using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;

namespace JiShe.CollectBus.IncrementalGenerator
{
    /// <summary>
    /// 复杂类型源生成器
    /// </summary>
    [Generator(LanguageNames.CSharp)]
    public class ComplexTypeSourceAnalyzers : IIncrementalGenerator
    {
        private const string AttributeFullName = "JiShe.CollectBus.Analyzers.Shared.SourceAnalyzersAttribute";
        private const string SourceEntityAccessorFactoryNamespace = "JiShe.CollectBus.Analyzers.Shared";

        public void Initialize(IncrementalGeneratorInitializationContext context)
        {
            //Debugger.Launch();


            // 步骤1：筛选带有 [SourceAnalyzers] 的类
            var classDeclarations = context.SyntaxProvider
                .CreateSyntaxProvider(
                    predicate: static (s, _) => IsClassWithAttribute(s),
                    transform: static (ctx, _) => GetClassDeclaration(ctx))
                .Where(static c => c is not null);

            // 步骤2：合并编译信息
            var compilationAndClasses = context.CompilationProvider.Combine(classDeclarations.Collect());

            context.RegisterSourceOutput(compilationAndClasses, (spc, source) =>
                GenerateCode(source.Left, source.Right!, spc)); 
        }

        private static bool IsClassWithAttribute(SyntaxNode node) => node is ClassDeclarationSyntax cds && cds.AttributeLists.Count > 0;
         
        private static ClassDeclarationSyntax GetClassDeclaration(GeneratorSyntaxContext context)
        {
            var classDecl = (ClassDeclarationSyntax)context.Node;
            var attributeType = context.SemanticModel.Compilation.GetTypeByMetadataName(AttributeFullName);

            foreach (var attribute in classDecl.AttributeLists.SelectMany(al => al.Attributes))
            {
                var symbol = context.SemanticModel.GetSymbolInfo(attribute).Symbol;
                if (symbol is IMethodSymbol ctor &&
                    SymbolEqualityComparer.Default.Equals(ctor.ContainingType, attributeType))
                {
                    return classDecl;
                }
            }
            return null;
        }

        /// <summary>
        /// 递归获取所有层级的属性
        /// </summary>
        /// <param name="classSymbol"></param>
        /// <returns></returns>
        private static IEnumerable<IPropertySymbol> GetAllPropertiesInHierarchy(INamedTypeSymbol classSymbol)
        {
            var currentSymbol = classSymbol;
            while (currentSymbol != null)
            {
                foreach (var prop in currentSymbol.GetMembers().OfType<IPropertySymbol>())
                {
                    yield return prop;
                }
                currentSymbol = currentSymbol.BaseType; // 向上遍历基类
            }
        }

        /// <summary>
        /// 生成代码
        /// </summary>
        /// <param name="compilation"></param>
        /// <param name="classes"></param>
        /// <param name="context"></param>
        private static void GenerateCode(
            Compilation compilation,
            IEnumerable<ClassDeclarationSyntax> classes,
            SourceProductionContext context)
        {
            var processedTypes = new HashSet<ITypeSymbol>(SymbolEqualityComparer.Default);

            if (!classes.Any())
            {
                context.ReportDiagnostic(Diagnostic.Create(
                    new DiagnosticDescriptor("GEN002", "没有目标类",
                    "没有找到SourceAnalyzers标记的类", "Debug", DiagnosticSeverity.Warning, true),
                    Location.None));
            }

            foreach (var classDecl in classes.Distinct())
            {
                var model = compilation.GetSemanticModel(classDecl.SyntaxTree);
                var classSymbol = model.GetDeclaredSymbol(classDecl) as INamedTypeSymbol;

                if (classSymbol == null || !processedTypes.Add(classSymbol))
                {
                    context.ReportDiagnostic(Diagnostic.Create(
                        new DiagnosticDescriptor("GEN003", "无效符号",
                        $"类名称为{classDecl.Identifier.Text} 符号为空", "Error", DiagnosticSeverity.Error, true),
                        Location.None));
                    continue;
                }

                //context.ReportDiagnostic(Diagnostic.Create(
                //new DiagnosticDescriptor(
                //    "PA001",
                //    "Generated Accessors",
                //    $"Generating accessors for {classSymbol.Name}",
                //    "Performance",
                //    DiagnosticSeverity.Info,
                //    true),
                //Location.None));

                //// 新增：输出继承链信息
                //context.ReportDiagnostic(Diagnostic.Create(
                //    new DiagnosticDescriptor("HIERARCHY", "Class Hierarchy",
                //    $"Processing class: {classSymbol.Name}, BaseType: {classSymbol.BaseType?.Name}",
                //    "Debug", DiagnosticSeverity.Info, true),
                //    Location.None));

