using System;
using System.Collections.Generic;
using System.Linq;

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

namespace Syntriax.Engine.Core.Serialization;

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

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

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

        IUniverseObject universeObject;
        IStateEnable stateEnable;
        IBehaviourController behaviourController;
        List<IUniverseObject> children;

        parser.Consume<MappingStart>();

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

        if (parser.Consume<Scalar>().Value.CompareTo(nameof(IUniverseObject.Name)) != 0)
            throw new();
        name = parser.Consume<Scalar>().Value;

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

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

        if (parser.Consume<Scalar>().Value.CompareTo(nameof(IUniverseObject.BehaviourController)) != 0)
            throw new();
        behaviourController = (IBehaviourController)rootDeserializer(typeof(IBehaviourController))!;

        if (parser.Consume<Scalar>().Value.CompareTo(nameof(IUniverseObject.Children)) != 0)
            throw new();
        children = (List<IUniverseObject>)rootDeserializer(typeof(List<IUniverseObject>))!;

        parser.Consume<MappingEnd>();

        universeObject.Id = id;
        universeObject.Name = name;

        stateEnable.Assign(universeObject);
        universeObject.Assign(stateEnable);

        behaviourController.Assign(universeObject);
        universeObject.Assign(behaviourController);

        foreach (IUniverseObject child in children)
            universeObject.AddChild(child);

        return universeObject;
    }

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

        emitter.Emit(new MappingStart());

        emitter.Emit(new Scalar(nameof(IUniverseObject.Id)));
        emitter.Emit(new Scalar(universeObject.Id));

        emitter.Emit(new Scalar(nameof(IUniverseObject.Name)));
        emitter.Emit(new Scalar(universeObject.Name));

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

        emitter.Emit(new Scalar(nameof(IUniverseObject.StateEnable)));
        serializer(universeObject.StateEnable);

        emitter.Emit(new Scalar(nameof(IUniverseObject.BehaviourController)));
        serializer(universeObject.BehaviourController);

        emitter.Emit(new Scalar(nameof(IUniverseObject.Children)));
        serializer(universeObject.Children.Where(c => !c.GetType().HasAttribute<IgnoreSerializationAttribute>()));

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