#nullable enable

using System;
using System.Collections.Generic;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;

namespace SharpGen.Model
{
    public sealed class InteropMethodSignatureParameter
    {
        public InteropMethodSignatureParameter(InteropType interopType, CsMarshalCallableBase item, string? name = null)
        {
            InteropType = interopType ?? throw new ArgumentNullException(nameof(interopType));
            Item = item ?? throw new ArgumentNullException(nameof(item));
            Name = name ?? Wrap(item.Name ?? throw new ArgumentNullException(nameof(item)));
            InteropTypeSyntax = ParseTypeName(InteropType.TypeName);

            static string Wrap(string name) => name[0] == '@' ? $"_{name.Substring(1)}" : $"_{name}";
        }

        public InteropType InteropType { get; }
        public CsMarshalCallableBase Item { get; }
        public string Name { get; }
        public TypeSyntax InteropTypeSyntax { get; }

        private sealed class TypeEqualityComparer : IEqualityComparer<InteropMethodSignatureParameter>
        {
            public bool Equals(InteropMethodSignatureParameter? x, InteropMethodSignatureParameter? y)
            {
                if (ReferenceEquals(x, y)) return true;
                if (ReferenceEquals(x, null)) return false;
                if (ReferenceEquals(y, null)) return false;
                return x.GetType() == y.GetType() && x.InteropType.Equals(y.InteropType);
            }

            public int GetHashCode(InteropMethodSignatureParameter obj)
            {
                return obj.InteropType.GetHashCode();
            }
        }

        public static IEqualityComparer<InteropMethodSignatureParameter> TypeComparer { get; } =
            new TypeEqualityComparer();
    }
}