feat(lobby): mark the real last-played game on the lobby

CHANGELOG.md

@@ -9,6 +9,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Real "Last Played" highlight on the lobby (cu-03): the new
+  `LobbyViewModel` reads the most recent round from the Room `game_round`
+  ledger and the lobby marks that game's card with the existing LAST
+  PLAYED badge, instead of the static preview default. No game played yet
+  means no card is marked. Covered by `LobbyViewModelTest`.
+
 - Playable Blackjack (cu-06): the fifth and final game, completing the
   games card. `BlackjackViewModel` -> `GameRepository.startBlackjack`
   draws the shuffled 52-card deck on the C++/JNI engine (committed via the

app/src/main/java/com/plainstudio/stackcasino/feature/lobby/LobbyViewModel.kt

@@ -0,0 +1,35 @@
+package com.plainstudio.stackcasino.feature.lobby
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.plainstudio.stackcasino.domain.game.GameRepository
+import com.plainstudio.stackcasino.model.GameKey
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.stateIn
+import javax.inject.Inject
+
+/**
+ * Backs the lobby with the bits of real round data it needs today: the
+ * last game the user played, so its card can carry the "LAST PLAYED"
+ * highlight. Reads the Room-backed [GameRepository.rounds] (newest first),
+ * so the most recent round's game is the last played, or null when no
+ * round has been played yet.
+ */
+@HiltViewModel
+class LobbyViewModel
+    @Inject
+    constructor(
+        gameRepository: GameRepository,
+    ) : ViewModel() {
+        val lastPlayedGame: StateFlow<GameKey?> =
+            gameRepository.rounds
+                .map { rounds -> rounds.firstOrNull()?.game }
+                .stateIn(viewModelScope, SharingStarted.WhileSubscribed(STOP_TIMEOUT_MILLIS), null)
+
+        private companion object {
+            const val STOP_TIMEOUT_MILLIS = 5_000L
+        }
+    }

app/src/main/java/com/plainstudio/stackcasino/navigation/StackNavHost.kt

@@ -29,6 +29,7 @@ import com.plainstudio.stackcasino.feature.housewallet.HouseWalletScreen
 import com.plainstudio.stackcasino.feature.kyc.KycScreen
 import com.plainstudio.stackcasino.feature.lobby.LobbyScreen
 import com.plainstudio.stackcasino.feature.lobby.LobbyUiState
+import com.plainstudio.stackcasino.feature.lobby.LobbyViewModel
 import com.plainstudio.stackcasino.feature.lobby.previewLobbyData
 import com.plainstudio.stackcasino.feature.mines.MinesScreen
 import com.plainstudio.stackcasino.feature.mines.MinesViewModel
@@ -262,11 +263,14 @@ private fun NavGraphBuilder.addLobbyRoute(navController: NavHostController) {
         val unreadCount by notificationsViewModel.unreadCount.collectAsStateWithLifecycle()
         val walletViewModel: WalletViewModel = hiltViewModel()
         val wallet by walletViewModel.walletData.collectAsStateWithLifecycle()
+        val lobbyViewModel: LobbyViewModel = hiltViewModel()
+        val lastPlayed by lobbyViewModel.lastPlayedGame.collectAsStateWithLifecycle()
         var showNotifications by rememberSaveable { mutableStateOf(false) }
         val lobbyData =
             previewLobbyData().let {
                 it.copy(
                     balance = it.balance.copy(amountLabel = wallet.availableLabel),
+                    games = it.games.map { card -> card.copy(isLastPlayed = card.key == lastPlayed) },
                 )
             }
         LobbyScreen(

app/src/test/java/com/plainstudio/stackcasino/feature/lobby/LobbyViewModelTest.kt

@@ -0,0 +1,64 @@
+package com.plainstudio.stackcasino.feature.lobby
+
+import app.cash.turbine.test
+import com.plainstudio.stackcasino.domain.game.GameRepository
+import com.plainstudio.stackcasino.domain.game.GameRound
+import com.plainstudio.stackcasino.model.GameKey
+import com.plainstudio.stackcasino.model.RoundOutcome
+import com.plainstudio.stackcasino.testing.MainDispatcherRule
+import io.mockk.every
+import io.mockk.mockk
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Rule
+import org.junit.Test
+
+class LobbyViewModelTest {
+    @get:Rule
+    val mainDispatcherRule = MainDispatcherRule()
+
+    private val gameRepository = mockk<GameRepository>(relaxed = true)
+
+    @Test
+    fun `last played is the most recent round's game`() =
+        runTest {
+            every { gameRepository.rounds } returns flowOf(listOf(round(GameKey.Mines), round(GameKey.Crash)))
+
+            LobbyViewModel(gameRepository).lastPlayedGame.test {
+                var value = awaitItem()
+                while (value == null) value = awaitItem()
+                assertEquals(GameKey.Mines, value)
+                cancelAndIgnoreRemainingEvents()
+            }
+        }
+
+    @Test
+    fun `last played is null with no rounds`() =
+        runTest {
+            every { gameRepository.rounds } returns flowOf(emptyList())
+
+            LobbyViewModel(gameRepository).lastPlayedGame.test {
+                assertEquals(null, awaitItem())
+                cancelAndIgnoreRemainingEvents()
+            }
+        }
+
+    private fun round(game: GameKey) =
+        GameRound(
+            id = "round-id",
+            game = game,
+            pick = "",
+            stake = 10.0,
+            payout = 0.0,
+            outcome = RoundOutcome.Loss,
+            multiplier = 0.0,
+            currency = "USDC",
+            serverSeed = "s",
+            clientSeed = "c",
+            nonce = 1L,
+            hash = "h",
+            resultRaw = "",
+            timestamp = 0L,
+        )
+}