using System;
using UnitTestSharp;

namespace Konis.UnitTests
{
    public class ParticleStoreTests : TestFixture
    {
        private static Particle Aged(float age)
        {
            return new Particle { Age = age };
        }

        public class CtorTests : TestFixture
        {
            public void StartsEmptyAtTheCapacityGiven()
            {
                var store = new ParticleStore(capacity: 5, columnCount: 0);

                CheckEqual(0, store.Count);
                CheckEqual(5, store.Capacity);
                CheckEqual(5, store.Items.Length);
            }

            public void MakesEachColumnAsLongAsTheCapacity()
            {
                var store = new ParticleStore(capacity: 5, columnCount: 2);

                CheckEqual(2, store.Columns.Length);
                CheckEqual(5, store.Columns[0].Length);
                CheckEqual(5, store.Columns[1].Length);
            }

            public void ACapacityOfZero_IsAllowed()
            {
                CheckEqual(0, new ParticleStore(capacity: 0, columnCount: 1).Capacity);
            }

            public void ANegativeCapacity_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new ParticleStore(capacity: -1, columnCount: 0);
            }

            public void ANegativeColumnCount_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new ParticleStore(capacity: 1, columnCount: -1);
            }
        }

        public class AddTests : TestFixture
        {
            public void ReturnsTheNextIndexAndKeepsTheParticle()
            {
                var store = new ParticleStore(capacity: 3, columnCount: 0);

                CheckEqual(0, store.Add(Aged(1)));
                CheckEqual(1, store.Add(Aged(2)));
                CheckEqual(2, store.Count);
                CheckEqual(2f, store.Items[1].Age);
            }

            public void ToAFullStore_ReturnsMinusOneAndChangesNothing()
            {
                var store = new ParticleStore(capacity: 1, columnCount: 0);
                store.Add(Aged(1));

                CheckEqual(-1, store.Add(Aged(2)));
                CheckEqual(1, store.Count);
                CheckEqual(1f, store.Items[0].Age);
            }

            public void ToAStoreOfZeroCapacity_ReturnsMinusOne()
            {
                CheckEqual(-1, new ParticleStore(capacity: 0, columnCount: 0).Add(Aged(1)));
            }

            public void ZeroesTheColumnEntriesOfTheNewParticle()
            {
                var store = new ParticleStore(capacity: 2, columnCount: 1);
                store.Add(Aged(1));
                store.Add(Aged(2));
                store.Columns[0][1] = 7;
                store.RemoveAt(1);

                CheckEqual(1, store.Add(Aged(3)));
                CheckEqual(0f, store.Columns[0][1]);
            }

            public void LeavesTheColumnEntriesOfOtherParticlesAlone()
            {
                var store = new ParticleStore(capacity: 2, columnCount: 1);
                store.Add(Aged(1));
                store.Columns[0][0] = 4;

                store.Add(Aged(2));

                CheckEqual(4f, store.Columns[0][0]);
            }
        }

        public class RemoveAtTests : TestFixture
        {
            public void FromTheMiddle_MovesTheLastParticleIntoItsPlace()
            {
                var store = new ParticleStore(capacity: 4, columnCount: 0);
                store.Add(Aged(1));
                store.Add(Aged(2));
                store.Add(Aged(3));

                store.RemoveAt(0);

                CheckEqual(2, store.Count);
                CheckEqual(3f, store.Items[0].Age);
                CheckEqual(2f, store.Items[1].Age);
            }

            public void OfTheLastParticle_JustDropsIt()
            {
                var store = new ParticleStore(capacity: 4, columnCount: 0);
                store.Add(Aged(1));
                store.Add(Aged(2));

                store.RemoveAt(1);

                CheckEqual(1, store.Count);
                CheckEqual(1f, store.Items[0].Age);
            }

            public void OfTheOnlyParticle_LeavesTheStoreEmpty()
            {
                var store = new ParticleStore(capacity: 1, columnCount: 0);
                store.Add(Aged(1));

                store.RemoveAt(0);

                CheckEqual(0, store.Count);
            }

            public void MovesTheLastParticlesColumnEntriesToo()
            {
                var store = new ParticleStore(capacity: 4, columnCount: 2);
                store.Add(Aged(1));
                store.Add(Aged(2));
                store.Add(Aged(3));
                store.Columns[0][2] = 30;
                store.Columns[1][2] = 31;

                store.RemoveAt(0);

                CheckEqual(30f, store.Columns[0][0]);
                CheckEqual(31f, store.Columns[1][0]);
            }

            public void OfTheLastParticle_LeavesTheOthersColumnEntriesAlone()
            {
                var store = new ParticleStore(capacity: 4, columnCount: 1);
                store.Add(Aged(1));
                store.Add(Aged(2));
                store.Columns[0][0] = 10;

                store.RemoveAt(1);

                CheckEqual(10f, store.Columns[0][0]);
            }

            public void ANegativeIndex_Throws()
            {
                var store = new ParticleStore(capacity: 2, columnCount: 0);
                store.Add(Aged(1));

                CheckThrow(typeof(ArgumentOutOfRangeException));
                store.RemoveAt(-1);
            }

            public void AnIndexAtTheCount_Throws()
            {
                var store = new ParticleStore(capacity: 2, columnCount: 0);
                store.Add(Aged(1));

                CheckThrow(typeof(ArgumentOutOfRangeException));
                store.RemoveAt(1);
            }

            public void FromAnEmptyStore_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new ParticleStore(capacity: 2, columnCount: 0).RemoveAt(0);
            }
        }
    }
}