From 7ac3c436cae2fcc37841b9a6951c588d6b094a54 Mon Sep 17 00:00:00 2001
From: Feras Aldahlawi <faldahlawi@gmail.com>
Date: Sun, 19 May 2019 00:08:16 -0700
Subject: [PATCH] Fix MoveHalfPageUp (<C-u>) when first line is visible.
 (#3776)

* fix MoveHalfPageUp when first line is visible

* fix <C-u> when first line is visible
---
 src/actions/commands/actions.ts |  7 +++----
 test/mode/modeNormal.test.ts    | 21 +++++++++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/actions/commands/actions.ts b/src/actions/commands/actions.ts
index 4e8da5b51ce..eab38cd7042 100644
--- a/src/actions/commands/actions.ts
+++ b/src/actions/commands/actions.ts
@@ -734,13 +734,12 @@ class CommandMoveHalfPageUp extends CommandEditorScroll {
     const smoothScrolling = vscode.workspace.getConfiguration('editor').smoothScrolling;
     let lineOffset = 0;
     let editor = vscode.window.activeTextEditor!;
-    let startColumn = vimState.cursorStartPosition.character;
 
     let firstLine = editor.visibleRanges[0].start.line;
     let currentSelectionLine = vimState.cursorStopPosition.line;
-    lineOffset = currentSelectionLine - firstLine;
-
     let timesToRepeat = vimState.recordedState.count || 1;
+    lineOffset = firstLine === 0 ? 0 : (currentSelectionLine - firstLine);
+
     await vscode.commands.executeCommand('editorScroll', {
       to: this.to,
       by: this.by,
@@ -757,7 +756,7 @@ class CommandMoveHalfPageUp extends CommandEditorScroll {
       newPosition = new Position(editor.selection.active.line, editor.selection.active.character);
     } else {
       let newFirstLine = editor.visibleRanges[0].start.line;
-      newPosition = new Position(newFirstLine + lineOffset, startColumn);
+      newPosition = new Position(newFirstLine + lineOffset, 0);
     }
     vimState.cursorStopPosition = newPosition;
     return vimState;
diff --git a/test/mode/modeNormal.test.ts b/test/mode/modeNormal.test.ts
index ef7894127ce..ed8884ad222 100644
--- a/test/mode/modeNormal.test.ts
+++ b/test/mode/modeNormal.test.ts
@@ -2310,4 +2310,25 @@ suite('Mode Normal', () => {
       endMode: ModeName.Insert,
     });
   });
+
+  newTest({
+    title: 'can handle <C-u> when first line is visible and starting column is at the beginning',
+    start: ['hello world', 'hello', 'hi hello', '|foo'],
+    keysPressed: '<C-u>',
+    end: ['|hello world', 'hello', 'hi hello', 'foo'],
+  });
+
+  newTest({
+    title: 'can handle <C-u> when first line is visible and starting column is at the end',
+    start: ['hello world', 'hello', 'hi hello', 'very long line at the bottom|'],
+    keysPressed: '<C-u>',
+    end: ['|hello world', 'hello', 'hi hello', 'very long line at the bottom'],
+  });
+
+  newTest({
+    title: 'can handle <C-u> when first line is visible and starting column is in the middle',
+    start: ['hello world', 'hello', 'hi hello', 'very long line |at the bottom'],
+    keysPressed: '<C-u>',
+    end: ['|hello world', 'hello', 'hi hello', 'very long line at the bottom'],
+  });
 });