package org.psjava;

import org.psjava.util.Assertion;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.HashSet;

import java.util.List;

import java.util.Set;

public class BipartiteGraph<V> {

private Set<V> lefts = new HashSet<>();

private Set<V> rights = new HashSet<>();

private List<BipartiteGraphEdge<V>> edges = new ArrayList<>();

public void addLeft(V v) {

Assertion.ensure(!rights.contains(v), () -> "already in right side. vertex=" + v);

lefts.add(v);

}

public void addRight(V v) {

Assertion.ensure(!lefts.contains(v), () -> "already in left size. vertex=" + v);

rights.add(v);

}

public void addEdge(final V left, final V right) {

assertVertexExist(left, lefts);

assertVertexExist(right, rights);

edges.add(new BipartiteGraphEdge<>(left, right));

}

private void assertVertexExist(V v, Set<V> set) {

Assertion.ensure(set.contains(v), () -> "vertex is not in graph. vertex=" + v);

}

Collection<V> getLeftVertices() {

return Collections.unmodifiableCollection(lefts);

}

Collection<V> getRightVertices() {

return Collections.unmodifiableCollection(rights);

}

Collection<BipartiteGraphEdge<V>> getEdges() {

return Collections.unmodifiableCollection(edges);

}

}