Handle wrong lookup selection

Some of lookup suggestions can have unwanted behaviour like additional imports.
There wrong suggestions will be deleted and further lookup suggestions for this case will be ignored

platform/lang-impl/src/com/intellij/internal/retype/RetypeSession.kt

@@ -58,6 +58,9 @@ class RetypeSession(
   private val disposeLock = Any()
   private var typedRightBefore = false
 
+  private var skipLookupSuggestion = false
+  private var textBeforeLookupSelection: String? = null
+
   init {
     if (editor.selectionModel.hasSelection()) {
       pos = editor.selectionModel.selectionStart
@@ -128,8 +131,28 @@ class RetypeSession(
   private fun typeNext() {
     threadDumpAlarm.addRequest({ logThreadDump() }, threadDumpDelay)
 
+    if (document.text.take(pos) != originalText.take(pos)) {
+      // Unexpected changes before current cursor position
+      // (may be unwanted import)
+      if (textBeforeLookupSelection != null) {
+        // Unexpected changes was made by lookup.
+        // Restore previous text state and set flag to skip further suggestions until whitespace will be typed
+        WriteCommandAction.runWriteCommandAction(project) {
+          document.replaceText(textBeforeLookupSelection ?: return@runWriteCommandAction, document.modificationStamp + 1)
+        }
+        skipLookupSuggestion = true
+      }
+      else {
+        // There changes wasn't made by lookup, so we don't know how to handle them
+        // Restore text as it should be at this point without any intelligence
+        WriteCommandAction.runWriteCommandAction(project) {
+          document.replaceText(originalText.substring(0, pos) + originalText.substring(endPos), document.modificationStamp + 1)
+        }
+      }
+    }
+
     if (editor.caretModel.offset > pos) {
-      // Editor movement has been preformed
+      // Caret movement has been preformed
       // Move the caret forward until the characters match
       while (pos < document.textLength - tailLength
              && originalText[pos] == document.text[pos]
@@ -163,12 +186,13 @@ class RetypeSession(
     }
 
     val lookup = LookupManager.getActiveLookup(editor) as LookupImpl?
-    if (lookup != null) {
+    if (lookup != null && !skipLookupSuggestion) {
       val currentLookupElement = lookup.currentItem
       if (currentLookupElement?.shouldAccept(lookup.lookupStart) == true) {
         lookup.focusDegree = LookupImpl.FocusDegree.FOCUSED
         scriptBuilder?.append("${ActionCommand.PREFIX} ${IdeActions.ACTION_CHOOSE_LOOKUP_ITEM}\n")
         typedRightBefore = false
+        textBeforeLookupSelection = document.text
         executeEditorAction(IdeActions.ACTION_CHOOSE_LOOKUP_ITEM)
         queueNextOrStop()
         return
@@ -177,6 +201,11 @@ class RetypeSession(
 
     val c = originalText[pos++]
     typedChars++
+
+    // Reset lookup related variables
+    textBeforeLookupSelection = null
+    if (c == ' ') skipLookupSuggestion = false // We expecting new lookup suggestions
+
     if (c == '\n') {
       scriptBuilder?.append("${ActionCommand.PREFIX} ${IdeActions.ACTION_EDITOR_ENTER}\n")
       executeEditorAction(IdeActions.ACTION_EDITOR_ENTER)