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/**
 * Copyright (C) 2015 Red Hat, Inc.
 *
 * 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 io.fabric8.kubernetes.client;

import io.fabric8.kubernetes.api.builder.VisitableBuilder;
import io.fabric8.kubernetes.api.model.APIResourceList;
import io.fabric8.kubernetes.api.model.GenericKubernetesResource;
import io.fabric8.kubernetes.api.model.GenericKubernetesResourceList;
import io.fabric8.kubernetes.api.model.HasMetadata;
import io.fabric8.kubernetes.api.model.KubernetesResourceList;
import io.fabric8.kubernetes.client.dsl.NamespacedInOutCreateable;
import io.fabric8.kubernetes.client.dsl.Resource;
import io.fabric8.kubernetes.client.dsl.base.HasMetadataOperation;
import io.fabric8.kubernetes.client.dsl.base.ResourceDefinitionContext;
import io.fabric8.kubernetes.client.utils.ApiVersionUtil;
import io.fabric8.kubernetes.client.utils.KubernetesResourceUtil;
import io.fabric8.kubernetes.client.utils.Serialization;

import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;

public final class Handlers {

  private static final Map, ResourceHandler> RESOURCE_HANDLER_MAP = new ConcurrentHashMap<>();
  private static final Map, ResourceDefinitionContext> GENERIC_RESOURCE_HANDLER_MAP = new ConcurrentHashMap<>();
  
  private Handlers() {
    //Utility
  }

  public static , R extends Resource> void register(Class type, Function> operationConstructor) {
    if (RESOURCE_HANDLER_MAP.put(type, new ResourceHandlerImpl(type, operationConstructor)) != null) {
      throw new AssertionError(String.format("%s already registered", type.getName()));
    }
  }
  
  public static  void unregister(Class type) {
    RESOURCE_HANDLER_MAP.remove(type);
  }
  
  /**
   * Returns a {@link ResourceHandler} for the given item.  The client is optional, if it is supplied, then the server can be 
   * consulted for resource metadata if a generic item is passed in. 
   */
  public static > ResourceHandler get(T meta, BaseClient client) {
    Class type = (Class)meta.getClass();
    
    if (type.equals(GenericKubernetesResource.class)) {
      ResourceDefinitionContext rdc = getResourceDefinitionContext((GenericKubernetesResource)meta, client);
      
      if (rdc != null) {
        return new ResourceHandlerImpl(GenericKubernetesResource.class, GenericKubernetesResourceList.class, rdc);
      }
    }
    
    return get(type);
  }
  
  public static ResourceDefinitionContext getResourceDefinitionContext(String apiVersion, String kind, BaseClient client) {
    GenericKubernetesResource resource = new GenericKubernetesResource();
    resource.setKind(kind);
    resource.setApiVersion(apiVersion);
    return getResourceDefinitionContext(resource, client);
  }

  public static  ResourceDefinitionContext getResourceDefinitionContext(GenericKubernetesResource meta, BaseClient client) {
    // check if it's built-in
    Object value = Serialization.unmarshal(Serialization.asJson(meta));
    Class parsedType = (Class) value.getClass();
    
    ResourceDefinitionContext rdc = null;
    if (!parsedType.equals(GenericKubernetesResource.class)) {
      rdc = ResourceDefinitionContext.fromResourceType(parsedType);
    } else if (client != null) {
      // if a client has been supplied, we can try to look this up from the server
      String kind = meta.getKind();
      String apiVersion = meta.getApiVersion();
      if (kind == null || apiVersion == null) {
        return null;
      }
      String api = ApiVersionUtil.trimGroupOrNull(apiVersion);
      if (api == null) {
        return null;
      }
      String version = ApiVersionUtil.trimVersion(apiVersion);
      // assume that resource metadata won't change for the lifetime of the client
      rdc = GENERIC_RESOURCE_HANDLER_MAP.computeIfAbsent(Arrays.asList(kind, apiVersion), k -> {
        APIResourceList resourceList = client.getApiResources(apiVersion);
        if (resourceList == null) {
          return null;
        }
        return resourceList.getResources()
            .stream()
            .filter(r -> kind.equals(r.getKind()))
            .findFirst()
            .map(resource -> new ResourceDefinitionContext.Builder().withGroup(api)
                .withKind(kind)
                .withNamespaced(Boolean.TRUE.equals(resource.getNamespaced()))
                .withPlural(resource.getName())
                .withVersion(version)
                .build())
            .orElse(null);
      });        
    }
    return rdc;
  }

  private static > ResourceHandler get(Class type) {
    if (type.equals(GenericKubernetesResource.class)) {
      return null;
    }
    return (ResourceHandler) RESOURCE_HANDLER_MAP.computeIfAbsent(type, k -> new ResourceHandlerImpl<>(type, null));
  }
  
  public static , R extends Resource> HasMetadataOperation getOperation(Class type, Class listType, ClientContext clientContext) {
    ResourceHandler resourceHandler = get(type);
    if (resourceHandler == null) {
      throw new IllegalStateException();
    }
    return (HasMetadataOperation) resourceHandler.operation(clientContext, listType);
  }
  
  public static  HasMetadataOperation> getNonListingOperation(Class type, ClientContext clientContext) {
    return getOperation(type, KubernetesResourceUtil.inferListType(type), clientContext);
  }
  
  public static  boolean shouldRegister(Class type) {
    ResourceHandler handler = RESOURCE_HANDLER_MAP.get(type);
    return !RESOURCE_HANDLER_MAP.isEmpty() && (handler == null || !handler.hasOperation());
  }

  public static  NamespacedInOutCreateable getNamespacedHasMetadataCreateOnlyOperation(Class type, ClientContext clientContext) {
    HasMetadataOperation> operation = getNonListingOperation(type, clientContext);
    return operation::inNamespace;
  }
  
}