From 808533b11084b16fb57b0c98a7f978ce82768b3a Mon Sep 17 00:00:00 2001
From: Alex Plate <aleksei.plate@jetbrains.com>
Date: Fri, 26 Jan 2024 17:49:44 +0200
Subject: [PATCH] Fix(VIM-3260): Processing the offsets at the file end

---
 .../maddyhome/idea/vim/listener/VimListenerManager.kt | 11 +++++++++--
 .../com/maddyhome/idea/vim/api/EngineEditorHelper.kt  |  7 +++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/maddyhome/idea/vim/listener/VimListenerManager.kt b/src/main/java/com/maddyhome/idea/vim/listener/VimListenerManager.kt
index 2c6ab3943f..ba9189ea11 100644
--- a/src/main/java/com/maddyhome/idea/vim/listener/VimListenerManager.kt
+++ b/src/main/java/com/maddyhome/idea/vim/listener/VimListenerManager.kt
@@ -55,6 +55,7 @@ import com.maddyhome.idea.vim.VimTypedActionHandler
 import com.maddyhome.idea.vim.api.LocalOptionInitialisationScenario
 import com.maddyhome.idea.vim.api.Options
 import com.maddyhome.idea.vim.api.VimEditor
+import com.maddyhome.idea.vim.api.coerceOffset
 import com.maddyhome.idea.vim.api.getLineEndForOffset
 import com.maddyhome.idea.vim.api.getLineStartForOffset
 import com.maddyhome.idea.vim.api.injector
@@ -462,11 +463,17 @@ internal object VimListenerManager {
         if (lineEnd == endOffset - 1) {
           // When starting on an empty line and dragging vertically upwards onto
           // another line, the selection should include the entirety of the empty line
-          caret.setSelection(endOffset + 1, startOffset)
+          caret.setSelection(
+            ijVimEditor.coerceOffset(endOffset + 1).point,
+            ijVimEditor.coerceOffset(startOffset).point,
+          )
         } else if (lineEnd == startOffset + 1 && startOffset == endOffset) {
           // When dragging left from EOL on a non-empty line, the selection
           // should include the last character on the line
-          caret.setSelection(lineEnd, lineEnd - 1)
+          caret.setSelection(
+            ijVimEditor.coerceOffset(lineEnd).point,
+            ijVimEditor.coerceOffset(lineEnd - 1).point,
+          )
         }
       }
       //endregion
diff --git a/vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/EngineEditorHelper.kt b/vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/EngineEditorHelper.kt
index fc74be7d4a..6cd2bcc6f2 100644
--- a/vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/EngineEditorHelper.kt
+++ b/vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/EngineEditorHelper.kt
@@ -9,6 +9,7 @@
 package com.maddyhome.idea.vim.api
 
 import com.maddyhome.idea.vim.common.Graphemes
+import com.maddyhome.idea.vim.common.Offset
 import com.maddyhome.idea.vim.common.TextRange
 import java.nio.CharBuffer
 
@@ -293,3 +294,9 @@ public fun VimEditor.isLineEmpty(line: Int, allowBlanks: Boolean): Boolean {
   }
   return false
 }
+
+public fun VimEditor.coerceOffset(offset: Int): Offset {
+  if (offset < 0) return Offset(0)
+  if (offset > this.fileSize()) return Offset(this.fileSize().toInt())
+  return Offset(offset)
+}