using System;

using Syntriax.Engine.Core;

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

namespace Engine.Serialization;

internal class Vector2DYamlConverter : IYamlTypeConverter
{
    public bool Accepts(Type type) => type == typeof(Vector2D);

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

        parser.MoveNext();
        float x = 0.0f;
        float y = 0.0f;

        while (parser.Current != null && parser.Current is not MappingEnd)
        {
            var propertyName = ((Scalar)parser.Current).Value;
            parser.MoveNext();
            switch (propertyName)
            {
                case nameof(Vector2D.X): x = float.Parse(((Scalar)parser.Current).Value); break;
                case nameof(Vector2D.Y): y = float.Parse(((Scalar)parser.Current).Value); break;
            }
            parser.MoveNext();
        }
        return new Vector2D(x, y);
    }

    public void WriteYaml(IEmitter emitter, object? value, Type type)
    {
        var vector = (Vector2D)(value ?? throw new Exception());
        emitter.Emit(new MappingStart());
        emitter.Emit(new Scalar(nameof(Vector2D.X)));
        emitter.Emit(new Scalar(vector.X.ToString()));
        emitter.Emit(new Scalar(nameof(Vector2D.Y)));
        emitter.Emit(new Scalar(vector.Y.ToString()));
        emitter.Emit(new MappingEnd());
    }
}