feat: add persistence and restoration of email template filters in UI and backend

HrynCo.NotificationService.Web/Controllers/Admin/AdminTemplatesController.cs

@@ -40,14 +40,24 @@ public class AdminTemplatesController : Controller
 
     // GET /admin/templates/create
     [HttpGet("create")]
-    public IActionResult Create()
+    public IActionResult Create([FromQuery] string? serviceNameFilter, [FromQuery] string? keyFilter)
     {
-        return View("Edit", new EmailTemplateEditViewModel());
+        return View("Edit", new EmailTemplateEditViewModel
+        {
+            ServiceNameFilter = serviceNameFilter,
+            KeyFilter = keyFilter
+        });
     }
 
     // GET /admin/templates/{serviceName}/{key}/{languageCode}
     [HttpGet("{serviceName}/{key}/{languageCode}")]
-    public async Task<IActionResult> Edit(string serviceName, string key, string languageCode, CancellationToken ct)
+    public async Task<IActionResult> Edit(
+        string serviceName,
+        string key,
+        string languageCode,
+        [FromQuery] string? serviceNameFilter,
+        [FromQuery] string? keyFilter,
+        CancellationToken ct)
     {
         var result = await _mediator.Send(new GetEmailTemplateQuery(serviceName, key, languageCode), ct);
         if (!result.IsSuccess || result.Result is null)
@@ -63,7 +73,9 @@ public class AdminTemplatesController : Controller
             Subject = template.Subject,
             HtmlBody = template.HtmlBody,
             TextBody = template.TextBody,
-            VariablesJson = JsonSerializer.Serialize(template.Variables)
+            VariablesJson = JsonSerializer.Serialize(template.Variables),
+            ServiceNameFilter = serviceNameFilter,
+            KeyFilter = keyFilter
         };
 
         return View(vm);
@@ -127,15 +139,21 @@ public class AdminTemplatesController : Controller
             }
         }
 
-        return RedirectToAction(nameof(Index));
+        return RedirectToAction(nameof(Index), new { serviceName = model.ServiceNameFilter, key = model.KeyFilter });
     }
 
     // POST /admin/templates/{serviceName}/{key}/{languageCode}/delete
     [HttpPost("{serviceName}/{key}/{languageCode}/delete")]
     [ValidateAntiForgeryToken]
-    public async Task<IActionResult> Delete(string serviceName, string key, string languageCode, CancellationToken ct)
+    public async Task<IActionResult> Delete(
+        string serviceName,
+        string key,
+        string languageCode,
+        [FromForm] string? serviceNameFilter,
+        [FromForm] string? keyFilter,
+        CancellationToken ct)
     {
         await _mediator.Send(new DeleteEmailTemplateCommand(serviceName, key, languageCode), ct);
-        return RedirectToAction(nameof(Index));
+        return RedirectToAction(nameof(Index), new { serviceName = serviceNameFilter, key = keyFilter });
     }
 }

HrynCo.NotificationService.Web/Controllers/Admin/ViewModels/EmailTemplateEditViewModel.cs

@@ -25,6 +25,8 @@ public class EmailTemplateEditViewModel
 
     // JSON array: [{"name":"UserName","required":true}, ...]
     public string VariablesJson { get; set; } = "[]";
+    public string? ServiceNameFilter { get; set; }
+    public string? KeyFilter { get; set; }
 
     public bool IsNew => Id == null;
     public string PageTitle => IsNew ? "Create Email Template" : "Edit Email Template";

HrynCo.NotificationService.Web/Views/AdminTemplates/Edit.cshtml

@@ -10,6 +10,8 @@
     @Html.AntiForgeryToken()
     <input asp-for="Id" type="hidden" />
     <input type="hidden" name="IsNew" value="@Model.IsNew" />
+    <input asp-for="ServiceNameFilter" type="hidden" />
+    <input asp-for="KeyFilter" type="hidden" />
 
     @if (!ViewData.ModelState.IsValid)
     {
@@ -116,7 +118,7 @@
         <button type="submit" form="templateForm" class="btn btn-primary">
             <i class="bi bi-floppy me-1"></i> Save
         </button>
-        <a href="/admin/templates" class="btn btn-secondary">
+        <a href="/admin/templates@(string.IsNullOrWhiteSpace(Model.ServiceNameFilter) && string.IsNullOrWhiteSpace(Model.KeyFilter) ? string.Empty : $"?serviceName={Uri.EscapeDataString(Model.ServiceNameFilter ?? string.Empty)}&key={Uri.EscapeDataString(Model.KeyFilter ?? string.Empty)}")" class="btn btn-secondary">
             <i class="bi bi-x-lg me-1"></i> Cancel
         </a>
     }

