/* ShaderTargetCompileTool.cs */
/* Place this file in Assets/Editor/ */

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

public class ShaderTargetCompileTool : EditorWindow
{
    /* We validate shaders against the selected build target */
    private BuildTarget target = BuildTarget.PSP2;

    /* We keep generated probe assets isolated and disposable */
    private string tempRoot = "Assets/__ShaderCompileProbe";
    private string bundleName = "shader_compile_probe";

    /* We write a clean shader error report after the compile probe runs */
    private string reportPath = "Temp/ShaderCompileProbeReport.txt";
    private bool generateErrorReport = true;
    private bool reportAvailable = false;

    /* We control compile coverage */
    private bool includeVariants = true;
    private bool scrapeShaderPragmas = true;
    private bool includeUnityBuiltInPragmas = true;
    private bool includeVertexLightmapSafetyCombos = true;
    private bool exhaustiveMode = false;

    /* We cap generated variants in practical mode so compile time does not explode */
    private int maxGeneratedCombosPerShader = 256;

    private Vector2 scroll;
    private readonly List<string> log = new List<string>();

    /*
    We keep explicit known-good safety-net combos here.
    These are not the main variant source anymore; they are extra protection for Vita lighting cases.
    */
    private readonly string[][] vertexLightmapSafetyCombos =
    {
        new string[] { "VERTEXLIGHT_ON", "LIGHTMAP_ON" },
        new string[] { "VERTEXLIGHT_ON", "LIGHTMAP_ON", "DIRLIGHTMAP_COMBINED" },
        new string[] { "VERTEXLIGHT_ON", "LIGHTMAP_ON", "_NORMALMAP" },
        new string[] { "VERTEXLIGHT_ON", "LIGHTMAP_ON", "_METALLICGLOSSMAP" },
        new string[] { "VERTEXLIGHT_ON", "LIGHTMAP_ON", "_NORMALMAP", "_METALLICGLOSSMAP" },

        new string[] { "LIGHTMAP_ON", "_NORMALMAP" },
        new string[] { "LIGHTMAP_ON", "_METALLICGLOSSMAP" },
        new string[] { "LIGHTMAP_ON", "_NORMALMAP", "_METALLICGLOSSMAP" },

        new string[] { "VERTEXLIGHT_ON", "_NORMALMAP" },
        new string[] { "VERTEXLIGHT_ON", "_METALLICGLOSSMAP" },
        new string[] { "VERTEXLIGHT_ON", "_NORMALMAP", "_METALLICGLOSSMAP" }
    };

    /*
    We compile across common pass types.
    Unsupported pass/shader pairs are skipped safely.
    */
    private readonly PassType[] commonPasses =
    {
        PassType.Normal,
        PassType.ForwardBase,
        PassType.ForwardAdd,
        PassType.ShadowCaster,
        PassType.Meta,
        PassType.Vertex,
        PassType.Deferred,
        PassType.LightPrePassBase,
        PassType.LightPrePassFinal
    };

    [MenuItem("Tools/Vita/Compile Project Shaders")]
    public static void Open()
    {
        GetWindow<ShaderTargetCompileTool>("Shader Compile Probe");
    }

    private void OnEnable()
    {
        reportAvailable = File.Exists(reportPath);
    }

    private void OnGUI()
    {
        target = (BuildTarget)EditorGUILayout.EnumPopup("Build Target", target);

