// Copyright (c) All contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using MessagePack.Formatters;

namespace MessagePack.Resolvers
{
    public sealed class NativeGuidResolver : IFormatterResolver
    {
        /// <summary>
        /// The singleton instance that can be used.
        /// </summary>
        public static readonly NativeGuidResolver Instance = new NativeGuidResolver();

        private NativeGuidResolver()
        {
        }

        public IMessagePackFormatter<T> GetFormatter<T>()
        {
            return FormatterCache<T>.Formatter;
        }

        private static object GetFormatterHelper(Type t)
        {
            if (t == typeof(Guid))
            {
                return NativeGuidFormatter.Instance;
            }
            else if (t == typeof(Guid?))
            {
                return new StaticNullableFormatter<Guid>(NativeGuidFormatter.Instance);
            }

            return null;
        }

        private static class FormatterCache<T>
        {
            public static readonly IMessagePackFormatter<T> Formatter;

            static FormatterCache()
            {
                Formatter = (IMessagePackFormatter<T>)GetFormatterHelper(typeof(T));
            }
        }
    }
}