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

namespace Godot.SourceGenerators
{
    static class ExtensionMethods
    {
        public static bool TryGetGlobalAnalyzerProperty(
            this GeneratorExecutionContext context, string property, out string? value
        ) => context.AnalyzerConfigOptions.GlobalOptions
            .TryGetValue("build_property." + property, out value);

        public static bool AreGodotSourceGeneratorsDisabled(this GeneratorExecutionContext context)
            => context.TryGetGlobalAnalyzerProperty("GodotSourceGenerators", out string? toggle) &&
               toggle != null &&
               toggle.Equals("disabled", StringComparison.OrdinalIgnoreCase);

        public static bool IsGodotToolsProject(this GeneratorExecutionContext context)
            => context.TryGetGlobalAnalyzerProperty("IsGodotToolsProject", out string? toggle) &&
               toggle != null &&
               toggle.Equals("true", StringComparison.OrdinalIgnoreCase);

        private static bool InheritsFrom(this INamedTypeSymbol? symbol, string baseName)
        {
            if (symbol == null)
                return false;

            while (true)
            {
                if (symbol.ToString() == baseName)
                {
                    return true;
                }

                if (symbol.BaseType != null)
                {
                    symbol = symbol.BaseType;
                    continue;
                }

                break;
            }

            return false;
        }

        private static bool IsGodotScriptClass(
            this ClassDeclarationSyntax cds, Compilation compilation,
            out INamedTypeSymbol? symbol
        )
        {
            var sm = compilation.GetSemanticModel(cds.SyntaxTree);

            var classTypeSymbol = sm.GetDeclaredSymbol(cds);

            if (classTypeSymbol?.BaseType == null
                || !classTypeSymbol.BaseType.InheritsFrom(GodotClasses.Object))
            {
                symbol = null;
                return false;
            }

            symbol = classTypeSymbol;
            return true;
        }

        public static IEnumerable<(ClassDeclarationSyntax cds, INamedTypeSymbol symbol)> SelectGodotScriptClasses(
            this IEnumerable<ClassDeclarationSyntax> source,
            Compilation compilation
        )
        {
            foreach (var cds in source)
            {
                if (cds.IsGodotScriptClass(compilation, out var symbol))
                    yield return (cds, symbol!);
            }
        }

        public static bool IsNested(this TypeDeclarationSyntax cds)
            => cds.Parent is TypeDeclarationSyntax;

        public static bool IsPartial(this TypeDeclarationSyntax cds)
            => cds.Modifiers.Any(SyntaxKind.PartialKeyword);

        public static bool AreAllOuterTypesPartial(
            this TypeDeclarationSyntax cds,
            out TypeDeclarationSyntax? typeMissingPartial
        )
        {
            SyntaxNode? outerSyntaxNode = cds.Parent;

            while (outerSyntaxNode is TypeDeclarationSyntax outerTypeDeclSyntax)
            {
                if (!outerTypeDeclSyntax.IsPartial())
                {
                    typeMissingPartial = outerTypeDeclSyntax;
                    return false;
                }

                outerSyntaxNode = outerSyntaxNode.Parent;
            }

            typeMissingPartial = null;
            return true;
        }

        public static string GetDeclarationKeyword(this INamedTypeSymbol namedTypeSymbol)
        {
            string? keyword = namedTypeSymbol.DeclaringSyntaxReferences
                .OfType<TypeDeclarationSyntax>().FirstOrDefault()?
                .Keyword.Text;

            return keyword ?? namedTypeSymbol.TypeKind switch
            {
                TypeKind.Interface => "interface",
                TypeKind.Struct => "struct",
                _ => "class"
            };
        }

        private static SymbolDisplayFormat FullyQualifiedFormatOmitGlobal { get; } =
            SymbolDisplayFormat.FullyQualifiedFormat
                .WithGlobalNamespaceStyle(SymbolDisplayGlobalNamespaceStyle.Omitted);

        public static string FullQualifiedName(this ITypeSymbol symbol)
            => symbol.ToDisplayString(NullableFlowState.NotNull, FullyQualifiedFormatOmitGlobal);

        public static string FullQualifiedName(this INamespaceSymbol namespaceSymbol)
            => namespaceSymbol.ToDisplayString(FullyQualifiedFormatOmitGlobal);
    }
}