using Ryujinx.Graphics.Shader.IntermediateRepresentation;
using Ryujinx.Graphics.Shader.Translation;
using System.Globalization;

namespace Ryujinx.Graphics.Shader.CodeGen.Msl.Instructions
{
    static class IoMap
    {
        public static (string, AggregateType) GetMslBuiltIn(
            ShaderDefinitions definitions,
            IoVariable ioVariable,
            int location,
            int component,
            bool isOutput,
            bool isPerPatch)
        {
            return ioVariable switch
            {
                IoVariable.BaseInstance => ("base_instance", AggregateType.S32),
                IoVariable.BaseVertex => ("base_vertex", AggregateType.S32),
                IoVariable.ClipDistance => ("clip_distance", AggregateType.Array | AggregateType.FP32),
                IoVariable.FragmentOutputColor => ("color", AggregateType.Vector2 | AggregateType.Vector3 | AggregateType.Vector4),
                IoVariable.FragmentOutputDepth => ("depth", AggregateType.FP32),
                IoVariable.FrontFacing => ("front_facing", AggregateType.Bool),
                IoVariable.InstanceId => ("instance_id", AggregateType.S32),
                IoVariable.PointCoord => ("point_coord", AggregateType.Vector2),
                IoVariable.PointSize => ("point_size", AggregateType.FP32),
                IoVariable.Position => ("position", AggregateType.Vector4 | AggregateType.FP32),
                IoVariable.PrimitiveId => ("primitive_id", AggregateType.S32),
                IoVariable.UserDefined => GetUserDefinedVariableName(definitions, location, component, isOutput, isPerPatch),
                IoVariable.VertexId => ("vertex_id", AggregateType.S32),
                IoVariable.ViewportIndex => ("viewport_array_index", AggregateType.S32),
                _ => (null, AggregateType.Invalid),
            };
        }

        private static (string, AggregateType) GetUserDefinedVariableName(ShaderDefinitions definitions, int location, int component, bool isOutput, bool isPerPatch)
        {
            string name = isPerPatch
                ? DefaultNames.PerPatchAttributePrefix
                : (isOutput ? DefaultNames.OAttributePrefix : DefaultNames.IAttributePrefix);

            if (location < 0)
            {
                return (name, definitions.GetUserDefinedType(0, isOutput));
            }

            name += location.ToString(CultureInfo.InvariantCulture);

            if (definitions.HasPerLocationInputOrOutputComponent(IoVariable.UserDefined, location, component, isOutput))
            {
                name += "_" + "xyzw"[component & 3];
            }

            string prefix = "";
            switch (definitions.Stage)
            {
                case ShaderStage.Vertex:
                    prefix = "Vertex";
                    break;
                case ShaderStage.Fragment:
                    prefix = "Fragment";
                    break;
                case ShaderStage.Compute:
                    prefix = "Compute";
                    break;
            }

            prefix += isOutput ? "Out" : "In";

            return (prefix + "." + name, definitions.GetUserDefinedType(location, isOutput));
        }
    }
}