HrynCo.NotificationService.Web/Views/AdminTemplates/Index.cshtml

@@ -4,18 +4,24 @@
     ViewData["Title"] = "Email Templates";
     var serviceNameFilter = ViewData["ServiceNameFilter"] as string ?? string.Empty;
     var keyFilter = ViewData["KeyFilter"] as string ?? string.Empty;
+    var filterQuery = string.IsNullOrWhiteSpace(serviceNameFilter) && string.IsNullOrWhiteSpace(keyFilter)
+        ? string.Empty
+        : $"?serviceNameFilter={Uri.EscapeDataString(serviceNameFilter)}&keyFilter={Uri.EscapeDataString(keyFilter)}";
+    var listQuery = string.IsNullOrWhiteSpace(serviceNameFilter) && string.IsNullOrWhiteSpace(keyFilter)
+        ? string.Empty
+        : $"?serviceName={Uri.EscapeDataString(serviceNameFilter)}&key={Uri.EscapeDataString(keyFilter)}";
 }
 
 <div class="page-header">
     <h2><i class="bi bi-envelope-paper"></i> Email Templates</h2>
-    <a href="/admin/templates/create" class="btn btn-primary btn-sm">
+    <a href="/admin/templates/create@filterQuery" class="btn btn-primary btn-sm">
         <i class="bi bi-plus-lg me-1"></i> Create New Template
     </a>
 </div>
 
 <div class="card shadow-sm mb-3">
     <div class="card-body">
-        <form method="get" action="/admin/templates" class="row g-2 align-items-end">
+        <form id="templateFiltersForm" method="get" action="/admin/templates" class="row g-2 align-items-end">
             <div class="col-12 col-md-5">
                 <label class="form-label fw-semibold" for="serviceName">Service Name</label>
                 <input id="serviceName"
@@ -34,7 +40,7 @@
             </div>
             <div class="col-12 col-md-2 d-flex gap-2">
                 <button type="submit" class="btn btn-primary w-100">Filter</button>
-                <a href="/admin/templates" class="btn btn-outline-secondary w-100">Clear</a>
+                <a id="clearTemplateFilters" href="/admin/templates" class="btn btn-outline-secondary w-100">Clear</a>
             </div>
         </form>
     </div>
@@ -50,6 +56,61 @@
     </div>
 }
 
+<script>
+    (() => {
+        const storageKey = 'hrynco.notificationService.adminTemplates.filters';
+        const form = document.getElementById('templateFiltersForm');
+        const serviceNameInput = document.getElementById('serviceName');
+        const keyInput = document.getElementById('key');
+        const clearLink = document.getElementById('clearTemplateFilters');
+
+        if (!form || !serviceNameInput || !keyInput || !clearLink) {
+            return;
+        }
+
+        const saveState = () => {
+            const state = {
+                serviceName: serviceNameInput.value ?? '',
+                key: keyInput.value ?? ''
+            };
+
+            localStorage.setItem(storageKey, JSON.stringify(state));
+        };
+
+        const restoreState = () => {
+            const raw = localStorage.getItem(storageKey);
+            if (!raw) {
+                return false;
+            }
+
+            try {
+                const state = JSON.parse(raw);
+                const serviceName = typeof state.serviceName === 'string' ? state.serviceName : '';
+                const key = typeof state.key === 'string' ? state.key : '';
+
+                serviceNameInput.value = serviceName;
+                keyInput.value = key;
+
+                return serviceName.length > 0 || key.length > 0;
+            } catch {
+                localStorage.removeItem(storageKey);
+                return false;
+            }
+        };
+
+        form.addEventListener('submit', saveState);
+        clearLink.addEventListener('click', () => localStorage.removeItem(storageKey));
+
+        const hasQueryParams = new URLSearchParams(window.location.search).toString().length > 0;
+        if (!hasQueryParams && restoreState()) {
+            form.requestSubmit();
+            return;
+        }
+
+        saveState();
+    })();
+</script>
+
 @if (Model is null || Model.Count == 0)
 {
     <div class="card shadow-sm table-card">
@@ -85,13 +146,15 @@ else
                             <td>@t.LanguageCode</td>
                             <td>@t.Subject</td>
                             <td class="text-end">
-                                <a href="/admin/templates/@t.ServiceName/@t.Key/@t.LanguageCode"
+                                <a href="/admin/templates/@t.ServiceName/@t.Key/@t.LanguageCode@filterQuery"
                                    class="btn btn-sm btn-outline-primary me-1">
                                     <i class="bi bi-pencil"></i> Edit
                                 </a>
                                 <form method="post"
                                       action="/admin/templates/@t.ServiceName/@t.Key/@t.LanguageCode/delete"
                                       class="d-inline">
+                                    <input type="hidden" name="serviceNameFilter" value="@serviceNameFilter" />
+                                    <input type="hidden" name="keyFilter" value="@keyFilter" />
                                     @Html.AntiForgeryToken()
                                     <button type="submit"
                                             class="btn btn-sm btn-outline-danger"