using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using SharpDX;
using SharpDX.D3DCompiler;
using SharpDX.Direct3D11;
using T3.Core.DataTypes;
using T3.Core.IO;
using T3.Core.Settings;
using T3.Core.Logging;
using T3.Core.Model;
using T3.Core.Resource.Assets;
using ComputeShader = SharpDX.Direct3D11.ComputeShader;
using GeometryShader = SharpDX.Direct3D11.GeometryShader;
using PixelShader = SharpDX.Direct3D11.PixelShader;
using VertexShader = SharpDX.Direct3D11.VertexShader;

namespace T3.Core.Resource.ShaderCompiling;

/// <summary>
/// An implementation of the <see cref="ShaderCompiler"/> class that uses the DirectX 11 shader compiler from SharpDX
/// </summary>
// ReSharper disable once InconsistentNaming
public sealed partial class DX11ShaderCompiler : ShaderCompiler
{
    public Device Device { get; set; }

    protected override bool CompileShaderFromSource<TShader>(ShaderCompilationArgs args, out byte[] blob, out string errorMessage)
    {
        CompilationResult compilationResult = null;
        string resultMessage;
        bool success;
        var profile = _shaderProfiles[typeof(TShader)];
        try
        {
            ShaderFlags flags = ShaderFlags.None;
            #if DEBUG || FORCE_SHADER_DEBUG
            flags |= ShaderFlags.Debug;
            #endif

            if (CoreSettings.Config.SkipOptimization)
            {
                flags |= ShaderFlags.SkipOptimization;
            }
            compilationResult = ShaderBytecode.Compile(args.SourceCode, 
                                                       args.EntryPoint, 
                                                       profile, 
                                                       flags, 
                                                       EffectFlags.None, 
                                                       null, 
                                                       new IncludeHandler(args.Owner));

            success = compilationResult.ResultCode == Result.Ok;
            resultMessage = compilationResult.Message;
        }
        catch (Exception ce)
        {
            success = false;
            resultMessage = ce.Message;
        }

        if (success)
        {
            blob = compilationResult.Bytecode.Data;
            errorMessage = string.Empty;
        }
        else
        {
            resultMessage = ExtractMeaningfulShaderErrorMessage(resultMessage);
            errorMessage = resultMessage;
            blob = null;
        }

        return success;
    }
    
    protected override void CreateShaderInstance<TShader>(string name, in byte[] blob, out TShader shader)
    {
        // As shader type is generic we've to use Activator and PropertyInfo to create/set the shader object
        var shaderType = typeof(TShader);

        shader = (TShader)_shaderConstructors[shaderType].Invoke(Device, blob);
        
        var debugNameInfo = shaderType.GetProperty("DebugName");
        debugNameInfo?.SetValue(shader, name);
    }
    public static string ExtractMeaningfulShaderErrorMessage(string message)
    {
        var lines = message.Split(new[] { "\r\n", "\n" }, StringSplitOptions.RemoveEmptyEntries);

        (string ShaderName, string LineNumber, string ErrorMessage)? firstWarning = null;

        foreach (var line in lines)
        {
            var shaderErrorMatch = ShaderErrorPatternRegex().Match(line);
            if (shaderErrorMatch.Success)
            {
                var shaderName = shaderErrorMatch.Groups[1].Value;
                var lineNumber = shaderErrorMatch.Groups[2].Value;
                var errorMessage = shaderErrorMatch.Groups[3].Value.Trim();

                if (errorMessage.IndexOf("error", StringComparison.OrdinalIgnoreCase) >= 0)
                    return $"Line {lineNumber}: {errorMessage}\n\n{shaderName}";

                if (firstWarning == null && errorMessage.IndexOf("warning", StringComparison.OrdinalIgnoreCase) >= 0)
                    firstWarning = (shaderName, lineNumber, errorMessage);

                continue;
            }

            // Some compiler lines don't contain file/line info. Still prefer an error if one is present.
            if (line.IndexOf("error", StringComparison.OrdinalIgnoreCase) >= 0)
                return line.Trim();

            if (firstWarning == null && line.IndexOf("warning", StringComparison.OrdinalIgnoreCase) >= 0)
                firstWarning = (string.Empty, string.Empty, line.Trim());
        }

        if (firstWarning != null)
        {
            if (!string.IsNullOrEmpty(firstWarning.Value.ShaderName))
                return $"Line {firstWarning.Value.LineNumber}: {firstWarning.Value.ErrorMessage}\n\n{firstWarning.Value.ShaderName}";

            return firstWarning.Value.ErrorMessage;
        }

        return message;
    }
    
    /// <summary>
    /// Matches errors like....
    ///
    /// Failed to compile shader 'ComputeWobble': C:\Users\pixtur\coding\t3\Resources\compute-ColorGrade.hlsl(32,12-56): warning X3206: implicit truncation of vector type
    /// </summary>
    [GeneratedRegex(@"(.*?)\((.*)\):(.*)")]
    private static partial Regex ShaderErrorPatternRegex();

    private static readonly IReadOnlyDictionary<Type, Func<Device, byte[], AbstractShader> > _shaderConstructors = new Dictionary<Type, Func<Device, byte[], AbstractShader>>()
                                                                                   {
                                                                                       { typeof(T3.Core.DataTypes.VertexShader), (device, data) => new DataTypes.VertexShader(new VertexShader(device, data, null), data) },
                                                                                       { typeof(T3.Core.DataTypes.PixelShader), (device, data) => new DataTypes.PixelShader(new PixelShader(device, data, null), data) },
                                                                                       { typeof(T3.Core.DataTypes.ComputeShader), (device, data) => new DataTypes.ComputeShader(new ComputeShader(device, data, null), data) },
                                                                                       { typeof(T3.Core.DataTypes.GeometryShader), (device, data) => new DataTypes.GeometryShader(new GeometryShader(device, data, null), data) },
                                                                                   };
    
    private static readonly IReadOnlyDictionary<Type, string> _shaderProfiles = new Dictionary<Type, string>()
                                                                                   {
                                                                                       { typeof(T3.Core.DataTypes.VertexShader), "vs_5_0" },
                                                                                       { typeof(T3.Core.DataTypes.PixelShader), "ps_5_0" },
                                                                                       { typeof(T3.Core.DataTypes.ComputeShader), "cs_5_0" },
                                                                                       { typeof(T3.Core.DataTypes.GeometryShader), "gs_5_0" },
                                                                                   };

    private sealed class IncludeHandler : SharpDX.D3DCompiler.Include, IResourceConsumer
    {
        private StreamReader _streamReader;
        private readonly IResourceConsumer _owner;
        
        public IncludeHandler(IResourceConsumer owner)
        {
            _owner = owner;
        }

        public void Dispose()
        {
            Disposing?.Invoke(this); // Notify subscribers
            _streamReader?.Dispose();
        }

        public IDisposable Shadow { get; set; }

        public Stream Open(IncludeType type, string sharedIncludeFileName, Stream parentStream)
        {
            if(TryResolveSharedIncludeAsset(sharedIncludeFileName,  out var asset))
            {
                _streamReader = new StreamReader(asset.FullPath);
                return _streamReader.BaseStream;
            }

            Log.Error($"Could not locate include file '{sharedIncludeFileName}'");
            _streamReader = null;
            return null;
        }

        public void Close(Stream stream)
        {
            _streamReader.Close();
        }


        public IReadOnlyList<IResourcePackage> AvailableResourcePackages { get; }
        public SymbolPackage Package { get; }
        public event Action<IResourceConsumer> Disposing;
    }
}