using Google.Protobuf.WellKnownTypes;
using ZB.MOM.WW.MxGateway.Contracts.Proto;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Runtime;

namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Tests.Runtime;

/// <summary>
///     Tests for <see cref="MxValueEncoder"/>. Pinning each scalar + array case here
///     guards against accidental drift in the IWritable wire format.
/// </summary>
public sealed class MxValueEncoderTests
{
    /// <summary>Verifies that encoding a null value sets the IsNull flag.</summary>
    [Fact]
    public void Encode_Null_SetsIsNullFlag()
    {
        var v = MxValueEncoder.Encode(null);
        v.IsNull.ShouldBeTrue();
    }

    /// <summary>Verifies that encoding a boolean value encodes correctly.</summary>
    [Fact]
    public void Encode_Bool() => MxValueEncoder.Encode(true).BoolValue.ShouldBe(true);

    /// <summary>Verifies that narrow signed and unsigned types fit into Int32 encoding.</summary>
    /// <param name="input">The input value to encode.</param>
    /// <param name="expected">The expected encoded integer value.</param>
    [Theory]
    [InlineData((sbyte)-5, -5)]
    [InlineData((short)-1000, -1000)]
    [InlineData((byte)42, 42)]
    [InlineData((ushort)42_000, 42_000)]
    public void Encode_NarrowSignedAndUnsigned_FitsInInt32(object input, int expected)
    {
        var v = MxValueEncoder.Encode(input);
        v.KindCase.ShouldBe(MxValue.KindOneofCase.Int32Value);
        v.Int32Value.ShouldBe(expected);
    }

    /// <summary>Verifies that Int32 values round-trip through encoding.</summary>
    [Fact]
    public void Encode_Int32_RoundTrip() => MxValueEncoder.Encode(int.MinValue).Int32Value.ShouldBe(int.MinValue);

    /// <summary>Verifies that Int64 values round-trip through encoding.</summary>
    [Fact]
    public void Encode_Int64_RoundTrip()
    {
        var v = MxValueEncoder.Encode(long.MaxValue);
        v.KindCase.ShouldBe(MxValue.KindOneofCase.Int64Value);
        v.Int64Value.ShouldBe(long.MaxValue);
    }

    /// <summary>Verifies that UInt32 values fit in Int32 encoding.</summary>
    [Fact]
    public void Encode_UInt32_FitsInInt32() => MxValueEncoder.Encode((uint)int.MaxValue).Int32Value.ShouldBe(int.MaxValue);

    /// <summary>Verifies that float values encode correctly.</summary>
    [Fact]
    public void Encode_Float() => MxValueEncoder.Encode(3.14f).FloatValue.ShouldBe(3.14f);

    /// <summary>Verifies that double values encode correctly.</summary>
    [Fact]
    public void Encode_Double() => MxValueEncoder.Encode(2.71828).DoubleValue.ShouldBe(2.71828);

    /// <summary>Verifies that string values encode correctly.</summary>
    [Fact]
    public void Encode_String() => MxValueEncoder.Encode("hello").StringValue.ShouldBe("hello");

    /// <summary>Verifies that UTC DateTime values encode correctly.</summary>
    [Fact]
    public void Encode_DateTimeUtc()
    {
        var when = new DateTime(2026, 4, 29, 12, 0, 0, DateTimeKind.Utc);
        var v = MxValueEncoder.Encode(when);
        v.TimestampValue.ShouldNotBeNull();
        v.TimestampValue.ToDateTime().ShouldBe(when);
    }

    /// <summary>Verifies that local DateTime values are converted to UTC during encoding.</summary>
    [Fact]
    public void Encode_DateTimeLocal_ConvertsToUtc()
    {
        var local = new DateTime(2026, 4, 29, 12, 0, 0, DateTimeKind.Local);
        var v = MxValueEncoder.Encode(local);
        v.TimestampValue.ToDateTime().ShouldBe(local.ToUniversalTime());
    }

    /// <summary>Verifies that boolean arrays encode correctly.</summary>
    [Fact]
    public void Encode_BoolArray()
    {
        var v = MxValueEncoder.Encode(new[] { true, false, true });
        v.ArrayValue.BoolValues.Values.ToArray().ShouldBe(new[] { true, false, true });
        v.ArrayValue.Dimensions[0].ShouldBe(3u);
    }

    /// <summary>Verifies that double arrays encode correctly.</summary>
    [Fact]
    public void Encode_DoubleArray()
    {
        var v = MxValueEncoder.Encode(new[] { 1.0, 2.0, 3.5 });
        v.ArrayValue.DoubleValues.Values.ToArray().ShouldBe(new[] { 1.0, 2.0, 3.5 });
    }

    /// <summary>Verifies that string arrays encode correctly.</summary>
    [Fact]
    public void Encode_StringArray()
    {
        var v = MxValueEncoder.Encode(new[] { "a", "b" });
        v.ArrayValue.StringValues.Values.ToArray().ShouldBe(new[] { "a", "b" });
    }

    /// <summary>Verifies that all DateTime values in arrays are converted to UTC during encoding.</summary>
    [Fact]
    public void Encode_DateTimeArray_ConvertsAllToUtc()
    {
        var inputs = new[] { new DateTime(2026, 4, 29, 0, 0, 0, DateTimeKind.Utc) };
        var v = MxValueEncoder.Encode(inputs);
        v.ArrayValue.TimestampValues.Values[0].ToDateTime().ShouldBe(inputs[0]);
    }

    /// <summary>Verifies that encoding an unsupported type throws an exception.</summary>
    [Fact]
    public void Encode_UnsupportedType_Throws()
    {
        Should.Throw<ArgumentException>(() => MxValueEncoder.Encode(new { Foo = 1 }));
    }

    /// <summary>Verifies that all scalar types round-trip correctly through encode and decode.</summary>
    [Fact]
    public void RoundTrip_AllScalarTypes_DecodeMatchesOriginal()
    {
        // The encoder + decoder must be inverses for every scalar a Galaxy driver might
        // hand to a write. This pin-test catches accidental drift in either direction.
        object[] inputs = [true, 42, 12345L, 3.14f, 2.71828, "x"];
        foreach (var input in inputs)
        {
            var encoded = MxValueEncoder.Encode(input);
            var decoded = MxValueDecoder.Decode(encoded);
            decoded.ShouldBe(input);
        }
    }
}