        EditorGUILayout.Space();

        includeVariants = EditorGUILayout.Toggle("Create Variant Collection", includeVariants);
        scrapeShaderPragmas = EditorGUILayout.Toggle("Scrape Shader Pragmas", scrapeShaderPragmas);
        includeUnityBuiltInPragmas = EditorGUILayout.Toggle("Expand Unity Built-In Pragmas", includeUnityBuiltInPragmas);
        includeVertexLightmapSafetyCombos = EditorGUILayout.Toggle("Include Vertex/Lightmap Safety Combos", includeVertexLightmapSafetyCombos);
        exhaustiveMode = EditorGUILayout.Toggle("Exhaustive Mode", exhaustiveMode);
        generateErrorReport = EditorGUILayout.Toggle("Generate Error Report", generateErrorReport);

        if (!exhaustiveMode)
        {
            maxGeneratedCombosPerShader = EditorGUILayout.IntField(
                "Max Combos / Shader",
                maxGeneratedCombosPerShader
            );

            if (maxGeneratedCombosPerShader < 1)
                maxGeneratedCombosPerShader = 1;
        }

        EditorGUILayout.Space();

        if (GUILayout.Button("Compile Project Shaders For Target", GUILayout.Height(32)))
            CompileShaders();

        EditorGUILayout.Space();

        GUI.enabled = reportAvailable && File.Exists(reportPath);

        if (GUILayout.Button("Open Shader Compile Report", GUILayout.Height(26)))
            OpenShaderCompileReport();

        GUI.enabled = true;

        EditorGUILayout.Space();

        scroll = EditorGUILayout.BeginScrollView(scroll);

        for (int i = 0; i < log.Count; i++)
            EditorGUILayout.LabelField(log[i], EditorStyles.wordWrappedLabel);

        EditorGUILayout.EndScrollView();
    }

    private void CompileShaders()
    {
        log.Clear();
        reportAvailable = false;

        long editorLogStart = 0;

        if (generateErrorReport)
            editorLogStart = GetEditorLogLength();

        try
        {
            CleanupTempAssets();

            Directory.CreateDirectory(tempRoot);
            AssetDatabase.Refresh();

            string[] shaderGuids = AssetDatabase.FindAssets("t:Shader");

            int materialCount = 0;
            int variantCount = 0;

            ShaderVariantCollection svc = null;

            if (includeVariants)
                svc = new ShaderVariantCollection();

            for (int i = 0; i < shaderGuids.Length; i++)
            {
                string shaderPath = AssetDatabase.GUIDToAssetPath(shaderGuids[i]);

                if (shaderPath.StartsWith("Packages/"))
                    continue;

                Shader shader = AssetDatabase.LoadAssetAtPath<Shader>(shaderPath);

                if (shader == null)
                    continue;

                /*
                We create one dummy material per shader.
                This forces Unity to include the shader in the temporary AssetBundle compile.
                */
                Material mat = new Material(shader);

                string safeName = MakeSafeAssetName(shader.name);
                string matPath = tempRoot + "/" + safeName + ".mat";

                AssetDatabase.CreateAsset(mat, matPath);

                AssetImporter importer = AssetImporter.GetAtPath(matPath);
                importer.assetBundleName = bundleName;

                materialCount++;
                log.Add("Queued shader: " + shaderPath);

                if (includeVariants && svc != null)
                    variantCount += AddVariantsForShader(svc, shader, shaderPath);
            }

            if (includeVariants && svc != null)
            {
                string svcPath = tempRoot + "/GeneratedShaderVariants.shadervariants";

                AssetDatabase.CreateAsset(svc, svcPath);

                AssetImporter importer = AssetImporter.GetAtPath(svcPath);
                importer.assetBundleName = bundleName;

                log.Add("");
                log.Add("Generated ShaderVariantCollection variants: " + variantCount);
            }

            AssetDatabase.SaveAssets();
            AssetDatabase.Refresh();

            string outputPath = "Temp/ShaderCompileProbeBundles";

            if (!Directory.Exists(outputPath))
                Directory.CreateDirectory(outputPath);

            log.Add("");
            log.Add("Building temporary AssetBundle for: " + target);
            log.Add("Materials generated: " + materialCount);

            /*
            We use StrictMode so shader errors fail loudly.
            This makes the probe useful as a pre-build validation step.
            */
            BuildAssetBundleOptions options =
                BuildAssetBundleOptions.ForceRebuildAssetBundle |
                BuildAssetBundleOptions.StrictMode;

