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

namespace QWERTYkez.Mensura.Generator;

[Generator(LanguageNames.CSharp)]
internal class CollectionsOperatorsGenerator : IIncrementalGenerator
{
    private const string AttributeShortName = "CollectionsOperatorsGenerator";
    private const string AttributeFullName = AttributeShortName + "Attribute";

    private const string AttributeSource = @"namespace QWERTYkez.Mensura;

[System.AttributeUsage(System.AttributeTargets.Struct | System.AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
internal sealed class CollectionsOperatorsGeneratorAttribute : System.Attribute { }";

    public void Initialize(IncrementalGeneratorInitializationContext context)
    {
        context.RegisterPostInitializationOutput(context =>
            context.AddSource(
                $"{AttributeFullName}.g",
                SourceText.From(AttributeSource, Encoding.UTF8)));

        var operatorsPipeline =
            context.SyntaxProvider.CreateSyntaxProvider<KeyValuePair<ClassData, ImmutableArray<Operation>>>(
                (node, _) =>
                {
                    if (node is ClassDeclarationSyntax cds)
                    {
                        SyntaxNode sn = cds;
                        while (sn.Parent is not null &&
                               sn.Parent is not FileScopedNamespaceDeclarationSyntax)
                        {
                            sn = sn.Parent;
                        }
                        if (sn.Parent is FileScopedNamespaceDeclarationSyntax
                            && cds.TypeParameterList is null
                            &&
                            ((cds.Members.OfType<OperatorDeclarationSyntax>()
                                .Where(m => m.AttributeLists.SelectMany(al => al.Attributes)
                                        .Any(a => a.Name.GetText().ToString().Contains(AttributeShortName)))
                                .Any())
                            ||
                            (cds.Modifiers.Any(m => m.Text == "partial")
                                && cds.AttributeLists
                                    .SelectMany(al => al.Attributes)
                                    .Any(a => a.Name
                                        .GetText()
                                        .ToString()
                                        .Contains(AttributeShortName)))))
                        {
                            return true;
                        }
                    }
                    return false;
                },
                (syntax, _) =>
                {
                    string nameSpace;
                    var cds = (ClassDeclarationSyntax)syntax.Node;
                    {
                        SyntaxNode sn = cds;
                        while (sn.Parent is not FileScopedNamespaceDeclarationSyntax)
                        {
                            sn = sn.Parent!;
                        }
                        var nds = (FileScopedNamespaceDeclarationSyntax)sn.Parent;
                        nameSpace = nds.Name.ToString();
                    }
                    var Res = new StringBuilder();
                    {
                        Res.Append(cds.Modifiers);
                        Res.Append(" class ");
                        Res.Append(cds.Identifier.Text);
                        Res.Append(" ");
                        Res.Append(cds.BaseList);
                        Res.Append(" ");
                        Res.Append(cds.ConstraintClauses);
                    }

                    var operators = cds.Members.OfType<OperatorDeclarationSyntax>()
                        .Where(m => m.AttributeLists
                            .SelectMany(al => al.Attributes)
                            .Any(a => a.Name.GetText().ToString().Contains(AttributeShortName)))
                        .Where(mb => mb.ParameterList.Parameters.Count == 2)
                        .Select(mb => new Operation()
                        {
                            ReturnType = mb.ReturnType.ToString(),
                            OperatorToken = mb.OperatorToken.Text,
                            TypeA = mb.ParameterList.Parameters[0].Type!.ToString(),
                            TypeB = mb.ParameterList.Parameters[1].Type!.ToString(),
                        });
                    return new(new(nameSpace, cds.Identifier.Text, Res.ToString()), [.. operators]);
                })
            .Collect();

        context.RegisterSourceOutput(operatorsPipeline, GenerateOperators);
    }

    readonly static string[] CollectionTypes = ["MetricArray", "MetricList", "MetricObservableCollection"];
    static void GenerateOperators(SourceProductionContext context, ImmutableArray<KeyValuePair<ClassData, ImmutableArray<Operation>>> pairs)
    {
        foreach (var ng in pairs.GroupBy(c => c.Key.NameSpace))
        {
            StringBuilder document = new("namespace ");
            document.Append(ng.Key);
            document.Append(";");

