Vocaluxe/VocaluxeSongServer/Sources/ISongSource.cs

using System.Globalization;
using System.Text;
using VocaluxeSongServer.Contracts;

namespace VocaluxeSongServer.Sources
{
    /// <summary>A place where new songs can be found and downloaded (song database, song repository, ...).</summary>
    public interface ISongSource
    {
        string Id { get; }
        string Name { get; }
        string Description { get; }
        bool Enabled { get; }
        /// <summary>Why the source is disabled, or empty.</summary>
        string Hint { get; }

        Task<List<SearchResultDto>> SearchAsync(string query, CancellationToken ct);

        /// <summary>
        ///     Downloads the song into <paramref name="folder" /> (created by the caller, empty). Must leave a playable
        ///     UltraStar song there (text file + audio) or throw.
        /// </summary>
        Task DownloadAsync(string sourceId, string folder, IProgress<double> progress, CancellationToken ct);
    }

    public static class CSourceHelper
    {
        /// <summary>Lower case, without diacritics and punctuation, single spaces: for matching artists and titles.</summary>
        public static string Normalize(string s)
        {
            var sb = new StringBuilder();
            foreach (var c in s.Normalize(NormalizationForm.FormD))
            {
                var cat = CharUnicodeInfo.GetUnicodeCategory(c);
                if (cat == UnicodeCategory.NonSpacingMark)
                {
                    continue;
                }

                sb.Append(char.IsLetterOrDigit(c) ? char.ToLowerInvariant(c) : ' ');
            }

            return string.Join(' ', sb.ToString().Split(' ', StringSplitOptions.RemoveEmptyEntries));
        }

        /// <summary>True if every word of the query occurs in the text (both normalized).</summary>
        public static bool Matches(string normalizedQuery, string text)
        {
            var normalized = " " + Normalize(text) + " ";
            return normalizedQuery.Split(' ', StringSplitOptions.RemoveEmptyEntries).All(w => normalized.Contains(w));
        }

        /// <summary>A file or folder name without characters that are invalid on Windows or Linux.</summary>
        public static string SafeName(string name)
        {
            var invalid = "<>:\"/\\|?*".ToCharArray();
            var cleaned = new string(name.Select(c => invalid.Contains(c) || char.IsControl(c) ? '_' : c).ToArray()).Trim().TrimEnd('.');
            return cleaned.Length > 120 ? cleaned[..120] : cleaned;
        }

        /// <summary>Copies a stream and reports the bytes copied.</summary>
        public static async Task CopyAsync(Stream source, Stream target, Action<long> onBytes, CancellationToken ct)
        {
            var buffer = new byte[81920];
            int read;
            while ((read = await source.ReadAsync(buffer, ct)) > 0)
            {
                await target.WriteAsync(buffer.AsMemory(0, read), ct);
                onBytes(read);
            }
        }
    }
}