using System;
using System.Collections.Generic;
using System.Linq;
using FluentAssertions;
using GameCult.Caching.MessagePack;
using CultMath;
using MessagePack;
using MessagePack.Formatters;
using NUnit.Framework;

[assembly: CultCacheFormatterResolver(typeof(GameCult.Caching.Tests.CultMathSerializationTests.Float2Override))]

namespace GameCult.Caching.Tests
{
    public sealed class CultMathSerializationTests
    {
        private static readonly MessagePackSerializerOptions Options = CultDocumentMessagePackSerialization.Options;

        private static string Hex<T>(T value) => Convert.ToHexString(MessagePackSerializer.Serialize(value, Options));

        private static T Decode<T>(string hex) => MessagePackSerializer.Deserialize<T>(Convert.FromHexString(hex), Options);

        [MessagePackObject]
        public sealed class Carrier
        {
            [Key(0)] public float2 Position;
            [Key(1)] public float3? Velocity;
            [Key(2)] public float2[] Path = Array.Empty<float2>();
            [Key(3)] public List<int2> Cells = new();
        }

        // Bytes the pre-collapse CultVec2/CultVec3/CultRect encodings and Aetheria's Float2/Int2/Bool2/Float3/Float4
        // formatters produce: an array of components in declaration order, float32 as 0xCA.
        [Test]
        public void Float2_MatchesTheLegacyVectorBytes()
        {
            const string hex = "92CA3F800000CA40000000";
            Hex(new float2(1f, 2f)).Should().Be(hex);
            Decode<float2>(hex).Should().Be(new float2(1f, 2f));
        }

        [Test]
        public void Float3_MatchesTheLegacyVectorBytes()
        {
            const string hex = "93CA3F800000CA40000000CA40400000";
            Hex(new float3(1f, 2f, 3f)).Should().Be(hex);
            Decode<float3>(hex).Should().Be(new float3(1f, 2f, 3f));
        }

        [Test]
        public void Rect_MatchesTheLegacyCultRectBytes()
        {
            const string hex = "9292CABF800000CAC000000092CA40A00000CA40E00000";
            Hex(new rect(5f, 7f, -1f, -2f)).Should().Be(hex);
            Decode<rect>(hex).Should().Be(new rect(-1f, -2f, 5f, 7f));
        }

        [Test]
        public void ConsumerFormatterShapes_MatchByteForByte()
        {
            Hex(new float4(1f, 2f, 3f, 4f)).Should().Be("94CA3F800000CA40000000CA40400000CA40800000");
            Hex(new int2(3, -4)).Should().Be("9203FC");
            Hex(new bool2(true, false)).Should().Be("92C3C2");
        }

        [Test]
        public void Decode_SkipsExtraElements_AndLeavesMissingOnesZero()
        {
            Decode<float2>("93CA3F800000CA40000000CA40400000").Should().Be(new float2(1f, 2f));
            Decode<float3>("92CA3F800000CA40000000").Should().Be(new float3(1f, 2f, 0f));
            Decode<rect>("9392CABF800000CAC000000092CA40A00000CA40E0000001").Should().Be(new rect(-1f, -2f, 5f, 7f));
        }

        [Test]
        public void Decode_RefusesNilAndNonArrays()
        {
            Action nil = () => Decode<float2>("C0");
            nil.Should().Throw<MessagePackSerializationException>();
            Action notArray = () => Decode<float3>("01");
            notArray.Should().Throw<MessagePackSerializationException>();
        }