            var classes = ng.ToList().Select(c => (ClassData?)c.Key).ToList();
            var operations = ng.ToList().SelectMany(c => c.Value).ToList();
            var multiplications = operations.Where(op => op.OperatorToken == "*").ToList();
            var divisions = operations.Where(op => op.OperatorToken == "/").ToList();

            foreach (var ops in multiplications.GroupBy(op => op.TypeA))
            {
                var Class = classes.FirstOrDefault(cl => cl!.Value.ClassName == ops.Key);
                if (Class is not null)
                {
                    document.AppendLine();
                    document.AppendLine();
                    document.AppendLine(Class.Value.ClassHeader);
                    document.AppendLine("{");
                    foreach (var op in ops)
                        foreach (var ct in CollectionTypes)
                        {
                            document.AppendLine(@$"
    public static {ct}<{op.ReturnType}> operator *({op.TypeA} left, {ct}<{op.TypeB}> right) => right.MetricSelect(UU => left * UU);
    public static {ct}<{op.ReturnType}> operator *({ct}<{op.TypeB}> left, {op.TypeA} right) => left.MetricSelect(UU => UU * right);
");
                        }
                    document.Append("}");
                }
                else
                {
                    context.ReportDiagnostic(Diagnostic.Create(new(
                        "MSG0001",
                        "Need a class with an attribute",
                        $"It is necessary to have a empty partial class \"{ops.Key}\" with the attribute \"{AttributeShortName}\"",
                        "category",
                        DiagnosticSeverity.Error,
                        true), null, ops.Key));
                }
            }

            foreach (var ops in divisions.GroupBy(op => op.TypeA))
            {
                var Class = classes.FirstOrDefault(cl => cl!.Value.ClassName == ops.Key);
                if (Class is not null)
                {
                    document.AppendLine();
                    document.AppendLine();
                    document.AppendLine(Class.Value.ClassHeader);
                    document.AppendLine("{");
                    foreach (var op in ops)
                        foreach (var ct in CollectionTypes)
                        {
                            document.AppendLine(@$"
    public static {ct}<{op.ReturnType}> operator /({op.TypeA} left, {ct}<{op.TypeB}> right) => right.MetricSelect(UU => left / UU);
");
                        }
                    document.Append("}");
                }
                else
                {
                    context.ReportDiagnostic(Diagnostic.Create(new(
                        "MSG0001",
                        "Need a class with an attribute",
                        $"It is necessary to have a empty partial class \"{ops.Key}\" with the attribute \"{AttributeShortName}\"",
                        "category",
                        DiagnosticSeverity.Error,
                        true), null, ops.Key));
                }
            }
            foreach (var ops in divisions.GroupBy(op => op.TypeB))
            {
                var Class = classes.FirstOrDefault(cl => cl!.Value.ClassName == ops.Key);
                if (Class is not null)
                {
                    document.AppendLine();
                    document.AppendLine();
                    document.AppendLine(Class.Value.ClassHeader);
                    document.AppendLine("{");
                    foreach (var op in ops)
                        foreach (var ct in CollectionTypes)
                        {
                            document.AppendLine(@$"
    public static {ct}<{op.ReturnType}> operator /({ct}<{op.TypeA}> left, {op.TypeB} right) => left.MetricSelect(UU => UU / right);
");
                        }
                    document.Append("}");
                }
                else
                {
                    context.ReportDiagnostic(Diagnostic.Create(new(
                        "MSG0001",
                        "Need a class with an attribute",
                        $"It is necessary to have a empty partial class \"{ops.Key}\" with the attribute \"{AttributeShortName}\"",
                        "category",
                        DiagnosticSeverity.Error,
                        true), null, ops.Key));
                }
            }

            context.AddSource($"operations.{ng.Key}.g", document.ToString());
        }
    }
}

public struct ClassData(string nameSpace, string className, string classHeader)
{
    public string NameSpace = nameSpace;
    public string ClassName = className;
    public string ClassHeader = classHeader;
}
public struct Operation(string operatorToken, string typeA, string typeB, string returnType)
{
    public string ReturnType = returnType;
    public string OperatorToken = operatorToken;
    public string TypeA = typeA;
    public string TypeB = typeB;
}