Iceshrimp.NET/Iceshrimp.Frontend/Core/Services/MessageService.cs

using Iceshrimp.Shared.Schemas.Web;

namespace Iceshrimp.Frontend.Core.Services;

internal class MessageService
{
	public event EventHandler<NoteResponse>? AnyNoteChanged;
	public event EventHandler<NoteResponse>? AnyNoteDeleted;

	private readonly Dictionary<(string, Type), EventHandler<NoteResponse>> _noteChangedHandlers = new();

	public enum Type
	{
		Updated,
		Deleted
	}

	public NoteMessageHandler Register(string id, EventHandler<NoteResponse> func, Type type)
	{
		var tuple = (id, type);
		if (_noteChangedHandlers.ContainsKey(tuple))
		{
			_noteChangedHandlers[tuple] += func;
		}
		else
		{
			_noteChangedHandlers.Add(tuple, func);
		}

		return new NoteMessageHandler(func, id, type, this);
	}

	private void Unregister(string id, EventHandler<NoteResponse> func, Type type)
	{
		var tuple = (id, type);
		if (_noteChangedHandlers.ContainsKey(tuple))
		{
			#pragma warning disable CS8601
			_noteChangedHandlers[tuple] -= func;
			#pragma warning restore CS8601
		}
		else
		{
			throw new ArgumentException("Tried to unregister from callback that doesn't exist");
		}
	}

	public class NoteMessageHandler : IDisposable
	{
		private readonly EventHandler<NoteResponse> _handler;
		private readonly string                     _id;
		private readonly Type                       _type;
		private readonly MessageService             _messageService;

		public NoteMessageHandler(
			EventHandler<NoteResponse> handler, string id, Type type, MessageService messageService
		)
		{
			_handler        = handler;
			_id             = id;
			_type           = type;
			_messageService = messageService;
		}

		public void Dispose()
		{
			_messageService.Unregister(_id, _handler, _type);
		}
	}

	public Task UpdateNote(NoteResponse note)
	{
		AnyNoteChanged?.Invoke(this, note);
		_noteChangedHandlers.TryGetValue((note.Id, Type.Updated), out var xHandler);
		xHandler?.Invoke(this, note);
		return Task.CompletedTask;
	}

	public Task DeleteNote(NoteResponse note)
	{
		AnyNoteDeleted?.Invoke(this, note);
		_noteChangedHandlers.TryGetValue((note.Id, Type.Deleted), out var xHandler);
		xHandler?.Invoke(this, note);
		return Task.CompletedTask;
	}
}