        [Test]
        public void EveryFormattedType_RoundTrips()
        {
            RoundTrip(new float2(1.5f, -2f));
            RoundTrip(new float3(1f, 2f, 3f));
            RoundTrip(new float4(1f, 2f, 3f, 4f));
            RoundTrip(new double2(1e300, -2.5));
            RoundTrip(new double3(1, 2, 3));
            RoundTrip(new int2(-7, 900000));
            RoundTrip(new int3(1, -2, 3));
            RoundTrip(new int4(1, 2, 3, int.MinValue));
            RoundTrip(new bool2(true, false));
            RoundTrip(new bool3(false, true, true));
            RoundTrip(new bool4(true, false, false, true));
            RoundTrip(new quaternion(0.1f, 0.2f, 0.3f, 0.9f));
            RoundTrip(new Color32(255, 128, 0, 7));
            RoundTrip(new CultMath.Random(12345u));
            RoundTrip(new float2x2(1f, 2f, 3f, 4f));
            RoundTrip(new float3x3(1f, 2f, 3f, 4f, 5f, 6f, 7f, 8f, 9f));
            RoundTrip(new rect(-1f, -2f, 5f, 7f));
            RoundTrip(new CultCellular(new float4(1, 2, 3, 4), new float4(5, 6, 7, 8), 0.25f));
            RoundTrip(new CultPhasor(new float4(1, 2, 3, 4), new float4(5, 6, 7, 8)));
            RoundTrip(new SpanNoise(new float4(1, 2, 3, 4), 0.25f, 0.5f));
            RoundTrip(new SpanPath { midpoint = new float3(1f, 2f, 3f), velocity = new float3(4f, 5f, 6f), speed = 7f, acceleration = 8f, halfLength = 9f });
            RoundTrip(new SpanStage { frequency = 1f, stretch = 2f, axis = new float3(3f, 4f, 5f), shift = new float3(6f, 7f, 8f), offset = new float3(9f, 10f, 11f), octaveStep = new float3(12f, 13f, 14f) });
            RoundTrip(new CultSiteCells(new float4(1, 2, 3, 4), new float4(5, 6, 7, 8), 9f, 10f));
            RoundTrip(new CultSiteCells(new float4(0, 0, 0, 1.0e30f), new float4(0, 0, 0, 1.0e30f), -1f, -1f));
        }

        [Test]
        public void Matrices_AreArraysOfRows()
        {
            Hex(new float2x2(1f, 2f, 3f, 4f)).Should().Be("9292CA3F800000CA4000000092CA40400000CA40800000");
        }


        [Test]
        public void EveryShape_IsPinnedByteForByte()
        {
            Hex(new double2(1d, 2d)).Should().Be("92CB3FF0000000000000CB4000000000000000");
            Hex(new double3(1d, 2d, 3d)).Should().Be("93CB3FF0000000000000CB4000000000000000CB4008000000000000");
            Hex(new int3(1, -2, 3)).Should().Be("9301FE03");
            Hex(new int4(1, 2, 3, -1)).Should().Be("94010203FF");
            Hex(new bool3(true, false, true)).Should().Be("93C3C2C3");
            Hex(new bool4(false, true, true, false)).Should().Be("94C2C3C3C2");
            Hex(new quaternion(1f, 2f, 3f, 4f)).Should().Be("94CA3F800000CA40000000CA40400000CA40800000");
            Hex(new Color32(255, 128, 0, 7)).Should().Be("94CCFFCC800007");
            Hex(new CultMath.Random(12345u)).Should().Be("91CD3039");
            Hex(new float3x3(1f, 2f, 3f, 4f, 5f, 6f, 7f, 8f, 9f)).Should().Be(
                "93" +
                "93CA3F800000CA40000000CA40400000" +
                "93CA40800000CA40A00000CA40C00000" +
                "93CA40E00000CA41000000CA41100000");
            Hex(new CultCellular(new float4(1f, 2f, 3f, 4f), new float4(5f, 6f, 7f, 8f), 0.25f)).Should().Be(
                "93" +
                "94CA3F800000CA40000000CA40400000CA40800000" +
                "94CA40A00000CA40C00000CA40E00000CA41000000" +
                "CA3E800000");
            Hex(new CultPhasor(new float4(1f, 2f, 3f, 4f), new float4(5f, 6f, 7f, 8f))).Should().Be(
                "92" +
                "94CA3F800000CA40000000CA40400000CA40800000" +
                "94CA40A00000CA40C00000CA40E00000CA41000000");
            Hex(new SpanNoise(new float4(1f, 2f, 3f, 4f), 0.25f, 0.5f)).Should().Be(
                "93" +
                "94CA3F800000CA40000000CA40400000CA40800000" +
                "CA3E800000" +
                "CA3F000000");
            Hex(new SpanPath { midpoint = new float3(1f, 2f, 3f), velocity = new float3(4f, 5f, 6f), speed = 7f, acceleration = 8f, halfLength = 9f }).Should().Be(
                "95" +
                "93CA3F800000CA40000000CA40400000" +
                "93CA40800000CA40A00000CA40C00000" +
                "CA40E00000CA41000000CA41100000");
            Hex(new SpanStage { frequency = 1f, stretch = 2f, axis = new float3(3f, 4f, 5f), shift = new float3(6f, 7f, 8f), offset = new float3(9f, 10f, 11f), octaveStep = new float3(12f, 13f, 14f) }).Should().Be(
                "96" +
                "CA3F800000" +
                "CA40000000" +
                "93CA40400000CA40800000CA40A00000" +
                "93CA40C00000CA40E00000CA41000000" +
                "93CA41100000CA41200000CA41300000" +
                "93CA41400000CA41500000CA41600000");
            Hex(new CultSiteCells(new float4(1, 2, 3, 4), new float4(5, 6, 7, 8), 9f, 10f)).Should().Be(
                "94" +
                "94CA3F800000CA40000000CA40400000CA40800000" +
                "94CA40A00000CA40C00000CA40E00000CA41000000" +
                "CA41100000" +
                "CA41200000");
        }

