/*
 * 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 MutableNetwork with user-defined properties. 
A network built by this class will have the following properties by default:

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

MutableNetwork<String, Integer> flightNetwork =
    NetworkBuilder.directed().allowsParallelEdges(true).build();
flightNetwork.addEdge("LAX", "ATL", 3025);
flightNetwork.addEdge("LAX", "ATL", 1598);
flightNetwork.addEdge("ATL", "LAX", 2450);

Author:
James Sexton, Joshua O'Madadhain
Since:
20.0/**
 * A builder for constructing instances of {@link MutableNetwork} with user-defined properties.
 *
 * <p>A network built by this class will have the following properties by default:
 *
 * <ul>
 *   <li>does not allow parallel edges
 *   <li>does not allow self-loops
 *   <li>orders {@link Network#nodes()} and {@link Network#edges()} in the order in which the
 *       elements were added
 * </ul>
 *
 * <p>Example of use:
 *
 * <pre>{@code
 * MutableNetwork<String, Integer> flightNetwork =
 *     NetworkBuilder.directed().allowsParallelEdges(true).build();
 * flightNetwork.addEdge("LAX", "ATL", 3025);
 * flightNetwork.addEdge("LAX", "ATL", 1598);
 * flightNetwork.addEdge("ATL", "LAX", 2450);
 * }</pre>
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @since 20.0
 */
@Beta
public final class NetworkBuilder<N, E> extends AbstractGraphBuilder<N> {
  boolean allowsParallelEdges = false;
  ElementOrder<? super E> edgeOrder = ElementOrder.insertion();
  Optional<Integer> expectedEdgeCount = Optional.absent();

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

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

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

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

  
Specifies whether the network will allow parallel edges. Attempting to add a parallel edge to a network that does not allow them will throw an UnsupportedOperationException. /**
   * Specifies whether the network will allow parallel edges. Attempting to add a parallel edge to a
   * network that does not allow them will throw an {@link UnsupportedOperationException}.
   */
  public NetworkBuilder<N, E> allowsParallelEdges(boolean allowsParallelEdges) {
    this.allowsParallelEdges = allowsParallelEdges;
    return this;
  }

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

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

  
Specifies the expected number of edges in the network.
Throws:
IllegalArgumentException – if expectedEdgeCount is negative/**
   * Specifies the expected number of edges in the network.
   *
   * @throws IllegalArgumentException if {@code expectedEdgeCount} is negative
   */
  public NetworkBuilder<N, E> expectedEdgeCount(int expectedEdgeCount) {
    this.expectedEdgeCount = Optional.of(checkNonNegative(expectedEdgeCount));
    return this;
  }

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

  
Specifies the order of iteration for the elements of Network.edges(). /** Specifies the order of iteration for the elements of {@link Network#edges()}. */
  public <E1 extends E> NetworkBuilder<N, E1> edgeOrder(ElementOrder<E1> edgeOrder) {
    NetworkBuilder<N, E1> newBuilder = cast();
    newBuilder.edgeOrder = checkNotNull(edgeOrder);
    return newBuilder;
  }

  
Returns an empty MutableNetwork with the properties of this NetworkBuilder. /** Returns an empty {@link MutableNetwork} with the properties of this {@link NetworkBuilder}. */
  public <N1 extends N, E1 extends E> MutableNetwork<N1, E1> build() {
    return new ConfigurableMutableNetwork<>(this);
  }

  @SuppressWarnings("unchecked")
  private <N1 extends N, E1 extends E> NetworkBuilder<N1, E1> cast() {
    return (NetworkBuilder<N1, E1>) this;
  }
}