/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.apache.maven.di.impl;
  
  import java.util.Collection;
  import java.util.List;
  import java.util.Set;
  import java.util.function.Consumer;
  import java.util.function.Function;
  import java.util.function.Supplier;
  
  import org.apache.maven.di.Key;
  
  import static java.util.stream.Collectors.toSet;
  
  public abstract class BindingInitializer<T> {
  
      private final Set<Key<?>> dependencies;
  
      protected BindingInitializer(Set<Key<?>> dependencies) {
          this.dependencies = dependencies;
      }
  
      public Set<Key<?>> getDependencies() {
          return dependencies;
      }
  
      public abstract Consumer<T> compile(Function<Key<?>, Supplier<?>> compiler);
  
      public static <T> BindingInitializer<T> combine(List<BindingInitializer<T>> bindingInitializers) {
          Set<Key<?>> deps = bindingInitializers.stream()
                  .map(BindingInitializer::getDependencies)
                  .flatMap(Collection::stream)
                  .collect(toSet());
          return new BindingInitializer<T>(deps) {
              @Override
              public Consumer<T> compile(Function<Key<?>, Supplier<?>> compiler) {
                  return instance -> bindingInitializers.stream()
                          .map(bindingInitializer -> bindingInitializer.compile(compiler))
                          .forEach(i -> i.accept(instance));
              }
          };
      }
  }