Closes #2713: Weave in "onboarding state" and split adapter items accordingly

we're ensuring that it has been initialized.

I wonder if we could just make background services load eagerly (they're lazy init now), instead.

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

@@ -55,6 +55,7 @@ import org.mozilla.fenix.home.sessioncontrol.SessionControlViewModel
 import org.mozilla.fenix.home.sessioncontrol.Tab
 import org.mozilla.fenix.home.sessioncontrol.TabAction
 import org.mozilla.fenix.home.sessioncontrol.TabCollection
+import org.mozilla.fenix.home.sessioncontrol.OnboardingState
 import org.mozilla.fenix.lib.Do
 import org.mozilla.fenix.mvi.ActionBusFactory
 import org.mozilla.fenix.mvi.getAutoDisposeObservable
@@ -638,7 +639,13 @@ class HomeFragment : Fragment(), CoroutineScope {
     }
 
     private fun currentMode(): Mode = if (!onboarding.userHasBeenOnboarded()) {
-        Mode.Onboarding
+        // TODO monitor account state changes somewhere in this class via AccountObserver + `accountManager.register()`.
+        val account = requireComponents.backgroundServices.accountManager.authenticatedAccount()
+        if (account == null) {
+            Mode.Onboarding(OnboardingState.SignedOut)
+        } else {
+            Mode.Onboarding(OnboardingState.ManuallySignedIn)
+        }
     } else if ((activity as HomeActivity).browsingModeManager.isPrivate) {
         Mode.Private
     } else {

app/src/main/java/org/mozilla/fenix/home/sessioncontrol/SessionControlComponent.kt

@@ -64,10 +64,23 @@ fun List<Tab>.toSessionBundle(context: Context): MutableList<Session> {
 
     return sessionBundle
 }
+
+/**
+ * Describes various onboarding states.
+ */
+enum class OnboardingState {
+    // signed out, no account carried over from Fennec.
+    SignedOut,
+    // auto-signed in, via a Fennec account.
+    AutoSignedIn,
+    // manually signed in while in onboarding.
+    ManuallySignedIn
+}
+
 sealed class Mode {
     object Normal : Mode()
     object Private : Mode()
-    object Onboarding : Mode()
+    data class Onboarding(val state: OnboardingState) : Mode()
 }
 
 data class SessionControlState(

app/src/main/java/org/mozilla/fenix/home/sessioncontrol/SessionControlUIView.kt

@@ -61,25 +61,51 @@ private fun privateModeAdapterItems(tabs: List<Tab>): List<AdapterItem> {
     return items
 }
 
-private fun onboardingAdapterItems(): List<AdapterItem> = listOf(
-    AdapterItem.OnboardingHeader,
-    AdapterItem.OnboardingSectionHeader() { it.getString(R.string.onboarding_fxa_section_header) },
-    AdapterItem.OnboardingFirefoxAccount,
-    AdapterItem.OnboardingSectionHeader() {
-        val appName = it.getString(R.string.app_name)
-        it.getString(R.string.onboarding_feature_section_header, appName)
-    },
-    AdapterItem.OnboardingThemePicker,
-    AdapterItem.OnboardingTrackingProtection,
-    AdapterItem.OnboardingPrivateBrowsing,
-    AdapterItem.OnboardingPrivacyNotice,
-    AdapterItem.OnboardingFinish
-)
+private fun onboardingAdapterItems(onboardingState: OnboardingState): List<AdapterItem> {
+    val items: MutableList<AdapterItem> = mutableListOf(AdapterItem.OnboardingHeader)
+
+    // TODO customize the UI based on different account states.
+    // Customize FxA items based on where we are with the account state:
+    items.addAll(when (onboardingState) {
+        OnboardingState.SignedOut -> {
+            listOf(
+                AdapterItem.OnboardingSectionHeader { it.getString(R.string.onboarding_fxa_section_header) },
+                AdapterItem.OnboardingFirefoxAccount
+            )
+        }
+        OnboardingState.AutoSignedIn -> {
+            listOf(
+                AdapterItem.OnboardingSectionHeader { it.getString(R.string.onboarding_fxa_section_header) },
+                AdapterItem.OnboardingFirefoxAccount
+            )
+        }
+        OnboardingState.ManuallySignedIn -> {
+            listOf(
+                AdapterItem.OnboardingSectionHeader { it.getString(R.string.onboarding_fxa_section_header) },
+                AdapterItem.OnboardingFirefoxAccount
+            )
+        }
+    })
+
+    items.addAll(listOf(
+        AdapterItem.OnboardingSectionHeader {
+            val appName = it.getString(R.string.app_name)
+            it.getString(R.string.onboarding_feature_section_header, appName)
+        },
+        AdapterItem.OnboardingThemePicker,
+        AdapterItem.OnboardingTrackingProtection,
+        AdapterItem.OnboardingPrivateBrowsing,
+        AdapterItem.OnboardingPrivacyNotice,
+        AdapterItem.OnboardingFinish
+    ))
+
+    return items
+}
 
 private fun SessionControlState.toAdapterList(): List<AdapterItem> = when (mode) {
     is Mode.Normal -> normalModeAdapterItems(tabs, collections, expandedCollections)
     is Mode.Private -> privateModeAdapterItems(tabs)
-    is Mode.Onboarding -> onboardingAdapterItems()
+    is Mode.Onboarding -> onboardingAdapterItems(mode.state)
 }
 
 private fun collectionTabItems(collection: TabCollection) = collection.tabs.mapIndexed { index, tab ->