package it.univr.di.cstnu.util;

import it.unimi.dsi.fastutil.objects.Object2IntMap;
import it.unimi.dsi.fastutil.objects.ObjectSet;
import it.univr.di.cstnu.graph.LabeledNode;

import javax.annotation.Nonnull;

/**
 * This interface defines the methods for managing distances between nodes in a graph. It is designed to represent all-pairs-shortest-paths distances.
 */
@SuppressWarnings("InterfaceWithOnlyOneDirectInheritor")
public interface GraphDistances {
	/**
	 * @param source      the source node
	 * @param destination the destination node
	 *
	 * @return the distance between a source node and the destination one if a finite distance exists, +∞ otherwise
	 */
	int getDistance(@Nonnull LabeledNode source, @Nonnull LabeledNode destination);

	/**
	 * @return the source nodes present in the matrix, if any, an empty list otherwise.
	 */
	ObjectSet<LabeledNode> getNodes();

	/**
	 * @param node the node
	 *
	 * @return the map (node, distance) of nodes reachable from 'node' if there are any, an empty set otherwise.
	 */
	Object2IntMap<LabeledNode> getReachable(@Nonnull LabeledNode node);

	/**
	 * Sets the new distance between a source node and the destination node.
	 *
	 * @param source      the source node.
	 * @param destination the destination node.
	 * @param distance    the new distance between source and destination.
	 */
	void putDistance(@Nonnull LabeledNode source, @Nonnull LabeledNode destination, int distance);

	/**
	 * Sets the new distance between a source node and all destination nodes in destinations. All previous nodes reachable by the source are removed.
	 *
	 * @param source       the source node.
	 * @param destinations a map of all (reachable destination, distance) from the source node.
	 */
	void putDistances(@Nonnull LabeledNode source, @Nonnull Object2IntMap<LabeledNode> destinations);

	/**
	 * Remove the distance between source node and destination one.
	 *
	 * @param source      the source node
	 * @param destination the destination node
	 */
	void removeDistance(@Nonnull LabeledNode source, @Nonnull LabeledNode destination);
}