using Annulus.CSG;

namespace Annulus.UnitTests.CSG
{
    public class DisjointSetsTests : UnitTestSharp.TestFixture
    {
        public class FindTests : UnitTestSharp.TestFixture
        {
            public void IndicesNeverMerged_AreTheirOwnSets()
            {
                DisjointSets sets = new DisjointSets(3);

                CheckEqual(0, sets.Find(0));
                CheckEqual(1, sets.Find(1));
                CheckEqual(2, sets.Find(2));
            }

            public void MergedIndices_ShareARepresentative()
            {
                DisjointSets sets = new DisjointSets(4);
                sets.Union(1, 3);

                CheckEqual(sets.Find(1), sets.Find(3));
                CheckFalse(sets.Find(1) == sets.Find(0));
            }

            public void LongChainOfMerges_JoinsEveryMember()
            {
                DisjointSets sets = new DisjointSets(6);
                for (int i = 0; i < 5; ++i)
                {
                    sets.Union(i, i + 1);
                }

                for (int i = 1; i < 6; ++i)
                {
                    CheckEqual(sets.Find(0), sets.Find(i));
                }
            }
        }

        public class UnionTests : UnitTestSharp.TestFixture
        {
            public void MergingTwoSetsTwice_ChangesNothing()
            {
                DisjointSets sets = new DisjointSets(3);
                sets.Union(0, 2);
                int representative = sets.Find(0);

                sets.Union(2, 0);

                CheckEqual(representative, sets.Find(2));
                CheckFalse(sets.Find(1) == representative);
            }

            public void MergingAnIndexWithItself_ChangesNothing()
            {
                DisjointSets sets = new DisjointSets(2);

                sets.Union(1, 1);

                CheckEqual(1, sets.Find(1));
                CheckEqual(0, sets.Find(0));
            }

            public void MergingMembersOfTwoSets_JoinsTheWholeSets()
            {
                DisjointSets sets = new DisjointSets(4);
                sets.Union(0, 1);
                sets.Union(2, 3);

                sets.Union(1, 2);

                CheckEqual(sets.Find(0), sets.Find(3));
            }
        }
    }
}