                //context.ReportDiagnostic(Diagnostic.Create(
                //new DiagnosticDescriptor("PA002", "Class Found",
                //$"Processing class: {classSymbol.Name}", "Debug", DiagnosticSeverity.Warning, true),
                //Location.None));

                var code = BuildAccessorsForType(classSymbol, compilation, processedTypes);

                //System.Diagnostics.Debug.WriteLine($"Generated code for {classSymbol.Name}:\n{code}"); // 调试输出

                context.AddSource($"{classSymbol.Name}Extension.g.cs", code);


                var code3 = BuildAccessorsForType2(classSymbol, compilation, processedTypes);
                context.AddSource($"{classSymbol.Name}Accessor.g.cs", code3);

                //code.AppendLine($"namespace {classSymbol.ContainingNamespace.ToDisplayString()};");
                //if (classSymbol.ContainingNamespace.ToDisplayString() == "JiShe.CollectBus.IoTDB")
                //{

                //}
            }

            // 生成工厂注册代码
            context.AddSource("SourceEntityAccessorFactory.g.cs", BuildFactoryCode());
        }

        /// <summary>
        /// 构建类的属性访问器代码
        /// </summary>
        /// <param name="classSymbol"></param>
        /// <param name="compilation"></param>
        /// <param name="processedTypes"></param>
        /// <returns></returns>
        private static string BuildAccessorsForType(
           INamedTypeSymbol classSymbol,
           Compilation compilation,
           HashSet<ITypeSymbol> processedTypes)
        {
            var code = new StringBuilder();
            code.AppendLine("#pragma warning disable CS0419 // 禁用警告");
            code.AppendLine("// Generated code for " + classSymbol.Name);
            code.AppendLine("// <auto-generated/>");
            code.AppendLine("#nullable enable");
            code.AppendLine($"namespace {classSymbol.ContainingNamespace.ToDisplayString()};");
            code.AppendLine();

            code.AppendLine($"public static class {classSymbol.Name}Extension{GetGenericParams(classSymbol)}");
            code.AppendLine("{");

            foreach (var prop in GetAllPropertiesInHierarchy(classSymbol))
            {
                if (prop.IsIndexer) continue;
                GeneratePropertyAccessorsForType(prop, code, compilation, processedTypes);
            }

            code.AppendLine("}");
            return code.ToString();
        }

        /// <summary>
        /// 构建类的属性访问器代码
        /// </summary>
        /// <param name="classSymbol"></param>
        /// <param name="compilation"></param>
        /// <param name="processedTypes"></param>
        /// <returns></returns>
        private static string BuildAccessorsForType2(
           INamedTypeSymbol classSymbol,
           Compilation compilation,
           HashSet<ITypeSymbol> processedTypes)
        {
            var code = new StringBuilder();
            code.AppendLine("#pragma warning disable CS0419 // 禁用警告");
            code.AppendLine("// Generated code for " + classSymbol.Name);
            code.AppendLine("// <auto-generated/>");
            code.AppendLine("#nullable enable");
            code.AppendLine($"namespace {classSymbol.ContainingNamespace.ToDisplayString()};");
            code.AppendLine();

            code.AppendLine($"public sealed class {classSymbol.Name}Accessor : ISourceEntityAccessor<{classSymbol.Name}>");
            code.AppendLine("{");

            foreach (var prop in GetAllPropertiesInHierarchy(classSymbol))
            {
                if (prop.IsIndexer) continue;
                GeneratePropertyAccessorsForType(prop, code, compilation, processedTypes);
            }

            code.AppendLine("}");

            //var code3 = $@"
            //    public sealed class {classSymbol.Name}Accessor : ISourceEntityAccessor<{classSymbol.Name}>
            //    {{
            //        public object GetPropertyValue({classSymbol.Name} entity, string propName) => propName switch
            //        {{
            //            {GeneratePropertyCases(classSymbol)}
            //            _ => throw new ArgumentException(""无效属性名"")
            //        }};

            //        {GenerateTupleSupport(classSymbol)}
            //    }}";

            return code.ToString();
        }

        /// <summary>
        /// 获取泛型参数
        /// </summary>
        /// <param name="symbol"></param>
        /// <returns></returns>
        public static string GetGenericParams(INamedTypeSymbol symbol)
        {
            if (!symbol.IsGenericType) return "";
            var parameters = symbol.TypeParameters.Select(t => t.Name);
            return $"<{string.Join(", ", parameters)}>";
        }

