using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Formats;
using SixLabors.ImageSharp.Metadata.Profiles.Exif;
using Umbraco.Cms.Core.Media;
using Size = System.Drawing.Size;

namespace Umbraco.Cms.Imaging.ImageSharp.Media;

public sealed class ImageSharpDimensionExtractor : IImageDimensionExtractor
{
    private readonly DecoderOptions _decoderOptions;

    /// <inheritdoc />
    public IEnumerable<string> SupportedImageFileTypes { get; }

    /// <summary>
    /// Initializes a new instance of the <see cref="ImageSharpDimensionExtractor" /> class.
    /// </summary>
    /// <param name="decoderOptions">The configuration.</param>
    public ImageSharpDimensionExtractor(DecoderOptions decoderOptions)
    {
        _decoderOptions = decoderOptions ?? throw new ArgumentNullException(nameof(decoderOptions));

        SupportedImageFileTypes = decoderOptions.Configuration.ImageFormats.SelectMany(f => f.FileExtensions).ToArray();
    }

    /// <inheritdoc />
    public Size? GetDimensions(Stream? stream)
    {
        Size? size = null;

        if (stream == null)
        {
            return size;
        }

        ImageInfo imageInfo = Image.Identify(_decoderOptions, stream);
        if (imageInfo != null)
        {
            size = IsExifOrientationRotated(imageInfo)
                ? new Size(imageInfo.Height, imageInfo.Width)
                : new Size(imageInfo.Width, imageInfo.Height);
        }

        return size;
    }

    private static bool IsExifOrientationRotated(ImageInfo imageInfo)
        => GetExifOrientation(imageInfo) switch
        {
            ExifOrientationMode.LeftTop
                or ExifOrientationMode.RightTop
                or ExifOrientationMode.RightBottom
                or ExifOrientationMode.LeftBottom => true,
            _ => false,
        };

    private static ushort GetExifOrientation(ImageInfo imageInfo)
    {

        if(imageInfo.Metadata.ExifProfile != null && imageInfo.Metadata.ExifProfile.TryGetValue(ExifTag.Orientation, out IExifValue<ushort>? orientation))
        {
            if (orientation.DataType == ExifDataType.Short)
            {
                return orientation.Value;
            }

            return Convert.ToUInt16(orientation.Value);
        }

        return ExifOrientationMode.Unknown;
    }
}