Apq.Cfg/Apq.Cfg.SourceGenerator/CodeEmitter.cs

using System;
using System.Collections.Immutable;
using System.Text;

namespace Apq.Cfg.SourceGenerator;

/// <summary>
/// 代码生成器，生成配置绑定代码
/// </summary>
internal static class CodeEmitter
{
    /// <summary>
    /// 生成配置类的绑定代码
    /// </summary>
    public static string EmitBinderClass(ConfigClassInfo classInfo)
    {
        var sb = new StringBuilder();

        sb.AppendLine("// <auto-generated/>");
        sb.AppendLine("// 此文件由 Apq.Cfg.SourceGenerator 自动生成，请勿手动修改");
        sb.AppendLine("#nullable enable");
        sb.AppendLine();

        // 命名空间
        if (!string.IsNullOrEmpty(classInfo.Namespace))
        {
            sb.AppendLine($"namespace {classInfo.Namespace}");
            sb.AppendLine("{");
        }

        // partial 类
        var indent = string.IsNullOrEmpty(classInfo.Namespace) ? "" : "    ";
        sb.AppendLine($"{indent}partial class {classInfo.ClassName}");
        sb.AppendLine($"{indent}{{");

        // BindFrom 静态方法
        EmitBindFromMethod(sb, classInfo, indent + "    ");

        // BindTo 实例方法（绑定到已有实例）
        EmitBindToMethod(sb, classInfo, indent + "    ");

        sb.AppendLine($"{indent}}}");

        if (!string.IsNullOrEmpty(classInfo.Namespace))
        {
            sb.AppendLine("}");
        }

        return sb.ToString();
    }

    /// <summary>
    /// 生成 BindFrom 静态方法
    /// </summary>
    private static void EmitBindFromMethod(StringBuilder sb, ConfigClassInfo classInfo, string indent)
    {
        sb.AppendLine($"{indent}/// <summary>");
        sb.AppendLine($"{indent}/// 从配置节创建并绑定配置对象（零反射）");
        sb.AppendLine($"{indent}/// </summary>");
        sb.AppendLine($"{indent}/// <param name=\"section\">配置节</param>");
        sb.AppendLine($"{indent}/// <returns>绑定后的配置对象</returns>");
        sb.AppendLine($"{indent}[global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]");
        sb.AppendLine($"{indent}public static {classInfo.ClassName} BindFrom(global::Apq.Cfg.ICfgSection section)");
        sb.AppendLine($"{indent}{{");
        sb.AppendLine($"{indent}    if (section == null) throw new global::System.ArgumentNullException(nameof(section));");
        sb.AppendLine();
        sb.AppendLine($"{indent}    var result = new {classInfo.ClassName}();");
        sb.AppendLine($"{indent}    BindTo(section, result);");
        sb.AppendLine($"{indent}    return result;");
        sb.AppendLine($"{indent}}}");
        sb.AppendLine();
    }

    /// <summary>
    /// 生成 BindTo 静态方法
    /// </summary>
    private static void EmitBindToMethod(StringBuilder sb, ConfigClassInfo classInfo, string indent)
    {
        sb.AppendLine($"{indent}/// <summary>");
        sb.AppendLine($"{indent}/// 将配置节绑定到已有对象（零反射）");
        sb.AppendLine($"{indent}/// </summary>");
        sb.AppendLine($"{indent}/// <param name=\"section\">配置节</param>");
        sb.AppendLine($"{indent}/// <param name=\"target\">目标对象</param>");
        sb.AppendLine($"{indent}[global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]");
        sb.AppendLine($"{indent}public static void BindTo(global::Apq.Cfg.ICfgSection section, {classInfo.ClassName} target)");
        sb.AppendLine($"{indent}{{");
        sb.AppendLine($"{indent}    if (section == null) throw new global::System.ArgumentNullException(nameof(section));");
        sb.AppendLine($"{indent}    if (target == null) throw new global::System.ArgumentNullException(nameof(target));");
        sb.AppendLine();

