// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#nullable disable

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

namespace Microsoft.CodeAnalysis.CSharp.Extensions;

internal static partial class MemberDeclarationSyntaxExtensions
{
    private static readonly ConditionalWeakTable<MemberDeclarationSyntax, Dictionary<string, ImmutableArray<SyntaxToken>>> s_declarationCache = new();

    public static LocalDeclarationMap GetLocalDeclarationMap(this MemberDeclarationSyntax member)
        => new(s_declarationCache.GetValue(member, static member =>
        {
            var dictionary = DeclarationFinder.GetAllDeclarations(member);
            return dictionary.ToDictionary(kvp => kvp.Key, kvp => kvp.Value.AsImmutable());
        }));

    public static SyntaxToken GetNameToken(this MemberDeclarationSyntax member)
    {
        if (member != null)
        {
            switch (member.Kind())
            {
                case SyntaxKind.EnumDeclaration:
                    return ((EnumDeclarationSyntax)member).Identifier;
                case SyntaxKind.ClassDeclaration:
#if !OLDER_ROSLYN
                case SyntaxKind.ExtensionBlockDeclaration:
                case SyntaxKind.UnionDeclaration:
#endif
                case SyntaxKind.InterfaceDeclaration:
                case SyntaxKind.RecordDeclaration:
                case SyntaxKind.RecordStructDeclaration:
                case SyntaxKind.StructDeclaration:
                    return ((TypeDeclarationSyntax)member).Identifier;
                case SyntaxKind.DelegateDeclaration:
                    return ((DelegateDeclarationSyntax)member).Identifier;
                case SyntaxKind.FieldDeclaration:
                    return ((FieldDeclarationSyntax)member).Declaration.Variables.First().Identifier;
                case SyntaxKind.EventFieldDeclaration:
                    return ((EventFieldDeclarationSyntax)member).Declaration.Variables.First().Identifier;
                case SyntaxKind.PropertyDeclaration:
                    return ((PropertyDeclarationSyntax)member).Identifier;
                case SyntaxKind.EventDeclaration:
                    return ((EventDeclarationSyntax)member).Identifier;
                case SyntaxKind.MethodDeclaration:
                    return ((MethodDeclarationSyntax)member).Identifier;
                case SyntaxKind.ConstructorDeclaration:
                    return ((ConstructorDeclarationSyntax)member).Identifier;
                case SyntaxKind.DestructorDeclaration:
                    return ((DestructorDeclarationSyntax)member).Identifier;
                case SyntaxKind.IndexerDeclaration:
                    return ((IndexerDeclarationSyntax)member).ThisKeyword;
                case SyntaxKind.OperatorDeclaration:
                    return ((OperatorDeclarationSyntax)member).OperatorToken;
            }
        }

        // Conversion operators don't have names.
        return default;
    }

    public static int GetArity(this MemberDeclarationSyntax member)
    {
        if (member != null)
        {
            switch (member.Kind())
            {
                case SyntaxKind.ClassDeclaration:
#if !OLDER_ROSLYN
                case SyntaxKind.ExtensionBlockDeclaration:
                case SyntaxKind.UnionDeclaration:
#endif
                case SyntaxKind.InterfaceDeclaration:
                case SyntaxKind.RecordDeclaration:
                case SyntaxKind.RecordStructDeclaration:
                case SyntaxKind.StructDeclaration:
                    return ((TypeDeclarationSyntax)member).Arity;
                case SyntaxKind.DelegateDeclaration:
                    return ((DelegateDeclarationSyntax)member).Arity;
                case SyntaxKind.MethodDeclaration:
                    return ((MethodDeclarationSyntax)member).Arity;
            }
        }

