/*
 * 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.checkArgument;
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 MutableValueGraph or ImmutableValueGraph 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 
Examples of use:

// Building a mutable value graph
MutableValueGraph<String, Double> graph =
    ValueGraphBuilder.undirected().allowsSelfLoops(true).build();
graph.putEdgeValue("San Francisco", "San Francisco", 0.0);
graph.putEdgeValue("San Jose", "San Jose", 0.0);
graph.putEdgeValue("San Francisco", "San Jose", 48.4);
// Building an immutable value graph
ImmutableValueGraph<String, Double> immutableGraph =
    ValueGraphBuilder.undirected()
        .allowsSelfLoops(true)
        .<String, Double>immutable()
        .putEdgeValue("San Francisco", "San Francisco", 0.0)
        .putEdgeValue("San Jose", "San Jose", 0.0)
        .putEdgeValue("San Francisco", "San Jose", 48.4)
        .build();

Author:
James Sexton, Joshua O'Madadhain
Type parameters:
<N> – The most general node type this builder will support. This is normally Object unless it is constrained by using a method like AbstractGraphBuilder<N>.nodeOrder, or the builder is constructed based on an existing ValueGraph using from(ValueGraph<Object,Object>).
<V> – The most general value type this builder will support. This is normally Object unless the builder is constructed based on an existing Graph using from(ValueGraph<Object,Object>).
Since:
20.0/**
 * A builder for constructing instances of {@link MutableValueGraph} or {@link ImmutableValueGraph}
 * 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>Examples of use:
 *
 * <pre>{@code
 * // Building a mutable value graph
 * MutableValueGraph<String, Double> graph =
 *     ValueGraphBuilder.undirected().allowsSelfLoops(true).build();
 * graph.putEdgeValue("San Francisco", "San Francisco", 0.0);
 * graph.putEdgeValue("San Jose", "San Jose", 0.0);
 * graph.putEdgeValue("San Francisco", "San Jose", 48.4);
 *
 * // Building an immutable value graph
 * ImmutableValueGraph<String, Double> immutableGraph =
 *     ValueGraphBuilder.undirected()
 *         .allowsSelfLoops(true)
 *         .<String, Double>immutable()
 *         .putEdgeValue("San Francisco", "San Francisco", 0.0)
 *         .putEdgeValue("San Jose", "San Jose", 0.0)
 *         .putEdgeValue("San Francisco", "San Jose", 48.4)
 *         .build();
 * }</pre>
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @param <N> The most general node type this builder will support. This is normally {@code Object}
 *     unless it is constrained by using a method like {@link #nodeOrder}, or the builder is
 *     constructed based on an existing {@code ValueGraph} using {@link #from(ValueGraph)}.
 * @param <V> The most general value type this builder will support. This is normally {@code Object}
 *     unless the builder is constructed based on an existing {@code Graph} using {@link
 *     #from(ValueGraph)}.
 * @since 20.0
 */
@Beta
public final class ValueGraphBuilder<N, V> extends AbstractGraphBuilder<N> {

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

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

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

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

  
Returns an Builder with the properties of this ValueGraphBuilder. 
The returned builder can be used for populating an ImmutableValueGraph. 
Note that the returned builder will always have AbstractGraphBuilder<N>.incidentEdgeOrder set to ElementOrder.stable(), regardless of the value that was set in this builder. 
Since:
28.0/**
   * Returns an {@link ImmutableValueGraph.Builder} with the properties of this {@link
   * ValueGraphBuilder}.
   *
   * <p>The returned builder can be used for populating an {@link ImmutableValueGraph}.
   *
   * <p>Note that the returned builder will always have {@link #incidentEdgeOrder} set to {@link
   * ElementOrder#stable()}, regardless of the value that was set in this builder.
   *
   * @since 28.0
   */
  public <N1 extends N, V1 extends V> ImmutableValueGraph.Builder<N1, V1> immutable() {
    ValueGraphBuilder<N1, V1> castBuilder = cast();
    return new ImmutableValueGraph.Builder<>(castBuilder);
  }

