Added cache clear button, added cache size estimation

src/Controllers/SettingsController.cs

@@ -58,7 +58,7 @@ public class SettingsController : Controller
         }
         AdminSettingsModel currentSettingsModel = await _ldap.GetAdminSettingsModelAsync();
         await _ldap.SetAdminSettingsModelAsync(adminSettingsRequestModel.AdminSettingsModel);
-        if (adminSettingsRequestModel.AdminSettingsModel.UserImagePreloadType != currentSettingsModel.UserImagePreloadType)
+        if (adminSettingsRequestModel.AdminSettingsModel.UserImagePreloadType != UserImagePreloadType.None)
         {
             IEnumerable<UserModel> users = await _ldap.ListUsersAsync();
             Task _ = ImageHelper.PreloadUsers(users, adminSettingsRequestModel.AdminSettingsModel.UserImagePreloadType);
@@ -67,4 +67,18 @@ public class SettingsController : Controller
             Success = true
         };
     }
+
+    [Authorize(Roles = "CanManageSettings")]
+    [HttpPost("ClearUserImageCache")]
+    public bool ClearUserImageCache()
+    {
+        ImageHelper.ImageCache = [];
+        return true;
+    }
+    [Authorize(Roles = "CanManageSettings")]
+    [HttpPost("UserImageCacheSize")]
+    public string UserImageCacheSize()
+    {
+        return ImageHelper.ToHumanReadableSize(ImageHelper.GetImageCacheSize());
+    }
 }

src/Helpers/ImageHelper.cs

@@ -53,4 +53,66 @@ public static class ImageHelper
             Thread.Sleep(10);
         }
     }
+
+    public static long GetImageCacheSize()
+    {
+        long size = 0;
+        int stringOverhead = GetStringOverhead();
+        int arrayOverhead = GetArrayOverhead();
+        foreach (var kvOuter in ImageCache)
+        {
+            foreach (var kvInner in kvOuter.Value)
+            {
+                size += System.Text.ASCIIEncoding.Unicode.GetByteCount(kvInner.Key);
+                size += stringOverhead;
+
+                // byte[] size
+                if (kvInner.Value != null)
+                    size += kvInner.Value.Length + arrayOverhead;
+            }
+        }
+        return size;
+    }
+
+    public static string ToHumanReadableSize(long bytes)
+    {
+        string[] sizes = ["B", "KB", "MB", "GB", "TB", "PB"];
+        double len = bytes;
+        int order = 0;
+
+        while (len >= 1024 && order < sizes.Length - 1)
+        {
+            order++;
+            len /= 1024;
+        }
+
+        return $"{len:0.##} {sizes[order]}";
+    }
+
+    private static int GetStringOverhead()
+    {
+        // Object header size
+        int header = IntPtr.Size == 8 ? 16 : 8; // 16 bytes on x64, 8 on x86
+
+        int size =
+            header +
+            sizeof(int) +                // string length field
+            sizeof(char);                // null terminator
+
+        return size;
+    }
+
+    private static int GetArrayOverhead()
+    {
+        // On x64 object header = 16 bytes; on x86 = 8 bytes
+        int header = IntPtr.Size == 8 ? 16 : 8;
+
+        // Array length field = 4 bytes
+        int lengthField = sizeof(int);
+
+        // Padding on x64 to align the elements (so the first element is aligned)
+        int padding = IntPtr.Size == 8 ? 4 : 0;
+
+        return header + lengthField + padding;
+    }
 }

src/Resources/Views.Settings.Admin.de.resx

@@ -101,4 +101,7 @@
   <data name="userImagePreloadType_FullSized" xml:space="preserve">
     <value>48x48 + 256x256</value>
   </data>
+  <data name="Cache cleared successfully" xml:space="preserve">
+    <value>Cache wurde erfolgreich geleert.</value>
+  </data>
 </root>

src/Services/ImagePreloadService.cs

@@ -20,7 +20,7 @@ public class ImagePreloadService : IHostedService
         if (adminSettingsModel.UserImagePreloadType is not null && adminSettingsModel.UserImagePreloadType != UserImagePreloadType.None)
         {
             IEnumerable<UserModel> users = _ldap.ListUsersAsync().Result;
-            _logger.LogTrace("Preloading user images");
+            _logger.LogInformation("Preloading user images with preload type {adminSettingsModel.UserImagePreloadType}", [adminSettingsModel.UserImagePreloadType]);
             return ImageHelper.PreloadUsers(users, adminSettingsModel.UserImagePreloadType);
         }
         return Task.CompletedTask;

