From 0ba37372daaf31c93bd2610c07d28fba587bb61d Mon Sep 17 00:00:00 2001
From: Kuba Niegowski <j.niegowski@cksource.com>
Date: Mon, 19 Jun 2023 17:50:39 +0200
Subject: [PATCH] Fixed beforeInput target ranges that start before the
 editable element.

---
 .../src/view/observer/inputobserver.ts        | 15 ++++++++++--
 .../tests/view/observer/inputobserver.js      | 24 +++++++++++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/packages/ckeditor5-engine/src/view/observer/inputobserver.ts b/packages/ckeditor5-engine/src/view/observer/inputobserver.ts
index 9f1efa2aac3..cc0c39841d9 100644
--- a/packages/ckeditor5-engine/src/view/observer/inputobserver.ts
+++ b/packages/ckeditor5-engine/src/view/observer/inputobserver.ts
@@ -79,8 +79,19 @@ export default class InputObserver extends DomEventObserver<'beforeinput'> {
 			// @if CK_DEBUG_TYPING // }
 		} else if ( domTargetRanges.length ) {
 			targetRanges = domTargetRanges.map( domRange => {
-				return view.domConverter.domRangeToView( domRange )!;
-			} );
+				// Sometimes browser provides range that starts before editable node.
+				// We try to fall back to collapsed range at the valid end position.
+				// See https://github.com/ckeditor/ckeditor5/issues/14411.
+				// See https://github.com/ckeditor/ckeditor5/issues/14050.
+				const viewStart = view.domConverter.domPositionToView( domRange.startContainer, domRange.startOffset );
+				const viewEnd = view.domConverter.domPositionToView( domRange.endContainer, domRange.endOffset );
+
+				if ( viewStart ) {
+					return view.createRange( viewStart, viewEnd );
+				} else if ( viewEnd ) {
+					return view.createRange( viewEnd );
+				}
+			} ).filter( ( range ): range is ViewRange => !!range );
 
 			// @if CK_DEBUG_TYPING // if ( ( window as any ).logCKETyping ) {
 			// @if CK_DEBUG_TYPING // 	console.info( '%c[InputObserver]%c using target ranges:',
diff --git a/packages/ckeditor5-engine/tests/view/observer/inputobserver.js b/packages/ckeditor5-engine/tests/view/observer/inputobserver.js
index 206440bd8a8..97d0bafcf92 100644
--- a/packages/ckeditor5-engine/tests/view/observer/inputobserver.js
+++ b/packages/ckeditor5-engine/tests/view/observer/inputobserver.js
@@ -133,6 +133,30 @@ describe( 'InputObserver', () => {
 				expect( viewRange2.end.offset ).to.equal( 2 );
 			} );
 
+			it( 'should provide fixed editing view ranges corresponding to DOM ranges passed along with the DOM event', () => {
+				const domRange = global.document.createRange();
+
+				// [<div contenteditable="true">
+				// <p>fo]o</p>
+				domRange.setStartBefore( domEditable );
+				domRange.setEnd( domEditable.firstChild.firstChild, 2 );
+
+				fireMockNativeBeforeInput( {
+					getTargetRanges: () => [ domRange ]
+				} );
+
+				expect( evtData.targetRanges ).to.have.length( 1 );
+
+				const viewRange = evtData.targetRanges[ 0 ];
+
+				expect( viewRange ).to.be.instanceOf( Range );
+
+				expect( viewRange.start.parent ).to.equal( viewRoot.getChild( 0 ).getChild( 0 ) );
+				expect( viewRange.start.offset ).to.equal( 2 );
+				expect( viewRange.end.parent ).to.equal( viewRoot.getChild( 0 ).getChild( 0 ) );
+				expect( viewRange.end.offset ).to.equal( 2 );
+			} );
+
 			it( 'should provide a range encompassing the selected object when selection is fake', () => {
 				const domRange = global.document.createRange();