using System.Security.Cryptography;

namespace VideoDownloader.Server;

/// <summary>저장 폴더 미디어 라이브러리: 파일 나열/조회(ID = SHA-256 경로 해시 12자).</summary>
public static class MediaLibrary
{
    private static readonly string[] VideoExts = { ".mp4", ".mkv", ".webm", ".ts", ".mov", ".m4v", ".avi", ".mp3", ".m4a" };

    public static List<LibraryItemDto> List(string folder)
    {
        var result = new List<LibraryItemDto>();
        try
        {
            if (string.IsNullOrEmpty(folder) || !Directory.Exists(folder)) return result;
            foreach (var f in Directory.EnumerateFiles(folder).OrderByDescending(f => File.GetLastWriteTimeUtc(f)))
            {
                var ext = Path.GetExtension(f).ToLowerInvariant();
                if (!VideoExts.Contains(ext)) continue;
                var fi = new FileInfo(f);
                result.Add(new LibraryItemDto(IdOf(f), fi.Name, fi.Length, fi.LastWriteTimeUtc));
            }
        }
        catch { }
        return result;
    }

    public static (string FullPath, string FileName)? Find(string folder, string id)
    {
        try
        {
            if (string.IsNullOrEmpty(folder) || !Directory.Exists(folder)) return null;
            foreach (var f in Directory.EnumerateFiles(folder))
                if (IdOf(f) == id) return (f, Path.GetFileName(f));
        }
        catch { }
        return null;
    }

    private static string IdOf(string path)
    {
        var hash = SHA256.HashData(System.Text.Encoding.UTF8.GetBytes(Path.GetFullPath(path)));
        return Convert.ToHexString(hash)[..12].ToLowerInvariant();
    }
}