Modal option for Pay Button

closes #796

BTCPayServer/Controllers/PublicController.cs

@@ -37,7 +37,6 @@ namespace BTCPayServer.Controllers
         
         [HttpPost]
         [Route("api/v1/invoices")]
-        [MediaTypeAcceptConstraintAttribute("text/html")]
         [IgnoreAntiforgeryToken]
         [EnableCors(CorsPolicies.All)]
         public async Task<IActionResult> PayButtonHandle([FromForm]PayButtonViewModel model, CancellationToken cancellationToken)
@@ -78,6 +77,15 @@ namespace BTCPayServer.Controllers
                 ModelState.AddModelError("Store", e.Message);
                 return View();
             }
+            
+            if (model.JsonResponse)
+            {
+                return Json(new
+                {
+                    InvoiceId = invoice.Data.Id,
+                    InvoiceUrl = invoice.Data.Url
+                });
+            }
 
             if (string.IsNullOrEmpty(model.CheckoutQueryString))
             {