From faa72d6b4266a520c31075c44bd7ce6b3ca0cd1d Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <basleijdekkers@gmail.com>
Date: Fri, 9 May 2025 10:39:08 +0200
Subject: [PATCH] Stop Move line up/down at the top/bottom correctly with
 multi-caret (IJ-CR-160892)

GitOrigin-RevId: adec4f82c09efaa52db71b94ebaa5ac9d89271c5
---
 .../moveUpDown/BaseMoveHandler.java           | 38 +++++++++++++++----
 1 file changed, 30 insertions(+), 8 deletions(-)

diff --git a/platform/lang-impl/src/com/intellij/codeInsight/editorActions/moveUpDown/BaseMoveHandler.java b/platform/lang-impl/src/com/intellij/codeInsight/editorActions/moveUpDown/BaseMoveHandler.java
index ba9cbd0d118d..b9cd51a24467 100644
--- a/platform/lang-impl/src/com/intellij/codeInsight/editorActions/moveUpDown/BaseMoveHandler.java
+++ b/platform/lang-impl/src/com/intellij/codeInsight/editorActions/moveUpDown/BaseMoveHandler.java
@@ -7,6 +7,7 @@ import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.editor.actionSystem.EditorWriteActionHandler;
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.util.Key;
 import com.intellij.psi.PsiFile;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
@@ -20,6 +21,7 @@ import java.util.List;
  */
 @ApiStatus.Internal
 public abstract class BaseMoveHandler extends EditorWriteActionHandler.ForEachCaret {
+  private static final Key<Key<?>> FIRST_CARET_VETO = new Key<>("FIRST_CARET_VETO");
   protected final boolean isDown;
 
   public BaseMoveHandler(boolean down) {
@@ -36,7 +38,14 @@ public abstract class BaseMoveHandler extends EditorWriteActionHandler.ForEachCa
     final Document document = editor.getDocument();
     int textLength = document.getTextLength();
     List<Caret> adjusted = null;
-    for (Caret c : editor.getCaretModel().getAllCarets()) {
+    final List<Caret> carets = editor.getCaretModel().getAllCarets();
+    final Project project = editor.getProject();
+    assert project != null;
+    final PsiFile file = getPsiFile(project, editor);
+
+    final MoverWrapper mover = getSuitableMover(editor, file);
+    if (movementVetoed(caret, carets, mover == null)) return;
+    for (Caret c : carets) {
       if (c != caret && c.getLogicalPosition().column == 0) {
         if (adjusted == null) adjusted = new ArrayList<>();
         int offset = c.getOffset();
@@ -45,11 +54,6 @@ public abstract class BaseMoveHandler extends EditorWriteActionHandler.ForEachCa
       }
     }
 
-    final Project project = editor.getProject();
-    assert project != null;
-    final PsiFile file = getPsiFile(project, editor);
-
-    final MoverWrapper mover = getSuitableMover(editor, file);
     if (mover != null && mover.getInfo().toMove2 != null) {
       LineRange range = mover.getInfo().toMove;
       if ((range.startLine > 0 || isDown) && (range.endLine < document.getLineCount() || !isDown)) {
@@ -65,12 +69,30 @@ public abstract class BaseMoveHandler extends EditorWriteActionHandler.ForEachCa
     }
   }
 
+  private boolean movementVetoed(@NotNull Caret caret, List<Caret> carets, boolean blocked) {
+    Caret firstCaret = isDown ? carets.get(carets.size() - 1) : carets.get(0);
+    if (caret == firstCaret) {
+      if (blocked) {
+        firstCaret.putUserData(FIRST_CARET_VETO, FIRST_CARET_VETO);
+        return true;
+      }
+    }
+    else {
+      boolean vetoed = firstCaret.getUserData(FIRST_CARET_VETO) != null;
+      if (vetoed) {
+        Caret lastCaret = isDown ? carets.get(0) : carets.get(carets.size() - 1);
+        if (caret == lastCaret) firstCaret.putUserData(FIRST_CARET_VETO, null);
+        return true;
+      }
+    }
+    return false;
+  }
+
   @Override
   public boolean isEnabledForCaret(@NotNull Editor editor, @NotNull Caret caret, DataContext dataContext) {
     if (editor.isViewer() || editor.isOneLineMode()) return false;
     final Project project = editor.getProject();
-    if (project == null || project.isDisposed()) return false;
-    return true;
+    return project != null && !project.isDisposed();
   }
 
   protected abstract @Nullable PsiFile getPsiFile(@NotNull Project project, @NotNull Editor editor);