Part 5: Refactor HomeMenu<->HomeFragment interaction

This refactor "reverses" relationship between these two classes, allowing
HomeMenu to inform its parent, HomeFragment, of any changes to the menu.

Once that's in place, we start observing account manager changes (once its ready)
for account problems.

This solves two problems:
- initialization of the account manager is no longer necessary to build a home menu
- home menu now starts observing changes to the account manager's state (before it was static)

app/src/main/java/org/mozilla/fenix/home/HomeFragment.kt

@@ -64,7 +64,7 @@ import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import mozilla.appservices.places.BookmarkRoot
-import mozilla.components.browser.menu.ext.getHighlight
+import mozilla.components.browser.menu.view.MenuButton
 import mozilla.components.browser.session.Session
 import mozilla.components.browser.session.SessionManager
 import mozilla.components.browser.state.store.BrowserStore
@@ -107,6 +107,7 @@ import org.mozilla.fenix.theme.ThemeManager
 import org.mozilla.fenix.utils.FragmentPreDrawManager
 import org.mozilla.fenix.utils.allowUndo
 import org.mozilla.fenix.whatsnew.WhatsNew
+import java.lang.ref.WeakReference
 import kotlin.math.abs
 import kotlin.math.min
 
@@ -321,20 +322,13 @@ class HomeFragment : Fragment() {
             }
         }
 
-        with(view.menuButton) {
-            menuBuilder = createHomeMenu(context!!).menuBuilder
+        createHomeMenu(context!!, WeakReference(view.menuButton))
 
-            val primaryTextColor = ContextCompat.getColor(
-                context,
-                ThemeManager.resolveAttribute(R.attr.primaryText, context)
-            )
+        view.menuButton.setColorFilter(ContextCompat.getColor(
+            context!!,
+            ThemeManager.resolveAttribute(R.attr.primaryText, context!!)
+        ))
 
-            setColorFilter(primaryTextColor)
-
-            // Immediately check for `What's new` highlight. If home items that change over time
-            // are added, this will need to be called repeatedly.
-            setHighlight(menuBuilder?.items?.getHighlight())
-        }
         view.toolbar.compoundDrawablePadding =
             view.resources.getDimensionPixelSize(R.dimen.search_bar_search_engine_icon_padding)
         view.toolbar_wrapper.setOnClickListener {
@@ -607,8 +601,10 @@ class HomeFragment : Fragment() {
     }
 
     @SuppressWarnings("ComplexMethod")
-    private fun createHomeMenu(context: Context): HomeMenu {
-        return HomeMenu(context) {
+    private fun createHomeMenu(context: Context, menuButtonView: WeakReference<MenuButton>) = HomeMenu(
+        this,
+        context,
+        onItemTapped = {
             when (it) {
                 HomeMenu.Item.Settings -> {
                     invokePendingDeleteJobs()
@@ -676,8 +672,10 @@ class HomeFragment : Fragment() {
                     )
                 }
             }
-        }
-    }
+        },
+        onHighlightPresent = { menuButtonView.get()?.setHighlight(it) },
+        onMenuBuilderChanged = { menuButtonView.get()?.menuBuilder = it }
+    )
 
     private fun subscribeToTabCollections(): Observer<List<TabCollection>> {
         return Observer<List<TabCollection>> {

app/src/main/java/org/mozilla/fenix/home/HomeMenu.kt

@@ -6,12 +6,18 @@ package org.mozilla.fenix.home
 
 import android.content.Context
 import androidx.core.content.ContextCompat.getColor
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleOwner
 import mozilla.components.browser.menu.BrowserMenuBuilder
 import mozilla.components.browser.menu.BrowserMenuHighlight
+import mozilla.components.browser.menu.ext.getHighlight
 import mozilla.components.browser.menu.item.BrowserMenuCategory
 import mozilla.components.browser.menu.item.BrowserMenuDivider
 import mozilla.components.browser.menu.item.BrowserMenuHighlightableItem
 import mozilla.components.browser.menu.item.BrowserMenuImageText
+import mozilla.components.concept.sync.AccountObserver
+import mozilla.components.concept.sync.AuthType
+import mozilla.components.concept.sync.OAuthAccount
 import mozilla.components.support.ktx.android.content.getColorFromAttr
 import org.mozilla.fenix.R
 import org.mozilla.fenix.ext.components
@@ -20,8 +26,11 @@ import org.mozilla.fenix.utils.Settings
 import org.mozilla.fenix.whatsnew.WhatsNew
 
 class HomeMenu(
+    private val lifecycleOwner: LifecycleOwner,
     private val context: Context,
-    private val onItemTapped: (Item) -> Unit = {}
+    private val onItemTapped: (Item) -> Unit = {},
+    private val onMenuBuilderChanged: (BrowserMenuBuilder) -> Unit = {},
+    private val onHighlightPresent: (BrowserMenuHighlight) -> Unit = {}
 ) {
     sealed class Item {
         object WhatsNew : Item()
@@ -34,9 +43,6 @@ class HomeMenu(
         object Sync : Item()
     }
 
