content: /*
   * Copyright 1999-2022 Alibaba Group Holding Ltd.
   *
   * 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.
   *
   */
  
  package com.alibaba.nacos.istio.xds;
  
  import com.alibaba.nacos.istio.api.ApiGenerator;
  import com.alibaba.nacos.istio.misc.IstioConfig;
  import com.alibaba.nacos.istio.model.IstioEndpoint;
  import com.alibaba.nacos.istio.model.IstioService;
  import com.alibaba.nacos.istio.model.PushRequest;
  import com.google.protobuf.Any;
  import com.google.protobuf.UInt32Value;
  import io.envoyproxy.envoy.config.core.v3.TrafficDirection;
  import io.envoyproxy.envoy.config.endpoint.v3.ClusterLoadAssignment;
  import io.envoyproxy.envoy.config.endpoint.v3.LbEndpoint;
  import io.envoyproxy.envoy.config.endpoint.v3.LocalityLbEndpoints;
  import io.envoyproxy.envoy.service.discovery.v3.Resource;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import static com.alibaba.nacos.istio.api.ApiConstants.ENDPOINT_TYPE;
  import static com.alibaba.nacos.istio.util.IstioCrdUtil.buildClusterName;
  import static com.alibaba.nacos.istio.util.IstioCrdUtil.parseClusterNameToServiceName;
  
  /**.
   * @author RocketEngine26
   * @date 2022/7/24 15:28
   */
  public final class EdsGenerator implements ApiGenerator<Any> {
      
      private static volatile EdsGenerator singleton = null;
      
      public static EdsGenerator getInstance() {
          if (singleton == null) {
              synchronized (EdsGenerator.class) {
                  if (singleton == null) {
                      singleton = new EdsGenerator();
                  }
              }
          }
          return singleton;
      }
      
      @Override
      public List<Any> generate(PushRequest pushRequest) {
          List<Any> result = new ArrayList<>();
          IstioConfig istioConfig = pushRequest.getResourceSnapshot().getIstioConfig();
          Map<String, IstioService> istioServiceMap = pushRequest.getResourceSnapshot().getIstioResources().getIstioServiceMap();
          if (pushRequest.getReason().size() != 0) {
              for (String reason : pushRequest.getReason()) {
                  IstioService istioService = istioServiceMap.get(reason);
                  String name = buildClusterName(TrafficDirection.OUTBOUND, "",
                          reason + '.' + istioConfig.getDomainSuffix(), istioService.getPort());
                  Any any = buildEndpoint(name, istioService);
                  if (any != null) {
                      result.add(any);
                  }
              }
          } else {
              for (Map.Entry<String, IstioService> entry : istioServiceMap.entrySet()) {
                  String name = buildClusterName(TrafficDirection.OUTBOUND, "",
                          entry.getKey() + '.' + istioConfig.getDomainSuffix(), entry.getValue().getPort());
                  Any any = buildEndpoint(name, entry.getValue());
                  if (any != null) {
                      result.add(any);
                  }
              }
          }
          return result;
      }
      
      @Override
      public List<Resource> deltaGenerate(PushRequest pushRequest) {
          if (pushRequest.isFull()) {
              return null;
          }
          
          List<Resource> result = new ArrayList<>();
          Set<String> reason = pushRequest.getReason();
          IstioConfig istioConfig = pushRequest.getResourceSnapshot().getIstioConfig();
          Map<String, IstioService> istioServiceMap = pushRequest.getResourceSnapshot().getIstioResources().getIstioServiceMap();
          
          if (pushRequest.getSubscribe().size() != 0) {
              for (String subscribe : pushRequest.getSubscribe()) {
                  String serviceName = parseClusterNameToServiceName(subscribe, istioConfig.getDomainSuffix());
                  if (reason.contains(serviceName)) {
                      if (istioServiceMap.containsKey(serviceName)) {
                          Any any = buildEndpoint(subscribe, istioServiceMap.get(serviceName));
                          if (any != null) {
                              result.add(Resource.newBuilder().setResource(any).setVersion(pushRequest.getResourceSnapshot().getVersion()).build());
                          } else {
                              pushRequest.addRemoved(subscribe);
                          }
                      } else {
                          pushRequest.addRemoved(subscribe);
                      }
                  }
              }
          } else {
              for (Map.Entry<String, IstioService> entry : istioServiceMap.entrySet()) {
                  String name = buildClusterName(TrafficDirection.OUTBOUND, "",
                          entry.getKey() + '.' + istioConfig.getDomainSuffix(), entry.getValue().getPort());
                  Any any = buildEndpoint(name, entry.getValue());
                  if (any != null) {
                      result.add(Resource.newBuilder().setResource(any).setVersion(pushRequest.getResourceSnapshot().getVersion()).build());
                  } else {
                      pushRequest.addRemoved(name);
                  }
              }
          }
          
          return result;
      }
      
      private static Any buildEndpoint(String name, IstioService istioService) {
          if (istioService.getHosts().isEmpty()) {
              return null;
          }
          
          List<IstioEndpoint> istioEndpoints = istioService.getHosts();
          Map<String, LocalityLbEndpoints.Builder> llbEndpointsBuilder = new HashMap<>(istioEndpoints.size());
      
          for (IstioEndpoint istioEndpoint : istioEndpoints) {
              String label = istioEndpoint.getStringLocality();
              LbEndpoint lbEndpoint = istioEndpoint.getLbEndpoint();
          
              if (!llbEndpointsBuilder.containsKey(label)) {
                  LocalityLbEndpoints.Builder llbEndpointBuilder = LocalityLbEndpoints.newBuilder()
                          .setLocality(istioEndpoint.getLocality()).addLbEndpoints(lbEndpoint);
                  llbEndpointsBuilder.put(label, llbEndpointBuilder);
              } else {
                  llbEndpointsBuilder.get(label).addLbEndpoints(lbEndpoint);
              }
          }
      
          List<LocalityLbEndpoints> listlle = new ArrayList<>();
          for (LocalityLbEndpoints.Builder builder : llbEndpointsBuilder.values()) {
              int weight = 0;
              for (LbEndpoint lbEndpoint : builder.getLbEndpointsList()) {
                  weight += lbEndpoint.getLoadBalancingWeight().getValue();
              }
              LocalityLbEndpoints lle = builder.setLoadBalancingWeight(UInt32Value.newBuilder().setValue(weight)).build();
              listlle.add(lle);
          }
          
          if (listlle.size() == 0) {
              return null;
          }
          
          ClusterLoadAssignment cla = ClusterLoadAssignment.newBuilder().setClusterName(name).addAllEndpoints(listlle).build();
          return Any.newBuilder().setValue(cla.toByteString()).setTypeUrl(ENDPOINT_TYPE).build();
      }
  }