From 75fb37d1018705ee313c52948fb130d8ba002a14 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miko=C5=82aj=20Trzci=C5=84ski?=
 <mtrzcinski@internships.svevn.com>
Date: Mon, 23 Sep 2024 14:51:20 +0200
Subject: [PATCH] [#66130] scroll editor on preview click

---
 src/MystEditor.js              |  9 ++++++++-
 src/extensions/syncDualPane.js | 32 ++++++++++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/MystEditor.js b/src/MystEditor.js
index 48c7b47..5d11467 100644
--- a/src/MystEditor.js
+++ b/src/MystEditor.js
@@ -12,6 +12,7 @@ import useCollaboration from "./hooks/useCollaboration";
 import useComments from "./hooks/useComments";
 import ResolvedComments from "./components/Resolved";
 import { handlePreviewFold } from "./hooks/markdownFoldButtons";
+import { handlePreviewClickToScroll } from "./extensions/syncDualPane";
 
 if (!window.myst_editor?.isFresh) {
   resetCache();
@@ -224,7 +225,13 @@ const MystEditor = ({
             />
           <//>
           <${FlexWrapper} id="preview-wrapper"
-            ><${Preview} ref=${preview} mode=${mode} onClick=${(ev) => handlePreviewFold(ev, text.lineMap)}
+            ><${Preview}
+              ref=${preview}
+              mode=${mode}
+              onClick=${(ev) => {
+                handlePreviewFold(ev, text.lineMap);
+                handlePreviewClickToScroll(ev, text.lineMap, preview);
+              }}
               ><${PreviewFocusHighlight} className="cm-previewFocus" /><//
           ><//>
           ${mode === "Diff" && html`<${FlexWrapper}><${Diff} root=${parent} oldText=${initialText} text=${text} /><//>`}
diff --git a/src/extensions/syncDualPane.js b/src/extensions/syncDualPane.js
index 12b5ca7..db1bf3c 100644
--- a/src/extensions/syncDualPane.js
+++ b/src/extensions/syncDualPane.js
@@ -1,9 +1,10 @@
 import { EditorView } from "codemirror";
 import { markdownUpdatedStateEffect } from "../hooks/useText";
-import { findNearestElementForLine } from "../hooks/markdownSourceMap";
+import { findNearestElementForLine, getLineById } from "../hooks/markdownSourceMap";
+import { EditorSelection } from "@codemirror/state";
 
 const previewTopPadding = 20;
-const debounceTimeout = 50;
+const debounceTimeout = 100;
 
 export const syncPreviewWithCursor = (lineMap, preview) => {
   let timeout;
@@ -50,3 +51,30 @@ function scrollPreviewElemIntoView({ view, matchingLine, matchingElem, behavior
   const top = matchingRect.top + preview.scrollTop - elemScrollOffset - previewRect.top + editor.scrollTop;
   preview.scrollTo({ top, behavior });
 }
+
+export function handlePreviewClickToScroll(/** @type {{ target: HTMLElement }} */ ev, lineMap, preview) {
+  const id = ev.target.getAttribute("data-line-id");
+  if (!id) return;
+
+  const lineNumber = getLineById(lineMap.current, id);
+  const line = window.myst_editor.main_editor.state.doc.line(lineNumber);
+  const lineBlock = window.myst_editor.main_editor.lineBlockAt(line.from);
+  const targetRect = ev.target.getBoundingClientRect();
+  const previewRect = preview.current.getBoundingClientRect();
+  const editor = window.myst_editor.main_editor.dom.parentElement;
+
+  const editorScrollOffset = targetRect.top;
+  const top = lineBlock.top - editorScrollOffset + previewRect.top + previewTopPadding;
+  editor.scrollTo({
+    top,
+    behavior: "smooth",
+  });
+  function setCursor() {
+    window.myst_editor.main_editor.dispatch({
+      selection: EditorSelection.create([EditorSelection.range(line.to, line.to)]),
+    });
+    window.myst_editor.main_editor.focus();
+    editor.removeEventListener("scrollend", setCursor);
+  }
+  editor.addEventListener("scrollend", setCursor);
+}