-    val menuBuilder by lazy { BrowserMenuBuilder(menuItems) }
-
-    private val hasAccountProblem get() = context.components.backgroundServices.accountManager.accountNeedsReauth()
     private val primaryTextColor =
         ThemeManager.resolveAttribute(R.attr.primaryText, context)
     private val syncDisconnectedColor = ThemeManager.resolveAttribute(R.attr.syncDisconnected, context)
@@ -45,21 +51,7 @@ class HomeMenu(
     private val menuCategoryTextColor =
         ThemeManager.resolveAttribute(R.attr.menuCategoryText, context)
 
-    private val menuItems by lazy {
-
-        val reconnectToSyncItem = BrowserMenuHighlightableItem(
-            context.getString(R.string.sync_reconnect),
-            R.drawable.ic_sync_disconnected,
-            iconTintColorResource = syncDisconnectedColor,
-            textColorResource = primaryTextColor,
-            highlight = BrowserMenuHighlight.HighPriority(
-                backgroundTint = syncDisconnectedBackgroundColor
-            ),
-            isHighlighted = { true }
-        ) {
-            onItemTapped.invoke(Item.Sync)
-        }
-
+    private val coreMenuItems by lazy {
         val whatsNewItem = BrowserMenuHighlightableItem(
             context.getString(R.string.browser_menu_whats_new),
             R.drawable.ic_whats_new,
@@ -103,16 +95,7 @@ class HomeMenu(
             onItemTapped.invoke(Item.Help)
         }
 
-        val quitItem = BrowserMenuImageText(
-            context.getString(R.string.delete_browsing_data_on_quit_action),
-            R.drawable.ic_exit,
-            primaryTextColor
-        ) {
-            onItemTapped.invoke(Item.Quit)
-        }
-
-        val items = listOfNotNull(
-            if (hasAccountProblem) reconnectToSyncItem else null,
+        listOfNotNull(
             whatsNewItem,
             BrowserMenuDivider(),
             BrowserMenuCategory(
@@ -125,8 +108,66 @@ class HomeMenu(
             settingsItem,
             helpItem,
             if (Settings.getInstance(context).shouldDeleteBrowsingDataOnQuit) quitItem else null
-        )
+        ).also { items ->
+            items.getHighlight()?.let { onHighlightPresent(it) }
+        }
+    }
 
-        items
+    init {
+        // Report initial state.
+        onMenuBuilderChanged(BrowserMenuBuilder(coreMenuItems))
+
+        // Observe account state changes, and update menu item builder with a new set of items.
+        context.components.backgroundServices.accountManagerAvailableQueue.runIfReadyOrQueue {
+            // This task isn't relevant if our parent fragment isn't around anymore.
+            if (lifecycleOwner.lifecycle.currentState == Lifecycle.State.DESTROYED) {
+                return@runIfReadyOrQueue
+            }
+            context.components.backgroundServices.accountManager.register(object : AccountObserver {
+                override fun onAuthenticationProblems() {
+                    onMenuBuilderChanged(BrowserMenuBuilder(
+                        listOf(reconnectToSyncItem) + coreMenuItems
+                    ))
+                }
+
+                override fun onAuthenticated(account: OAuthAccount, authType: AuthType) {
+                    onMenuBuilderChanged(BrowserMenuBuilder(
+                        coreMenuItems
+                    ))
+                }
+
+                override fun onLoggedOut() {
+                    onMenuBuilderChanged(BrowserMenuBuilder(
+                        coreMenuItems
+                    ))
+                }
+            }, lifecycleOwner)
+        }
+    }
+
+    // 'Reconnect' and 'Quit' items aren't needed most of the time, so we'll only create the if necessary.
+    private val reconnectToSyncItem by lazy {
+        BrowserMenuHighlightableItem(
+            context.getString(R.string.sync_reconnect),
+            R.drawable.ic_sync_disconnected,
+            iconTintColorResource = syncDisconnectedColor,
+            textColorResource = primaryTextColor,
+            highlight = BrowserMenuHighlight.HighPriority(
+                backgroundTint = syncDisconnectedBackgroundColor
+            ),
+            isHighlighted = { true }
+        ) {
+            onItemTapped.invoke(Item.Sync)
+        }
+    }
+
+    private val quitItem by lazy {
+        BrowserMenuImageText(
+            context.getString(R.string.delete_browsing_data_on_quit_action),
+            R.drawable.ic_exit,
+            primaryTextColor
+        ) {
+            onItemTapped.invoke(Item.Quit)
+        }
     }
 }