osu-lazer/osu.Game/IO/StableStorage.cs

// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

using System;
using System.IO;
using System.Linq;
using osu.Framework.Platform;

namespace osu.Game.IO
{
    /// <summary>
    /// A storage pointing to an osu-stable installation.
    /// Provides methods for handling installations with a custom Song folder location.
    /// </summary>
    public class StableStorage : DesktopStorage
    {
        private const string stable_default_songs_path = "Songs";

        private readonly DesktopGameHost host;
        private readonly Lazy<string> songsPath;

        public StableStorage(string path, DesktopGameHost host)
            : base(path, host)
        {
            this.host = host;

            songsPath = new Lazy<string>(locateSongsDirectory);
        }

        /// <summary>
        /// Returns a <see cref="Storage"/> pointing to the osu-stable Songs directory.
        /// </summary>
        public Storage GetSongStorage() => new DesktopStorage(songsPath.Value, host);

        private string locateSongsDirectory()
        {
            var configurationFiles = GetFiles(".", $"osu!.{Environment.UserName}.cfg");

            // GetFiles returns case insensitive results, so multiple files could exist.
            // Prefer a case-correct match, but fallback to any available.
            string usableConfigFile =
                configurationFiles.FirstOrDefault(f => f.Contains(Environment.UserName, StringComparison.Ordinal))
                ?? configurationFiles.FirstOrDefault();

            if (usableConfigFile != null)
            {
                using (var stream = GetStream(usableConfigFile))
                using (var textReader = new StreamReader(stream))
                {
                    string line;

                    while ((line = textReader.ReadLine()) != null)
                    {
                        if (!line.StartsWith("BeatmapDirectory", StringComparison.OrdinalIgnoreCase)) continue;

                        string customDirectory = line.Split('=').LastOrDefault()?.Trim();
                        if (customDirectory != null && Path.IsPathFullyQualified(customDirectory))
                            return customDirectory;

                        break;
                    }
                }
            }

            return GetFullPath(stable_default_songs_path);
        }
    }
}