0.4.11

LanMountainDesktop/Services/LauncherSettingsService.cs

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+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text.Json;
+using LanMountainDesktop.Models;
+
+namespace LanMountainDesktop.Services;
+
+public sealed class LauncherSettingsService
+{
+    private static readonly JsonSerializerOptions SerializerOptions = new()
+    {
+        WriteIndented = true
+    };
+    private static readonly object CacheGate = new();
+    private static readonly TimeSpan CacheProbeInterval = TimeSpan.FromMilliseconds(400);
+
+    private static string? _cachedPath;
+    private static LauncherSettingsSnapshot? _cachedSnapshot;
+    private static DateTime _cachedWriteTimeUtc = DateTime.MinValue;
+    private static DateTime _lastProbeUtc = DateTime.MinValue;
+
+    private readonly string _settingsPath;
+    private readonly string _legacyAppSettingsPath;
+
+    public LauncherSettingsService()
+    {
+        var appData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
+        var settingsDirectory = Path.Combine(appData, "LanMountainDesktop");
+        _settingsPath = Path.Combine(settingsDirectory, "launcher-settings.json");
+        _legacyAppSettingsPath = Path.Combine(settingsDirectory, "settings.json");
+    }
+
+    public LauncherSettingsSnapshot Load()
+    {
+        try
+        {
+            lock (CacheGate)
+            {
+                var nowUtc = DateTime.UtcNow;
+                if (TryGetCachedWithoutProbe(nowUtc, out var cached))
+                {
+                    return cached;
+                }
+
+                var hasFile = File.Exists(_settingsPath);
+                var writeTimeUtc = hasFile
+                    ? File.GetLastWriteTimeUtc(_settingsPath)
+                    : DateTime.MinValue;
+
+                _lastProbeUtc = nowUtc;
+                if (TryGetCachedAfterProbe(writeTimeUtc, out cached))
+                {
+                    return cached;
+                }
+
+                LauncherSettingsSnapshot loadedSnapshot;
+                var loadedFromLegacy = false;
+                if (hasFile)
+                {
+                    loadedSnapshot = LoadSnapshotFromDisk();
+                }
+                else if (TryLoadLegacySnapshot(out var migratedSnapshot))
+                {
+                    loadedSnapshot = migratedSnapshot;
+                    loadedFromLegacy = true;
+                }
+                else
+                {
+                    loadedSnapshot = new LauncherSettingsSnapshot();
+                }
+
+                var normalizedSnapshot = NormalizeSnapshot(loadedSnapshot);
+                if (loadedFromLegacy)
+                {
+                    writeTimeUtc = PersistSnapshotToDisk(normalizedSnapshot);
+                }
+
+                UpdateCache(normalizedSnapshot, writeTimeUtc, nowUtc);
+                return normalizedSnapshot.Clone();
+            }
+        }
+        catch
+        {
+            return new LauncherSettingsSnapshot();
+        }
+    }
+
+    public void Save(LauncherSettingsSnapshot snapshot)
+    {
+        var snapshotToPersist = NormalizeSnapshot(snapshot);
+
+        try
+        {
+            var writeTimeUtc = PersistSnapshotToDisk(snapshotToPersist);
+
+            lock (CacheGate)
+            {
+                UpdateCache(snapshotToPersist, writeTimeUtc, DateTime.UtcNow);
+            }
+        }
+        catch
+        {
+            // Swallow persistence errors to keep UI interactions uninterrupted.
