improve logic for determining whether a git log editor tab should be closable

platform/vcs-log/impl/src/com/intellij/vcs/log/impl/IdeVcsLogManager.kt

@@ -4,7 +4,6 @@ package com.intellij.vcs.log.impl
 import com.intellij.openapi.application.EdtImmediate
 import com.intellij.openapi.application.UiImmediate
 import com.intellij.openapi.components.service
-import com.intellij.openapi.fileEditor.FileEditorManager
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.Disposer
 import com.intellij.openapi.vfs.VirtualFile
@@ -22,7 +21,6 @@ import com.intellij.vcs.log.impl.VcsLogNavigationUtil.showCommit
 import com.intellij.vcs.log.impl.VcsLogNavigationUtil.showCommitSync
 import com.intellij.vcs.log.ui.MainVcsLogUi
 import com.intellij.vcs.log.ui.VcsLogUiEx
-import com.intellij.vcs.log.ui.editor.VcsLogVirtualFileSystem
 import com.intellij.vcs.log.util.VcsLogUtil
 import com.intellij.vcs.log.visible.filters.VcsLogFilterObject
 import kotlinx.coroutines.CoroutineScope
@@ -62,9 +60,7 @@ internal class IdeVcsLogManager(
       mainUiHolderState.collect { holder ->
         val showLogInEditorWindow = service<VcsLogApplicationSettings>()[CommonUiProperties.SHOW_IN_EDITOR]
         val ui = if (showLogInEditorWindow) {
-          val file = VcsLogVirtualFileSystem.Holder.getInstance().
-          createVcsLogFile(project, "", null)
-          val editor = FileEditorManager.getInstance(project).openFile(file, false, true)
+          val editor = tabsManager.openEditorLogTab("", false, null)
           VcsLogEditorUtil.findVcsLogUi(editor,MainVcsLogUi::class.java)
         } else {
           createLogUi(getMainLogUiFactory(MAIN_LOG_ID, null))

platform/vcs-log/impl/src/com/intellij/vcs/log/impl/VcsLogTabsManager.kt

@@ -135,8 +135,8 @@ internal class VcsLogTabsManager(
     throw UnsupportedOperationException("Only log in editor or tool window is supported")
   }
 
-  private fun openEditorLogTab(tabId: String, focus: Boolean, filters: VcsLogFilterCollection?): Array<FileEditor> {
-    val file = VcsLogVirtualFileSystem.Holder.getInstance().createVcsLogFile(project, tabId, filters)
+  fun openEditorLogTab(tabId: String, focus: Boolean, filters: VcsLogFilterCollection?): Array<FileEditor> {
+    val file = VcsLogVirtualFileSystem.Holder.getInstance().createVcsLogFile(project, tabId, filters, uiProperties.tabs.isNotEmpty())
     installFilesListener()
     uiProperties.addTab(tabId, VcsLogTabLocation.EDITOR)
     return FileEditorManager.getInstance(project).openFile(file, focus, true)

platform/vcs-log/impl/src/com/intellij/vcs/log/ui/CanCloseVirtualLogFile.kt

@@ -10,6 +10,6 @@ class CanCloseVirtualLogFile: VirtualFilePreCloseCheck {
    * don't allow the first vcs log window to be closed
    */
   override fun canCloseFile(file: VirtualFile): Boolean {
-    return file !is DefaultVcsLogFile || !file.isFirstLogFile
+    return file !is DefaultVcsLogFile || file.canClose
   }
 }

platform/vcs-log/impl/src/com/intellij/vcs/log/ui/editor/DefaultVcsLogFile.kt

@@ -36,6 +36,8 @@ import javax.swing.JComponent
 internal class DefaultVcsLogFile(
   private val pathId: VcsLogVirtualFileSystem.VcsLogComplexPath,
   private var filters: VcsLogFilterCollection? = null,
+  // the first log file always gets created with an empty log ID in IdeVcsLogManager.createUi, which should never be closable
+  var canClose: Boolean = pathId.logId != ""
 ) :
   VcsLogFile(VcsLogTabsUtil.getFullName(pathId.logId)), VirtualFilePathWrapper { //NON-NLS not displayed
 
@@ -97,9 +99,6 @@ internal class DefaultVcsLogFile(
     return tabId.hashCode()
   }
 
-  // the first log file always gets created with an empty log ID in IdeVcsLogManager.createUi
-  val isFirstLogFile by lazy { pathId.logId == "" }
-
   companion object {
     private val LOG = logger<DefaultVcsLogFile>()
   }

platform/vcs-log/impl/src/com/intellij/vcs/log/ui/editor/VcsLogVirtualFileSystem.kt

@@ -13,15 +13,18 @@ internal class VcsLogVirtualFileSystem :
   ComplexPathVirtualFileSystem<VcsLogVirtualFileSystem.VcsLogComplexPath>(GsonComplexPathSerializer(VcsLogComplexPath::class.java)) {
 
   override fun findOrCreateFile(project: Project, path: VcsLogComplexPath): VirtualFile {
-    return createVcsLogFile(path, null)
+    return createVcsLogFile(path, null, true) // TODO: should this ever be false?
   }
 
-  fun createVcsLogFile(project: Project, tabId: String, filters: VcsLogFilterCollection?): VirtualFile {
-    return createVcsLogFile(VcsLogComplexPath(project.locationHash, project.locationHash, tabId), filters)
+  /**
+   * @param canClose if `null`, infer whether the file can be closed based on whether it's the initially opened one.
+   */
+  fun createVcsLogFile(project: Project, tabId: String, filters: VcsLogFilterCollection?, canClose: Boolean): VirtualFile {
+    return createVcsLogFile(VcsLogComplexPath(project.locationHash, project.locationHash, tabId), filters, canClose)
   }
 
-  private fun createVcsLogFile(pathId: VcsLogComplexPath, filters: VcsLogFilterCollection?): DefaultVcsLogFile {
-    return DefaultVcsLogFile(pathId, filters)
+  private fun createVcsLogFile(pathId: VcsLogComplexPath, filters: VcsLogFilterCollection?, canClose: Boolean): DefaultVcsLogFile {
+    return DefaultVcsLogFile(pathId, filters, canClose)
   }
 
   override fun getProtocol(): String = Holder.PROTOCOL