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/*
 * Copyright 2017 Huawei Technologies Co., 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 io.servicecomb.bizkeeper;

import com.netflix.hystrix.HystrixObservable;

import io.servicecomb.core.Invocation;
import io.servicecomb.swagger.invocation.Response;
import rx.Observable;
import rx.Subscription;
import rx.functions.Action0;
import rx.subjects.ReplaySubject;

public class BizkeeperHandlerDelegate {

  private BizkeeperHandler handler;

  public BizkeeperHandlerDelegate(BizkeeperHandler handler) {
    this.handler = handler;
  }

  protected HystrixObservable createBizkeeperCommand(Invocation invocation) {
    if (Configuration.INSTANCE.isFallbackForce(handler.groupname,
        invocation.getMicroserviceName(),
        invocation.getOperationMeta().getMicroserviceQualifiedName())) {
      return forceFallbackCommand(invocation);
    }
    return handler.createBizkeeperCommand(invocation);
  }

  protected HystrixObservable forceFallbackCommand(Invocation invocation) {
    return new HystrixObservable() {
      @Override
      public Observable observe() {
        ReplaySubject subject = ReplaySubject.create();
        final Subscription sourceSubscription = toObservable().subscribe(subject);
        return subject.doOnUnsubscribe(new Action0() {
          @Override
          public void call() {
            sourceSubscription.unsubscribe();
          }
        });
      }

      @Override
      public Observable toObservable() {
        return Observable.create(f -> {
          try {
            f.onNext(FallbackPolicyManager.getFallbackResponse(handler.groupname, invocation));
          } catch (Exception e) {
            f.onError(e);
          }
        });
      }
    };
  }
}