fix: Deck Options: "Back" works incorrectly if the manual is open

AnkiDroid/src/main/java/com/ichi2/anki/AbstractFlashcardViewer.kt

@@ -467,7 +467,7 @@ abstract class AbstractFlashcardViewer :
     }
 
     /** Invoked by [CardViewerWebClient.onPageFinished] */
-    override fun onPageFinished() {
+    override fun onPageFinished(view: WebView) {
         // intentionally blank
     }
 
@@ -2451,7 +2451,7 @@ abstract class AbstractFlashcardViewer :
             pageRenderStopwatch.logElapsed()
             Timber.d("Java onPageFinished triggered: %s", url)
             // onPageFinished will be called multiple times if the WebView redirects by setting window.location.href
-            onPageFinishedCallback?.onPageFinished()
+            onPageFinishedCallback?.onPageFinished(view)
             view.loadUrl("javascript:onPageFinished();")
         }
 

AnkiDroid/src/main/java/com/ichi2/anki/AnkiActivity.kt

@@ -122,7 +122,8 @@ open class AnkiActivity : AppCompatActivity, SimpleMessageDialogListener {
     }
 
     protected open fun onActionBarBackPressed(): Boolean {
-        finish()
+        Timber.v("onActionBarBackPressed")
+        onBackPressedDispatcher.onBackPressed()
         return true
     }
 

AnkiDroid/src/main/java/com/ichi2/anki/OnPageFinishedCallback.kt

@@ -16,9 +16,12 @@
 
 package com.ichi2.anki
 
+import android.webkit.WebView
+
 /**
  * Intended to be used with [android.webkit.WebViewClient.onPageFinished]
  */
-interface OnPageFinishedCallback {
-    fun onPageFinished()
+fun interface OnPageFinishedCallback {
+    /** @see android.webkit.WebViewClient.onPageFinished */
+    fun onPageFinished(view: WebView)
 }

AnkiDroid/src/main/java/com/ichi2/anki/Reviewer.kt

@@ -32,6 +32,7 @@ import android.os.Parcelable
 import android.text.SpannableString
 import android.text.style.UnderlineSpan
 import android.view.*
+import android.webkit.WebView
 import android.widget.*
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.annotation.*
@@ -1026,8 +1027,8 @@ open class Reviewer :
         }
     }
 
-    override fun onPageFinished() {
-        super.onPageFinished()
+    override fun onPageFinished(view: WebView) {
+        super.onPageFinished(view)
         onFlagChanged()
         onMarkChanged()
         if (!displayAnswer) {

AnkiDroid/src/main/java/com/ichi2/anki/pages/DeckOptions.kt

@@ -19,28 +19,47 @@ import android.content.Context
 import android.content.Intent
 import android.os.Bundle
 import android.webkit.WebView
+import androidx.activity.OnBackPressedCallback
 import androidx.fragment.app.FragmentActivity
 import anki.collection.OpChanges
 import com.ichi2.anki.CollectionManager
+import com.ichi2.anki.OnPageFinishedCallback
 import com.ichi2.anki.R
 import com.ichi2.anki.SingleFragmentActivity
+import com.ichi2.annotations.NeedsTest
 import com.ichi2.libanki.undoableOp
 import com.ichi2.libanki.updateDeckConfigsRaw
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
+import timber.log.Timber
 
+@NeedsTest("pressing back: icon + button should go to the previous screen")
+@NeedsTest("15130: pressing back: icon + button should return to options if the manual is open")
 class DeckOptions : PageFragment() {
     override val title: String
         get() = resources.getString(R.string.menu__deck_options)
     override val pageName = "deck-options"
     override lateinit var webViewClient: PageWebViewClient
     override var webChromeClient = PageChromeClient()
 
+    // handle going back from the manual
+    private val onBackCallback = object : OnBackPressedCallback(false) {
+        override fun handleOnBackPressed() {
+            Timber.v("webView: navigating back")
+            webView.goBack()
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         val deckId = arguments?.getLong(ARG_DECK_ID)
             ?: throw Exception("missing deck ID")
         webViewClient = DeckOptionsWebClient(deckId)
         super.onCreate(savedInstanceState)
+        requireActivity().onBackPressedDispatcher.addCallback(this, onBackCallback)
+        webViewClient.onPageFinishedCallback = OnPageFinishedCallback { view ->
+            Timber.v("canGoBack: %b", view.canGoBack())
+            onBackCallback.isEnabled = view.canGoBack()
+        }
     }
 
     class DeckOptionsWebClient(val deckId: Long) : PageWebViewClient() {

AnkiDroid/src/main/java/com/ichi2/anki/pages/PageWebViewClient.kt

@@ -21,6 +21,7 @@ import android.webkit.WebView
 import android.webkit.WebViewClient
 import androidx.core.view.isVisible
 import com.google.android.material.color.MaterialColors
+import com.ichi2.anki.OnPageFinishedCallback
 import com.ichi2.utils.toRGBHex
 import timber.log.Timber
 
@@ -32,6 +33,8 @@ open class PageWebViewClient : WebViewClient() {
     /** Wait for the provided promise to complete before showing the WebView */
     open val promiseToWaitFor: String? = null
 
+    var onPageFinishedCallback: OnPageFinishedCallback? = null
+
     override fun onPageStarted(view: WebView?, url: String?, favicon: Bitmap?) {
         super.onPageStarted(view, url, favicon)
         view?.let { webView ->
@@ -45,7 +48,7 @@ open class PageWebViewClient : WebViewClient() {
     override fun onPageFinished(view: WebView?, url: String?) {
         super.onPageFinished(view, url)
         if (view == null) return
-
+        onPageFinishedCallback?.onPageFinished(view)
         if (promiseToWaitFor == null) {
             /** [PageFragment.webView] is invisible by default to avoid flashes while
              * the page is loaded, and can be made visible again after it finishes loading */