/*
 * 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 com.google.inject.internal;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.inject.Key;
import com.google.inject.MembersInjector;
import com.google.inject.TypeLiteral;
import com.google.inject.internal.ProvisionListenerStackCallback.ProvisionCallback;
import com.google.inject.spi.InjectionListener;
import com.google.inject.spi.InjectionPoint;
import javax.annotation.Nullable;

/**
 * Injects members of instances of a given type.
 *
 * @author jessewilson@google.com (Jesse Wilson)
 */
final class MembersInjectorImpl<T> implements MembersInjector<T> {
  private final TypeLiteral<T> typeLiteral;
  private final InjectorImpl injector;
  // a null list means empty. Since it is common for many of these lists to be empty we can save
  // some memory lookups by representing empty as null.
  @Nullable private final ImmutableList<SingleMemberInjector> memberInjectors;
  @Nullable private final ImmutableList<MembersInjector<? super T>> userMembersInjectors;
  @Nullable private final ImmutableList<InjectionListener<? super T>> injectionListeners;
  @Nullable private final ImmutableList<MethodAspect> addedAspects;

  MembersInjectorImpl(
      InjectorImpl injector,
      TypeLiteral<T> typeLiteral,
      EncounterImpl<T> encounter,
      ImmutableList<SingleMemberInjector> memberInjectors) {
    this.injector = injector;
    this.typeLiteral = typeLiteral;
    this.memberInjectors = memberInjectors.isEmpty() ? null : memberInjectors;
    this.userMembersInjectors =
        encounter.getMembersInjectors().isEmpty() ? null : encounter.getMembersInjectors().asList();
    this.injectionListeners =
        encounter.getInjectionListeners().isEmpty()
            ? null
            : encounter.getInjectionListeners().asList();
    this.addedAspects =
        (InternalFlags.isBytecodeGenEnabled() && !encounter.getAspects().isEmpty())
            ? encounter.getAspects()
            : null;
  }

  public ImmutableList<SingleMemberInjector> getMemberInjectors() {
    return memberInjectors == null ? ImmutableList.<SingleMemberInjector>of() : memberInjectors;
  }

  @Override
  public void injectMembers(T instance) {
    TypeLiteral<T> localTypeLiteral = typeLiteral;
    try {
      injectAndNotify(instance, null, null, localTypeLiteral, false);
    } catch (InternalProvisionException ipe) {
      throw ipe.addSource(localTypeLiteral).toProvisionException();
    }
  }

  void injectAndNotify(
      final T instance,
      final Key<T> key, // possibly null!
      final ProvisionListenerStackCallback<T> provisionCallback, // possibly null!
      final Object source,
      final boolean toolableOnly)
      throws InternalProvisionException {
    if (instance == null) {
      return;
    }
    final InternalContext context = injector.enterContext();
    try {
      if (provisionCallback != null && provisionCallback.hasListeners()) {
        provisionCallback.provision(
            context,
            new ProvisionCallback<T>() {
              @Override
              public T call() throws InternalProvisionException {
                injectMembers(instance, context, toolableOnly);
                return instance;
              }
            });
      } else {
        injectMembers(instance, context, toolableOnly);
      }
    } finally {
      context.close();
    }

    // TODO: We *could* notify listeners too here,
    // but it's not clear if we want to.  There's no way to know
    // if a MembersInjector from the usersMemberInjector list wants
    // toolable injections, so do we really want to notify
    // about injection?  (We could take a strategy of only notifying
    // if atleast one InjectionPoint was toolable, in which case
    // the above callInContext could return 'true' if it injected
    // anything.)
    if (!toolableOnly) {
      notifyListeners(instance);
    }
  }

  void notifyListeners(T instance) throws InternalProvisionException {
    ImmutableList<InjectionListener<? super T>> localInjectionListeners = injectionListeners;
    if (localInjectionListeners == null) {
      // no listeners
      return;
    }
    // optimization: use manual for/each to save allocating an iterator here
    for (int i = 0; i < localInjectionListeners.size(); i++) {
      InjectionListener<? super T> injectionListener = localInjectionListeners.get(i);
      try {
        injectionListener.afterInjection(instance);
      } catch (RuntimeException e) {
        throw InternalProvisionException.errorNotifyingInjectionListener(
            injectionListener, typeLiteral, e);
      }
    }
  }

  void injectMembers(T t, InternalContext context, boolean toolableOnly)
      throws InternalProvisionException {
    ImmutableList<SingleMemberInjector> localMembersInjectors = memberInjectors;
    if (localMembersInjectors != null) {
      // optimization: use manual for/each to save allocating an iterator here
      for (int i = 0, size = localMembersInjectors.size(); i < size; i++) {
        SingleMemberInjector injector = localMembersInjectors.get(i);
        if (!toolableOnly || injector.getInjectionPoint().isToolable()) {
          injector.inject(context, t);
        }
      }
    }

    // TODO: There's no way to know if a user's MembersInjector wants toolable injections.
    if (!toolableOnly) {
      ImmutableList<MembersInjector<? super T>> localUsersMembersInjectors = userMembersInjectors;
      if (localUsersMembersInjectors != null) {
        // optimization: use manual for/each to save allocating an iterator here
        for (int i = 0; i < localUsersMembersInjectors.size(); i++) {
          MembersInjector<? super T> userMembersInjector = localUsersMembersInjectors.get(i);
          try {
            userMembersInjector.injectMembers(t);
          } catch (RuntimeException e) {
            throw InternalProvisionException.errorInUserInjector(
                userMembersInjector, typeLiteral, e);
          }
        }
      }
    }
  }

  @Override
  public String toString() {
    return "MembersInjector<" + typeLiteral + ">";
  }

  public ImmutableSet<InjectionPoint> getInjectionPoints() {
    ImmutableList<SingleMemberInjector> localMemberInjectors = memberInjectors;
    if (localMemberInjectors != null) {
      ImmutableSet.Builder<InjectionPoint> builder = ImmutableSet.builder();
      for (SingleMemberInjector memberInjector : localMemberInjectors) {
        builder.add(memberInjector.getInjectionPoint());
      }
      return builder.build();
    }
    return ImmutableSet.of();
  }

  public ImmutableList<MethodAspect> getAddedAspects() {
    return addedAspects == null ? ImmutableList.<MethodAspect>of() : addedAspects;
  }
}
