[QuickAccent] Persist characters usage between runs (#37577)

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fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request

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## PR Checklist

Persist characters usage between PowerToys/QuickAccent runs.

- [x] **Closes:** #26034
- [ ] **Communication:** I've discussed this with core contributors
already. If work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end user facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

<!-- Provide a more detailed description of the PR, other things fixed
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

- Persist the dictionaries used to determine the characters usage in a
JSON file
`%LOCALAPPDATA%\Microsoft\PowerToys\QuickAccent\UsageInfo.json`

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

Manually tested:

- JSON is saved when PowerToys is closed and the **Sort characters by
usage frequency** is on
- JSON is deleted when QuickAccent is called and **Sort characters by
usage frequency** is off
- JSON is read when QuickAccent is started and characters order is
applied from the previous run

---------

Co-authored-by: Gleb Khmyznikov <gleb.khmyznikov@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/modules/poweraccent/PowerAccent.Core/Models/UsageInfoData.cs

@@ -0,0 +1,13 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace PowerAccent.Core.Models
+{
+    public class UsageInfoData
+    {
+        public Dictionary<string, uint> CharacterUsageCounters { get; set; } = [];
+
+        public Dictionary<string, long> CharacterUsageTimestamp { get; set; } = [];
+    }
+}

src/modules/poweraccent/PowerAccent.Core/PowerAccent.cs

@@ -117,8 +117,8 @@ public partial class PowerAccent : IDisposable
         if (_settingService.SortByUsageFrequency)
         {
             characters = characters.OrderByDescending(character => _usageInfo.GetUsageFrequency(character))
-                .ThenByDescending(character => _usageInfo.GetLastUsageTimestamp(character)).
-                ToArray<string>();
+                .ThenByDescending(character => _usageInfo.GetLastUsageTimestamp(character))
+                .ToArray<string>();
         }
         else if (!_usageInfo.Empty())
         {
@@ -337,6 +337,14 @@ public partial class PowerAccent : IDisposable
         return _settingService.Position;
     }
 
+    public void SaveUsageInfo()
+    {
+        if (_settingService.SortByUsageFrequency)
+        {
+            _usageInfo.Save();
+        }
+    }
+
     public void Dispose()
     {
         _keyboardListener.UnInitHook();

src/modules/poweraccent/PowerAccent.Core/SerializationContext/SourceGenerationContext.cs

@@ -3,12 +3,14 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Text.Json.Serialization;
+using PowerAccent.Core.Models;
 using PowerAccent.Core.Services;
 
 namespace PowerAccent.Core.SerializationContext;
 
 [JsonSourceGenerationOptions(WriteIndented = true)]
 [JsonSerializable(typeof(SettingsService))]
+[JsonSerializable(typeof(UsageInfoData))]
 public partial class SourceGenerationContext : JsonSerializerContext
 {
 }

src/modules/poweraccent/PowerAccent.Core/Tools/CharactersUsageInfo.cs

@@ -2,12 +2,28 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.IO;
+using System.Text.Json;
+using ManagedCommon;
+using Microsoft.PowerToys.Settings.UI.Library;
+using PowerAccent.Core.Models;
+using PowerAccent.Core.SerializationContext;
+
 namespace PowerAccent.Core.Tools
 {
     public class CharactersUsageInfo
     {
-        private Dictionary<string, uint> _characterUsageCounters = new Dictionary<string, uint>();
-        private Dictionary<string, long> _characterUsageTimestamp = new Dictionary<string, long>();
+        private readonly string _filePath;
+        private readonly Dictionary<string, uint> _characterUsageCounters;
+        private readonly Dictionary<string, long> _characterUsageTimestamp;
+
+        public CharactersUsageInfo()
+        {
+            _filePath = new SettingsUtils().GetSettingsFilePath(PowerAccentSettings.ModuleName, "UsageInfo.json");
+            var data = GetUsageInfoData();
+            _characterUsageCounters = data.CharacterUsageCounters;
+            _characterUsageTimestamp = data.CharacterUsageTimestamp;
+        }
 
         public bool Empty()
         {
@@ -18,19 +34,18 @@ namespace PowerAccent.Core.Tools
         {
             _characterUsageCounters.Clear();
             _characterUsageTimestamp.Clear();
+            Delete();
         }
 
         public uint GetUsageFrequency(string character)
         {
             _characterUsageCounters.TryGetValue(character, out uint frequency);
-
             return frequency;
         }
 
         public long GetLastUsageTimestamp(string character)
         {
             _characterUsageTimestamp.TryGetValue(character, out long timestamp);
-
             return timestamp;
         }
 
@@ -47,5 +62,58 @@ namespace PowerAccent.Core.Tools
 
             _characterUsageTimestamp[character] = DateTimeOffset.Now.ToUnixTimeSeconds();
         }
+
+        public void Save()
+        {
+            var data = new UsageInfoData
+            {
+                CharacterUsageCounters = _characterUsageCounters,
+                CharacterUsageTimestamp = _characterUsageTimestamp,
+            };
+
+            try
+            {
+                var json = JsonSerializer.Serialize(data, SourceGenerationContext.Default.UsageInfoData);
+                File.WriteAllText(_filePath, json);
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError("Failed to save usage file", ex);
+            }
+        }
+
+        public void Delete()
+        {
+            try
+            {
+                if (File.Exists(_filePath))
+                {
+                    File.Delete(_filePath);
+                }
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError("Failed to delete usage file", ex);
+            }
+        }
+
+        private UsageInfoData GetUsageInfoData()
+        {
+            if (!File.Exists(_filePath))
+            {
+                return new UsageInfoData();
+            }
+
+            try
+            {
+                var json = File.ReadAllText(_filePath);
+                return JsonSerializer.Deserialize(json, SourceGenerationContext.Default.UsageInfoData) ?? new UsageInfoData();
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError("Failed to read usage file", ex);
+                return new UsageInfoData();
+            }
+        }
     }
 }

src/modules/poweraccent/PowerAccent.UI/Selector.xaml.cs

@@ -98,6 +98,7 @@ public partial class Selector : FluentWindow, IDisposable, INotifyPropertyChange
 
     protected override void OnClosed(EventArgs e)
     {
+        _powerAccent.SaveUsageInfo();
         _powerAccent.Dispose();
         base.OnClosed(e);
     }