feat: add test button to create channel form using ad-hoc smtp test endpoint

- Add TestSmtpCommand and TestSmtpHandler for ad-hoc smtp testing without saving
- Add POST /admin/channels/test-smtp endpoint accepting raw smtp settings
- Show Test button on both Create and Edit forms
- Test reads current form values so channel can be tested before saving

HrynCo.NotificationService.Services/EmailChannels/TestSmtp/TestSmtpCommand.cs

@@ -0,0 +1,18 @@
+using HrynCo.NotificationService.Services.Core;
+using MediatR;
+
+namespace HrynCo.NotificationService.Services.EmailChannels.TestSmtp;
+
+/// <summary>
+/// Sends a test email using the provided SMTP settings without persisting anything.
+/// </summary>
+public sealed record TestSmtpCommand(
+    string Host,
+    int Port,
+    string Username,
+    string Password,
+    bool UseSsl,
+    string FromEmail,
+    string FromName,
+    string ToEmail
+) : IRequest<ServiceResult<Core.Unit>>;

HrynCo.NotificationService.Services/EmailChannels/TestSmtp/TestSmtpHandler.cs

@@ -0,0 +1,52 @@
+using System.Net;
+using System.Net.Mail;
+using HrynCo.NotificationService.DAL.Abstract;
+using HrynCo.NotificationService.Services.Core;
+using HrynCo.NotificationService.Services.Logging;
+using static HrynCo.NotificationService.Services.Core.ServiceResultHelper;
+
+namespace HrynCo.NotificationService.Services.EmailChannels.TestSmtp;
+
+internal sealed class TestSmtpHandler
+    : RequestHandler<TestSmtpCommand, ServiceResult<Unit>>
+{
+    public TestSmtpHandler(
+        IContextualSerilogLogger<TestSmtpCommand> logger,
+        IUnitOfWork unitOfWork)
+        : base(logger, unitOfWork)
+    {
+    }
+
+    protected override async Task<ServiceResult<Unit>> DoOnHandle(
+        TestSmtpCommand request, CancellationToken cancellationToken)
+    {
+        try
+        {
+            using var client = new SmtpClient(request.Host, request.Port)
+            {
+                EnableSsl = request.UseSsl,
+                Credentials = string.IsNullOrWhiteSpace(request.Username)
+                    ? null
+                    : new NetworkCredential(request.Username, request.Password)
+            };
+
+            using var mail = new MailMessage
+            {
+                From = new MailAddress(request.FromEmail, request.FromName),
+                Subject = "✅ Test email from Notification Service",
+                Body = "<p>This is a test email sent from the <b>Notification Service</b> admin panel to verify the channel settings.</p>",
+                IsBodyHtml = true
+            };
+            mail.To.Add(new MailAddress(request.ToEmail));
+
+            await client.SendMailAsync(mail, cancellationToken);
+        }
+        catch (Exception ex)
+        {
+            Logger.Error(ex, "Ad-hoc SMTP test failed for host {Host}", request.Host);
+            return Failure<Unit>(ex.Message);
+        }
+
+        return Success(Unit.Value);
+    }
+}

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

@@ -5,6 +5,7 @@ using HrynCo.NotificationService.Services.EmailChannels.Delete;
 using HrynCo.NotificationService.Services.EmailChannels.Get;
 using HrynCo.NotificationService.Services.EmailChannels.GetUsageSummary;
 using HrynCo.NotificationService.Services.EmailChannels.Send;
+using HrynCo.NotificationService.Services.EmailChannels.TestSmtp;
 using HrynCo.NotificationService.Services.EmailChannels.Update;
 using HrynCo.NotificationService.Web.Controllers.Admin.ViewModels;
 using MediatR;
@@ -133,6 +134,20 @@ public class AdminChannelsController(IMediator mediator) : Controller
         return RedirectToAction(nameof(Index));
     }
 
