using System;
using System.Timers;
 
namespace Microsoft.Maui.Animations
{
	/// <inheritdoc/>
	public class Ticker : ITicker
	{
		Timer? _timer;
		bool _systemEnabled = true;
 
		/// <inheritdoc/>
		public virtual int MaxFps { get; set; } = 60;
 
		/// <inheritdoc/>
		public Action? Fire { get; set; }
 
		/// <inheritdoc/>
		public virtual bool IsRunning => _timer?.Enabled ?? false;
 
		/// <inheritdoc/>
		public virtual bool SystemEnabled
		{
			get
			{
				return _systemEnabled;
			}
			protected set
			{
				if (_systemEnabled != value)
				{
					_systemEnabled = value;
					OnSystemEnabledChanged();
				}
			}
		}
 
		/// <inheritdoc/>
		public virtual void Start()
		{
			if (_timer != null)
				return;
 
			_timer = new Timer
			{
				AutoReset = true,
				Interval = 1000 / MaxFps,
			};
 
			_timer.Elapsed += OnTimerElapsed;
			_timer.AutoReset = true;
			_timer.Start();
		}
 
		/// <inheritdoc/>
		public virtual void Stop()
		{
			if (_timer == null)
				return;
 
			_timer.AutoReset = false;
			_timer.Stop();
			_timer.Elapsed -= OnTimerElapsed;
			_timer.Dispose();
			_timer = null;
		}
 
		void OnTimerElapsed(object? sender, ElapsedEventArgs e) =>
			Fire?.Invoke();
 
		protected virtual void OnSystemEnabledChanged()
		{
			if (IsRunning && !_systemEnabled)
			{
				// Animations are disabled for some reason; we need to 
				// force the AnimationManager to process them again now
				// that the ticker is disabled. This will give it a chance
				// to force-finish any animations in progress.
				Fire?.Invoke();
			}
		}
	}
}