        /// <summary>
        /// 生成属性访问器代码
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="code"></param>
        /// <param name="compilation"></param>
        /// <param name="processedTypes"></param>
        private static void GeneratePropertyAccessorsForType(
            IPropertySymbol prop,
            StringBuilder code,
            Compilation compilation,
            HashSet<ITypeSymbol> processedTypes)
        {
            // 安全类型转换
            if (prop.Type is not ITypeSymbol propType) return;

            code.AppendLine($"    // Processing property: {prop.Name}");

            // 处理元组类型
            if (propType is INamedTypeSymbol { IsTupleType: true } tupleType)
            {
                GenerateTupleAccessors(prop, tupleType, code);
            }
            else if (propType is INamedTypeSymbol namedType)
            {
                GenerateStandardAccessors(prop, namedType, code);
                ProcessNestedType(namedType, compilation, processedTypes);
            }
        }

        /// <summary>
        /// 处理元组类型
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="tupleType"></param>
        /// <param name="code"></param>
        private static void GenerateTupleAccessors(IPropertySymbol prop, INamedTypeSymbol tupleType, StringBuilder code)
        {
            var elements = tupleType.TupleElements;
            var parentType = prop.ContainingType.ToDisplayString();

            for (int i = 0; i < elements.Length; i++)
            {
                var element = elements[i];
                if (element.Type is not ITypeSymbol elementType) continue;

                var elementName = element.CorrespondingTupleField?.Name ?? $"Item{i + 1}";
                code.AppendLine($"    public static {elementType.ToDisplayString()} Get{prop.Name}_{elementName}({parentType} obj) => obj.{prop.Name}.{elementName};");

                if (prop.SetMethod != null)
                {
                    var assignments = elements.Select((e, idx) =>
                        idx == i ? "value" : $"obj.{prop.Name}.{e.Name}");
                    code.AppendLine($"    public static void Set{prop.Name}_{elementName}({parentType} obj, {elementType.ToDisplayString()} value) => obj.{prop.Name} = ({string.Join(", ", assignments)});");
                }
            }
        }

        /// <summary>
        /// 生成标准属性的访问器
        /// </summary>
        /// <param name="prop"></param>
        /// <param name="propType"></param>
        /// <param name="code"></param>
        private static void GenerateStandardAccessors(IPropertySymbol prop, INamedTypeSymbol propType, StringBuilder code)
        {
            var parentType = prop.ContainingType.ToDisplayString();
            code.AppendLine($"    public static {propType.ToDisplayString()} Get{prop.Name}({parentType} obj) => obj.{prop.Name};");

            if (prop.SetMethod != null)
            {
                code.AppendLine($"    public static void Set{prop.Name}({parentType} obj, {propType.ToDisplayString()} value) => obj.{prop.Name} = value;");
            }
        }

        
        /// <summary>
        /// 处理嵌套类型
        /// </summary>
        /// <param name="typeSymbol"></param>
        /// <param name="compilation"></param>
        /// <param name="processedTypes"></param>
        private static void ProcessNestedType(ITypeSymbol typeSymbol, Compilation compilation, HashSet<ITypeSymbol> processedTypes)
        {
            if (typeSymbol is not INamedTypeSymbol namedType) return;
            if (!ShouldProcessNestedType(namedType)) return;
            if (!processedTypes.Add(namedType)) return;

            var code = BuildAccessorsForType(namedType, compilation, processedTypes);
        }

        /// <summary>
        /// 处理嵌套类型
        /// </summary>
        /// <param name="symbol"></param>
        /// <returns></returns>
        private static bool ShouldProcessNestedType(INamedTypeSymbol symbol)
        {
            return symbol.DeclaredAccessibility == Accessibility.Public &&
                   !symbol.IsTupleType &&
                   !symbol.IsAnonymousType &&
                   !symbol.IsImplicitlyDeclared &&
                   !symbol.Name.StartsWith("<");
        }

        /// <summary>
        /// 生成扩展类工厂代码
        /// </summary>
        /// <returns></returns>
        private static string BuildFactoryCode()
        {
            return """
            using System;
            using System.Collections.Concurrent;
            namespace JiShe.CollectBus.Analyzers.Shared;
            public static class SourceEntityAccessorFactory
            {
                private static readonly ConcurrentDictionary<Type, object> _accessors = new();
                
                public static ISourceEntityAccessor<T> GetAccessor<T>()
                {
                    if (!_accessors.TryGetValue(typeof(T), out var accessor))
                    {
                        accessor = Activator.CreateInstance(
                            Type.GetType($"{typeof(T).Namespace}.{typeof(T).Name}Accessor")!)!;
                        _accessors.TryAdd(typeof(T), accessor);
                    }
                    return (ISourceEntityAccessor<T>)accessor!;
                }
            }
            """;
        }
    }
}