+    // POST /admin/channels/test-smtp
+    [HttpPost("test-smtp")]
+    public async Task<IActionResult> TestSmtp([FromBody] TestSmtpRequest request, CancellationToken ct)
+    {
+        var result = await mediator.Send(new TestSmtpCommand(
+            request.Host, request.Port, request.Username, request.Password,
+            request.UseSsl, request.FromEmail, request.FromName, request.ToEmail), ct);
+
+        if (!result.IsSuccess)
+            return Ok(new { success = false, message = result.Error?.Message });
+
+        return Ok(new { success = true, message = $"Test email sent to {request.ToEmail}." });
+    }
+
     // POST /admin/channels/{id}/test
     [HttpPost("{id:guid}/test")]
     public async Task<IActionResult> Test(Guid id, [FromBody] TestChannelRequest request, CancellationToken ct)
@@ -165,3 +180,6 @@ public class AdminChannelsController(IMediator mediator) : Controller
 }
 
 public record TestChannelRequest(string ToEmail);
+public record TestSmtpRequest(
+    string Host, int Port, string Username, string Password,
+    bool UseSsl, string FromEmail, string FromName, string ToEmail);

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

@@ -121,82 +121,90 @@
         <button type="submit" form="channelForm" class="btn btn-primary">
             <i class="bi bi-floppy me-1"></i> Save
         </button>
-        @if (!Model.IsNew)
-        {
-            <button type="button" class="btn btn-success" id="testModalBtn">
-                <i class="bi bi-send me-1"></i> Test
-            </button>
-        }
+        <button type="button" class="btn btn-success" id="testModalBtn">
+            <i class="bi bi-send me-1"></i> Test
+        </button>
         <a href="/admin/channels" class="btn btn-secondary">
             <i class="bi bi-x-lg me-1"></i> Cancel
         </a>
     }
 </form>
 
-@if (!Model.IsNew)
-{
-    <div class="modal fade" id="testModal" tabindex="-1">
-        <div class="modal-dialog modal-dialog-centered">
-            <div class="modal-content">
-                <div class="modal-header">
-                    <h5 class="modal-title"><i class="bi bi-send me-2"></i>Send Test Email</h5>
-                    <button type="button" class="btn-close" data-bs-dismiss="modal"></button>
-                </div>
-                <div class="modal-body">
-                    <label for="testToEmail" class="form-label fw-semibold">Recipient Email</label>
-                    <input type="email" id="testToEmail" class="form-control" placeholder="you@example.com" />
-                    <div id="testResult" class="mt-3" style="display:none"></div>
-                </div>
-                <div class="modal-footer">
-                    <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
-                    <button type="button" class="btn btn-success" id="testSendBtn" onclick="sendTestEmail('@Model.Id')">
-                        <i class="bi bi-send me-1"></i> Send
-                    </button>
-                </div>
+<div class="modal fade" id="testModal" tabindex="-1">
+    <div class="modal-dialog modal-dialog-centered">
+        <div class="modal-content">
+            <div class="modal-header">
+                <h5 class="modal-title"><i class="bi bi-send me-2"></i>Send Test Email</h5>
+                <button type="button" class="btn-close" data-bs-dismiss="modal"></button>
+            </div>
+            <div class="modal-body">
+                <p class="text-muted small">Tests the current form settings — no need to save first.</p>
+                <label for="testToEmail" class="form-label fw-semibold">Recipient Email</label>
+                <input type="email" id="testToEmail" class="form-control" placeholder="you@example.com" />
+                <div id="testResult" class="mt-3" style="display:none"></div>
+            </div>
+            <div class="modal-footer">
+                <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
+                <button type="button" class="btn btn-success" id="testSendBtn" onclick="sendTestEmail()">
+                    <i class="bi bi-send me-1"></i> Send
+                </button>
             </div>
         </div>
     </div>
+</div>
 
