Match GV 147 API: 4-arg onLocationChange, onCanGoBack tracking

app/src/main/java/dev/nova/browser/TabManager.kt

@@ -1,6 +1,7 @@
 package dev.nova.browser
 
 import androidx.compose.runtime.mutableStateListOf
+import androidx.compose.runtime.mutableStateMapOf
 import androidx.compose.runtime.mutableStateOf
 import org.mozilla.geckoview.GeckoResult
 import org.mozilla.geckoview.GeckoRuntime
@@ -10,6 +11,10 @@ import org.mozilla.geckoview.WebExtension
 /**
  * Nova's tab model. One GeckoSession per tab; the UI activates a tab by
  * calling GeckoView.setSession() on the active tab's session.
+ *
+ * GeckoView does not expose canGoBack()/canGoForward() as polling methods —
+ * navigation state arrives via NavigationDelegate callbacks, so we track it
+ * here per tab.
  */
 class TabManager(private val runtime: GeckoRuntime) {
 
@@ -19,6 +24,10 @@ class TabManager(private val runtime: GeckoRuntime) {
     val tabs = mutableStateListOf<Tab>()
     val activeTabId = mutableStateOf<Int?>(null)
 
+    /** Navigation state per tab id, fed by NavigationDelegate callbacks. */
+    val canGoBackStates = mutableStateMapOf<Int, Boolean>()
+    val lastUrls = mutableStateMapOf<Int, String>()
+
     /** Installed built-in extension, wired in once available. */
     var devExtension: WebExtension? = null
 
@@ -40,18 +49,29 @@ class TabManager(private val runtime: GeckoRuntime) {
     }
 
     fun open(url: String): Tab {
+        val tabId = nextId++
         val session = GeckoSession()
 
+        session.navigationDelegate = object : GeckoSession.NavigationDelegate {
+            // GV 147 signature: (session, url, perms, hasUserGesture)
+            override fun onLocationChange(
+                session: GeckoSession,
+                url: String?,
+                perms: List<GeckoSession.PermissionDelegate.ContentPermission>,
+                hasUserGesture: Boolean,
+            ) {
+                if (url != null) lastUrls[tabId] = url
+            }
+
+            override fun onCanGoBack(session: GeckoSession, canGoBack: Boolean) {
+                canGoBackStates[tabId] = canGoBack
+            }
+        }
         session.progressDelegate = object : GeckoSession.ProgressDelegate {
             override fun onProgressChange(session: GeckoSession, progress: Int) {
                 // Hook for the loading bar (M2 milestone).
             }
         }
-        session.navigationDelegate = object : GeckoSession.NavigationDelegate {
-            override fun onLocationChange(session: GeckoSession, url: String?) {
-                // Hook for syncing the URL bar (M2 milestone).
-            }
-        }
 
         session.open(runtime)
 
@@ -60,7 +80,7 @@ class TabManager(private val runtime: GeckoRuntime) {
             session.webExtensionController.setMessageDelegate(ext, sessionMessageDelegate, "browser")
         }
 
-        val tab = Tab(nextId++, session)
+        val tab = Tab(tabId, session)
         tabs.add(tab)
         activeTabId.value = tab.id
         session.loadUri(url)
@@ -76,6 +96,8 @@ class TabManager(private val runtime: GeckoRuntime) {
         if (index == -1) return
         tabs[index].session.close()
         tabs.removeAt(index)
+        canGoBackStates.remove(id)
+        lastUrls.remove(id)
         if (activeTabId.value == id) {
             activeTabId.value = tabs.lastOrNull()?.id
         }
@@ -84,6 +106,10 @@ class TabManager(private val runtime: GeckoRuntime) {
     fun activeSession(): GeckoSession? =
         activeTabId.value?.let { id -> tabs.firstOrNull { it.id == id }?.session }
 
+    /** Whether the active tab can navigate back (delegate-tracked). */
+    fun canGoBack(): Boolean =
+        activeTabId.value?.let { canGoBackStates[it] == true } ?: false
+
     /** Called once the built-in extension finishes installing. */
     fun wireExtension(ext: WebExtension) {
         devExtension = ext