From 87a7cf733238bf16a1321104958a65abd486c285 Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Mon, 6 May 2024 12:33:09 +0200
Subject: [PATCH] Issue #2472 - Part 6: Fire cancel event and close modal
 <dialog> on [ESC]

This implementation is different than Mozilla, not indirectly queueing cancel
tasks to be arbitrarily ordered, but rather synchronously close in reverse
top layer order.
---
 dom/base/nsDocument.cpp        | 13 +++++++++++++
 dom/base/nsDocument.h          |  3 +++
 dom/base/nsIDocument.h         |  5 +++++
 dom/html/HTMLDialogElement.cpp | 21 +++++++++++++++++++++
 dom/html/HTMLDialogElement.h   |  1 +
 layout/base/nsPresShell.cpp    |  6 ++++++
 6 files changed, 49 insertions(+)

diff --git a/dom/base/nsDocument.cpp b/dom/base/nsDocument.cpp
index 68dfd7eebd..c13e775a94 100644
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -159,6 +159,7 @@
 #include "nsEscape.h"
 #include "nsObjectLoadingContent.h"
 #include "nsHtml5TreeOpExecutor.h"
+#include "mozilla/dom/HTMLDialogElement.h"
 #include "mozilla/dom/HTMLLinkElement.h"
 #include "mozilla/dom/HTMLMediaElement.h"
 #include "mozilla/dom/HTMLIFrameElement.h"
@@ -10138,6 +10139,18 @@ nsDocument::MozCancelFullScreen()
   return NS_OK;
 }
 
+void nsDocument::TryCancelDialog() {
+  // Check if the document is blocked by modal dialog
+  for (const nsWeakPtr& weakPtr : Reversed(mTopLayer)) {
+    nsCOMPtr<Element> element(do_QueryReferent(weakPtr));
+    if (HTMLDialogElement* dialog =
+            HTMLDialogElement::FromContentOrNull(element)) {
+      dialog->CancelDialog();
+      break;
+    }
+  }
+}
+
 void
 nsIDocument::ExitFullscreen()
 {
diff --git a/dom/base/nsDocument.h b/dom/base/nsDocument.h
index 16b93d245d..70bda75fed 100644
--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -918,6 +918,9 @@ public:
   // flag.
   bool SetFullscreenElement(Element* aElement);
 
+  // Cancel the dialog element if the document is blocked by the dialog
+  void TryCancelDialog();
+
   // Returns the top element from the full-screen stack.
   Element* GetTopLayerTop() override;
   // Return the fullscreen element in the top layer
diff --git a/dom/base/nsIDocument.h b/dom/base/nsIDocument.h
index 2a18c2259e..bf4b053f5e 100644
--- a/dom/base/nsIDocument.h
+++ b/dom/base/nsIDocument.h
@@ -1349,6 +1349,11 @@ public:
   virtual bool TopLayerPush(Element* aElement) = 0;
   virtual Element* TopLayerPop(FunctionRef<bool(Element*)> aPredicateFunc) = 0;
 
+  /**
+   * Cancel the dialog element if the document is blocked by the dialog.
+   */
+  virtual void TryCancelDialog() = 0;
+  
   /**
    * Synchronously cleans up the fullscreen state on the given document.
    *
diff --git a/dom/html/HTMLDialogElement.cpp b/dom/html/HTMLDialogElement.cpp
index 795b44dc1a..ef6d40b832 100644
--- a/dom/html/HTMLDialogElement.cpp
+++ b/dom/html/HTMLDialogElement.cpp
@@ -111,6 +111,27 @@ HTMLDialogElement::ShowModal(ErrorResult& aError)
   aError.SuppressException();
 }
 
+void HTMLDialogElement::CancelDialog() {
+  // 1) Let close be the result of firing an event named cancel at dialog, with
+  // the cancelable attribute initialized to true.
+  bool defaultAction = true;
+  nsContentUtils::DispatchTrustedEvent(
+      OwnerDoc(),
+      static_cast<nsIContent*>(this),
+      NS_LITERAL_STRING("cancel"),
+      false, /* can bubble */
+      true, /* can cancel */
+      &defaultAction);
+
+  // 2) If close is true and dialog has an open attribute, then close the dialog
+  // with no return value.
+  if (defaultAction) {
+    Optional<nsAString> retValue;
+    Close(retValue);
+  }
+}
+
+
 JSObject*
 HTMLDialogElement::WrapNode(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
 {
diff --git a/dom/html/HTMLDialogElement.h b/dom/html/HTMLDialogElement.h
index 6386452d91..4bc9ab879f 100644
--- a/dom/html/HTMLDialogElement.h
+++ b/dom/html/HTMLDialogElement.h
@@ -49,6 +49,7 @@ public:
   void ShowModal(ErrorResult& aError);
   
   bool IsInTopLayer() const;
+  void CancelDialog();
 
   nsString mReturnValue;
 
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 713b06cb96..36de447a32 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -8059,6 +8059,12 @@ PresShell::HandleEventInternal(WidgetEvent* aEvent,
               aEvent->mFlags.mDefaultPreventedByChrome) {
             mIsLastChromeOnlyEscapeKeyConsumed = true;
           }
+          if (aEvent->mMessage == eKeyDown &&
+              !aEvent->mFlags.mDefaultPrevented) {
+            if (nsIDocument* doc = GetDocument()) {
+              doc->TryCancelDialog();
+            }
+          }
         }
       }
       break;