/*
    * 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.execution.scope.internal;
  
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.IdentityHashMap;
  import java.util.LinkedList;
  import java.util.Map;
  
  import com.google.inject.Key;
  import com.google.inject.OutOfScopeException;
  import com.google.inject.Provider;
  import com.google.inject.Scope;
  import com.google.inject.util.Providers;
  import org.apache.maven.execution.MojoExecutionEvent;
  import org.apache.maven.execution.MojoExecutionListener;
  import org.apache.maven.execution.scope.WeakMojoExecutionListener;
  import org.apache.maven.plugin.MojoExecutionException;
  
  /**
   * MojoExecutionScope
   */
  public class MojoExecutionScope implements Scope, MojoExecutionListener {
      private static final Provider<Object> SEEDED_KEY_PROVIDER = new Provider<Object>() {
          public Object get() {
              throw new IllegalStateException();
          }
      };
  
      private static final class ScopeState {
          private final Map<Key<?>, Provider<?>> seeded = new HashMap<>();
  
          private final Map<Key<?>, Object> provided = new HashMap<>();
      }
  
      private final ThreadLocal<LinkedList<ScopeState>> values = new ThreadLocal<>();
  
      public MojoExecutionScope() {}
  
      public void enter() {
          LinkedList<ScopeState> stack = values.get();
          if (stack == null) {
              stack = new LinkedList<>();
              values.set(stack);
          }
          stack.addFirst(new ScopeState());
      }
  
      private ScopeState getScopeState() {
          LinkedList<ScopeState> stack = values.get();
          if (stack == null || stack.isEmpty()) {
              throw new IllegalStateException();
          }
          return stack.getFirst();
      }
  
      public void exit() throws MojoExecutionException {
          final LinkedList<ScopeState> stack = values.get();
          if (stack == null || stack.isEmpty()) {
              throw new IllegalStateException();
          }
          stack.removeFirst();
          if (stack.isEmpty()) {
              values.remove();
          }
      }
  
      public <T> void seed(Class<T> clazz, Provider<T> value) {
          getScopeState().seeded.put(Key.get(clazz), value);
      }
  
      public <T> void seed(Class<T> clazz, final T value) {
          getScopeState().seeded.put(Key.get(clazz), Providers.of(value));
      }
  
      public <T> Provider<T> scope(final Key<T> key, final Provider<T> unscoped) {
          return new Provider<T>() {
              @SuppressWarnings("unchecked")
              public T get() {
                  LinkedList<ScopeState> stack = values.get();
                  if (stack == null || stack.isEmpty()) {
                      throw new OutOfScopeException("Cannot access " + key + " outside of a scoping block");
                 }
 
                 ScopeState state = stack.getFirst();
 
                 Provider<?> seeded = state.seeded.get(key);
 
                 if (seeded != null) {
                     return (T) seeded.get();
                 }
 
                 T provided = (T) state.provided.get(key);
                 if (provided == null && unscoped != null) {
                     provided = unscoped.get();
                     state.provided.put(key, provided);
                 }
 
                 return provided;
             }
         };
     }
 
     @SuppressWarnings({"unchecked"})
     public static <T> Provider<T> seededKeyProvider() {
         return (Provider<T>) SEEDED_KEY_PROVIDER;
     }
 
     public void beforeMojoExecution(MojoExecutionEvent event) throws MojoExecutionException {
         for (WeakMojoExecutionListener provided : getProvidedListeners()) {
             provided.beforeMojoExecution(event);
         }
     }
 
     public void afterMojoExecutionSuccess(MojoExecutionEvent event) throws MojoExecutionException {
         for (WeakMojoExecutionListener provided : getProvidedListeners()) {
             provided.afterMojoExecutionSuccess(event);
         }
     }
 
     public void afterExecutionFailure(MojoExecutionEvent event) {
         for (WeakMojoExecutionListener provided : getProvidedListeners()) {
             provided.afterExecutionFailure(event);
         }
     }
 
     private Collection<WeakMojoExecutionListener> getProvidedListeners() {
         // the same instance can be provided multiple times under different Key's
         // deduplicate instances to avoid redundant beforeXXX/afterXXX callbacks
         IdentityHashMap<WeakMojoExecutionListener, Object> listeners = new IdentityHashMap<>();
         for (Object provided : getScopeState().provided.values()) {
             if (provided instanceof WeakMojoExecutionListener) {
                 listeners.put((WeakMojoExecutionListener) provided, null);
             }
         }
         return listeners.keySet();
     }
 }