        foreach (var prop in classInfo.Properties)
        {
            EmitPropertyBinding(sb, prop, indent + "    ");
        }

        sb.AppendLine($"{indent}}}");
    }

    /// <summary>
    /// 生成单个属性的绑定代码
    /// </summary>
    private static void EmitPropertyBinding(StringBuilder sb, PropertyInfo prop, string indent)
    {
        switch (prop.TypeKind)
        {
            case TypeKind.Simple:
                EmitSimplePropertyBinding(sb, prop, indent);
                break;

            case TypeKind.Array:
                EmitArrayPropertyBinding(sb, prop, indent);
                break;

            case TypeKind.List:
                EmitListPropertyBinding(sb, prop, indent);
                break;

            case TypeKind.HashSet:
                EmitHashSetPropertyBinding(sb, prop, indent);
                break;

            case TypeKind.Dictionary:
                EmitDictionaryPropertyBinding(sb, prop, indent);
                break;

            case TypeKind.Complex:
                EmitComplexPropertyBinding(sb, prop, indent);
                break;

            default:
                sb.AppendLine($"{indent}// TODO: 不支持的类型 {prop.TypeName} for {prop.Name}");
                break;
        }
    }

    /// <summary>
    /// 生成简单类型属性绑定
    /// </summary>
    private static void EmitSimplePropertyBinding(StringBuilder sb, PropertyInfo prop, string indent)
    {
        sb.AppendLine($"{indent}// {prop.Name}: {prop.TypeName}");
        sb.AppendLine($"{indent}{{");
        sb.AppendLine($"{indent}    var __value = section.Get(\"{prop.Name}\");");
        sb.AppendLine($"{indent}    if (__value != null)");
        sb.AppendLine($"{indent}    {{");

        // 根据类型生成转换代码
        var baseType = prop.TypeName.TrimEnd('?');
        var convertCode = GetConvertCode(prop.TypeName, "__value");

        // string 和 Uri 是引用类型，不需要 .Value
        if (baseType == "string" || baseType == "System.String")
        {
            sb.AppendLine($"{indent}        target.{prop.Name} = {convertCode};");
        }
        else if (baseType == "System.Uri")
        {
            sb.AppendLine($"{indent}        target.{prop.Name} = {convertCode};");
        }
        else if (prop.IsNullable)
        {
            sb.AppendLine($"{indent}        target.{prop.Name} = {convertCode};");
        }
        else
        {
            sb.AppendLine($"{indent}        var __converted = {convertCode};");
            sb.AppendLine($"{indent}        if (__converted != null) target.{prop.Name} = __converted.Value;");
        }

        sb.AppendLine($"{indent}    }}");
        sb.AppendLine($"{indent}}}");
        sb.AppendLine();
    }

    /// <summary>
    /// 生成数组属性绑定
    /// </summary>
    private static void EmitArrayPropertyBinding(StringBuilder sb, PropertyInfo prop, string indent)
    {
        var elementType = prop.ElementTypeName ?? "object";

        sb.AppendLine($"{indent}// {prop.Name}: {prop.TypeName}");
        sb.AppendLine($"{indent}{{");
        sb.AppendLine($"{indent}    var __childSection = section.GetSection(\"{prop.Name}\");");
        sb.AppendLine($"{indent}    var __keys = __childSection.GetChildKeys()");
        sb.AppendLine($"{indent}        .Where(k => int.TryParse(k, out _))");
        sb.AppendLine($"{indent}        .OrderBy(k => int.Parse(k))");
        sb.AppendLine($"{indent}        .ToList();");
        sb.AppendLine($"{indent}    if (__keys.Count > 0)");
        sb.AppendLine($"{indent}    {{");
        sb.AppendLine($"{indent}        var __array = new {elementType}[__keys.Count];");
        sb.AppendLine($"{indent}        for (int __i = 0; __i < __keys.Count; __i++)");
        sb.AppendLine($"{indent}        {{");

