using System;
using System.Collections.Generic;
using Engine.Serialization.DTOs;

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

namespace Engine.Serialization;

internal class GameManagerYamlConverter : IYamlTypeConverter
{
    public bool Accepts(Type type) => type == typeof(GameManagerDTO);

    public object ReadYaml(IParser parser, Type type)
    {
        if (parser.Current is not MappingStart)
            throw new InvalidOperationException("Expected MappingStart");

        parser.MoveNext();
        var gameManager = new GameManagerDTO();
        while (parser.Current != null && parser.Current is not MappingEnd)
        {
            var propertyName = ((Scalar)parser.Current).Value;
            parser.MoveNext();
            switch (propertyName)
            {
                case nameof(GameManagerDTO.ClassType):
                    gameManager.ClassType = ((Scalar)parser.Current).Value;
                    break;
                case nameof(GameManagerDTO.GameObjects):
                    gameManager.GameObjects = (List<GameObjectDTO>)new GameObjectDTOListConverter().ReadYaml(parser, typeof(List<GameObjectDTO>));
                    break;
            }
            parser.MoveNext();
        }
        return gameManager;
    }

    public void WriteYaml(IEmitter emitter, object? value, Type type)
    {
        var gameManager = (GameManagerDTO)(value ?? throw new Exception());

        GameObjectDTOListConverter gameObjectDTOListConverter = new();

        emitter.Emit(new MappingStart());
        emitter.Emit(new Scalar(nameof(GameManagerDTO.ClassType)));
        emitter.Emit(new Scalar(gameManager.ClassType));
        emitter.Emit(new Scalar(nameof(GameManagerDTO.GameObjects)));
        gameObjectDTOListConverter.WriteYaml(emitter, gameManager.GameObjects, typeof(List<GameObjectDTO>));
        emitter.Emit(new MappingEnd());
    }
}