        [Test]
        public void Color32_MissingAlphaDecodesAsOpaque()
        {
            Decode<Color32>("93CCFFCC8000").Should().Be(new Color32(255, 128, 0, 255));
            Decode<Color32>("94CCFFCC800007").Should().Be(new Color32(255, 128, 0, 7));
        }


        [Test]
        public void Random_StateZero_IsTheGeneratorDefaultSeed()
        {
            // CultMath's generator maps state 0 to its default seed, so a zero or missing state is not degenerate.
            var reference = new CultMath.Random(0u);
            var expected = new[] { reference.NextUInt(), reference.NextUInt(), reference.NextUInt() };

            foreach (var hex in new[] { "9100", "90" })
            {
                var decoded = Decode<CultMath.Random>(hex);
                new[] { decoded.NextUInt(), decoded.NextUInt(), decoded.NextUInt() }.Should().Equal(expected);
            }
        }
        [Test]
        public void ConsumerResolvers_WinOverCultMathResolver()
        {
            var overridden = CultDocumentMessagePackSerialization.OptionsFor(typeof(Float2Override).Assembly);

            MessagePackSerializer.Serialize(new float2(1f, 2f), overridden).Should().Equal(0xC3);
            Hex(new float2(1f, 2f)).Should().Be("92CA3F800000CA40000000");
        }

        public sealed class Float2Override : IFormatterResolver
        {
            public static readonly Float2Override Instance = new();

            public IMessagePackFormatter<T>? GetFormatter<T>() =>
                typeof(T) == typeof(float2) ? (IMessagePackFormatter<T>)(object)Formatter.Instance : null;

            private sealed class Formatter : IMessagePackFormatter<float2>
            {
                public static readonly Formatter Instance = new();
                public void Serialize(ref MessagePackWriter writer, float2 value, MessagePackSerializerOptions options) => writer.Write(true);
                public float2 Deserialize(ref MessagePackReader reader, MessagePackSerializerOptions options) => throw new NotSupportedException();
            }
        }
        [Test]
        public void EveryPublicCultMathValueType_HasAFormatter()
        {
            var valueTypes = typeof(float2).Assembly.GetExportedTypes()
                .Where(t => t.IsValueType && !t.IsEnum)
                .ToHashSet();

            valueTypes.Except(CultMathResolver.FormattedTypes).Should().BeEmpty(
                "every public CultMath value type serializes through CultMathResolver");
            CultMathResolver.FormattedTypes.Except(valueTypes).Should().BeEmpty();
        }

        [Test]
        public void TheDefaultChain_ComposesMathIntoNullablesCollectionsAndDocuments()
        {
            var value = new Carrier
            {
                Position = new float2(1f, 2f),
                Velocity = new float3(3f, 4f, 5f),
                Path = new[] { new float2(0f, 1f), new float2(2f, 3f) },
                Cells = new List<int2> { new int2(1, 2) },
            };

            var decoded = MessagePackSerializer.Deserialize<Carrier>(MessagePackSerializer.Serialize(value, Options), Options);

            decoded.Position.Should().Be(value.Position);
            decoded.Velocity.Should().Be(value.Velocity);
            decoded.Path.Should().Equal(value.Path);
            decoded.Cells.Should().Equal(value.Cells);
            MessagePackSerializer.Serialize(new Carrier(), Options).Should().NotBeEmpty();

            var absent = MessagePackSerializer.Deserialize<Carrier>(MessagePackSerializer.Serialize(new Carrier(), Options), Options);
            absent.Velocity.Should().BeNull();
        }

        private static void RoundTrip<T>(T value)
        {
            var bytes = MessagePackSerializer.Serialize(value, Options);
            MessagePackSerializer.Deserialize<T>(bytes, Options).Should().Be(value);
        }
    }
}