        EmitElementBinding(sb, elementType, "__childSection", "__keys[__i]", $"__array[__i]", indent + "            ");

        sb.AppendLine($"{indent}        }}");
        sb.AppendLine($"{indent}        target.{prop.Name} = __array;");
        sb.AppendLine($"{indent}    }}");
        sb.AppendLine($"{indent}}}");
        sb.AppendLine();
    }

    /// <summary>
    /// 生成 List 属性绑定
    /// </summary>
    private static void EmitListPropertyBinding(StringBuilder sb, PropertyInfo prop, string indent)
    {
        var elementType = prop.ElementTypeName ?? "object";

        sb.AppendLine($"{indent}// {prop.Name}: {prop.TypeName}");
        sb.AppendLine($"{indent}{{");
        sb.AppendLine($"{indent}    var __childSection = section.GetSection(\"{prop.Name}\");");
        sb.AppendLine($"{indent}    var __keys = __childSection.GetChildKeys()");
        sb.AppendLine($"{indent}        .Where(k => int.TryParse(k, out _))");
        sb.AppendLine($"{indent}        .OrderBy(k => int.Parse(k))");
        sb.AppendLine($"{indent}        .ToList();");
        sb.AppendLine($"{indent}    if (__keys.Count > 0)");
        sb.AppendLine($"{indent}    {{");
        sb.AppendLine($"{indent}        var __list = new global::System.Collections.Generic.List<{elementType}>(__keys.Count);");
        sb.AppendLine($"{indent}        foreach (var __key in __keys)");
        sb.AppendLine($"{indent}        {{");

        EmitElementBindingForCollection(sb, elementType, "__childSection", "__key", "__list", indent + "            ");

        sb.AppendLine($"{indent}        }}");
        sb.AppendLine($"{indent}        target.{prop.Name} = __list;");
        sb.AppendLine($"{indent}    }}");
        sb.AppendLine($"{indent}}}");
        sb.AppendLine();
    }

    /// <summary>
    /// 生成 HashSet 属性绑定
    /// </summary>
    private static void EmitHashSetPropertyBinding(StringBuilder sb, PropertyInfo prop, string indent)
    {
        var elementType = prop.ElementTypeName ?? "object";

        sb.AppendLine($"{indent}// {prop.Name}: {prop.TypeName}");
        sb.AppendLine($"{indent}{{");
        sb.AppendLine($"{indent}    var __childSection = section.GetSection(\"{prop.Name}\");");
        sb.AppendLine($"{indent}    var __keys = __childSection.GetChildKeys()");
        sb.AppendLine($"{indent}        .Where(k => int.TryParse(k, out _))");
        sb.AppendLine($"{indent}        .OrderBy(k => int.Parse(k))");
        sb.AppendLine($"{indent}        .ToList();");
        sb.AppendLine($"{indent}    if (__keys.Count > 0)");
        sb.AppendLine($"{indent}    {{");
        sb.AppendLine($"{indent}        var __set = new global::System.Collections.Generic.HashSet<{elementType}>();");
        sb.AppendLine($"{indent}        foreach (var __key in __keys)");
        sb.AppendLine($"{indent}        {{");

        EmitElementBindingForSet(sb, elementType, "__childSection", "__key", "__set", indent + "            ");

        sb.AppendLine($"{indent}        }}");
        sb.AppendLine($"{indent}        target.{prop.Name} = __set;");
        sb.AppendLine($"{indent}    }}");
        sb.AppendLine($"{indent}}}");
        sb.AppendLine();
    }

