using System;

using YamlDotNet.Core;
using YamlDotNet.Core.Events;
using YamlDotNet.Serialization;

namespace Syntriax.Engine.Core.Serialization;

public class BehaviourSerializer : IEngineTypeYamlSerializer
{
    private const string SERIALIZED_SCALAR_NAME = "Properties";

    public bool Accepts(Type type) => typeof(IBehaviour).IsAssignableFrom(type);

    public object? ReadYaml(IParser parser, Type type, ObjectDeserializer rootDeserializer)
    {
        string id;
        int priority;

        IBehaviour behaviour;
        IStateEnable stateEnable;

        parser.Consume<MappingStart>();

        if (parser.Consume<Scalar>().Value.CompareTo(nameof(IBehaviour.Id)) != 0)
            throw new();
        id = parser.Consume<Scalar>().Value;

        if (parser.Consume<Scalar>().Value.CompareTo(nameof(IBehaviour.Priority)) != 0)
            throw new();
        priority = int.Parse(parser.Consume<Scalar>().Value);

        if (parser.Consume<Scalar>().Value.CompareTo(SERIALIZED_SCALAR_NAME) != 0)
            throw new();
        SerializedClass instanceSerializedClass = (SerializedClass)rootDeserializer(typeof(SerializedClass))!;
        behaviour = (IBehaviour)instanceSerializedClass.CreateInstance();

        if (parser.Consume<Scalar>().Value.CompareTo(nameof(IBehaviour.StateEnable)) != 0)
            throw new();
        stateEnable = (IStateEnable)rootDeserializer(typeof(IStateEnable))!;

        parser.Consume<MappingEnd>();

        behaviour.Id = id;
        behaviour.Priority = priority;

        stateEnable.Assign(behaviour);
        behaviour.Assign(stateEnable);

        return behaviour;
    }

    public void WriteYaml(IEmitter emitter, object? value, Type type, ObjectSerializer serializer)
    {
        IBehaviour behaviour = (IBehaviour)value!;

        emitter.Emit(new MappingStart());

        emitter.Emit(new Scalar(nameof(IBehaviour.Id)));
        emitter.Emit(new Scalar(behaviour.Id));

        emitter.Emit(new Scalar(nameof(IBehaviour.Priority)));
        emitter.Emit(new Scalar(behaviour.Priority.ToString()));

        emitter.Emit(new Scalar(SERIALIZED_SCALAR_NAME));
        serializer(new SerializedClass(behaviour));

        emitter.Emit(new Scalar(nameof(IBehaviour.StateEnable)));
        serializer(behaviour.StateEnable);

        emitter.Emit(new MappingEnd());
    }
}