using System.Text;
using EmbyToolbox.Models;

namespace EmbyToolbox.Services;

public sealed class TrackStructureComparer
{
    public string BuildSignature(IReadOnlyList<TrackOverrideEntry> tracks)
    {
        var sb = new StringBuilder(tracks.Count * 40);
        for (var i = 0; i < tracks.Count; i++)
        {
            var t = tracks[i];
            if (i > 0)
            {
                sb.Append("||");
            }

            sb.Append((int)t.Source);
            sb.Append('|');
            sb.Append((int)t.StreamKind);
            sb.Append('|');
            if (t.StreamKind is MediaStreamKind.Audio or MediaStreamKind.Subtitle)
            {
                sb.Append(NormalizeToken(t.Language));
                sb.Append('|');
                sb.Append(NormalizeToken(t.Title));
                sb.Append('|');
            }
            sb.Append(NormalizeToken(ResolveCodecToken(t)));
        }

        return sb.ToString();
    }

    private static string ResolveCodecToken(TrackOverrideEntry t)
    {
        if (!string.IsNullOrWhiteSpace(t.ExternalStreamCodec))
        {
            return t.ExternalStreamCodec!;
        }

        return t.StreamKind == MediaStreamKind.Attachment ? "attachment" : string.Empty;
    }

    private static string NormalizeToken(string? value)
    {
        if (string.IsNullOrWhiteSpace(value))
        {
            return string.Empty;
        }

        var normalized = value.Trim().ToLowerInvariant();
        return normalized.Replace("  ", " ", StringComparison.Ordinal);
    }
}