    /// <summary>
    /// 生成 Dictionary 属性绑定
    /// </summary>
    private static void EmitDictionaryPropertyBinding(StringBuilder sb, PropertyInfo prop, string indent)
    {
        var keyType = prop.KeyTypeName ?? "string";
        var valueType = prop.ElementTypeName ?? "object";

        sb.AppendLine($"{indent}// {prop.Name}: {prop.TypeName}");
        sb.AppendLine($"{indent}{{");
        sb.AppendLine($"{indent}    var __childSection = section.GetSection(\"{prop.Name}\");");
        sb.AppendLine($"{indent}    var __keys = __childSection.GetChildKeys().ToList();");
        sb.AppendLine($"{indent}    if (__keys.Count > 0)");
        sb.AppendLine($"{indent}    {{");
        sb.AppendLine($"{indent}        var __dict = new global::System.Collections.Generic.Dictionary<{keyType}, {valueType}>();");
        sb.AppendLine($"{indent}        foreach (var __key in __keys)");
        sb.AppendLine($"{indent}        {{");

        // 键转换
        if (keyType == "string")
        {
            sb.AppendLine($"{indent}            var __dictKey = __key;");
        }
        else
        {
            var keyConvert = GetConvertCode(keyType, "__key");
            sb.AppendLine($"{indent}            var __dictKeyNullable = {keyConvert};");
            sb.AppendLine($"{indent}            if (__dictKeyNullable == null) continue;");
            sb.AppendLine($"{indent}            var __dictKey = __dictKeyNullable.Value;");
        }

        EmitElementBindingForDictionary(sb, valueType, "__childSection", "__key", "__dict", "__dictKey", indent + "            ");

        sb.AppendLine($"{indent}        }}");
        sb.AppendLine($"{indent}        target.{prop.Name} = __dict;");
        sb.AppendLine($"{indent}    }}");
        sb.AppendLine($"{indent}}}");
        sb.AppendLine();
    }

    /// <summary>
    /// 生成复杂对象属性绑定
    /// </summary>
    private static void EmitComplexPropertyBinding(StringBuilder sb, PropertyInfo prop, string indent)
    {
        // 获取全局限定的类型名，移除可空标记
        var baseTypeName = prop.TypeName.TrimEnd('?');
        var globalTypeName = baseTypeName.StartsWith("global::") ? baseTypeName : $"global::{baseTypeName}";

        sb.AppendLine($"{indent}// {prop.Name}: {prop.TypeName} (复杂对象)");
        sb.AppendLine($"{indent}{{");
        sb.AppendLine($"{indent}    var __childSection = section.GetSection(\"{prop.Name}\");");
        sb.AppendLine($"{indent}    var __childKeys = __childSection.GetChildKeys().ToList();");
        sb.AppendLine($"{indent}    if (__childKeys.Count > 0)");
        sb.AppendLine($"{indent}    {{");

        // 使用生成的 BindFrom 方法
        sb.AppendLine($"{indent}        target.{prop.Name} = {globalTypeName}.BindFrom(__childSection);");

        sb.AppendLine($"{indent}    }}");
        sb.AppendLine($"{indent}}}");
        sb.AppendLine();
    }

    /// <summary>
    /// 生成元素绑定代码（用于数组）
    /// </summary>
    private static void EmitElementBinding(StringBuilder sb, string elementType, string sectionVar, string keyVar, string targetVar, string indent)
    {
        if (IsSimpleTypeName(elementType))
        {
            var baseType = elementType.TrimEnd('?');
            sb.AppendLine($"{indent}var __elemValue = {sectionVar}.Get({keyVar});");
            sb.AppendLine($"{indent}if (__elemValue != null)");
            sb.AppendLine($"{indent}{{");
            var convertCode = GetConvertCode(elementType, "__elemValue");

