KTIJ-10606 [kotlin] Move function to class: offload validation to background thread

Validator expects the result synchronously.
Checking class presence in it can lead to freezes.
The fix moves the class search before launching the validation,
which makes it possible to run the search read action on a pooled thread instead of EDT.

(cherry picked from commit 452eb04f1f30a7adbc012146d58881351b7c75c0)

GitOrigin-RevId: 7d41d2ff6bbd9b413551425c983dadab83278f43

plugins/kotlin/refactorings/kotlin.refactorings.k2/src/org/jetbrains/kotlin/idea/k2/refactoring/move/ui/K2MoveToClassDialog.kt

@@ -2,6 +2,7 @@
 package org.jetbrains.kotlin.idea.k2.refactoring.move.ui
 
 import com.intellij.ide.util.TreeJavaClassChooserDialog
+import com.intellij.openapi.application.ModalityState
 import com.intellij.openapi.application.ReadAction
 import com.intellij.openapi.fileEditor.FileEditorManager
 import com.intellij.openapi.observable.properties.AtomicBooleanProperty
@@ -26,6 +27,7 @@ import com.intellij.ui.dsl.builder.RowLayout
 import com.intellij.ui.dsl.builder.panel
 import com.intellij.ui.dsl.builder.toMutableProperty
 import com.intellij.util.Alarm
+import com.intellij.util.concurrency.AppExecutorUtil
 import com.intellij.util.ui.JBUI
 import com.intellij.util.ui.UIUtil
 import org.jetbrains.annotations.ApiStatus
@@ -117,18 +119,17 @@ class K2MoveToClassDialog(
         text = candidateList.selectedValue?.targetClassFqName?.asString().orEmpty()
     }
 
+    private var isTargetClassFound = true
+
     /**
      * Installs a validator for the target class text field.
      * The validator checks that the inserted FQ name can be resolved to a [KtClassOrObject].
-     * The validation can happen not more often than once per [VALIDATION_DELAY_MILLIS] ms.
+     * The validation cannot happen more often than once per [VALIDATION_DELAY_MILLIS] ms.
      */
     private fun TextFieldWithBrowseButton.installTargetClassValidator() {
         ComponentValidator(disposable).withValidator {
-            val isValid = ReadAction.nonBlocking(Callable {
-                currentTargetClass() != null
-            }).executeSynchronously()
-            okAction.isEnabled = isValid
-            if (!isValid) {
+            okAction.isEnabled = isTargetClassFound
+            if (!isTargetClassFound && classChooser.text.isNotEmpty()) {
                 ValidationInfo(KotlinBundle.message("refactoring.cannot.find.target.class"), textField)
             } else null
         }.installOn(textField)
@@ -137,7 +138,14 @@ class K2MoveToClassDialog(
             override fun textChanged(e: DocumentEvent) {
                 validationAlarm.cancelAllRequests()
                 validationAlarm.addRequest({
-                    ComponentValidator.getInstance(textField).ifPresent { validator -> validator.revalidate() }
+                    ComponentValidator.getInstance(textField).ifPresent { validator ->
+                        ReadAction.nonBlocking(Callable {
+                            currentTargetClass() != null
+                        }).finishOnUiThread(ModalityState.stateForComponent(this@installTargetClassValidator)) {
+                            isTargetClassFound = it
+                            validator.revalidate()
+                        }.submit(AppExecutorUtil.getAppExecutorService())
+                    }
                 }, delayMillis = VALIDATION_DELAY_MILLIS)
             }
         })