using System.Collections.Generic;
using SkiaSharp;

namespace Jellyfin.Drawing.Skia
{
    /// <summary>
    /// Class containing helper methods for working with SkiaSharp.
    /// </summary>
    public static class SkiaHelper
    {
        /// <summary>
        /// Ensures the result is a success
        /// by throwing an exception when that's not the case.
        /// </summary>
        /// <param name="result">The result returned by Skia.</param>
        public static void EnsureSuccess(SKCodecResult result)
        {
            if (result != SKCodecResult.Success)
            {
                throw new SkiaCodecException(result);
            }
        }

        /// <summary>
        /// Gets the next valid image as a bitmap.
        /// </summary>
        /// <param name="skiaEncoder">The current skia encoder.</param>
        /// <param name="paths">The list of image paths.</param>
        /// <param name="currentIndex">The current checked indes.</param>
        /// <param name="newIndex">The new index.</param>
        /// <returns>A valid bitmap, or null if no bitmap exists after <c>currentIndex</c>.</returns>
        public static SKBitmap? GetNextValidImage(SkiaEncoder skiaEncoder, IReadOnlyList<string> paths, int currentIndex, out int newIndex)
        {
            var imagesTested = new Dictionary<int, int>();
            SKBitmap? bitmap = null;

            while (imagesTested.Count < paths.Count)
            {
                if (currentIndex >= paths.Count)
                {
                    currentIndex = 0;
                }

                bitmap = skiaEncoder.Decode(paths[currentIndex], false, null, out _);

                imagesTested[currentIndex] = 0;

                currentIndex++;

                if (bitmap != null)
                {
                    break;
                }
            }

            newIndex = currentIndex;
            return bitmap;
        }
    }
}