            AssetBundleManifest manifest = BuildPipeline.BuildAssetBundles(
                outputPath,
                options,
                target
            );

            log.Add("");

            if (manifest != null)
                log.Add("Shader compile probe completed. Check Console / report for errors.");
            else
                log.Add("AssetBundle build failed. Check Console / report for shader errors.");
        }
        finally
        {
            if (generateErrorReport)
            {
                string newLogText = ReadEditorLogFrom(editorLogStart);
                WriteShaderCompileReport(newLogText);

                reportAvailable = File.Exists(reportPath);

                log.Add("");
                log.Add("Shader compile report written to:");
                log.Add(reportPath);
            }

            CleanupTempAssets();
            AssetDatabase.Refresh();
            Repaint();
        }
    }

    private int AddVariantsForShader(ShaderVariantCollection svc, Shader shader, string shaderPath)
    {
        int added = 0;

        List<string[]> combos = new List<string[]>();

        if (scrapeShaderPragmas)
        {
            ShaderVariantScanResult scan = ScanShaderAndIncludes(shaderPath);
            combos.AddRange(BuildKeywordCombos(scan));

            log.Add("  Pragmas found: " + scan.keywordGroups.Count + " groups, " + scan.skipKeywords.Count + " skipped keywords");
            log.Add("  Generated pragma combos: " + combos.Count);
        }

        if (includeVertexLightmapSafetyCombos)
        {
            for (int i = 0; i < vertexLightmapSafetyCombos.Length; i++)
                combos.Add(vertexLightmapSafetyCombos[i]);
        }

        combos = DeduplicateCombos(combos);

        for (int p = 0; p < commonPasses.Length; p++)
        {
            PassType passType = commonPasses[p];

            added += TryAddVariant(svc, shader, passType, new string[0]);

            for (int c = 0; c < combos.Count; c++)
                added += TryAddVariant(svc, shader, passType, combos[c]);
        }

        return added;
    }

    private ShaderVariantScanResult ScanShaderAndIncludes(string shaderPath)
    {
        ShaderVariantScanResult result = new ShaderVariantScanResult();

        HashSet<string> visited = new HashSet<string>();
        ScanFileRecursive(shaderPath, result, visited);

        return result;
    }

    private void ScanFileRecursive(
        string assetPath,
        ShaderVariantScanResult result,
        HashSet<string> visited
    )
    {
        if (string.IsNullOrEmpty(assetPath))
            return;

        if (visited.Contains(assetPath))
            return;

        visited.Add(assetPath);

        string fullPath = Path.GetFullPath(assetPath);

        if (!File.Exists(fullPath))
            return;

        string directory = Path.GetDirectoryName(assetPath);
        string[] lines = File.ReadAllLines(fullPath);

        bool inBlockComment = false;

        for (int i = 0; i < lines.Length; i++)
        {
            string line = StripComments(lines[i], ref inBlockComment).Trim();

            if (string.IsNullOrEmpty(line))
                continue;

            if (line.StartsWith("#include"))
            {
                string includePath = ExtractIncludePath(line);

                if (!string.IsNullOrEmpty(includePath))
                {
                    string resolved = ResolveIncludeAssetPath(directory, includePath);

                    if (!string.IsNullOrEmpty(resolved))
                        ScanFileRecursive(resolved, result, visited);
                }

                continue;
            }

            if (!line.StartsWith("#pragma"))
                continue;

            ParsePragmaLine(line, result);
        }
    }

    private void ParsePragmaLine(string line, ShaderVariantScanResult result)
    {
        string[] tokens = SplitTokens(line);

        if (tokens.Length < 2)
            return;

        string pragmaType = tokens[1];

        if (pragmaType == "skip_variants")
        {
            for (int i = 2; i < tokens.Length; i++)
            {
                if (!string.IsNullOrEmpty(tokens[i]))
                    result.skipKeywords.Add(tokens[i]);
            }

            return;
        }

        if (includeUnityBuiltInPragmas && IsUnityBuiltInVariantPragma(pragmaType))
        {
            AddUnityBuiltInKeywordGroups(pragmaType, result);
            return;
        }

        if (!IsExplicitVariantPragma(pragmaType))
            return;

