using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using TBL.CSharp.Serialization.Marshal.Context;

namespace TBL.CSharp.Serialization.Marshal
{
    /// <summary>
    /// Marshal 风格的序列化工具类
    /// <para>非线程安全的</para>
    /// </summary>
    public static class Marshal
    {
        /// <summary>
        /// 类型标记 Id
        /// </summary>
        public static class TypeId
        {
            /// <summary>
            /// 空引用
            /// </summary>
            public const byte Null = (byte)'0';
            
            /// <summary>
            /// 布尔值
            /// </summary>
            public const byte True = (byte)'T', False = (byte)'F';
            
            /// <summary>
            /// 符号及链接
            /// </summary>
            public const byte Symbol = (byte)':', SymbolLink = (byte)';';

            /// <summary>
            /// 对象及链接
            /// </summary>
            public const byte Object = (byte)'o', ObjectLink = (byte)'&';

            /// <summary>
            /// 对象字段
            /// </summary>
            public const byte ObjectFields = (byte)'*';

            /// <summary>
            /// 对象尾
            /// </summary>
            public const byte ObjectEnd = (byte)'!';

            /// <summary>
            /// 字符串
            /// </summary>
            public const byte String = (byte)'"';

            /// <summary>
            /// 元组
            /// </summary>
            public const byte Tuple = (byte)'t';

            /// <summary>
            /// 容器
            /// </summary>
            public const byte List = (byte)'[', Dictionary = (byte)'{';

            /// <summary>
            /// 数字类型
            /// </summary>
            public const byte
                Int8 = (byte)'b',
                Int8Unsigned = (byte)'B',
                Int16 = (byte)'s',
                Int16Unsigned = (byte)'S',
                Int32 = (byte)'i',
                Int32Unsigned = (byte)'I',
                Int64 = (byte)'l',
                Int64Unsigned = (byte)'L',
                Single = (byte)'r', 
                Double = (byte)'R';

            /// <summary>
            /// <see cref="IStreamSerializable"/>
            /// </summary>
            public const byte SpecialStreamFull = (byte)'W', SpecialStream = (byte)'w';

            /// <summary>
            /// <see cref="IProxiedSerializable"/>
            /// </summary>
            public const byte SpecialProxiedFull = (byte)'P', SpecialProxied = (byte)'p';

            /// <summary>
            /// <see cref="IUnsafeSerializable"/>
            /// </summary>
            public const byte SpecialUnsafeFull = (byte)'K', SpecialUnsafe = (byte)'k';

            /// <summary>
            /// 额外支持
            /// </summary>
            public const byte ExternalSupport = (byte)'E';

            /// <summary>
            /// 某类型是否应该用构造方法初始化
            /// </summary>
            public static bool IsShouldInitialize(byte typeId) =>
                typeId == SpecialStreamFull ||
                typeId == SpecialProxiedFull ||
                typeId == SpecialUnsafeFull;
        }

        /// <summary>
        /// 默认的序列化上下文
        /// </summary>
        private static readonly MarshalContextBasic DefaultContext = new MarshalContextBasic();

        /// <summary>
        /// 类型字段缓存表
        /// </summary>
        private static readonly IDictionary<Type, FieldInfo[]> TypeFieldsCache = new Dictionary<Type, FieldInfo[]>();

        #region Type

        /// <summary>
        /// 元组类型表
        /// </summary>
        public static readonly ISet<Type> ValueTupleTypes = new HashSet<Type>()
        {
            typeof(ValueTuple<>),
            typeof(ValueTuple<,>),
            typeof(ValueTuple<,,>),
            typeof(ValueTuple<,,,>),
            typeof(ValueTuple<,,,,>),
            typeof(ValueTuple<,,,,,>),
            typeof(ValueTuple<,,,,,,>),
            typeof(ValueTuple<,,,,,,,>)
        };
        
        /// <summary>
        /// 是否为可序列化元组
        /// </summary>
        public static bool IsSerializableTuple(this Type type)
        {
            return type.IsGenericType && type.IsValueType &&
                   ValueTupleTypes.Contains(type.GetGenericTypeDefinition());
        }
        
        /// <summary>
        /// 获取一个类型的实例字段
        /// </summary>
        public static IEnumerable<FieldInfo> GetInstanceFields(this Type type) =>
            type.GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);

        /// <summary>
        /// 该字段是否不参与序列化
        /// </summary>
        public static bool IsNonSerialized(this Type type, FieldInfo field) =>
            field.IsNotSerialized || type.GetEvent(field.Name) != null;

        #endregion
        
        /// <summary>
        /// 获取一个类型的字段组
        /// <para>做过缓存处理，重复使用可以提高性能</para>
        /// </summary>
        public static FieldInfo[] GetTypeFields(Type type)
        {
            // 使用类型字段缓存加速处理
            if (!TypeFieldsCache.TryGetValue(type, out var fieldInfos))
            {
                TypeFieldsCache.Add(type, 
                    fieldInfos = type.GetInstanceFields()
                        .Where(field => !type.IsNonSerialized(field)).ToArray());
            }
            return fieldInfos;
        }

        /// <summary>
        /// 获得字节序转换后的非托管值
        /// </summary>
        public static unsafe T EndianConvert<T>(this T value) where T : unmanaged
        {
            var size = sizeof(T);
            var data = (byte*) &value;
            var buffer = stackalloc byte[size];
            var lastIndex = size - 1;
            for (var i = 0; i < size; i++)
            {
                buffer[i] = data[lastIndex - i];
            }
            return *(T*) buffer;
        }

        /// <summary>
        /// 获得字节序转换后的非托管值
        /// </summary>
        /// <param name="value">要处理的值</param>
        /// <param name="isConvert">是否执行转换，如否则原样输出</param>
        public static unsafe T EndianConvert<T>(this T value, bool isConvert) where T : unmanaged =>
            isConvert ? value.EndianConvert() : value;

        /// <summary>
        /// 使用默认上下文序列化对象
        /// </summary>
        public static void Serialize(this IMarshalSerializer serializer,
            object self, Stream stream)
        {
            DefaultContext.Clear();
            serializer.Serialize(self, stream, DefaultContext);
        }

        /// <summary>
        /// 使用默认上下文和指定目标对象进行反序列化
        /// <para>序列化结果如不匹配，将不会对目标对象进行操作</para>
        /// </summary>
        public static object Deserialize(this IMarshalSerializer serializer,
            Stream stream, object target)
        {
            DefaultContext.Clear();
            return serializer.Deserialize(stream, DefaultContext, target);
        }

        /// <summary>
        /// 使用默认上下文进行反序列化
        /// </summary>
        public static object Deserialize(this IMarshalSerializer serializer,
            Stream stream) => Deserialize(serializer, stream, null);
    }
}