            // string 是引用类型，直接赋值
            if (baseType == "string" || baseType == "System.String")
            {
                sb.AppendLine($"{indent}    {targetVar} = {convertCode};");
            }
            else
            {
                sb.AppendLine($"{indent}    var __converted = {convertCode};");
                sb.AppendLine($"{indent}    if (__converted != null) {targetVar} = __converted.Value;");
            }
            sb.AppendLine($"{indent}}}");
        }
        else
        {
            var globalType = elementType.StartsWith("global::") ? elementType : $"global::{elementType}";
            sb.AppendLine($"{indent}var __elemSection = {sectionVar}.GetSection({keyVar});");
            sb.AppendLine($"{indent}{targetVar} = {globalType}.BindFrom(__elemSection);");
        }
    }

    /// <summary>
    /// 生成元素绑定代码（用于 List）
    /// </summary>
    private static void EmitElementBindingForCollection(StringBuilder sb, string elementType, string sectionVar, string keyVar, string listVar, string indent)
    {
        if (IsSimpleTypeName(elementType))
        {
            var baseType = elementType.TrimEnd('?');
            sb.AppendLine($"{indent}var __elemValue = {sectionVar}.Get({keyVar});");
            sb.AppendLine($"{indent}if (__elemValue != null)");
            sb.AppendLine($"{indent}{{");
            var convertCode = GetConvertCode(elementType, "__elemValue");

            // string 是引用类型，直接添加
            if (baseType == "string" || baseType == "System.String")
            {
                sb.AppendLine($"{indent}    {listVar}.Add({convertCode});");
            }
            else
            {
                sb.AppendLine($"{indent}    var __converted = {convertCode};");
                sb.AppendLine($"{indent}    if (__converted != null) {listVar}.Add(__converted.Value);");
            }
            sb.AppendLine($"{indent}}}");
        }
        else
        {
            var globalType = elementType.StartsWith("global::") ? elementType : $"global::{elementType}";
            sb.AppendLine($"{indent}var __elemSection = {sectionVar}.GetSection({keyVar});");
            sb.AppendLine($"{indent}var __elem = {globalType}.BindFrom(__elemSection);");
            sb.AppendLine($"{indent}if (__elem != null) {listVar}.Add(__elem);");
        }
    }

    /// <summary>
    /// 生成元素绑定代码（用于 HashSet）
    /// </summary>
    private static void EmitElementBindingForSet(StringBuilder sb, string elementType, string sectionVar, string keyVar, string setVar, string indent)
    {
        if (IsSimpleTypeName(elementType))
        {
            var baseType = elementType.TrimEnd('?');
            sb.AppendLine($"{indent}var __elemValue = {sectionVar}.Get({keyVar});");
            sb.AppendLine($"{indent}if (__elemValue != null)");
            sb.AppendLine($"{indent}{{");
            var convertCode = GetConvertCode(elementType, "__elemValue");

            // string 是引用类型，直接添加
            if (baseType == "string" || baseType == "System.String")
            {
                sb.AppendLine($"{indent}    {setVar}.Add({convertCode});");
            }
            else
            {
                sb.AppendLine($"{indent}    var __converted = {convertCode};");
                sb.AppendLine($"{indent}    if (__converted != null) {setVar}.Add(__converted.Value);");
            }
            sb.AppendLine($"{indent}}}");
        }
        else
        {
            var globalType = elementType.StartsWith("global::") ? elementType : $"global::{elementType}";
            sb.AppendLine($"{indent}var __elemSection = {sectionVar}.GetSection({keyVar});");
            sb.AppendLine($"{indent}var __elem = {globalType}.BindFrom(__elemSection);");
            sb.AppendLine($"{indent}if (__elem != null) {setVar}.Add(__elem);");
        }
    }

    /// <summary>
    /// 生成元素绑定代码（用于 Dictionary）
    /// </summary>
    private static void EmitElementBindingForDictionary(StringBuilder sb, string valueType, string sectionVar, string keyVar, string dictVar, string dictKeyVar, string indent)
    {
        if (IsSimpleTypeName(valueType))
        {
            var baseType = valueType.TrimEnd('?');
            sb.AppendLine($"{indent}var __elemValue = {sectionVar}.Get({keyVar});");
            sb.AppendLine($"{indent}if (__elemValue != null)");
            sb.AppendLine($"{indent}{{");
            var convertCode = GetConvertCode(valueType, "__elemValue");