  
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. 
The default value is false. /**
   * 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}.
   *
   * <p>The default value is {@code false}.
   */
  public ValueGraphBuilder<N, V> 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 ValueGraphBuilder<N, V> expectedNodeCount(int expectedNodeCount) {
    this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount));
    return this;
  }

  
Specifies the order of iteration for the elements of Graph.nodes(). 
The default value is insertion order. /**
   * Specifies the order of iteration for the elements of {@link Graph#nodes()}.
   *
   * <p>The default value is {@link ElementOrder#insertion() insertion order}.
   */
  public <N1 extends N> ValueGraphBuilder<N1, V> nodeOrder(ElementOrder<N1> nodeOrder) {
    ValueGraphBuilder<N1, V> newBuilder = cast();
    newBuilder.nodeOrder = checkNotNull(nodeOrder);
    return newBuilder;
  }

  
Specifies the order of iteration for the elements of ValueGraph.edges(), ValueGraph.adjacentNodes(Object), ValueGraph.predecessors(Object), ValueGraph.successors(Object) and ValueGraph.incidentEdges(Object). 
The default value is unordered for mutable graphs. For immutable graphs, this value is ignored; they always have a 
stable order. 
Throws:
IllegalArgumentException – if incidentEdgeOrder is not either 
    ElementOrder.unordered() or ElementOrder.stable().
Since:
29.0/**
   * Specifies the order of iteration for the elements of {@link ValueGraph#edges()}, {@link
   * ValueGraph#adjacentNodes(Object)}, {@link ValueGraph#predecessors(Object)}, {@link
   * ValueGraph#successors(Object)} and {@link ValueGraph#incidentEdges(Object)}.
   *
   * <p>The default value is {@link ElementOrder#unordered() unordered} for mutable graphs. For
   * immutable graphs, this value is ignored; they always have a {@link ElementOrder#stable()
   * stable} order.
   *
   * @throws IllegalArgumentException if {@code incidentEdgeOrder} is not either {@code
   *     ElementOrder.unordered()} or {@code ElementOrder.stable()}.
   * @since 29.0
   */
  public <N1 extends N> ValueGraphBuilder<N1, V> incidentEdgeOrder(
      ElementOrder<N1> incidentEdgeOrder) {
    checkArgument(
        incidentEdgeOrder.type() == ElementOrder.Type.UNORDERED
            || incidentEdgeOrder.type() == ElementOrder.Type.STABLE,
        "The given elementOrder (%s) is unsupported. incidentEdgeOrder() only supports"
            + " ElementOrder.unordered() and ElementOrder.stable().",
        incidentEdgeOrder);
    ValueGraphBuilder<N1, V> newBuilder = cast();
    newBuilder.incidentEdgeOrder = checkNotNull(incidentEdgeOrder);
    return newBuilder;
  }
  
Returns an empty MutableValueGraph with the properties of this ValueGraphBuilder. /**
   * Returns an empty {@link MutableValueGraph} with the properties of this {@link
   * ValueGraphBuilder}.
   */
  public <N1 extends N, V1 extends V> MutableValueGraph<N1, V1> build() {
    return new StandardMutableValueGraph<>(this);
  }

  ValueGraphBuilder<N, V> copy() {
    ValueGraphBuilder<N, V> newBuilder = new ValueGraphBuilder<>(directed);
    newBuilder.allowsSelfLoops = allowsSelfLoops;
    newBuilder.nodeOrder = nodeOrder;
    newBuilder.expectedNodeCount = expectedNodeCount;
    newBuilder.incidentEdgeOrder = incidentEdgeOrder;
    return newBuilder;
  }

  @SuppressWarnings("unchecked")
  private <N1 extends N, V1 extends V> ValueGraphBuilder<N1, V1> cast() {
    return (ValueGraphBuilder<N1, V1>) this;
  }
}