-    <script>
-        document.addEventListener('click', function (e) {
-            if (e.target.closest('#testModalBtn')) {
-                bootstrap.Modal.getOrCreateInstance(document.getElementById('testModal')).show();
-            }
-        });
-
-        async function sendTestEmail(channelId) {
-            const toEmail = document.getElementById('testToEmail').value.trim();
-            const resultDiv = document.getElementById('testResult');
-            const sendBtn = document.getElementById('testSendBtn');
-
-            if (!toEmail) {
-                resultDiv.style.display = 'block';
-                resultDiv.innerHTML = '<div class="alert alert-warning mb-0">Please enter a recipient email.</div>';
-                return;
-            }
-
-            sendBtn.disabled = true;
-            sendBtn.innerHTML = '<span class="spinner-border spinner-border-sm me-1"></span> Sending…';
-            resultDiv.style.display = 'none';
-
-            try {
-                const resp = await fetch(`/admin/channels/${channelId}/test`, {
-                    method: 'POST',
-                    headers: { 'Content-Type': 'application/json' },
-                    body: JSON.stringify({ toEmail })
-                });
-                const data = await resp.json();
-                resultDiv.style.display = 'block';
-                resultDiv.innerHTML = data.success
-                    ? `<div class="alert alert-success mb-0"><i class="bi bi-check-circle me-1"></i>${data.message}</div>`
-                    : `<div class="alert alert-danger mb-0"><i class="bi bi-x-circle me-1"></i>${data.message}</div>`;
-            } catch (e) {
-                resultDiv.style.display = 'block';
-                resultDiv.innerHTML = `<div class="alert alert-danger mb-0">Request failed: ${e.message}</div>`;
-            } finally {
-                sendBtn.disabled = false;
-                sendBtn.innerHTML = '<i class="bi bi-send me-1"></i> Send';
-            }
+<script>
+    document.addEventListener('click', function (e) {
+        if (e.target.closest('#testModalBtn')) {
+            document.getElementById('testResult').style.display = 'none';
+            bootstrap.Modal.getOrCreateInstance(document.getElementById('testModal')).show();
         }
-    </script>
-}
+    });
+
+    async function sendTestEmail() {
+        const toEmail = document.getElementById('testToEmail').value.trim();
+        const resultDiv = document.getElementById('testResult');
+        const sendBtn = document.getElementById('testSendBtn');
+
+        if (!toEmail) {
+            resultDiv.style.display = 'block';
+            resultDiv.innerHTML = '<div class="alert alert-warning mb-0">Please enter a recipient email.</div>';
+            return;
+        }
+
+        const form = document.getElementById('channelForm');
+        const payload = {
+            host: form.querySelector('[name="Host"]').value,
+            port: parseInt(form.querySelector('[name="Port"]').value, 10),
+            username: form.querySelector('[name="Username"]').value,
+            password: form.querySelector('[name="Password"]').value,
+            useSsl: form.querySelector('[name="UseSsl"]').checked,
+            fromEmail: form.querySelector('[name="FromEmail"]').value,
+            fromName: form.querySelector('[name="FromName"]').value,
+            toEmail
+        };
+
+        sendBtn.disabled = true;
+        sendBtn.innerHTML = '<span class="spinner-border spinner-border-sm me-1"></span> Sending…';
+        resultDiv.style.display = 'none';
+
+        try {
+            const resp = await fetch('/admin/channels/test-smtp', {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                body: JSON.stringify(payload)
+            });
+            const data = await resp.json();
+            resultDiv.style.display = 'block';
+            resultDiv.innerHTML = data.success
+                ? `<div class="alert alert-success mb-0"><i class="bi bi-check-circle me-1"></i>${data.message}</div>`
+                : `<div class="alert alert-danger mb-0"><i class="bi bi-x-circle me-1"></i>${data.message}</div>`;
+        } catch (e) {
+            resultDiv.style.display = 'block';
+            resultDiv.innerHTML = `<div class="alert alert-danger mb-0">Request failed: ${e.message}</div>`;
+        } finally {
+            sendBtn.disabled = false;
+            sendBtn.innerHTML = '<i class="bi bi-send me-1"></i> Send';
+        }
+    }
+</script>