add: 在LocalStorage里面存储文法

Frontend/Services/GrammarStorageService.cs

@@ -0,0 +1,62 @@
+using Blazored.LocalStorage;
+using Katheryne.Abstractions;
+
+namespace Frontend.Services;
+
+public class GrammarStorageService
+{
+    private const string GrammarTextKey = "GrammarText";
+    
+    private readonly ILocalStorageService _localStorage;
+    private readonly ILogger<GrammarStorageService> _logger;
+    private readonly IChatRobotFactory _robotFactory;
+
+    public GrammarStorageService(ILocalStorageService localStorage,
+        ILogger<GrammarStorageService> logger,
+        IChatRobotFactory robotFactory)
+    {
+        _localStorage = localStorage;
+        _logger = logger;
+        _robotFactory = robotFactory;
+    }
+
+    /// <summary>
+    /// 尝试从LocalStorage中恢复之前设置的文法
+    /// </summary>
+    /// <returns>恢复文法是否成功</returns>
+    public async Task<bool> RestoreGrammar()
+    {
+        _logger.LogDebug("Try to restore grammar text.");
+
+        string result = await _localStorage.GetItemAsync<string>(GrammarTextKey);
+
+        if (result == default)
+        {
+            return false;
+        }
+        
+        _logger.LogDebug("Restore grammar text successfully.");
+        _robotFactory.SetGrammar(result);
+        return true;
+    }
+
+    /// <summary>
+    /// 保存当前设置使用的文法
+    /// </summary>
+    public async Task StoreGrammar()
+    {
+        if (!string.IsNullOrEmpty(_robotFactory.GrammarText))
+        {
+            _logger.LogDebug("Store current grammar text.");
+            await _localStorage.SetItemAsync(GrammarTextKey, _robotFactory.GrammarText);
+        }
+    }
+
+    /// <summary>
+    /// 清除当前设置的文法
+    /// </summary>
+    public async Task RemoveGrammar()
+    {
+        await _localStorage.RemoveItemAsync(GrammarTextKey);
+    }
+}