using Microsoft.CodeAnalysis;
using Misaki.HighPerformance.Mathematics.CodeGen.Models;
using System.Text;

namespace Misaki.HighPerformance.Mathematics.CodeGen.Generators
{
    internal abstract class GeneratorBase
    {
        protected const string INLINE_METHOD_ATTRIBUTE = "[global::System.Runtime.CompilerServices.MethodImpl(global::System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining | global::System.Runtime.CompilerServices.MethodImplOptions.AggressiveOptimization)]";

        protected static readonly string[] s_matrixComponents = new[] { "c0", "c1", "c2", "c3" };
        protected static readonly string[] s_vectorComponents = new[] { "x", "y", "z", "w" };

        protected readonly StringBuilder sourceBuilder = new();
        protected NumericTypeInfo typeInfo = null!;

        public string Generate(NumericTypeInfo typeInfo)
        {
            this.typeInfo = typeInfo;
            sourceBuilder.Clear();

            Initialize();

            GenerateHeader();
            GenerateNamespaceStart();
            GenerateTypeStart();

            GenerateBody();

            GenerateTypeEnd();
            GenerateNamespaceEnd();

            return sourceBuilder.ToString();
        }

        protected void StartRegion(string name)
        {
            sourceBuilder.AppendLine($@"
#region {name}");
        }

        protected void EndRegion()
        {
            sourceBuilder.AppendLine($@"
#endregion");
        }

        protected virtual void Initialize()
        {
        }

        protected virtual void GenerateHeader()
        {
            sourceBuilder.AppendLine(@"// <auto-generated>
// This code is generated by tool. Do not edit manually.
// Update this file may introduce incorrect behavior and will be lost if the code is regenerated.
// To update this file, edit the generator in the Misaki.HighPerformance.Mathematics.CodeGen and recompile it.
// </auto-generated>
");
            sourceBuilder.AppendLine("#nullable enable");
        }

        protected virtual void GenerateNamespaceStart()
        {
            sourceBuilder.Append($@"
namespace {typeInfo.TypeSymbol.ContainingNamespace.ToDisplayString()}
{{");
        }

        protected virtual void GenerateTypeStart()
        {
            sourceBuilder.Append($@"
    //[global::System.Runtime.CompilerServices.SkipLocalsInit]
    public partial struct {typeInfo.TypeSymbol.Name} : global::System.IEquatable<{typeInfo.TypeSymbol.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)}>
    {{");
        }

        protected abstract void GenerateBody();

        protected virtual void GenerateTypeEnd()
        {
            sourceBuilder.Append($@"
    }}");
        }

        protected virtual void GenerateNamespaceEnd()
        {
            sourceBuilder.Append($@"
}}");
        }
    }
}