+        }
+    }
+
+    private bool TryGetCachedWithoutProbe(DateTime nowUtc, out LauncherSettingsSnapshot snapshot)
+    {
+        if (string.Equals(_cachedPath, _settingsPath, StringComparison.Ordinal) &&
+            _cachedSnapshot is not null &&
+            nowUtc - _lastProbeUtc < CacheProbeInterval)
+        {
+            snapshot = _cachedSnapshot.Clone();
+            return true;
+        }
+
+        snapshot = null!;
+        return false;
+    }
+
+    private bool TryGetCachedAfterProbe(DateTime writeTimeUtc, out LauncherSettingsSnapshot snapshot)
+    {
+        if (string.Equals(_cachedPath, _settingsPath, StringComparison.Ordinal) &&
+            _cachedSnapshot is not null &&
+            writeTimeUtc == _cachedWriteTimeUtc)
+        {
+            snapshot = _cachedSnapshot.Clone();
+            return true;
+        }
+
+        snapshot = null!;
+        return false;
+    }
+
+    private LauncherSettingsSnapshot LoadSnapshotFromDisk()
+    {
+        try
+        {
+            var json = File.ReadAllText(_settingsPath);
+            var snapshot = JsonSerializer.Deserialize<LauncherSettingsSnapshot>(json, SerializerOptions);
+            return NormalizeSnapshot(snapshot);
+        }
+        catch
+        {
+            return new LauncherSettingsSnapshot();
+        }
+    }
+
+    private bool TryLoadLegacySnapshot(out LauncherSettingsSnapshot snapshot)
+    {
+        snapshot = new LauncherSettingsSnapshot();
+
+        try
+        {
+            if (!File.Exists(_legacyAppSettingsPath))
+            {
+                return false;
+            }
+
+            var legacyJson = File.ReadAllText(_legacyAppSettingsPath);
+            var legacy = JsonSerializer.Deserialize<LegacyLauncherSettingsSnapshot>(legacyJson, SerializerOptions);
+            if (legacy is null)
+            {
+                return false;
+            }
+
+            snapshot = new LauncherSettingsSnapshot
+            {
+                HiddenLauncherFolderPaths = legacy.HiddenLauncherFolderPaths ?? [],
+                HiddenLauncherAppPaths = legacy.HiddenLauncherAppPaths ?? []
+            };
+
+            return true;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    private DateTime PersistSnapshotToDisk(LauncherSettingsSnapshot snapshot)
+    {
+        var directory = Path.GetDirectoryName(_settingsPath);
+        if (!string.IsNullOrWhiteSpace(directory))
+        {
+            Directory.CreateDirectory(directory);
+        }
+
+        var json = JsonSerializer.Serialize(snapshot, SerializerOptions);
+        File.WriteAllText(_settingsPath, json);
+
+        return File.Exists(_settingsPath)
+            ? File.GetLastWriteTimeUtc(_settingsPath)
+            : DateTime.UtcNow;
+    }
+
+    private static LauncherSettingsSnapshot NormalizeSnapshot(LauncherSettingsSnapshot? snapshot)
+    {
+        var normalized = snapshot?.Clone() ?? new LauncherSettingsSnapshot();
+        normalized.HiddenLauncherFolderPaths = NormalizeKeys(normalized.HiddenLauncherFolderPaths);
+        normalized.HiddenLauncherAppPaths = NormalizeKeys(normalized.HiddenLauncherAppPaths);
+        return normalized;
+    }
+
+    private static List<string> NormalizeKeys(IReadOnlyList<string>? values)
+    {
+        if (values is null || values.Count == 0)
+        {
+            return [];
+        }
+
+        return values
+            .Where(value => !string.IsNullOrWhiteSpace(value))
+            .Select(value => value.Trim())
+            .Distinct(StringComparer.OrdinalIgnoreCase)
+            .OrderBy(value => value, StringComparer.OrdinalIgnoreCase)
+            .ToList();
+    }
+
+    private void UpdateCache(LauncherSettingsSnapshot snapshot, DateTime writeTimeUtc, DateTime probeTimeUtc)
+    {
+        _cachedPath = _settingsPath;
+        _cachedSnapshot = snapshot.Clone();
+        _cachedWriteTimeUtc = writeTimeUtc;
+        _lastProbeUtc = probeTimeUtc;
+    }
+
+    private sealed class LegacyLauncherSettingsSnapshot
+    {
+        public List<string>? HiddenLauncherFolderPaths { get; set; }
+
+        public List<string>? HiddenLauncherAppPaths { get; set; }
+    }
+}