            // string 是引用类型，直接赋值
            if (baseType == "string" || baseType == "System.String")
            {
                sb.AppendLine($"{indent}    {dictVar}[{dictKeyVar}] = {convertCode};");
            }
            else
            {
                sb.AppendLine($"{indent}    var __converted = {convertCode};");
                sb.AppendLine($"{indent}    if (__converted != null) {dictVar}[{dictKeyVar}] = __converted.Value;");
            }
            sb.AppendLine($"{indent}}}");
        }
        else
        {
            var globalType = valueType.StartsWith("global::") ? valueType : $"global::{valueType}";
            sb.AppendLine($"{indent}var __elemSection = {sectionVar}.GetSection({keyVar});");
            sb.AppendLine($"{indent}var __elem = {globalType}.BindFrom(__elemSection);");
            sb.AppendLine($"{indent}if (__elem != null) {dictVar}[{dictKeyVar}] = __elem;");
        }
    }

    /// <summary>
    /// 获取类型转换代码
    /// </summary>
    private static string GetConvertCode(string typeName, string valueVar)
    {
        // 移除可空标记
        var baseType = typeName.TrimEnd('?');

        return baseType switch
        {
            "string" => valueVar,
            "int" or "System.Int32" => $"int.TryParse({valueVar}, out var __intVal) ? __intVal : (int?)null",
            "long" or "System.Int64" => $"long.TryParse({valueVar}, out var __longVal) ? __longVal : (long?)null",
            "short" or "System.Int16" => $"short.TryParse({valueVar}, out var __shortVal) ? __shortVal : (short?)null",
            "byte" or "System.Byte" => $"byte.TryParse({valueVar}, out var __byteVal) ? __byteVal : (byte?)null",
            "sbyte" or "System.SByte" => $"sbyte.TryParse({valueVar}, out var __sbyteVal) ? __sbyteVal : (sbyte?)null",
            "uint" or "System.UInt32" => $"uint.TryParse({valueVar}, out var __uintVal) ? __uintVal : (uint?)null",
            "ulong" or "System.UInt64" => $"ulong.TryParse({valueVar}, out var __ulongVal) ? __ulongVal : (ulong?)null",
            "ushort" or "System.UInt16" => $"ushort.TryParse({valueVar}, out var __ushortVal) ? __ushortVal : (ushort?)null",
            "float" or "System.Single" => $"float.TryParse({valueVar}, global::System.Globalization.NumberStyles.Float, global::System.Globalization.CultureInfo.InvariantCulture, out var __floatVal) ? __floatVal : (float?)null",
            "double" or "System.Double" => $"double.TryParse({valueVar}, global::System.Globalization.NumberStyles.Float, global::System.Globalization.CultureInfo.InvariantCulture, out var __doubleVal) ? __doubleVal : (double?)null",
            "decimal" or "System.Decimal" => $"decimal.TryParse({valueVar}, global::System.Globalization.NumberStyles.Number, global::System.Globalization.CultureInfo.InvariantCulture, out var __decimalVal) ? __decimalVal : (decimal?)null",
            "bool" or "System.Boolean" => $"bool.TryParse({valueVar}, out var __boolVal) ? __boolVal : (bool?)null",
            "char" or "System.Char" => $"({valueVar}.Length > 0 ? {valueVar}[0] : (char?)null)",
            "System.DateTime" => $"global::System.DateTime.TryParse({valueVar}, out var __dtVal) ? __dtVal : (global::System.DateTime?)null",
            "System.DateTimeOffset" => $"global::System.DateTimeOffset.TryParse({valueVar}, out var __dtoVal) ? __dtoVal : (global::System.DateTimeOffset?)null",
            "System.TimeSpan" => $"global::System.TimeSpan.TryParse({valueVar}, out var __tsVal) ? __tsVal : (global::System.TimeSpan?)null",
            "System.Guid" => $"global::System.Guid.TryParse({valueVar}, out var __guidVal) ? __guidVal : (global::System.Guid?)null",
            "System.DateOnly" => $"global::System.DateOnly.TryParse({valueVar}, out var __doVal) ? __doVal : (global::System.DateOnly?)null",
            "System.TimeOnly" => $"global::System.TimeOnly.TryParse({valueVar}, out var __toVal) ? __toVal : (global::System.TimeOnly?)null",
            "System.Uri" => $"global::System.Uri.TryCreate({valueVar}, global::System.UriKind.RelativeOrAbsolute, out var __uriVal) ? __uriVal : null",
            _ when baseType.Contains(".") => $"global::System.Enum.TryParse<{baseType}>({valueVar}, true, out var __enumVal) ? __enumVal : ({baseType}?)null",
            _ => $"global::System.Enum.TryParse<{baseType}>({valueVar}, true, out var __enumVal) ? __enumVal : ({baseType}?)null"
        };
    }

