/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

package registry

import (
	"dubbo.apache.org/dubbo-go/v3/common"
	"github.com/apache/dubbo-kubernetes/pkg/core/resources/apis/mesh"
	core_model "github.com/apache/dubbo-kubernetes/pkg/core/resources/model"
	"github.com/apache/dubbo-kubernetes/pkg/events"
	"github.com/apache/dubbo-kubernetes/pkg/util/rmkey"
	"sync"
)

import (
	"dubbo.apache.org/dubbo-go/v3/registry"

	gxset "github.com/dubbogo/gost/container/set"
	"github.com/dubbogo/gost/gof/observer"
)

type ServiceMappingChangedListenerImpl struct {
	oldServiceNames *gxset.HashSet
	listener        registry.NotifyListener
	interfaceKey    string
	systemNamespace string

	mux           sync.Mutex
	delSDRegistry registry.ServiceDiscovery
	eventWriter   events.Emitter
}

func NewMappingListener(
	oldServiceNames *gxset.HashSet,
	listener registry.NotifyListener,
	writer events.Emitter,
	systemNamespace string,
) *ServiceMappingChangedListenerImpl {
	return &ServiceMappingChangedListenerImpl{
		listener:        listener,
		oldServiceNames: oldServiceNames,
		eventWriter:     writer,
		systemNamespace: systemNamespace,
	}
}

// OnEvent on ServiceMappingChangedEvent the service mapping change event
func (lstn *ServiceMappingChangedListenerImpl) OnEvent(e observer.Event) error {
	lstn.mux.Lock()

	sm, ok := e.(*registry.ServiceMappingChangeEvent)
	if !ok {
		return nil
	}
	newServiceNames := sm.GetServiceNames()
	oldServiceNames := lstn.oldServiceNames
	// serviceMapping is orderly
	if newServiceNames.Empty() || oldServiceNames.String() == newServiceNames.String() {
		return nil
	}

	interfaceName, _, _ := common.ParseServiceKey(sm.GetServiceKey())
	if lstn.eventWriter != nil {
		go func() {
			lstn.eventWriter.Send(events.ResourceChangedEvent{
				Operation: events.Delete,
				Type:      mesh.DataplaneType,
				Key: core_model.ResourceKey{
					Name: rmkey.GenerateMappingResourceKey(interfaceName, ""),
				},
			})
		}()
	}
	err := lstn.updateListener(lstn.interfaceKey, newServiceNames)
	if err != nil {
		return err
	}
	lstn.oldServiceNames = newServiceNames
	lstn.mux.Unlock()

	return nil
}

func (lstn *ServiceMappingChangedListenerImpl) updateListener(interfaceKey string, apps *gxset.HashSet) error {
	delSDListener := NewDubboSDNotifyListener(apps)
	delSDListener.AddListenerAndNotify(interfaceKey, lstn.listener)
	err := lstn.delSDRegistry.AddListener(delSDListener)
	return err
}

// Stop on ServiceMappingChangedEvent the service mapping change event
func (lstn *ServiceMappingChangedListenerImpl) Stop() {}