/*
    * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
    *
    * This library is free software; you can redistribute it and/or
    * modify it under the terms of the GNU Lesser General Public
    * License as published by the Free Software Foundation; either
    * version 2.1 of the License, or (at your option) any later version.
    *
    * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
   *
   * Additionally licensed with:
   *
   * 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.spf4j.reflect;
  
  import com.google.common.graph.GraphBuilder;
  import com.google.common.graph.MutableGraph;
  import com.google.common.reflect.TypeToken;
  import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  import java.lang.reflect.Type;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import org.spf4j.ds.Graphs;
  
  /**
   * @author Zoltan Farkas
   */
  public final class GraphTypeMap<H> implements TypeMap<H> {
  
    private final MutableGraph<TypeToken> typeGraph;
  
    private final Map<TypeToken, H> handlers;
  
    public GraphTypeMap() {
      this(16);
    }
  
    public GraphTypeMap(final int expectedSize) {
      typeGraph = GraphBuilder.directed().allowsSelfLoops(false)
              .expectedNodeCount(expectedSize).build();
      handlers = new HashMap<>(expectedSize);
    }
  
    @Override
    public Set<H> getAll(final Type t) {
      Set<H> result = new HashSet<>(1);
      TypeToken tt = TypeToken.of(t);
      MutableGraph<TypeToken> traverseGraph = Graphs.clone(typeGraph);
      Set<TypeToken> nodes = traverseGraph.nodes();
      List<TypeToken> nodesToRemove = new ArrayList<>();
      do {
        for (TypeToken token : nodes) {
          if (traverseGraph.inDegree(token) == 0) {
            nodesToRemove.add(token);
            if (tt.isSubtypeOf(token)) {
              result.add(handlers.get(token));
            }
          }
        }
        for (TypeToken token : nodesToRemove) {
          if (!traverseGraph.removeNode(token)) {
            throw new IllegalStateException("Cannot remove " + token + " from " + traverseGraph);
          }
        }
        nodesToRemove.clear();
        nodes = traverseGraph.nodes();
      } while (result.isEmpty() && !nodes.isEmpty());
      return result;
    }
  
  
    @Override
    @SuppressFBWarnings("RV_RETURN_VALUE_IGNORED")
    public boolean putIfNotPresent(final Type type, final H value) {
      TypeToken<?> nType = TypeToken.of(type);
      if (typeGraph.addNode(nType)) {
        handlers.put(nType, value);
       for (TypeToken t : typeGraph.nodes()) {
         if (!nType.equals(t)) {
           if (nType.isSubtypeOf(t)) {
             typeGraph.putEdge(nType, t);
           } else if (t.isSubtypeOf(nType)) {
             typeGraph.putEdge(t, nType);
           }
         }
       }
       return true;
     } else {
       return false;
     }
   }
 
   @Override
   public boolean remove(final Type type) {
     TypeToken<?> tt = TypeToken.of(type);
     if (typeGraph.removeNode(tt)) {
       handlers.remove(tt);
       return true;
     } else {
       return false;
     }
   }
 
   @Override
   public String toString() {
     return "GraphTypeMap{" + "typeGraph=" + typeGraph + ", handlers=" + handlers + '}';
   }
 
   @Override
   public H getExact(final Type t) {
     return handlers.get(TypeToken.of(t));
   }
 
 }