        List<string> keywords = new List<string>();

        for (int i = 2; i < tokens.Length; i++)
        {
            string token = tokens[i];

            if (string.IsNullOrEmpty(token))
                continue;

            if (token == "_")
                continue;

            if (IsIgnoredPragmaToken(token))
                continue;

            keywords.Add(token);
        }

        if (keywords.Count > 0)
            result.keywordGroups.Add(keywords.ToArray());
    }

    private List<string[]> BuildKeywordCombos(ShaderVariantScanResult scan)
    {
        List<string[]> combos = new List<string[]>();

        /*
        We add single-keyword variants first.
        This gives useful coverage even when capped mode stops full expansion early.
        */
        for (int g = 0; g < scan.keywordGroups.Count; g++)
        {
            for (int k = 0; k < scan.keywordGroups[g].Length; k++)
            {
                string keyword = scan.keywordGroups[g][k];

                if (!scan.skipKeywords.Contains(keyword))
                    combos.Add(new string[] { keyword });
            }
        }

        List<string[]> generated = new List<string[]>();
        BuildKeywordCrossProduct(scan.keywordGroups, scan.skipKeywords, 0, new List<string>(), generated);

        for (int i = 0; i < generated.Count; i++)
        {
            combos.Add(generated[i]);

            if (!exhaustiveMode && combos.Count >= maxGeneratedCombosPerShader)
                break;
        }

        return DeduplicateCombos(combos);
    }

    private void BuildKeywordCrossProduct(
        List<string[]> groups,
        HashSet<string> skipKeywords,
        int groupIndex,
        List<string> current,
        List<string[]> output
    )
    {
        if (!exhaustiveMode && output.Count >= maxGeneratedCombosPerShader)
            return;

        if (groupIndex >= groups.Count)
        {
            if (current.Count > 0)
                output.Add(current.ToArray());

            return;
        }

        /*
        We include the no-keyword option for each group.
        This approximates shader_feature and keeps multi_compile coverage practical.
        */
        BuildKeywordCrossProduct(groups, skipKeywords, groupIndex + 1, current, output);

        string[] group = groups[groupIndex];

        for (int i = 0; i < group.Length; i++)
        {
            string keyword = group[i];

            if (skipKeywords.Contains(keyword))
                continue;

            current.Add(keyword);
            BuildKeywordCrossProduct(groups, skipKeywords, groupIndex + 1, current, output);
            current.RemoveAt(current.Count - 1);

            if (!exhaustiveMode && output.Count >= maxGeneratedCombosPerShader)
                return;
        }
    }

    private bool IsExplicitVariantPragma(string pragmaType)
    {
        return
            pragmaType == "multi_compile" ||
            pragmaType == "multi_compile_local" ||
            pragmaType == "shader_feature" ||
            pragmaType == "shader_feature_local";
    }

    private bool IsUnityBuiltInVariantPragma(string pragmaType)
    {
        return
            pragmaType == "multi_compile_fwdbase" ||
            pragmaType == "multi_compile_fwdadd" ||
            pragmaType == "multi_compile_fwdadd_fullshadows" ||
            pragmaType == "multi_compile_shadowcaster" ||
            pragmaType == "multi_compile_fog";
    }

