package com.ctrip.apollo.configservice.controller;

 import com.google.common.base.Joiner;

 import com.google.common.base.Strings;

 import com.google.common.collect.FluentIterable;

 import com.google.common.collect.Lists;

 import com.google.common.collect.Maps;

 import com.google.gson.Gson;

 import com.google.gson.reflect.TypeToken;

 import com.ctrip.apollo.biz.entity.AppNamespace;

 import com.ctrip.apollo.biz.entity.Release;

 import com.ctrip.apollo.biz.service.AppNamespaceService;

 import com.ctrip.apollo.biz.service.ConfigService;

 import com.ctrip.apollo.core.ConfigConsts;

 import com.ctrip.apollo.core.dto.ApolloConfig;

 import com.dianping.cat.Cat;

 import org.springframework.beans.factory.annotation.Autowired;

 import org.springframework.web.bind.annotation.PathVariable;

 import org.springframework.web.bind.annotation.RequestMapping;

 import org.springframework.web.bind.annotation.RequestMethod;

 import org.springframework.web.bind.annotation.RequestParam;

 import org.springframework.web.bind.annotation.RestController;

 import java.io.IOException;

 import java.lang.reflect.Type;

 import java.util.List;

 import java.util.Map;

 import java.util.Objects;

 import javax.servlet.http.HttpServletResponse;

 /**

  * @author Jason Song(song_s@ctrip.com)

  */

 @RestController

 @RequestMapping("/configs")

 public class ConfigController {

   @Autowired

   private ConfigService configService;

   @Autowired

   private AppNamespaceService appNamespaceService;

   private static final Gson gson = new Gson();

   private static final Type configurationTypeReference =

       new TypeToken<Map<java.lang.String, java.lang.String>>() {

       }.getType();

   private static final Joiner STRING_JOINER = Joiner.on(ConfigConsts.CLUSTER_NAMESPACE_SEPARATOR);

   @RequestMapping(value = "/{appId}/{clusterName}", method = RequestMethod.GET)

   public ApolloConfig queryConfig(@PathVariable String appId, @PathVariable String clusterName,

                                   @RequestParam(value = "dataCenter", required = false) String dataCenter,

                                   @RequestParam(value = "releaseKey", defaultValue = "-1") String clientSideReleaseKey,

                                   HttpServletResponse response) throws IOException {

     return this.queryConfig(appId, clusterName, ConfigConsts.NAMESPACE_DEFAULT, dataCenter,

         clientSideReleaseKey, response);

   }

   @RequestMapping(value = "/{appId}/{clusterName}/{namespace}", method = RequestMethod.GET)

   public ApolloConfig queryConfig(@PathVariable String appId, @PathVariable String clusterName,

                                   @PathVariable String namespace,

                                   @RequestParam(value = "dataCenter", required = false) String dataCenter,

                                   @RequestParam(value = "releaseKey", defaultValue = "-1") String clientSideReleaseKey,

                                   HttpServletResponse response) throws IOException {

     List<Release> releases = Lists.newLinkedList();

     Release currentAppRelease = configService.findRelease(appId, clusterName, namespace);

     if (currentAppRelease != null) {

       releases.add(currentAppRelease);

     }

     //if namespace is not 'application', should check if it's a public configuration

     if (!Objects.equals(ConfigConsts.NAMESPACE_DEFAULT, namespace)) {

       Release publicRelease = this.findPublicConfig(appId, namespace, dataCenter);

       if (!Objects.isNull(publicRelease)) {

         releases.add(publicRelease);

       }

     }

     if (releases.isEmpty()) {

       response.sendError(HttpServletResponse.SC_NOT_FOUND,

           String.format(

               "Could not load configurations with appId: %s, clusterName: %s, namespace: %s",

               appId, clusterName, namespace));

       Cat.logEvent("Apollo.Config.NotFound",

           assembleKey(appId, clusterName, namespace, dataCenter));

       return null;

     }

     String mergedReleaseKey = FluentIterable.from(releases).transform(

         input -> String.valueOf(input.getReleaseKey())).join(STRING_JOINER);

     if (mergedReleaseKey.equals(clientSideReleaseKey)) {

       // Client side configuration is the same with server side, return 304

       response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);

       Cat.logEvent("Apollo.Config.NotModified",

           assembleKey(appId, clusterName, namespace, dataCenter));

       return null;

     }

     ApolloConfig apolloConfig = new ApolloConfig(appId, clusterName, namespace, mergedReleaseKey);

     apolloConfig.setConfigurations(mergeReleaseConfigurations(releases));

     Cat.logEvent("Apollo.Config.Found", assembleKey(appId, clusterName, namespace, dataCenter));

     return apolloConfig;

   }

   /**

    * @param applicationId the application which uses public config

    * @param namespace     the namespace

    * @param dataCenter    the datacenter

    */

   private Release findPublicConfig(String applicationId, String namespace, String dataCenter) {

     AppNamespace appNamespace = appNamespaceService.findByNamespaceName(namespace);

     //check whether the namespace's appId equals to current one

     if (Objects.isNull(appNamespace) || Objects.equals(applicationId, appNamespace.getAppId())) {

       return null;

     }

     String publicConfigAppId = appNamespace.getAppId();

     //try to load via data center

     if (!Objects.isNull(dataCenter)) {

       Release dataCenterRelease =

           configService.findRelease(publicConfigAppId, dataCenter, namespace);

       if (!Objects.isNull(dataCenterRelease)) {

         return dataCenterRelease;

       }

     }

     //fallback to default release

     return configService

         .findRelease(publicConfigAppId, ConfigConsts.CLUSTER_NAME_DEFAULT, namespace);

   }

   /**

    * Merge configurations of releases.

    * Release in lower index override those in higher index

    */

   Map<String, String> mergeReleaseConfigurations(List<Release> releases) {

     Map<String, String> result = Maps.newHashMap();

     for (Release release : Lists.reverse(releases)) {

       result.putAll(gson.fromJson(release.getConfigurations(), configurationTypeReference));

     }

     return result;

   }

   private String assembleKey(String appId, String cluster, String namespace, String datacenter) {

     List<String> keyParts = Lists.newArrayList(appId, cluster, namespace);

     if (!Strings.isNullOrEmpty(datacenter)) {

       keyParts.add(datacenter);

     }

     return STRING_JOINER.join(keyParts);

   }

 }