using System;
using System.Linq;

using Engine.Serialization.DTOs;

using Syntriax.Engine.Core;

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

namespace Engine.Serialization;

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

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

        parser.MoveNext();
        var transform = new TransformDTO();
        while (parser.Current != null && parser.Current is not MappingEnd)
        {
            var propertyName = ((Scalar)parser.Current).Value;
            parser.MoveNext();
            switch (propertyName)
            {
                case nameof(TransformDTO.ParentId):
                    transform.ParentId = new Vector2DYamlConverter().ReadYaml(parser, typeof(Vector2D))?.ToString();
                    break;
                case nameof(TransformDTO.Position):
                    transform.Position = (Vector2D)(new Vector2DYamlConverter().ReadYaml(parser, typeof(Vector2D)) ?? new Exception());
                    break;
                case nameof(TransformDTO.Scale):
                    transform.Scale = (Vector2D)(new Vector2DYamlConverter().ReadYaml(parser, typeof(Vector2D)) ?? new Exception());
                    break;
                case nameof(TransformDTO.Rotation):
                    transform.Rotation = float.Parse(((Scalar)parser.Current).Value);
                    break;
            }
            parser.MoveNext();
        }
        return transform;
    }

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

        Vector2DYamlConverter vector2DYamlConverter = new();

        emitter.Emit(new MappingStart());
        if (transform.ParentId is not null)
        {
            emitter.Emit(new Scalar(nameof(TransformDTO.ParentId)));
            emitter.Emit(new Scalar(transform.ParentId));
        }
        emitter.Emit(new Scalar(nameof(TransformDTO.Position)));
        vector2DYamlConverter.WriteYaml(emitter, transform.Position, typeof(Vector2D));
        emitter.Emit(new Scalar(nameof(TransformDTO.Scale)));
        vector2DYamlConverter.WriteYaml(emitter, transform.Scale, typeof(Vector2D));
        emitter.Emit(new Scalar(nameof(TransformDTO.Rotation)));
        emitter.Emit(new Scalar(transform.Rotation.ToString()));
        emitter.Emit(new MappingEnd());
    }
}