using System.Collections.Generic;
using UnityEditor;
using UnityEditor.Build;
using UnityEditor.Rendering;
using UnityEngine;
using UnityEngine.Rendering;

namespace Unity.FPS.EditorExt
{
    // Simple example of stripping of a debug build configuration
    class ShaderBuildStripping : IPreprocessShaders
    {
        List<ShaderKeyword> m_ExcludedKeywords;

        public ShaderBuildStripping()
        {
#if MANUAL_SHADER_STRIPPING
            m_ExcludedKeywords = new List<ShaderKeyword>
            {
                new ShaderKeyword("DEBUG"),
                // ifdef
                new ShaderKeyword("UNITY_GATHER_SUPPORTED"),
                new ShaderKeyword("UNITY_POSTFX_SSR"),
                new ShaderKeyword("DISTORT"),
                new ShaderKeyword("BLUR_HIGH_QUALITY"),
                new ShaderKeyword("UNITY_CAN_COMPILE_TESSELLATION"),
                new ShaderKeyword("ENABLE_WIND"),
                new ShaderKeyword("WIND_EFFECT_FROND_RIPPLE_ADJUST_LIGHTING"),
                new ShaderKeyword("LOD_FADE_CROSSFADE"),
                new ShaderKeyword("DYNAMICLIGHTMAP_ON"),
                new ShaderKeyword("EDITOR_VISUALIZATION"),
                new ShaderKeyword("UNITY_INSTANCING_ENABLED"),
                new ShaderKeyword("STEREO_MULTIVIEW_ON"),
                new ShaderKeyword("STEREO_INSTANCING_ON"),
                new ShaderKeyword("SOFTPARTICLES_ON"),
                new ShaderKeyword("PIXELSNAP_ON"),
                new ShaderKeyword("SHADER_API_D3D11"),
                // if defined()
                new ShaderKeyword("SHADER_API_VULKAN"),
                new ShaderKeyword("UNITY_SINGLE_PASS_STEREO"),
                new ShaderKeyword("FOG_LINEAR"),
                new ShaderKeyword("FOG_EXP"),
                new ShaderKeyword("FOG_EXP2"),
                new ShaderKeyword("UNITY_PASS_DEFERRED"),
                new ShaderKeyword("LIGHTMAP_ON"),
                new ShaderKeyword("_PARALLAXMAP"),
                new ShaderKeyword("SHADOWS_SCREEN"),
            };
#endif
        }

        // Multiple callback may be implemented. 
        // The first one executed is the one where callbackOrder is returning the smallest number.
        public int callbackOrder
        {
            get { return 0; }
        }

        public void OnProcessShader(
            Shader shader, ShaderSnippetData snippet, IList<ShaderCompilerData> shaderCompilerData)
        {
#if MANUAL_SHADER_STRIPPING
            // In development, don't strip debug variants
            if (EditorUserBuildSettings.development)
                return;

            for (int i = 0; i < shaderCompilerData.Count; ++i)
            {
                bool mustStrip = false;
                foreach (var kw in m_ExcludedKeywords)
                {
                    if (shaderCompilerData[i].shaderKeywordSet.IsEnabled(kw))
                    {
                        mustStrip = true;
                        break;
                    }
                }

                if (mustStrip)
                {
                    shaderCompilerData.RemoveAt(i);
                    --i;
                }
            }
#endif
        }
    }
}