[PM-33518] feat: Add isInAppUpgradeAvailableFlow to PremiumStateManager

Combine isInAppBillingSupportedFlow and MobilePremiumUpgrade feature
flag into a single StateFlow for determining whether to route premium
upgrade CTAs to the in-app PlanScreen or the web vault URL.

Author: SaintPatrck

app/src/main/kotlin/com/x8bit/bitwarden/data/billing/manager/PremiumStateManager.kt

@@ -1,5 +1,6 @@
 package com.x8bit.bitwarden.data.billing.manager
 
+import com.bitwarden.core.data.manager.model.FlagKey
 import kotlinx.coroutines.flow.StateFlow
 
 /**
@@ -16,6 +17,13 @@ interface PremiumStateManager {
      */
     val isPremiumUpgradeBannerEligibleFlow: StateFlow<Boolean>
 
+    /**
+     * Emits `true` when the in-app upgrade flow is available (i.e., in-app billing is
+     * supported and the [FlagKey.MobilePremiumUpgrade] feature flag is enabled),
+     * or `false` otherwise.
+     */
+    val isInAppUpgradeAvailableFlow: StateFlow<Boolean>
+
     /**
      * Marks the Premium upgrade banner as dismissed for the current user.
      */

app/src/main/kotlin/com/x8bit/bitwarden/data/billing/manager/PremiumStateManagerImpl.kt

@@ -89,6 +89,19 @@ class PremiumStateManagerImpl(
                 initialValue = false,
             )
 
+    override val isInAppUpgradeAvailableFlow: StateFlow<Boolean> =
+        combine(
+            billingRepository.isInAppBillingSupportedFlow,
+            featureFlagManager.getFeatureFlagFlow(FlagKey.MobilePremiumUpgrade),
+        ) { isInAppBillingSupported, featureFlagEnabled ->
+            isInAppBillingSupported && featureFlagEnabled
+        }
+            .stateIn(
+                scope = unconfinedScope,
+                started = SharingStarted.Eagerly,
+                initialValue = false,
+            )
+
     override fun dismissPremiumUpgradeBanner() {
         val activeUserId = authDiskSource.userState?.activeUserId ?: return
         settingsDiskSource.storePremiumUpgradeBannerDismissed(

app/src/test/kotlin/com/x8bit/bitwarden/data/billing/manager/PremiumStateManagerImplTest.kt

@@ -330,6 +330,46 @@ class PremiumStateManagerImplTest {
         }
     }
 
+    @Test
+    fun `isInAppUpgradeAvailableFlow should emit true when billing supported and flag enabled`() =
+        runTest {
+            val manager = createManager()
+            manager.isInAppUpgradeAvailableFlow.test {
+                assertTrue(awaitItem())
+            }
+        }
+
+    @Test
+    fun `isInAppUpgradeAvailableFlow should emit false when billing not supported`() =
+        runTest {
+            mutableIsInAppBillingSupportedFlow.value = false
+            val manager = createManager()
+            manager.isInAppUpgradeAvailableFlow.test {
+                assertFalse(awaitItem())
+            }
+        }
+
+    @Test
+    fun `isInAppUpgradeAvailableFlow should emit false when feature flag disabled`() =
+        runTest {
+            mutableMobilePremiumUpgradeFlagFlow.value = false
+            val manager = createManager()
+            manager.isInAppUpgradeAvailableFlow.test {
+                assertFalse(awaitItem())
+            }
+        }
+
+    @Test
+    fun `isInAppUpgradeAvailableFlow should emit false when both conditions are false`() =
+        runTest {
+            mutableIsInAppBillingSupportedFlow.value = false
+            mutableMobilePremiumUpgradeFlagFlow.value = false
+            val manager = createManager()
+            manager.isInAppUpgradeAvailableFlow.test {
+                assertFalse(awaitItem())
+            }
+        }
+
     @Test
     fun `dismissPremiumUpgradeBanner should store dismissed state for active user`() {
         val manager = createManager()