Fix GutenbergKit editor issues during dark mode toggle (#22135)

* Remove isEditorStarted flag to fix content loss during activity restart

The isEditorStarted flag was preventing editor reinitialization during
activity restarts, but this caused content loss because:

1. Activity restart triggers new fragment creation
2. isEditorStarted gets reset to false in onDestroy()
3. startWithEditorSettings() gets called but always rebuilds from original data
4. Current editor content is lost instead of being preserved

Root cause: The flag was designed to prevent duplicate initialization within
a single fragment instance, but during activity restarts, we WANT the editor
to reinitialize with the current content, not block reinitialization entirely.

Changes:
- Remove isEditorStarted field and related state management
- Remove isEditorStarted checks in startWithEditorSettings()
- Allow editor to reinitialize after activity restart
- Fixes content loss during dark mode toggle

* Fix double ViewPager setup during auth state changes

Prevent duplicate editor initialization by:
1. Only calling fetchWpComCookies() if not already in Success state
2. Adding ViewPager state check to prevent duplicate setup
3. Using distinctUntilChanged() to prevent duplicate LiveData emissions
4. Consolidating Success handling logic in handleSuccessfulAuth()

Changes:
- Check auth state before calling fetchWpComCookies()
- Add ViewPager adapter check with error logging for duplicate setup attempts
- Add distinctUntilChanged() to auth state observer
- Extract handleSuccessfulAuth() for consistent Success state handling
- Remove debug logging from production code

Author: oguzkocer

WordPress/src/main/java/org/wordpress/android/ui/posts/EditPostActivity.kt

@@ -41,6 +41,7 @@ import androidx.fragment.app.FragmentManager
 import androidx.fragment.app.FragmentPagerAdapter
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.ViewModelProvider
+import androidx.lifecycle.distinctUntilChanged
 import com.automattic.android.tracks.crashlogging.CrashLogging
 import com.automattic.android.tracks.crashlogging.JsException
 import com.automattic.android.tracks.crashlogging.JsExceptionCallback
@@ -617,8 +618,13 @@ class EditPostActivity : BaseAppCompatActivity(), EditorFragmentActivity, Editor
                 )
             }
             siteModel.isWPCom && !siteModel.isWPComAtomic && siteModel.isPrivate -> {
-                showIfNecessary(fragmentManager)
-                editPostAuthViewModel.fetchWpComCookies()
+                val currentAuthState = editPostAuthViewModel.wpComCookieAuthState.value
+                if (currentAuthState !is EditPostAuthViewModel.WpComCookieAuthState.Success) {
+                    showIfNecessary(fragmentManager)
+                    editPostAuthViewModel.fetchWpComCookies()
+                } else {
+                    handleSuccessfulWpComCookieAuthState()
+                }
             }
             else -> {
                 setupViewPager()
@@ -991,18 +997,13 @@ class EditPostActivity : BaseAppCompatActivity(), EditorFragmentActivity, Editor
             updateUIForDestination(destination)
         }
 
-        editPostAuthViewModel.wpComCookieAuthState.observe(this) { authState ->
+        editPostAuthViewModel.wpComCookieAuthState.distinctUntilChanged().observe(this) { authState ->
             when (authState) {
                 is EditPostAuthViewModel.WpComCookieAuthState.Loading -> {
                     showIfNecessary(supportFragmentManager)
                 }
                 is EditPostAuthViewModel.WpComCookieAuthState.Success -> {
-                    if (isShowing(supportFragmentManager)) {
-                        setupViewPager()
-                        dismissIfNecessary(supportFragmentManager)
-                    } else {
-                        setupViewPager()
-                    }
+                    handleSuccessfulWpComCookieAuthState()
                 }
                 is EditPostAuthViewModel.WpComCookieAuthState.Error -> {
                     if (isShowing(supportFragmentManager)) {
@@ -1078,7 +1079,26 @@ class EditPostActivity : BaseAppCompatActivity(), EditorFragmentActivity, Editor
         invalidateOptionsMenu()
     }
 
