// Copyright 2003, Trustees of Indiana University
// Please see the license in the file ../LICENSE

using GCollections;

public class adj_list_edge<Vertex>: GraphEdge<Vertex> {
  private Vertex source_, target_;

  public adj_list_edge(Vertex s, Vertex t) {
    source_ = s;
    target_ = t;
  }

  public Vertex source {get {return source_;}}
  public Vertex target {get {return target_;}}

  public override string ToString() {
    return "edge(" + source_ + " -> " + target_ + ")";
  }

  public override int GetHashCode() {
    return source_.GetHashCode() + target_.GetHashCode();
  }

  public override bool Equals(object o) {
    adj_list_edge<Vertex> oo = (adj_list_edge<Vertex>)(o);
    if (oo == null) return false;
    return (source_.Equals(oo.source) && target_.Equals(oo.target));
  }
}

public class adjacency_list
  : VertexListAndIncidenceAndEdgeListGraph<
    int,
    adj_list_edge<int>,
    IEnumerable<int>,
    IEnumerable<adj_list_edge<int> >,
    IEnumerable<adj_list_edge<int> > > {

  public adjacency_list() {
    vertices_ = new ArrayList<int>();
    edges_ = new HashMap<int, ArrayList<adj_list_edge<int> > >();
    all_edges_ = new ArrayList<adj_list_edge<int> >();
  }

  private ArrayList<int> vertices_;
  public IEnumerable<int> vertices() {
    return vertices_;
  }
  public int num_vertices() {
    return vertices_.Count;
  }

  private HashMap<int, ArrayList<adj_list_edge<int> > > edges_;
  private ArrayList<adj_list_edge<int> > all_edges_;

  public IEnumerable<adj_list_edge<int> > out_edges(int v) {
    return edges_[v];
  }

  public int out_degree(int v) {
    return edges_[v].Count;
  }

  public void add_vertex(int v) {
    vertices_.AddLast(v);
    edges_[v] = new ArrayList<adj_list_edge<int> >();
  }

  public void add_edge(int u, int v) {
    adj_list_edge<int> edge = new adj_list_edge<int>(u,v);
    edges_[u].AddLast(edge);
    all_edges_.AddLast(edge);
  }

  public IEnumerable<adj_list_edge<int> > edges() {
    return all_edges_;
  }
}