    private void AddUnityBuiltInKeywordGroups(string pragmaType, ShaderVariantScanResult result)
    {
        if (pragmaType == "multi_compile_fwdbase")
        {
            result.keywordGroups.Add(new string[] { "DIRECTIONAL" });
            result.keywordGroups.Add(new string[] { "LIGHTMAP_ON" });
            result.keywordGroups.Add(new string[] { "DIRLIGHTMAP_COMBINED" });
            result.keywordGroups.Add(new string[] { "DYNAMICLIGHTMAP_ON" });
            result.keywordGroups.Add(new string[] { "VERTEXLIGHT_ON" });
            result.keywordGroups.Add(new string[] { "SHADOWS_SCREEN", "SHADOWS_DEPTH" });
            return;
        }

        if (pragmaType == "multi_compile_fwdadd")
        {
            result.keywordGroups.Add(new string[] { "POINT", "DIRECTIONAL", "SPOT" });
            return;
        }

        if (pragmaType == "multi_compile_fwdadd_fullshadows")
        {
            result.keywordGroups.Add(new string[] { "POINT", "DIRECTIONAL", "SPOT" });
            result.keywordGroups.Add(new string[] { "SHADOWS_DEPTH", "SHADOWS_CUBE", "SHADOWS_SCREEN" });
            return;
        }

        if (pragmaType == "multi_compile_shadowcaster")
        {
            result.keywordGroups.Add(new string[] { "SHADOWS_DEPTH", "SHADOWS_CUBE" });
            return;
        }

        if (pragmaType == "multi_compile_fog")
        {
            result.keywordGroups.Add(new string[] { "FOG_LINEAR", "FOG_EXP", "FOG_EXP2" });
            return;
        }
    }

    private bool IsIgnoredPragmaToken(string token)
    {
        if (token.StartsWith("//"))
            return true;

        if (token == "nolightmap")
            return true;

        if (token == "nodirlightmap")
            return true;

        if (token == "nodynlightmap")
            return true;

        if (token == "noforwardadd")
            return true;

        if (token == "novertexlight")
            return true;

        if (token == "noambient")
            return true;

        if (token == "interpolateview")
            return true;

        if (token == "halfasview")
            return true;

        if (token == "addshadow")
            return true;

        if (token == "fullforwardshadows")
            return true;

        return false;
    }

    private List<string[]> DeduplicateCombos(List<string[]> combos)
    {
        List<string[]> result = new List<string[]>();
        HashSet<string> seen = new HashSet<string>();

        for (int i = 0; i < combos.Count; i++)
        {
            string[] combo = NormalizeCombo(combos[i]);
            string key = string.Join(" ", combo);

            if (string.IsNullOrEmpty(key))
                continue;

            if (seen.Contains(key))
                continue;

            seen.Add(key);
            result.Add(combo);
        }

        return result;
    }

    private string[] NormalizeCombo(string[] combo)
    {
        List<string> clean = new List<string>();
        HashSet<string> seen = new HashSet<string>();

        for (int i = 0; i < combo.Length; i++)
        {
            string keyword = combo[i];

            if (string.IsNullOrEmpty(keyword))
                continue;

            if (keyword == "_")
                continue;

            if (seen.Contains(keyword))
                continue;

            seen.Add(keyword);
            clean.Add(keyword);
        }

        clean.Sort();
        return clean.ToArray();
    }

    private int TryAddVariant(
        ShaderVariantCollection svc,
        Shader shader,
        PassType passType,
        string[] keywords
    )
    {
        try
        {
            ShaderVariantCollection.ShaderVariant variant =
                new ShaderVariantCollection.ShaderVariant(shader, passType, keywords);

            if (!svc.Contains(variant))
            {
                svc.Add(variant);
                return 1;
            }
        }
        catch
        {
            /*
            Some shaders do not support certain passes or keyword combinations.
            We skip those so the probe keeps moving.
            */
        }

        return 0;
    }

    private long GetEditorLogLength()
    {
        string path = GetEditorLogPath();

        if (string.IsNullOrEmpty(path))
            return 0;

        if (!File.Exists(path))
            return 0;

