using System;
using UnityEngine;
using UnityEngine.Profiling;
using UnityEngine.Rendering;

namespace FidelityFX
{
    internal abstract class FfxPassBase: IDisposable
    {
        private readonly string _techName;
        private string _passName;
        
        protected ComputeShader ComputeShader;
        protected int KernelIndex;

        protected FfxPassBase(string techName)
        {
            _techName = techName;
        }

        protected virtual void InitComputeShader(string passName, ComputeShader shader, string kernelName = "CS")
        {
            if (shader == null)
            {
                throw new MissingReferenceException($"Shader for {_techName} pass '{passName}' could not be loaded! Please ensure it is included in the project correctly.");
            }

            _passName = passName;
            ComputeShader = shader;
            KernelIndex = ComputeShader.FindKernel(kernelName);
        }

        public virtual void Dispose()
        {
        }

        protected ProfilerSampler ProfilerSample(CommandBuffer commandBuffer)
        {
            return new ProfilerSampler(_passName, commandBuffer);
        }

        protected readonly struct ProfilerSampler : IDisposable
        {
            private readonly string _name;
            private readonly CommandBuffer _commandBuffer;

            public ProfilerSampler(string name, CommandBuffer commandBuffer)
            {
                _name = name;
                _commandBuffer = commandBuffer;
                _commandBuffer.BeginSample(_name);
            }
            
            public void Dispose()
            {
                _commandBuffer.EndSample(_name);
            }
        }
    }

    internal abstract class FfxPassWithFlags<TFlags> : FfxPassBase
        where TFlags: Enum
    {
        protected readonly TFlags Flags;

        protected FfxPassWithFlags(string techName, TFlags flags) : base(techName)
        {
            Flags = flags;
        }

        protected override void InitComputeShader(string passName, ComputeShader shader, string kernelName = "CS")
        {
            base.InitComputeShader(passName, shader, kernelName);
            SetupShaderKeywords();
        }

        protected abstract void SetupShaderKeywords();
    }
}