import net.datastructures.Edge;
import net.datastructures.InvalidPositionException;
import net.datastructures.Vertex;

/**
 * An interface for a directed graph. modified from net.datastructures.Graph version 4.0
 * @author Roberto Tamassia, morgan wahl
 */
public interface DirectedGraph<V, E> {
	/** Returns the number of vertices of the graph */
	public int numVertices();

	/** Returns the number of edges of the graph */
	public int numEdges();

	/** Returns the vertices of the graph as an iterable collection */
	public Iterable<Vertex<V>> vertices();

	/** Returns the edges of the graph as an iterable collection */
	public Iterable<Edge<E>> edges();

	/** Replaces the element of a given vertex with a new element and
	 returns the old element */
	public V replace(Vertex<V> p, V o) throws InvalidPositionException;

	/** Replaces the element of a given edge with a new element and
	 returns the old element */
	public E replace(Edge<E> p, E o) throws InvalidPositionException;

	/** Returns the incoming edges to a vertex as an iterable collection */
	public Iterable<Edge<E>> incomingEdges(Vertex<V> v)
			throws InvalidPositionException;

	/** Returns the outgoing edges to a vertex as an iterable collection */
	public Iterable<Edge<E>> outgoingEdges(Vertex<V> v)
			throws InvalidPositionException;

	/** Returns the start and end vertices, in that order, of a edge as an array of length 2 */
	public Vertex[] endVertices(Edge<E> e) throws InvalidPositionException;

	/** Returns the other endvertex of an incident edge */
	public Vertex<V> opposite(Vertex<V> v, Edge<E> e)
			throws InvalidPositionException;

	/** Tests whether two vertices are adjacent */
	public boolean areAdjacent(Vertex<V> u, Vertex<V> v)
			throws InvalidPositionException;

	/** Inserts and return a new vertex with a given element */
	public Vertex<V> insertVertex(V o);

	/** Inserts and return a new edge with a given element from one vertex to another */
	public Edge<E> insertEdge(Vertex<V> from, Vertex<V> to, E o)
			throws InvalidPositionException;

	/** Removes a vertex and all its incident edges and returns the
	 element stored at the removed vertex */
	public V removeVertex(Vertex<V> v) throws InvalidPositionException;

	/** Removes an edge and return its element */
	public E removeEdge(Edge<E> e) throws InvalidPositionException;
}