, "
                    "the scheduler will auto select target host."))

    on_shared_storage = forms.BooleanField(label=_("Shared Storage"),
                                           initial=False, required=False)

    def __init__(self, request, *args, **kwargs):
        super().__init__(request, *args, **kwargs)
        initial = kwargs.get('initial', {})
        self.fields['target_host'].choices = \
            self.populate_host_choices(request, initial)

    def populate_host_choices(self, request, initial):
        hosts = initial.get('hosts')
        current_host = initial.get('current_host')
        host_list = sorted([(host, host)
                            for host in hosts
                            if host != current_host])
        if host_list:
            host_list.insert(0, ("", _("Select a target host")))
        else:
            host_list.insert(0, ("", _("No other hosts available.")))
        return host_list

    def handle(self, request, data):
        try:
            current_host = data['current_host']
            target_host = data['target_host']
            on_shared_storage = data['on_shared_storage']
            # The target_host value will be an empty string when the target
            # host wasn't specified. But the evacuate api doesn't allow
            # an empty string. So set None as the target_host value.
            if not target_host:
                target_host = None
            api.nova.evacuate_host(request, current_host,
                                   target_host, on_shared_storage)

            msg = _('Starting to evacuate host: %s.') % current_host
            messages.success(request, msg)
            return True
        except Exception:
            redirect = reverse('horizon:admin:hypervisors:index')
            msg = _('Failed to evacuate host: %s.') % data['current_host']
            exceptions.handle(request, message=msg, redirect=redirect)
            return False


class DisableServiceForm(forms.SelfHandlingForm):
    host = forms.CharField(label=_("Host"),
                           widget=forms.TextInput(
                           attrs={"readonly": "readonly"}))
    reason = forms.CharField(max_length=255,
                             label=_("Reason"),
                             required=False)

    def handle(self, request, data):
        try:
            host = data["host"]
            reason = data["reason"]
            api.nova.service_disable(request, host, "nova-compute",
                                     reason=reason)
            msg = _("Disabled compute service for host: %s.") % host
            messages.success(request, msg)
            return True
        except Exception:
            redirect = reverse('horizon:admin:hypervisors:index')
            msg = _("Failed to disable compute service for host: %s.") % \
                data["host"]
            exceptions.handle(request, message=msg, redirect=redirect)
            return False


class MigrateHostForm(forms.SelfHandlingForm):
    current_host = forms.CharField(
        label=_("Current Host"),
        required=False,
        widget=forms.TextInput(
            attrs={'readonly': 'readonly'})
    )

    migrate_type = forms.ChoiceField(
        label=_('Running Instance Migration Type'),
        choices=[
            ('live_migrate', _('Live Migrate')),
            ('cold_migrate', _('Cold Migrate'))
        ],
        widget=forms.ThemableSelectWidget(
            attrs={
                'class': 'switchable',
                'data-slug': 'source'
            }
        )
    )

    disk_over_commit = forms.BooleanField(
        label=_("Disk Over Commit"),
        initial=False,
        required=False,
        widget=forms.CheckboxInput(
            attrs={
                'class': 'switched',
                'data-switch-on': 'source',
                'data-source-live_migrate': _('Disk Over Commit')
            }
        )
    )

    block_migration = forms.BooleanField(
        label=_("Block Migration"),
        initial=False,
        required=False,
        widget=forms.CheckboxInput(
            attrs={
                'class': 'switched',
                'data-switch-on': 'source',
                'data-source-live_migrate': _('Block Migration')
            }
        )
    )

    def handle(self, request, data):
        try:
            current_host = data['current_host']
            migrate_type = data['migrate_type']
            disk_over_commit = data['disk_over_commit']
            block_migration = data['block_migration']
            live_migrate = migrate_type == 'live_migrate'
            api.nova.migrate_host(
                request,
                current_host,
                live_migrate=live_migrate,
                disk_over_commit=disk_over_commit,
                block_migration=block_migration
            )
            msg = _('Starting to migrate host: %(current)s') % \
                {'current': current_host}
            messages.success(request, msg)
            return True
        except Exception:
            msg = _('Failed to migrate host "%s".') % data['current_host']
            redirect = reverse('horizon:admin:hypervisors:index')
            exceptions.handle(request, message=msg, redirect=redirect)
            return False
