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


namespace mROA.Codegen;

/// <summary>
/// A sample source generator that creates a custom report based on class properties. The target class should be annotated with the 'Generators.ReportAttribute' attribute.
/// When using the source code as a baseline, an incremental source generator is preferable because it reduces the performance overhead.
/// </summary>
[Generator]
public class mROASourceGenerator : IIncrementalGenerator
{
    private const string Namespace = "mROA.Implementation";
    private const string AttributeName = "SharedObjectInterafceAttribute";

    private const string AttributeSourceCode = $@"// <auto-generated/>

namespace {Namespace}
{{
    [System.AttributeUsage(System.AttributeTargets.Class)]
    public class {AttributeName} : System.Attribute
    {{
    }}
}}";

    public void Initialize(IncrementalGeneratorInitializationContext context)
    {
        // Filter classes annotated with the [Report] attribute. Only filtered Syntax Nodes can trigger code generation.
        var provider = context.SyntaxProvider
            .CreateSyntaxProvider(
                (s, _) => s is InterfaceDeclarationSyntax,
                (ctx, _) => GetClassDeclarationForSourceGen(ctx))
            .Where(t => t.reportAttributeFound)
            .Select((t, _) => t.Item1);

        // Generate the source code.
        context.RegisterSourceOutput(context.CompilationProvider.Combine(provider.Collect()),
            ((ctx, t) => GenerateCode(ctx, t.Left, t.Right)));
    }

    /// <summary>
    /// Checks whether the Node is annotated with the [Report] attribute and maps syntax context to the specific node type (ClassDeclarationSyntax).
    /// </summary>
    /// <param name="context">Syntax context, based on CreateSyntaxProvider predicate</param>
    /// <returns>The specific cast and whether the attribute was found.</returns>
    private static (InterfaceDeclarationSyntax, bool reportAttributeFound) GetClassDeclarationForSourceGen(
        GeneratorSyntaxContext context)
    {
        var classDeclarationSyntax = (InterfaceDeclarationSyntax)context.Node;

        // Go through all attributes of the class.
        foreach (AttributeListSyntax attributeListSyntax in classDeclarationSyntax.AttributeLists)
        foreach (AttributeSyntax attributeSyntax in attributeListSyntax.Attributes)
        {
            if (context.SemanticModel.GetSymbolInfo(attributeSyntax).Symbol is not IMethodSymbol attributeSymbol)
                continue; // if we can't get the symbol, ignore it

            string attributeName = attributeSymbol.ContainingType.ToDisplayString();

            // Check the full name of the [Report] attribute.
            if (attributeName == "mROA.Implementation.Attributes.SharedObjectInterfaceAttribute")
                return (classDeclarationSyntax, true);
        }

        return (classDeclarationSyntax, false);
    }

    /// <summary>
    /// Generate code action.
    /// It will be executed on specific nodes (ClassDeclarationSyntax annotated with the [Report] attribute) changed by the user.
    /// </summary>
    /// <param name="context">Source generation context used to add source files.</param>
    /// <param name="compilation">Compilation used to provide access to the Semantic Model.</param>
    /// <param name="classes">Nodes annotated with the [Report] attribute that trigger the generate action.</param>
    private void GenerateCode(SourceProductionContext context, Compilation compilation,
        ImmutableArray<InterfaceDeclarationSyntax> classes)
    {
        var methods = new List<(string, IMethodSymbol)>();
        var frontendContextRepo = new List<string>();
        // Go through all filtered class declarations.
        var declarations = classes.ToList().OrderBy(i => i.Identifier.Text).ToList();
        foreach (var classDeclarationSyntax in declarations)
        {
            // We need to get semantic model of the class to retrieve metadata.
            var semanticModel = compilation.GetSemanticModel(classDeclarationSyntax.SyntaxTree);


            // Symbols allow us to get the compile-time information.
            if (semanticModel.GetDeclaredSymbol(classDeclarationSyntax) is not INamedTypeSymbol classSymbol)
                continue;


            var namespaceName = classSymbol.ContainingNamespace.ToDisplayString();

            // 'Identifier' means the token of the node. Get class name from the syntax node.
            var className = classDeclarationSyntax.Identifier.Text;

            // Go through all class members with a particular type (property) to generate method lines.
            var methodBody = classSymbol.GetMembers()
                .OfType<IMethodSymbol>().OrderBy(i => i.Name);

            var originalName = className;
            // Build up the source code
            className = className.TrimStart('I') + "RemoteEndpoint";


            var methodsText = new List<string>();

            foreach (var method in methodBody)
            {
                var index = methods.Count;
                methods.Add((namespaceName + "." + originalName, method));
                var sb = new StringBuilder();


                bool isAsync = method.ReturnType.Name == "Task";
                bool isVoid = method.ReturnType.Name == "Void" || method.ReturnType.ToString() == "Task";
                bool isParametrized = method.Parameters.Length == 1 && !isAsync ||
                                      method.Parameters.Length == 2 && isAsync;