        FileInfo info = new FileInfo(path);
        return info.Length;
    }

    private string ReadEditorLogFrom(long startOffset)
    {
        string path = GetEditorLogPath();

        if (string.IsNullOrEmpty(path))
            return "";

        if (!File.Exists(path))
            return "";

        using (FileStream stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
        {
            if (startOffset < 0)
                startOffset = 0;

            if (startOffset > stream.Length)
                startOffset = 0;

            stream.Seek(startOffset, SeekOrigin.Begin);

            using (StreamReader reader = new StreamReader(stream))
                return reader.ReadToEnd();
        }
    }

    private string GetEditorLogPath()
    {
#if UNITY_EDITOR_WIN
        return Path.Combine(
            System.Environment.GetFolderPath(System.Environment.SpecialFolder.LocalApplicationData),
            "Unity/Editor/Editor.log"
        );
#elif UNITY_EDITOR_OSX
        return Path.Combine(
            System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal),
            "Library/Logs/Unity/Editor.log"
        );
#else
        return "";
#endif
    }

    private void WriteShaderCompileReport(string logText)
    {
        string reportDirectory = Path.GetDirectoryName(reportPath);

        if (!string.IsNullOrEmpty(reportDirectory) && !Directory.Exists(reportDirectory))
            Directory.CreateDirectory(reportDirectory);

        List<string> report = new List<string>();

        report.Add("Shader Compile Probe Report");
        report.Add("Target: " + target);
        report.Add("Generated: " + System.DateTime.Now);
        report.Add("");

        if (string.IsNullOrEmpty(logText))
        {
            report.Add("No new Editor.log text was captured during shader compile probe.");
            File.WriteAllLines(reportPath, report.ToArray());
            return;
        }

        string[] lines = logText.Split('\n');

        string lastProgram = "";
        string lastPass = "";
        string lastKeywords = "";
        string lastPlatformDefines = "";
        int errorCount = 0;

        for (int i = 0; i < lines.Length; i++)
        {
            string line = lines[i].Trim();

            if (line.StartsWith("Compiling "))
                lastProgram = line;

            if (line.StartsWith("Pass"))
                lastPass = line;

            if (line.StartsWith("Keywords:"))
                lastKeywords = line.Substring("Keywords:".Length).Trim();

            if (line.StartsWith("Platform defines:"))
                lastPlatformDefines = line.Substring("Platform defines:".Length).Trim();

            if (IsShaderErrorLine(line))
            {
                errorCount++;

                report.Add("------------------------------------------------------------");
                report.Add("Error #" + errorCount);
                report.Add("");
                report.Add(line);

                if (!string.IsNullOrEmpty(lastProgram))
                    report.Add("Program: " + lastProgram);

                if (!string.IsNullOrEmpty(lastPass))
                    report.Add("Pass: " + lastPass);

                if (!string.IsNullOrEmpty(lastKeywords))
                    report.Add("Keywords: " + lastKeywords);

                if (!string.IsNullOrEmpty(lastPlatformDefines))
                    report.Add("Platform Defines: " + lastPlatformDefines);

                report.Add("");
                report.Add("Context:");

                /*
                We include nearby compiler lines because Unity often places the actual
                failed expression, source line, or platform compiler message nearby.
                */
                for (int c = i + 1; c < lines.Length && c < i + 12; c++)
                {
                    string context = lines[c].Trim();

                    if (string.IsNullOrEmpty(context))
                        continue;

                    if (IsShaderErrorLine(context) && c != i)
                        break;

                    report.Add(context);
                }

                report.Add("");
            }
        }

        if (errorCount == 0)
            report.Add("No shader compile errors were detected in the captured Editor.log section.");

