using ln.json;
using ln.json.mapping;
using ln.logging;
using System;
using System.Text;
using System.Reflection;
using System.Collections.Generic;

namespace ln.objects.serialization.json
{
    public class JSONSerializer : Serializer
    {
        public JSONMapper Mapper { get; }
        public ObjectStore ObjectStore { get; }

        public JSONSerializer(ObjectStore objectStore)
        {
            ObjectStore = objectStore;
            Mapper = new JSONMapper() { DefaultBindingFlags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, DefaultMappingFlags = JSONObjectMappingFlags.FIELDS };
            Mapper.OnRequestCustomSerialization += Mapper_OnRequestCustomSerialization;

            Mapper.AddMappingFactory(
                typeof(IList<>),
                (Type targetType, out JSONMapping mapping) =>
                {
                    mapping = (JSONMapping)Activator.CreateInstance(typeof(LazyListMapping<>).MakeGenericType(targetType.GetGenericArguments()), objectStore);
                    return false;
                });

        }

        private bool Mapper_OnRequestCustomSerialization(object o, out JSONValue json)
        {
            if (!ReferenceEquals(null, o) && !o.GetType().IsValueType && !o.GetType().IsInterface && Mapper.GetOrBuildMapping(o.GetType(), out JSONMapping mapping) && mapping is JSONObjectMapping)
            {
                if (TryLookupReference(o, out object reference))
                {
                    json = new JSONString(Convert.ToBase64String(((Guid)reference).ToByteArray()));
                    return true;
                }
            }
            json = null;
            return false;
        }

        public override bool SerializeObject(object o, out byte[] serializedBytes)
        {
            if (ReferenceEquals(null, o))
            {
                serializedBytes = new byte[0];
                return true;
            }

            if (Mapper.GetOrBuildMapping(o.GetType(), out JSONMapping mapping))
            {
                JSONValue json = mapping.ToJson(Mapper, o);
                serializedBytes = Encoding.UTF8.GetBytes(json.ToString());
                if (ObjectStore.DEBUG)
                    Logging.Log(LogLevel.DEBUG, "Serialized: {0}", json.ToString());

                return true;
            }

            throw new NotSupportedException();
        }
    }
}