using System;
using System.Threading;
using System.Threading.Tasks;
using UIKit;
 
namespace Microsoft.Maui.Platform
{
	internal static class ImageSourcePartExtensions
	{
		public static async Task<IImageSourceServiceResult<UIImage>?> UpdateSourceAsync(
			this IImageSourcePart image,
			UIView destinationContext,
			IImageSourceServiceProvider services,
			Action<UIImage?> setImage,
			float imageScale = 1.0f,
			CancellationToken cancellationToken = default)
		{
			image.UpdateIsLoading(false);
 
			var imageSource = image.Source;
			if (imageSource == null)
				return null;
 
			var events = image as IImageSourcePartEvents;
 
			events?.LoadingStarted();
			image.UpdateIsLoading(true);
 
			try
			{
				var service = services.GetRequiredImageSourceService(imageSource);
 
				var result = await service.GetImageAsync(imageSource, imageScale, cancellationToken);
				var uiImage = result?.Value;
 
				var applied = !cancellationToken.IsCancellationRequested && imageSource == image.Source;
 
				// only set the image if we are still on the same one
				if (applied)
				{
					setImage.Invoke(uiImage);
					if (destinationContext is UIImageView imageView)
						imageView.UpdateIsAnimationPlaying(image);
				}
 
				events?.LoadingCompleted(applied);
 
				return result;
			}
			catch (OperationCanceledException)
			{
				// no-op
				events?.LoadingCompleted(false);
			}
			catch (Exception ex)
			{
				setImage?.Invoke(null);
				events?.LoadingFailed(ex);
			}
			finally
			{
				// only mark as finished if we are still working on the same image
				if (imageSource == image.Source)
				{
					image.UpdateIsLoading(false);
				}
			}
 
			return null;
		}
	}
}