using System;
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 : ISourceGenerator
    {
        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
    {{
    }}
}}";

        /// <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(GeneratorExecutionContext 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() == "System.Threading.Tasks.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 tokenInsert = isAsync
                        ? isParametrized
                            ? ", cancellationToken : " + method.Parameters[1].Name
                            : ", cancellationToken : " + method.Parameters[0].Name
                        : String.Empty;
                    var caller = isVoid
                        ? $"CallAsync({index}{parameterLink}{tokenInsert})"
                        : isAsync
                            ? $"GetResultAsync<{ExtractTaskType(method.ReturnType)}>({index}{parameterLink}{tokenInsert})"
                            : $"GetResultAsync<{ToFullString(method.ReturnType)}>({index}{parameterLink}{tokenInsert})";

                    if (!isVoid)
                        prefix = "return " + prefix;

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

                    sb.AppendLine("\t\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}\", new Type[] {{{string.Join(", ", i.Item2.Parameters.Select(p => $"typeof({p.Type.ToDisplayString()})"))}}})")
                //     .ToList();
                var methodsStringed = methods.Select(i =>
                        $"typeof({i.Item1}).GetMethod(\"{i.Item2.Name}\")")
                    .ToList();

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

namespace mROA.Codegen
{{
    public class CoCodegenMethodRepository : IMethodRepository
    {{
        private readonly List<MethodInfo> _methods = new () {{
            {string.Join(",\r\n\t\t\t", methodsStringed)}
        }};

        public MethodInfo GetMethod(int id)
        {{
            if (id == -1)
                return typeof(IDisposable).GetMethod(""Dispose"");

            if (_methods.Count <= id)
                return null;
            
            return _methods[id];
        }}

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

namespace mROA.Codegen
{{
    public sealed class RemoteTypeBinder
    {{
        static RemoteTypeBinder(){{
            RemoteContextRepository.RemoteTypes = new Dictionary<Type, Type> {{
            {string.Join(", \r\n\t\t\t", frontendContextRepo)}}};
        }}
    }}
}}
";
                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);
        }

        public void Initialize(GeneratorInitializationContext context)
        {
        }

        public void Execute(GeneratorExecutionContext context)
        {
            var trees = context.Compilation.SyntaxTrees;

            var interfaces = new List<InterfaceDeclarationSyntax>();
            foreach (var tree in trees)
            {
                var node = tree.GetRoot() as CompilationUnitSyntax;

                foreach (var member in node.Members)
                {
                    if (member is InterfaceDeclarationSyntax ids)
                    {
                        interfaces.Add(ids);
                    }
                    else if (member is NamespaceDeclarationSyntax nds)
                    {
                        foreach (var inside in nds.Members)

                            if (inside is InterfaceDeclarationSyntax ids2)
                                if (ContainsSOIAttribute(ids2.AttributeLists, context, ids2))
                                    interfaces.Add(ids2);
                    }
                }
            }

            GenerateCode(context, context.Compilation, interfaces.ToImmutableArray());
        }

        private bool ContainsSOIAttribute(SyntaxList<AttributeListSyntax> attributes, GeneratorExecutionContext context,
            InterfaceDeclarationSyntax interfaceDeclarationSyntax)
        {
            foreach (AttributeListSyntax attributeListSyntax in attributes)
            foreach (AttributeSyntax attributeSyntax in attributeListSyntax.Attributes)
            {
                if (context.Compilation.GetSemanticModel(interfaceDeclarationSyntax.SyntaxTree)
                        .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 true;
            }

            return false;
        }
    }
}