Improve WebView multi-window UX (#2662)

- Navigation history for lower windows is preserved when a popup is opened
- Back gesture will close a popup window rather than the entire WebView activity when there is no previous page
- The leftmost close button closes the entire activity as before
- When a popup window is shown, a new button appears to close just that window

(cherry picked from commit 855eea2ada8c09404dee99a965325913b246618f)

app/src/main/java/eu/kanade/presentation/webview/WebViewScreenContent.kt

@@ -5,6 +5,7 @@ import android.graphics.Bitmap
 import android.os.Message
 import android.webkit.WebResourceRequest
 import android.webkit.WebView
+import androidx.activity.compose.BackHandler
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
@@ -28,7 +29,9 @@ import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.vector.ImageVector
 import androidx.compose.ui.platform.LocalUriHandler
+import androidx.compose.ui.res.vectorResource
 import androidx.compose.ui.unit.dp
 import cafe.adriel.voyager.core.stack.mutableStateStackOf
 import com.kevinnzou.web.AccompanistWebChromeClient
@@ -36,12 +39,13 @@ import com.kevinnzou.web.AccompanistWebViewClient
 import com.kevinnzou.web.LoadingState
 import com.kevinnzou.web.WebContent
 import com.kevinnzou.web.WebView
+import com.kevinnzou.web.WebViewNavigator
 import com.kevinnzou.web.WebViewState
-import com.kevinnzou.web.rememberWebViewNavigator
 import eu.kanade.presentation.components.AppBar
 import eu.kanade.presentation.components.AppBarActions
 import eu.kanade.presentation.components.WarningBanner
 import eu.kanade.tachiyomi.BuildConfig
+import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.util.system.getHtml
 import eu.kanade.tachiyomi.util.system.setDefaultSettings
 import kotlinx.collections.immutable.persistentListOf
@@ -50,13 +54,13 @@ import tachiyomi.i18n.MR
 import tachiyomi.presentation.core.components.material.Scaffold
 import tachiyomi.presentation.core.i18n.stringResource
 
-class WebViewWindow(webContent: WebContent) {
+class WebViewWindow(webContent: WebContent, val navigator: WebViewNavigator) {
     var state by mutableStateOf(WebViewState(webContent))
     var popupMessage: Message? = null
         private set
     var webView: WebView? = null
 
-    constructor(popupMessage: Message) : this(WebContent.NavigatorOnly) {
+    constructor(popupMessage: Message, navigator: WebViewNavigator) : this(WebContent.NavigatorOnly, navigator) {
         this.popupMessage = popupMessage
     }
 }
@@ -72,27 +76,20 @@ fun WebViewScreenContent(
     headers: Map<String, String> = emptyMap(),
     onUrlChange: (String) -> Unit = {},
 ) {
+    val coroutineScope = rememberCoroutineScope()
+
     val windowStack = remember {
         mutableStateStackOf(
             WebViewWindow(
                 WebContent.Url(url = url, additionalHttpHeaders = headers),
+                WebViewNavigator(coroutineScope),
             ),
         )
     }
 
     val currentWindow = windowStack.lastItemOrNull!!
+    val navigator = currentWindow.navigator
 
-    val popState: (() -> Unit) = remember {
-        {
-            if (windowStack.size == 1) {
-                onNavigateUp()
-            } else {
-                windowStack.pop()
-            }
-        }
-    }
-
-    val navigator = rememberWebViewNavigator()
     val uriHandler = LocalUriHandler.current
     val scope = rememberCoroutineScope()
 
@@ -161,7 +158,7 @@ fun WebViewScreenContent(
             ): Boolean {
                 // if it wasn't initiated by a user gesture, we should ignore it like a normal browser would
                 if (isUserGesture) {
-                    windowStack.push(WebViewWindow(resultMsg))
+                    windowStack.push(WebViewWindow(resultMsg, WebViewNavigator(coroutineScope)))
                     return true
                 }
                 return false
@@ -176,6 +173,18 @@ fun WebViewScreenContent(
         return webView
     }
 
+    val popState = remember<() -> Unit> {
+        {
+            if (windowStack.size == 1) {
+                onNavigateUp()
+            } else {
+                windowStack.pop()
+            }
+        }
+    }
+
+    BackHandler(windowStack.size > 1, popState)
+
     Scaffold(
         topBar = {
             Box {
@@ -183,7 +192,7 @@ fun WebViewScreenContent(
                     AppBar(
                         title = currentWindow.state.pageTitle ?: initialTitle,
                         subtitle = currentUrl,
-                        navigateUp = popState,
+                        navigateUp = onNavigateUp,
                         navigationIcon = Icons.Outlined.Close,
                         actions = {
                             AppBarActions(
@@ -224,7 +233,18 @@ fun WebViewScreenContent(
                                         title = stringResource(MR.strings.pref_clear_cookies),
                                         onClick = { onClearCookies(currentUrl) },
                                     ),
-                                ),
+                                ).builder().apply {
+                                    if (windowStack.size > 1) {
+                                        add(
+                                            0,
+                                            AppBar.Action(
+                                                title = stringResource(MR.strings.action_webview_close_tab),
+                                                icon = ImageVector.vectorResource(R.drawable.ic_tab_close_24px),
+                                                onClick = popState,
+                                            ),
+                                        )
+                                    }
+                                }.build(),
                             )
                         },
                     )
@@ -297,7 +317,7 @@ fun WebViewScreenContent(
                         // The composable is being disposed but the WebView object is not.
                         // When the WebView element is recomposed, we will want the WebView to resume from its state
                         // before it was unmounted, we won't want it to reset back to its original target.
-                        window.state = WebViewState(WebContent.NavigatorOnly)
+                        window.state.content = WebContent.NavigatorOnly
                     }
                 },
                 client = webClient,