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/**
 * Copyright (C) 2009 Google 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 org.elasticsearch.util.inject;

import org.elasticsearch.util.collect.ImmutableList;
import org.elasticsearch.util.collect.Lists;
import org.elasticsearch.util.inject.internal.Errors;
import org.elasticsearch.util.inject.internal.ErrorsException;
import org.elasticsearch.util.inject.internal.FailableCache;
import org.elasticsearch.util.inject.spi.InjectionPoint;
import org.elasticsearch.util.inject.spi.TypeListenerBinding;

import java.lang.reflect.Field;
import java.util.List;
import java.util.Set;

/**
 * Members injectors by type.
 *
 * @author [email protected] (Jesse Wilson)
 */
class MembersInjectorStore {
  private final InjectorImpl injector;
  private final ImmutableList typeListenerBindings;

  private final FailableCache, MembersInjectorImpl> cache
      = new FailableCache, MembersInjectorImpl>() {
    @Override protected MembersInjectorImpl create(TypeLiteral type, Errors errors)
        throws ErrorsException {
      return createWithListeners(type, errors);
    }
  };

  MembersInjectorStore(InjectorImpl injector,
      List typeListenerBindings) {
    this.injector = injector;
    this.typeListenerBindings = ImmutableList.copyOf(typeListenerBindings);
  }

  /**
   * Returns true if any type listeners are installed. Other code may take shortcuts when there
   * aren't any type listeners.
   */
  public boolean hasTypeListeners() {
    return !typeListenerBindings.isEmpty();
  }

  /**
   * Returns a new complete members injector with injection listeners registered.
   */
  @SuppressWarnings("unchecked") // the MembersInjector type always agrees with the passed type
  public  MembersInjectorImpl get(TypeLiteral key, Errors errors) throws ErrorsException {
    return (MembersInjectorImpl) cache.get(key, errors);
  }

  /**
   * Creates a new members injector and attaches both injection listeners and method aspects.
   */
  private  MembersInjectorImpl createWithListeners(TypeLiteral type, Errors errors)
      throws ErrorsException {
    int numErrorsBefore = errors.size();

    Set injectionPoints;
    try {
      injectionPoints = InjectionPoint.forInstanceMethodsAndFields(type);
    } catch (ConfigurationException e) {
      errors.merge(e.getErrorMessages());
      injectionPoints = e.getPartialValue();
    }
    ImmutableList injectors = getInjectors(injectionPoints, errors);
    errors.throwIfNewErrors(numErrorsBefore);

    EncounterImpl encounter = new EncounterImpl(errors, injector.lookups);
    for (TypeListenerBinding typeListener : typeListenerBindings) {
      if (typeListener.getTypeMatcher().matches(type)) {
        try {
          typeListener.getListener().hear(type, encounter);
        } catch (RuntimeException e) {
          errors.errorNotifyingTypeListener(typeListener, type, e);
        }
      }
    }
    encounter.invalidate();
    errors.throwIfNewErrors(numErrorsBefore);

    return new MembersInjectorImpl(injector, type, encounter, injectors);
  }

  /**
   * Returns the injectors for the specified injection points.
   */
  ImmutableList getInjectors(
      Set injectionPoints, Errors errors) {
    List injectors = Lists.newArrayList();
    for (InjectionPoint injectionPoint : injectionPoints) {
      try {
        Errors errorsForMember = injectionPoint.isOptional()
            ? new Errors(injectionPoint)
            : errors.withSource(injectionPoint);
        SingleMemberInjector injector = injectionPoint.getMember() instanceof Field
            ? new SingleFieldInjector(this.injector, injectionPoint, errorsForMember)
            : new SingleMethodInjector(this.injector, injectionPoint, errorsForMember);
        injectors.add(injector);
      } catch (ErrorsException ignoredForNow) {
        // ignored for now
      }
    }
    return ImmutableList.copyOf(injectors);
  }
}