#nullable disable
//
// Tweener.cs
//
// Author:
//       Jason Smith <jason.smith@xamarin.com>
//
// Copyright (c) 2012 Microsoft.Maui.Controls Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
 
using System;
using Microsoft.Maui.Animations;
 
namespace Microsoft.Maui.Controls
{
	internal class TweenerAnimation : Animation
	{
		readonly Func<long, bool> _step;
 
		public TweenerAnimation(Func<long, bool> step)
		{
			_step = step;
		}
 
		protected override void OnTick(double millisecondsSinceLastUpdate)
		{
			var running = _step.Invoke((long)millisecondsSinceLastUpdate);
			HasFinished = !running;
 
			if (HasFinished)
				Finished?.Invoke();
		}
 
		internal override void ForceFinish()
		{
			if (HasFinished)
			{
				return;
			}
 
			HasFinished = true;
 
			// The tweeners use long.MaxValue for in-band signaling that they should
			// jump to the end of the animation 
			_ = _step.Invoke(long.MaxValue);
		}
	}
 
	internal class Tweener
	{
		readonly IAnimationManager _animationManager;
		long _lastMilliseconds;
		int _animationManagerKey;
		long _frames;
 
		public Tweener(uint length, IAnimationManager animationManager)
		{
			Value = 0.0f;
			Length = length;
			_animationManager = animationManager;
			Loop = false;
		}
 
		public Tweener(uint length, uint rate, IAnimationManager animationManager)
		{
			Value = 0.0f;
			Length = length;
			Rate = rate;
			_animationManager = animationManager;
			Loop = false;
		}
 
		public AnimatableKey Handle { get; set; }
 
		public uint Length { get; }
 
		public uint Rate { get; } = 1;
 
		public bool Loop { get; set; }
 
		public double Value { get; set; }
 
		public event EventHandler Finished;
		public event EventHandler ValueUpdated;
 
		public void Pause()
		{
			if (_animationManagerKey != 0)
			{
				_animationManager.Remove(_animationManagerKey);
				_animationManagerKey = 0;
			}
		}
 
		bool Step(long step)
		{
			if (step == long.MaxValue)
			{
				// Signal that the Tweener is being force to move to the finished state, 
				// usually because the underlying Ticker has been disabled by the system
				FinishImmediately();
				return false;
			}
			else
			{
				long ms = step + _lastMilliseconds;
				Value = Math.Min(1.0f, ms / (double)Length);
				_lastMilliseconds = ms;
			}
 
			long wantedFrames = (_lastMilliseconds / Rate) + 1;
			if (wantedFrames > _frames || Value >= 1.0f)
			{
				ValueUpdated?.Invoke(this, EventArgs.Empty);
			}
 
			_frames = wantedFrames;
 
			if (Value >= 1.0f)
			{
				if (Loop)
				{
					_lastMilliseconds = 0;
					Value = 0.0f;
					return true;
				}
 
				Finished?.Invoke(this, EventArgs.Empty);
 
				Value = 0.0f;
				_animationManagerKey = 0;
				return false;
			}
 
			return true;
		}
 
		public void Start()
		{
			Pause();
 
			_lastMilliseconds = 0;
			_frames = 0;
 
			if (!_animationManager.Ticker.SystemEnabled)
			{
				// The Ticker's disabled, probably because the system has animations disabled
				// The Tweener should move immediately to the finished state and shut down
				FinishImmediately();
				return;
			}
 
			_animationManagerKey = _animationManager.Insert(Step);
 
			if (!_animationManager.Ticker.IsRunning)
				_animationManager.Ticker.Start();
		}
 
		void FinishImmediately()
		{
			Value = 1.0f;
 
			ValueUpdated?.Invoke(this, EventArgs.Empty);
			Finished?.Invoke(this, EventArgs.Empty);
 
			Value = 0.0f;
			_animationManagerKey = 0;
		}
 
		public void Stop()
		{
			Pause();
			Finished?.Invoke(this, EventArgs.Empty);
			Value = 0.0f;
		}
 
		~Tweener()
		{
			if (_animationManagerKey != 0)
			{
				try
				{
					_animationManager.Remove(_animationManagerKey);
				}
				catch (InvalidOperationException)
				{
				}
			}
			_animationManagerKey = 0;
		}
	}
}