+    private fun handleSuccessfulWpComCookieAuthState() {
+        if (isShowing(supportFragmentManager)) {
+            setupViewPager()
+            dismissIfNecessary(supportFragmentManager)
+        } else {
+            setupViewPager()
+        }
+    }
+
     private fun setupViewPager() {
+        // Check if ViewPager is already configured
+        if (viewPager?.adapter != null) {
+            AppLog.e(
+                AppLog.T.EDITOR,
+                "EditPostActivity: setupViewPager() called but ViewPager already has adapter" +
+                        " - possible duplicate setup"
+            )
+            return
+        }
+
         // Set up the ViewPager with the sections adapter.
         viewPager = findViewById(R.id.pager)
         viewPager?.adapter = sectionsPagerAdapter

WordPress/src/main/java/org/wordpress/android/ui/posts/editor/GutenbergKitEditorFragment.kt

@@ -66,7 +66,6 @@ class GutenbergKitEditorFragment : EditorFragmentAbstract(), EditorMediaUploadLi
     private var openMediaLibraryListener: OpenMediaLibraryListener? = null
     private var onLogJsExceptionListener: LogJsExceptionListener? = null
 
-    private var isEditorStarted = false
     private var isEditorDidMount = false
     private var rootView: View? = null
 
@@ -78,7 +77,6 @@ class GutenbergKitEditorFragment : EditorFragmentAbstract(), EditorMediaUploadLi
 
         if (savedInstanceState != null) {
             isHtmlModeEnabled = savedInstanceState.getBoolean(KEY_HTML_MODE_ENABLED)
-            isEditorStarted = savedInstanceState.getBoolean(KEY_EDITOR_STARTED)
             isEditorDidMount = savedInstanceState.getBoolean(KEY_EDITOR_DID_MOUNT)
             mFeaturedImageId = savedInstanceState.getLong(ARG_FEATURED_IMAGE_ID)
         }
@@ -235,7 +233,6 @@ class GutenbergKitEditorFragment : EditorFragmentAbstract(), EditorMediaUploadLi
 
     override fun onSaveInstanceState(outState: Bundle) {
         outState.putBoolean(KEY_HTML_MODE_ENABLED, isHtmlModeEnabled)
-        outState.putBoolean(KEY_EDITOR_STARTED, isEditorStarted)
         outState.putBoolean(KEY_EDITOR_DID_MOUNT, isEditorDidMount)
         outState.putLong(ARG_FEATURED_IMAGE_ID, mFeaturedImageId)
     }
@@ -464,7 +461,6 @@ class GutenbergKitEditorFragment : EditorFragmentAbstract(), EditorMediaUploadLi
             historyChangeListener = null
             featuredImageChangeListener = null
         }
-        isEditorStarted = false
         super.onDestroy()
     }
 
@@ -507,12 +503,11 @@ class GutenbergKitEditorFragment : EditorFragmentAbstract(), EditorMediaUploadLi
     }
 
     fun startWithEditorSettings(editorSettings: String) {
-        if (gutenbergView == null || isEditorStarted) {
+        if (gutenbergView == null) {
             return
         }
 
         val config = buildEditorConfiguration(editorSettings)
-        isEditorStarted = true
         gutenbergView?.start(config)
     }
 
@@ -583,7 +578,6 @@ class GutenbergKitEditorFragment : EditorFragmentAbstract(), EditorMediaUploadLi
     companion object {
         private const val GUTENBERG_EDITOR_NAME = "gutenberg"
         private const val KEY_HTML_MODE_ENABLED = "KEY_HTML_MODE_ENABLED"
-        private const val KEY_EDITOR_STARTED = "KEY_EDITOR_STARTED"
         private const val KEY_EDITOR_DID_MOUNT = "KEY_EDITOR_DID_MOUNT"
         private const val ARG_IS_NEW_POST = "param_is_new_post"
         private const val ARG_GUTENBERG_WEB_VIEW_AUTH_DATA = "param_gutenberg_web_view_auth_data"