using System.IO;
using EmbyToolbox.Models;

namespace EmbyToolbox.Services;

/// <summary>MPEG-TS remux: генерация PTS и fallback при ошибках mux.</summary>
public static class MpegTsTimestampHelpers
{
    /// <summary>Входной файл распознан как MPEG Transport Stream (.ts / m2ts или format_name mpegts).</summary>
    public static bool IsMpegTsInput(MediaAnalysisResult? media, string? fileName)
    {
        if (media is null)
        {
            return false;
        }

        var blob = ((media.ContainerFormat ?? string.Empty) + "," + (media.FormatName ?? string.Empty)).ToLowerInvariant();
        if (blob.Contains("mpegts", StringComparison.Ordinal)
            || blob.Contains("mpeg-ts", StringComparison.Ordinal)
            || blob.Contains("m2ts", StringComparison.Ordinal))
        {
            return true;
        }

        if (!string.IsNullOrEmpty(fileName))
        {
            var ext = Path.GetExtension(fileName);
            if (ext.Equals(".ts", StringComparison.OrdinalIgnoreCase)
                || ext.Equals(".m2ts", StringComparison.OrdinalIgnoreCase)
                || ext.Equals(".mts", StringComparison.OrdinalIgnoreCase))
            {
                return true;
            }
        }

        return false;
    }

    /// <summary>Сообщения ffmpeg при copy/remux без валидных PTS.</summary>
    public static bool LooksLikeTimestampMuxFailure(string? stderr)
    {
        if (string.IsNullOrWhiteSpace(stderr))
        {
            return false;
        }

        var s = stderr.AsSpan();
        return ContainsLoose(s, "unknown timestamp")
               || ContainsLoose(s, "Timestamps are unset")
               || ContainsLoose(s, "unset in a packet")
               || ContainsLoose(s, "Can't write packet with unknown timestamp");
    }

    private static bool ContainsLoose(ReadOnlySpan<char> haystack, string needle)
    {
        return haystack.Contains(needle, StringComparison.OrdinalIgnoreCase);
    }
}