        return 0;
    }

#nullable enable

    public static TypeParameterListSyntax? GetTypeParameterList(this MemberDeclarationSyntax member)
    {
        if (member != null)
        {
            switch (member.Kind())
            {
                case SyntaxKind.ClassDeclaration:
#if !OLDER_ROSLYN
                case SyntaxKind.ExtensionBlockDeclaration:
                case SyntaxKind.UnionDeclaration:
#endif
                case SyntaxKind.InterfaceDeclaration:
                case SyntaxKind.RecordDeclaration:
                case SyntaxKind.RecordStructDeclaration:
                case SyntaxKind.StructDeclaration:
                    return ((TypeDeclarationSyntax)member).TypeParameterList;
                case SyntaxKind.DelegateDeclaration:
                    return ((DelegateDeclarationSyntax)member).TypeParameterList;
                case SyntaxKind.MethodDeclaration:
                    return ((MethodDeclarationSyntax)member).TypeParameterList;
            }
        }

        return null;
    }

#nullable disable

    public static MemberDeclarationSyntax WithParameterList(
        this MemberDeclarationSyntax member,
        BaseParameterListSyntax parameterList)
    {
        if (member != null)
        {
            switch (member.Kind())
            {
                case SyntaxKind.DelegateDeclaration:
                    return ((DelegateDeclarationSyntax)member).WithParameterList((ParameterListSyntax)parameterList);
                case SyntaxKind.MethodDeclaration:
                    return ((MethodDeclarationSyntax)member).WithParameterList((ParameterListSyntax)parameterList);
                case SyntaxKind.ConstructorDeclaration:
                    return ((ConstructorDeclarationSyntax)member).WithParameterList((ParameterListSyntax)parameterList);
                case SyntaxKind.IndexerDeclaration:
                    return ((IndexerDeclarationSyntax)member).WithParameterList((BracketedParameterListSyntax)parameterList);
                case SyntaxKind.OperatorDeclaration:
                    return ((OperatorDeclarationSyntax)member).WithParameterList((ParameterListSyntax)parameterList);
                case SyntaxKind.ConversionOperatorDeclaration:
                    return ((ConversionOperatorDeclarationSyntax)member).WithParameterList((ParameterListSyntax)parameterList);
            }
        }

        return null;
    }

    public static TypeSyntax GetMemberType(this MemberDeclarationSyntax member)
    {
        if (member != null)
        {
            switch (member.Kind())
            {
                case SyntaxKind.DelegateDeclaration:
                    return ((DelegateDeclarationSyntax)member).ReturnType;
                case SyntaxKind.MethodDeclaration:
                    return ((MethodDeclarationSyntax)member).ReturnType;
                case SyntaxKind.OperatorDeclaration:
                    return ((OperatorDeclarationSyntax)member).ReturnType;
                case SyntaxKind.PropertyDeclaration:
                    return ((PropertyDeclarationSyntax)member).Type;
                case SyntaxKind.IndexerDeclaration:
                    return ((IndexerDeclarationSyntax)member).Type;
                case SyntaxKind.EventDeclaration:
                    return ((EventDeclarationSyntax)member).Type;
                case SyntaxKind.EventFieldDeclaration:
                    return ((EventFieldDeclarationSyntax)member).Declaration.Type;
                case SyntaxKind.FieldDeclaration:
                    return ((FieldDeclarationSyntax)member).Declaration.Type;
            }
        }

        return null;
    }

    public static bool HasMethodShape(this MemberDeclarationSyntax memberDeclaration)
        => memberDeclaration is BaseMethodDeclarationSyntax;

    public static BlockSyntax GetBody(this MemberDeclarationSyntax memberDeclaration)
        => (memberDeclaration as BaseMethodDeclarationSyntax)?.Body;

    public static ArrowExpressionClauseSyntax GetExpressionBody(this MemberDeclarationSyntax memberDeclaration)
        => memberDeclaration switch
        {
            BaseMethodDeclarationSyntax method => method.ExpressionBody,
            IndexerDeclarationSyntax indexer => indexer.ExpressionBody,
            PropertyDeclarationSyntax property => property.ExpressionBody,
            _ => null,
        };

    public static MemberDeclarationSyntax WithBody(this MemberDeclarationSyntax memberDeclaration, BlockSyntax body)
        => (memberDeclaration as BaseMethodDeclarationSyntax)?.WithBody(body);
}