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/**
 * Copyright (C) 2008 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.inject.Binder;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.Provides;
import com.google.inject.TypeLiteral;
import static com.google.inject.internal.Preconditions.checkNotNull;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.Message;
import com.google.inject.util.Modules;
import java.lang.annotation.Annotation;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.util.List;

/**
 * Creates bindings to methods annotated with {@literal @}{@link Provides}. Use the scope and
 * binding annotations on the provider method to configure the binding.
 *
 * @author [email protected] (Bob Lee)
 * @author [email protected] (Jesse Wilson)
 */
public final class ProviderMethodsModule implements Module {
  private final Object delegate;
  private final TypeLiteral typeLiteral;

  private ProviderMethodsModule(Object delegate) {
    this.delegate = checkNotNull(delegate, "delegate");
    this.typeLiteral = TypeLiteral.get(this.delegate.getClass());
  }

  /**
   * Returns a module which creates bindings for provider methods from the given module.
   */
  public static Module forModule(Module module) {
    return forObject(module);
  }

  /**
   * Returns a module which creates bindings for provider methods from the given object.
   * This is useful notably for GIN
   */
  public static Module forObject(Object object) {
    // avoid infinite recursion, since installing a module always installs itself
    if (object instanceof ProviderMethodsModule) {
      return Modules.EMPTY_MODULE;
    }

    return new ProviderMethodsModule(object);
  }
  public synchronized void configure(Binder binder) {
    for (ProviderMethod providerMethod : getProviderMethods(binder)) {
      providerMethod.configure(binder);
    }
  }

  public List> getProviderMethods(Binder binder) {
    List> result = Lists.newArrayList();
    for (Class c = delegate.getClass(); c != Object.class; c = c.getSuperclass()) {
      for (Method method : c.getDeclaredMethods()) {
        if (method.isAnnotationPresent(Provides.class)) {
          result.add(createProviderMethod(binder, method));
        }
      }
    }
    return result;
  }

   ProviderMethod createProviderMethod(Binder binder, final Method method) {
    binder = binder.withSource(method);
    Errors errors = new Errors(method);

    // prepare the parameter providers
    List> dependencies = Lists.newArrayList();
    List> parameterProviders = Lists.newArrayList();
    List> parameterTypes = typeLiteral.getParameterTypes(method);
    Annotation[][] parameterAnnotations = method.getParameterAnnotations();
    for (int i = 0; i < parameterTypes.size(); i++) {
      Key key = getKey(errors, parameterTypes.get(i), method, parameterAnnotations[i]);
      dependencies.add(Dependency.get(key));
      parameterProviders.add(binder.getProvider(key));
    }

    @SuppressWarnings("unchecked") // Define T as the method's return type.
    TypeLiteral returnType = (TypeLiteral) typeLiteral.getReturnType(method);

    Key key = getKey(errors, returnType, method, method.getAnnotations());
    Class scopeAnnotation
        = Annotations.findScopeAnnotation(errors, method.getAnnotations());

    for (Message message : errors.getMessages()) {
      binder.addError(message);
    }

    return new ProviderMethod(key, method, delegate, ImmutableSet.copyOf(dependencies),
        parameterProviders, scopeAnnotation);
  }

   Key getKey(Errors errors, TypeLiteral type, Member member, Annotation[] annotations) {
    Annotation bindingAnnotation = Annotations.findBindingAnnotation(errors, member, annotations);
    return bindingAnnotation == null ? Key.get(type) : Key.get(type, bindingAnnotation);
  }

  @Override public boolean equals(Object o) {
    return o instanceof ProviderMethodsModule
        && ((ProviderMethodsModule) o).delegate == delegate;
  }

  @Override public int hashCode() {
    return delegate.hashCode();
  }
}