        File.WriteAllLines(reportPath, report.ToArray());
    }

    private bool IsShaderErrorLine(string line)
    {
        if (line.StartsWith("Shader error in"))
            return true;

        if (line.IndexOf("CGPROGRAM", System.StringComparison.OrdinalIgnoreCase) >= 0 &&
            line.IndexOf("error", System.StringComparison.OrdinalIgnoreCase) >= 0)
            return true;

        if (line.IndexOf("program", System.StringComparison.OrdinalIgnoreCase) >= 0 &&
            line.IndexOf("error", System.StringComparison.OrdinalIgnoreCase) >= 0)
            return true;

        return false;
    }

    private void OpenShaderCompileReport()
    {
        if (!File.Exists(reportPath))
        {
            EditorUtility.DisplayDialog(
                "Shader Compile Report",
                "No shader compile report exists yet. Run the compile probe first.",
                "OK"
            );

            reportAvailable = false;
            Repaint();
            return;
        }

        EditorUtility.OpenWithDefaultApp(reportPath);
    }

    private string ExtractIncludePath(string line)
    {
        int firstQuote = line.IndexOf("\"");
        int lastQuote = line.LastIndexOf("\"");

        if (firstQuote >= 0 && lastQuote > firstQuote)
            return line.Substring(firstQuote + 1, lastQuote - firstQuote - 1);

        int firstAngle = line.IndexOf("<");
        int lastAngle = line.LastIndexOf(">");

        if (firstAngle >= 0 && lastAngle > firstAngle)
            return line.Substring(firstAngle + 1, lastAngle - firstAngle - 1);

        return null;
    }

    private string ResolveIncludeAssetPath(string currentDirectory, string includePath)
    {
        string relativePath = NormalizeAssetPath(Path.Combine(currentDirectory, includePath));

        if (File.Exists(Path.GetFullPath(relativePath)))
            return relativePath;

        string directPath = NormalizeAssetPath(includePath);

        if (File.Exists(Path.GetFullPath(directPath)))
            return directPath;

        return null;
    }

    private string NormalizeAssetPath(string path)
    {
        return path.Replace("\\", "/");
    }

    private string StripComments(string line, ref bool inBlockComment)
    {
        string output = "";
        int i = 0;

        while (i < line.Length)
        {
            if (inBlockComment)
            {
                int end = line.IndexOf("*/", i);

                if (end < 0)
                    return output;

                inBlockComment = false;
                i = end + 2;
                continue;
            }

            int lineComment = line.IndexOf("//", i);
            int blockComment = line.IndexOf("/*", i);

            if (lineComment >= 0 && (blockComment < 0 || lineComment < blockComment))
            {
                output += line.Substring(i, lineComment - i);
                return output;
            }

            if (blockComment >= 0)
            {
                output += line.Substring(i, blockComment - i);
                inBlockComment = true;
                i = blockComment + 2;
                continue;
            }

            output += line.Substring(i);
            return output;
        }

        return output;
    }

    private string[] SplitTokens(string line)
    {
        return line.Split(
            new char[] { ' ', '\t' },
            System.StringSplitOptions.RemoveEmptyEntries
        );
    }

    private string MakeSafeAssetName(string input)
    {
        string output = input;

        output = output.Replace("/", "_");
        output = output.Replace("\\", "_");
        output = output.Replace(":", "_");
        output = output.Replace("*", "_");
        output = output.Replace("?", "_");
        output = output.Replace("\"", "_");
        output = output.Replace("<", "_");
        output = output.Replace(">", "_");
        output = output.Replace("|", "_");

        return output;
    }

    private void CleanupTempAssets()
    {
        if (AssetDatabase.IsValidFolder(tempRoot))
            AssetDatabase.DeleteAsset(tempRoot);

        string outputPath = "Temp/ShaderCompileProbeBundles";

        if (Directory.Exists(outputPath))
            Directory.Delete(outputPath, true);
    }

    /*
    We keep scan output grouped so future expansion can track variants per pass/subshader.
    For now, we aggregate groups globally per shader.
    */
    private class ShaderVariantScanResult
    {
        public readonly List<string[]> keywordGroups = new List<string[]>();
        public readonly HashSet<string> skipKeywords = new HashSet<string>();
    }
}