src/Views/Settings/Admin.cshtml

@@ -1,3 +1,4 @@
+@using Berufsschule_HAM.Helpers
 @using Berufsschule_HAM.Services
 @using Microsoft.AspNetCore.Html
 @using Microsoft.AspNetCore.Mvc.Localization
@@ -11,12 +12,13 @@
 @{
     ViewData["Title"] = T["Users"];
     List<string> supportedBarcodeTypes = ["code128c", "ean13", "ean8", "upc", "itf14", "itf"];
+    string userImageCacheSize = ImageHelper.ToHumanReadableSize(ImageHelper.GetImageCacheSize());
 }
 
 <form id="updateSettings" style="margin-bottom: 4rem !important" method="post" asp-controller="Settings" asp-action="Admin">
     <div class="row g-3">
         <h4 class="fw-bold">@T["General settings"]</h4>
-        <div class="col-md-6">
+        <div class="col-md-3">
             <label class="form-label" for="updateHashAlgorithm">@T["Default hash algorithm"]</label>
             <select type="text" name="DefaultHashAlgorithm" id="updateHashAlgorithm" class="form-control">
                 @foreach (string algorithm in ldap.HashAlgorithms.Keys)
@@ -26,7 +28,7 @@
                 }
             </select>
         </div>
-        <div class="col-md-6">
+        <div class="col-md-3">
             <label class="form-label" for="updateBarcodeType">@T["Barcode type"]</label>
             <span 
                 id="barcodeInfoIcon"
@@ -48,15 +50,15 @@
                 }
             </select>
         </div>
-        <div class="col-md-6">
+        <div class="col-md-3">
             <label class="form-label" for="updateBarcodeText">@T["Barcode text"]</label>
             <input type="text" name="BarcodeText" id="updateBarcodeText" class="form-control" value="@Model.BarcodeText" />
         </div>
-        <div class="col-md-6">
+        <div class="col-md-4">
             <label class="form-label" for="updateMaxDownloadableUserImageSize">@T["Max downloadable user image size"]</label>
             <input type="number" id="updateMaxDownloadableUserImageSize" name="MaxDownloadableUserImageSize" class="form-control" value="@Model.MaxDownloadableUserImageSize" />
         </div>
-        <div class="col-md-6">
+        <div class="col-md-3">
             <label class="form-label" for="updateUserImagePreloadType">@T["User image preloading"]</label>
             <select type="text" name="UserImagePreloadType" id="updateUserImagePreloadType" class="form-control" />
                 @foreach (UserImagePreloadType userImagePreloadType in Enum.GetValues(typeof(UserImagePreloadType)))
@@ -65,6 +67,10 @@
                 }
             </select>
         </div>
+        <div class="col-md-4">
+            <p class="form-label">@T["Current user image cache utilization:"] <span id="userImageCacheSize">@userImageCacheSize</span></p>
+            <button class="form-control btn btn-danger" type="button" id="clearCacheBtn">@T["Clear user image cache"]</button>
+        </div>
     </div>
     <div class="mt-3 p-2 bg border rounded d-flex justify-content-between align-items-center"
         data-bs-toggle="collapse"
@@ -124,6 +130,40 @@
 </form>
 
 <script defer>
+
+    document.getElementById("clearCacheBtn").addEventListener("click", async () => {
+        try {
+            const response = await fetch("/Settings/ClearUserImageCache", {
+                method: "POST",
+                headers: {
+                    "X-Requested-With": "XMLHttpRequest"
+                }
+            });
+
+            if (!response.ok) {
+                throw new Error("Request failed: " + response.status);
+            }
+
+            document.getElementById("userImageCacheSize").textContent = "0 B";
+            showToast('@T["Cache cleared successfully"]', 'success');
+        } catch (err) {
+            console.error(err);
+            showToast('@T["Error contacting server"]', 'danger');
+        }
+    });
+
+    setInterval(() => {
+        fetch('/Settings/UserImageCacheSize', {
+            method: 'POST'
+        })
+        .then(res => res.text())
+        .then(text => {
+            document.querySelector('#userImageCacheSize').textContent = text;
+        })
+        .catch(err => console.error('Cache-size fetch failed:', err));
+    }, 1000);
+
+
     document.addEventListener('DOMContentLoaded', () => {
         const updateForm = document.getElementById('updateSettings');
         updateForm.addEventListener('submit', async e => {