using System;

using System.Collections.Generic;

using System.Reflection;

using System.Runtime.Serialization;

using System.Threading;

namespace ServiceStack.Text

{

public class CachedTypeInfo

{

static Dictionary<Type, CachedTypeInfo> CacheMap = new Dictionary<Type, CachedTypeInfo>();

public static CachedTypeInfo Get(Type type)

{

if (CacheMap.TryGetValue(type, out var value))

return value;

var instance = new CachedTypeInfo(type);

Dictionary<Type, CachedTypeInfo> snapshot, newCache;

do

{

snapshot = CacheMap;

newCache = new Dictionary<Type, CachedTypeInfo>(CacheMap)

{

[type] = instance

};

} while (!ReferenceEquals(

Interlocked.CompareExchange(ref CacheMap, newCache, snapshot), snapshot));

return instance;

}

public CachedTypeInfo(Type type)

{

EnumInfo = EnumInfo.GetEnumInfo(type);

}

internal readonly EnumInfo EnumInfo;

}

public class EnumInfo

{

public static EnumInfo GetEnumInfo(Type type)

{

if (type.IsEnum)

return new EnumInfo(type);

var nullableType = Nullable.GetUnderlyingType(type);

if (nullableType?.IsEnum == true)

return new EnumInfo(nullableType);

return null;

}

private readonly Type enumType;

private EnumInfo(Type enumType)

{

this.enumType = enumType;

enumMemberReverseLookup = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);

var enumMembers = enumType.GetFields(BindingFlags.Public | BindingFlags.Static);

foreach (var fi in enumMembers)

{

var enumValue = fi.GetValue(null);

var strEnum = fi.Name;

var enumMemberAttr = fi.FirstAttribute<EnumMemberAttribute>();

if (enumMemberAttr?.Value != null)

{

if (enumMemberValues == null)

{

enumMemberValues = new Dictionary<object, string>();

}

enumMemberValues[enumValue] = enumMemberAttr.Value;

enumMemberReverseLookup[enumMemberAttr.Value] = enumValue;

}

else

{

enumMemberReverseLookup[strEnum] = enumValue;

}

}

isEnumFlag = enumType.IsEnumFlags();

}

private readonly bool isEnumFlag;

private readonly Dictionary<object, string> enumMemberValues;

private readonly Dictionary<string, object> enumMemberReverseLookup;

public object GetSerializedValue(object enumValue)

{

if (enumMemberValues != null && enumMemberValues.TryGetValue(enumValue, out var memberValue))

return memberValue;

if (isEnumFlag || JsConfig.TreatEnumAsInteger)

return enumValue;

return enumValue.ToString();

}

public object Parse(string serializedValue)

{

if (enumMemberReverseLookup.TryGetValue(serializedValue, out var enumValue))

return enumValue;

return Enum.Parse(enumType, serializedValue, ignoreCase: true); //Also parses quoted int values, e.g. "1"

}

}

}