using Godot;
using System.Collections.Generic;

namespace  BITKit;

public interface IMetaDisplayElement
{
    string Text { get; }
    Vector3 Position { get; }
}
public partial class UXMetaService : Control
{
    #region 静态方法
    private static readonly Queue<IMetaDisplayElement> AddQueue = new();
    private static readonly Queue<IMetaDisplayElement> RemoveQueue = new();
    private static readonly List<IMetaDisplayElement> Elements = new();
    public static void Register(IMetaDisplayElement element) => AddQueue.Enqueue(element);
    public static void UnRegister(IMetaDisplayElement element) => RemoveQueue.Enqueue(element);
    #endregion
    #region 实例方法
    private readonly Dictionary<IMetaDisplayElement, Label> _dictionary = new();
    #endregion
    /// <summary>
    /// 标签预制体
    /// </summary>
    [Export] 
    private PackedScene labelTemplate;
    /// <summary>
    /// 主要处理过程
    /// </summary>
    /// <param name="delta"></param>
    public override void _Process(double delta)
    {
        //相机服务未初始化时返回
        if(CameraService.Singleton is null)return;
        //处理添加队列
        while (AddQueue.TryDequeue(out var newElement))
        {
            if (!Elements.TryAdd(newElement)) continue;
            var instance = labelTemplate.Instantiate<Label>();
            _dictionary.Add(newElement,instance);
            AddChild(instance);
        }
        //处理每个Element的数据
        foreach (var element in Elements)
        {
            if (_dictionary.TryGetValue(element, out var label) is false) continue;
            var pos = CameraService.Singleton.UnprojectPosition(element.Position);
            label.Position = pos;
            label.Text = element.Text;
        }
        //处理移除队列
        while (RemoveQueue.TryDequeue(out var removeElement))
        {
            if (!_dictionary.TryGetValue(removeElement, out var label)) continue;
            if (!_dictionary.TryRemove(removeElement)) continue;
            Elements.Remove(removeElement);
            label.QueueFree();
        }
    }
}