                //Creating signature
                sb.AppendLine("public" + (isAsync
                                  ? " async "
                                  : " ") +
                              $"{method.ReturnType.ToDisplayString()} {method.Name}({string.Join(", ", method.Parameters.Select(ToFullString))}){{");


                var prefix = isAsync ? "await " : "";
                var postfix = !isAsync ? (isVoid? ".Wait()" : ".GetAwaiter().GetResult()") : "";
                var parameterLink = isParametrized ? ", " + method.Parameters.First().Name : string.Empty;
                var caller = isVoid ? $"CallAsync({index}{parameterLink})" :
                    isAsync ? $"GetResultAsync<{ExtractTaskType(method.ReturnType)}>({index}{parameterLink})" :
                    $"GetResultAsync<{ToFullString(method.ReturnType)}>({index}{parameterLink})";

                if (!isVoid)
                    prefix = "return " + prefix;
                
                // if (method.ReturnType.OriginalDefinition.ToString() == "System.Threading.Tasks.Task<TResult>")
                // {
                //     var type = method.ReturnType.ToString();
                //     type = type.Substring(type.IndexOf('<') + 1);
                //     type = type.Substring(0, type.Length - 1);
                //     sb.AppendLine(
                //         $"\t\tvar response = await serialisationModule.GetFinalCommandExecution<{type}>(defaultCallRequestCodegen.CallRequestId);");
                //     sb.AppendLine($"\t\treturn ({type})response.Result;");
                // }
                // else if (!isAsync && method.ReturnType.ToDisplayString() != "void")
                // {
                //     var type = method.ReturnType.ToDisplayString();
                //     sb.AppendLine(
                //         $"\t\tvar response = serialisationModule.GetFinalCommandExecution<{type}>(defaultCallRequestCodegen.CallRequestId).GetAwaiter().GetResult();");
                //     sb.AppendLine($"\t\treturn ({type})response.Result;");
                // }
                // else
                // {
                //     sb.AppendLine(
                //         "\t\tserialisationModule.GetNextCommandExecution<FinalCommandExecution>(defaultCallRequestCodegen.CallRequestId).Wait();");
                // }
                //
                // sb.AppendLine("\t}");

                sb.AppendLine("\t\t" + prefix + caller + postfix+ ";");
                
                sb.AppendLine("\t}");

                methodsText.Add(sb.ToString());
            }

            var code = $@"// <auto-generated/>

using mROA;
using System;
using mROA.Implementation;
using System.Collections.Generic;
using mROA.Abstract;

namespace {namespaceName};

partial class {className} : RemoteObjectBase, {originalName}
{{
    public {className}(int id, IRepresentationModule representationModule) : base(id, representationModule)
    {{
    }}

    {string.Join("\r\n\t", methodsText)}
}}
";


            // Add the source code to the compilation.
            context.AddSource($"{className}.g.cs", SourceText.From(code, Encoding.UTF8));

            frontendContextRepo.Add(
                $"{{ typeof({classSymbol.ToDisplayString()}), typeof({namespaceName}.{className}) }}");
        }

        if (methods.Count != 0)
        {
            var methodsStringed = methods.Select(i =>
                    $"typeof({i.Item1}).GetMethod(\"{i.Item2.Name}\", [{string.Join(", ", i.Item2.Parameters.Select(p => $"typeof({p.Type.ToDisplayString()})"))}])")
                .ToList();

            var coCodegenRepoCode = @$"// <auto-generated/>
using System.Collections.Generic;
using System.Reflection;
using mROA.Abstract;

namespace mROA.Codegen;

public class CoCodegenMethodRepository : IMethodRepository
{{
    private readonly List<MethodInfo> _methods = [
        {string.Join(", // test comment\r\n\t\t", methodsStringed)}
    ];
    public MethodInfo GetMethod(int id)
    {{
        if (_methods.Count <= id)
            return null;
        
        return _methods[id];
    }}

    public int RegisterMethod(MethodInfo method)
    {{
        _methods.Add(method);
        return _methods.Count - 1;
    }}

    public IEnumerable<MethodInfo> GetMethods()
    {{
        return _methods;
    }}

    public void Inject<T>(T dependency)
    {{
    }}
}}
";
            context.AddSource($"CoCodegenMethodRepository.g.cs", SourceText.From(coCodegenRepoCode, Encoding.UTF8));
        }

        if (frontendContextRepo.Count != 0)
        {
            var fronendRepoCode = @$"// <auto-generated/>
using System.Collections.Frozen;
using mROA.Implementation;
using mROA.Abstract;

namespace mROA.Codegen;

public sealed class RemoteTypeBinder
{{
    static RemoteTypeBinder(){{
        RemoteContextRepository.RemoteTypes = new Dictionary<Type, Type> {{
        {string.Join(", \r\n\t\t", frontendContextRepo)}}}.ToFrozenDictionary();
    }}
}}
";
            context.AddSource("RemoteTypeBinder.g.cs", SourceText.From(fronendRepoCode, Encoding.UTF8));
        }
    }

    private static string ToFullString(IParameterSymbol parameter)
        => /*parameter.Type.ContainingNamespace is null*/
            /*?*/ parameter.ToDisplayString();
            /*: $"{parameter.Type.ContainingNamespace.ToDisplayString()}.{parameter.Type.MetadataName} {parameter.Name}";*/

    private static string ToFullString(ITypeSymbol type) =>
        // => type.ContainingNamespace is null || type.Name == "Void"
             type.ToDisplayString();
            // : $"{type.ContainingNamespace.ToDisplayString()}.{type.MetadataName}";

    private string ExtractTaskType(ITypeSymbol taskType)
    {
        var type = taskType.ToString();
        type = type.Substring(type.IndexOf('<') + 1);
        return type.Substring(0, type.Length - 1);
    }
}