package com.example.portfolio3;

// origin: <https://moodle.ruc.dk/course/section.php?id=211877>

import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/// Adjecency List Graph - A map from vertices to set of outedges from the vertex
public class AdjListGraph extends AbstractGraph {

	/// foo
	public AdjListGraph() { }

	/// foo
	private Map<Vertex,Set<Edge>> outEdge = new HashMap<>();

	/// foo
	public void insertEdge(final Vertex v1, final Vertex v2, final int w) {
		Edge e = new Edge(v1, v2, w);
		if (!outEdge.containsKey(e.from()))
			outEdge.put(e.from(), new HashSet<Edge>());
		outEdge.get(e.from()).add(e);
	}

	/// foo
	public Collection<Edge> edges() {
		Set<Edge> edges = new HashSet<>();
		for (Vertex v: outEdge.keySet())edges.addAll(outEdge.get(v));

		return edges;
	}

	/// foo
	public Collection<Edge> outEdge(final Vertex v) {
		if (!outEdge.containsKey(v))
			return new HashSet<Edge>();

		return outEdge.get(v);
	}

	/// foo
	public Integer getWeight(final Vertex v1, final Vertex v2) {

		// linear in number of outedges from vertices
		if (!outEdge.containsKey(v1))
			return null;
		for (Edge e: outEdge.get(v1)) {
			if (e.to() == v2)
				return e.weight();
		}

		return null;
	}
}