/*
 * Copyright (C) 2016 The Guava Authors
 *
 * 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.common.graph;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.graph.Graphs.checkNonNegative;

import com.google.common.annotations.Beta;
import com.google.common.base.Optional;

A builder for constructing instances of MutableGraph with user-defined properties. 
A graph built by this class will have the following properties by default:

  
does not allow self-loops
  
orders Graph.nodes() in the order in which the elements were added 
Example of use:

MutableGraph<String> graph = GraphBuilder.undirected().allowsSelfLoops(true).build();
graph.putEdge("bread", "bread");
graph.putEdge("chocolate", "peanut butter");
graph.putEdge("peanut butter", "jelly");

Author:
James Sexton, Joshua O'Madadhain
Since:
20.0/**
 * A builder for constructing instances of {@link MutableGraph} with user-defined properties.
 *
 * <p>A graph built by this class will have the following properties by default:
 *
 * <ul>
 *   <li>does not allow self-loops
 *   <li>orders {@link Graph#nodes()} in the order in which the elements were added
 * </ul>
 *
 * <p>Example of use:
 *
 * <pre>{@code
 * MutableGraph<String> graph = GraphBuilder.undirected().allowsSelfLoops(true).build();
 * graph.putEdge("bread", "bread");
 * graph.putEdge("chocolate", "peanut butter");
 * graph.putEdge("peanut butter", "jelly");
 * }</pre>
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @since 20.0
 */
@Beta
public final class GraphBuilder<N> extends AbstractGraphBuilder<N> {

  
Creates a new instance with the specified edge directionality. /** Creates a new instance with the specified edge directionality. */
  private GraphBuilder(boolean directed) {
    super(directed);
  }

  
Returns a GraphBuilder for building directed graphs. /** Returns a {@link GraphBuilder} for building directed graphs. */
  public static GraphBuilder<Object> directed() {
    return new GraphBuilder<>(true);
  }

  
Returns a GraphBuilder for building undirected graphs. /** Returns a {@link GraphBuilder} for building undirected graphs. */
  public static GraphBuilder<Object> undirected() {
    return new GraphBuilder<>(false);
  }

  
Returns a GraphBuilder initialized with all properties queryable from graph. 
The "queryable" properties are those that are exposed through the Graph interface, such as Graph.isDirected(). Other properties, such as expectedNodeCount(int), are not set in the new builder. /**
   * Returns a {@link GraphBuilder} initialized with all properties queryable from {@code graph}.
   *
   * <p>The "queryable" properties are those that are exposed through the {@link Graph} interface,
   * such as {@link Graph#isDirected()}. Other properties, such as {@link #expectedNodeCount(int)},
   * are not set in the new builder.
   */
  public static <N> GraphBuilder<N> from(Graph<N> graph) {
    return new GraphBuilder<N>(graph.isDirected())
        .allowsSelfLoops(graph.allowsSelfLoops())
        .nodeOrder(graph.nodeOrder());
  }

  
Specifies whether the graph will allow self-loops (edges that connect a node to itself). Attempting to add a self-loop to a graph that does not allow them will throw an UnsupportedOperationException. /**
   * Specifies whether the graph will allow self-loops (edges that connect a node to itself).
   * Attempting to add a self-loop to a graph that does not allow them will throw an {@link
   * UnsupportedOperationException}.
   */
  public GraphBuilder<N> allowsSelfLoops(boolean allowsSelfLoops) {
    this.allowsSelfLoops = allowsSelfLoops;
    return this;
  }

  
Specifies the expected number of nodes in the graph.
Throws:
IllegalArgumentException – if expectedNodeCount is negative/**
   * Specifies the expected number of nodes in the graph.
   *
   * @throws IllegalArgumentException if {@code expectedNodeCount} is negative
   */
  public GraphBuilder<N> expectedNodeCount(int expectedNodeCount) {
    this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount));
    return this;
  }

  
Specifies the order of iteration for the elements of Graph.nodes(). /** Specifies the order of iteration for the elements of {@link Graph#nodes()}. */
  public <N1 extends N> GraphBuilder<N1> nodeOrder(ElementOrder<N1> nodeOrder) {
    GraphBuilder<N1> newBuilder = cast();
    newBuilder.nodeOrder = checkNotNull(nodeOrder);
    return newBuilder;
  }

  
Returns an empty MutableGraph with the properties of this GraphBuilder. /** Returns an empty {@link MutableGraph} with the properties of this {@link GraphBuilder}. */
  public <N1 extends N> MutableGraph<N1> build() {
    return new ConfigurableMutableGraph<N1>(this);
  }

  @SuppressWarnings("unchecked")
  private <N1 extends N> GraphBuilder<N1> cast() {
    return (GraphBuilder<N1>) this;
  }
}