    /// <summary>
    /// 判断是否为简单类型名
    /// </summary>
    private static bool IsSimpleTypeName(string typeName)
    {
        var baseType = typeName.TrimEnd('?');
        return baseType switch
        {
            "string" or "int" or "long" or "short" or "byte" or "sbyte" or
            "uint" or "ulong" or "ushort" or "float" or "double" or "decimal" or
            "bool" or "char" or
            "System.String" or "System.Int32" or "System.Int64" or "System.Int16" or
            "System.Byte" or "System.SByte" or "System.UInt32" or "System.UInt64" or
            "System.UInt16" or "System.Single" or "System.Double" or "System.Decimal" or
            "System.Boolean" or "System.Char" or
            "System.DateTime" or "System.DateTimeOffset" or "System.TimeSpan" or
            "System.Guid" or "System.Uri" or "System.DateOnly" or "System.TimeOnly" => true,
            _ => false
        };
    }

    /// <summary>
    /// 生成扩展方法类
    /// </summary>
    public static string EmitExtensionsClass(ImmutableArray<ConfigClassInfo> classes)
    {
        var sb = new StringBuilder();

        sb.AppendLine("// <auto-generated/>");
        sb.AppendLine("// 此文件由 Apq.Cfg.SourceGenerator 自动生成，请勿手动修改");
        sb.AppendLine("#nullable enable");
        sb.AppendLine();
        sb.AppendLine("namespace Apq.Cfg");
        sb.AppendLine("{");
        sb.AppendLine("    /// <summary>");
        sb.AppendLine("    /// ICfgRoot 扩展方法（由源生成器生成）");
        sb.AppendLine("    /// </summary>");
        sb.AppendLine("    [global::System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]");
        sb.AppendLine("    internal static class CfgRootGeneratedExtensions");
        sb.AppendLine("    {");

        foreach (var classInfo in classes)
        {
            if (!classInfo.GenerateExtension)
                continue;

            var methodName = $"Get{classInfo.ClassName}";
            var sectionPath = classInfo.SectionPath;

            sb.AppendLine($"        /// <summary>");
            sb.AppendLine($"        /// 获取 {classInfo.ClassName} 配置（零反射）");
            sb.AppendLine($"        /// </summary>");
            sb.AppendLine($"        public static {classInfo.FullTypeName} {methodName}(this global::Apq.Cfg.ICfgRoot cfg)");
            sb.AppendLine($"        {{");
            sb.AppendLine($"            return {classInfo.FullTypeName}.BindFrom(cfg.GetSection(\"{sectionPath}\"));");
            sb.AppendLine($"        }}");
            sb.AppendLine();
        }

        sb.AppendLine("    }");
        sb.AppendLine("}");

        return sb.ToString();
    }
}