Yahtzee: end-of-game stats dialog compared with previous games

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_0177JQTtqM7EzJyXYiZYEJTX

app/src/main/java/org/prolibertate/games/MainActivity.kt

@@ -10,6 +10,7 @@ import org.prolibertate.games.net.LobbyController
 import org.prolibertate.games.net.ScorekeeperSession
 import org.prolibertate.games.score.ScorekeeperRepository
 import org.prolibertate.games.settings.SettingsRepository
+import org.prolibertate.games.settings.YahtzeeStatsRepository
 import org.prolibertate.games.ui.AppEnv
 import org.prolibertate.games.ui.AppRoot
 import org.prolibertate.games.ui.theme.ProLibertateTheme
@@ -43,6 +44,7 @@ class MainActivity : ComponentActivity() {
             ),
             peerId = peerId,
             saves = SavedGameStore(File(filesDir, "saved-games")),
+            yahtzeeStats = YahtzeeStatsRepository(applicationContext),
         )
 
         setContent {

app/src/main/java/org/prolibertate/games/game/yahtzee/YahtzeeStats.kt

@@ -0,0 +1,58 @@
+package org.prolibertate.games.game.yahtzee
+
+import kotlinx.serialization.Serializable
+
+/** What one finished game says about the local player's card. */
+@Serializable
+data class YahtzeeRecord(
+    val total: Int,
+    val gotBonus: Boolean,
+    /** Yahtzees scored, counting the extra ones that earned the hundred. */
+    val yahtzees: Int,
+    /** Boxes written in as nothing. */
+    val zeros: Int,
+    val players: Int,
+    val won: Boolean,
+)
+
+/** Builds the record of [seat]'s card in a finished game. Ties for first count as a win. */
+fun recordOf(state: YahtzeeState, seat: Int): YahtzeeRecord {
+    val card = state.cards[seat]
+    val mine = state.totalFor(seat)
+    val best = state.cards.indices.maxOf { state.totalFor(it) }
+    return YahtzeeRecord(
+        total = mine,
+        gotBonus = card.upperBonus > 0,
+        yahtzees = (if (card[YahtzeeCategory.YAHTZEE] == YAHTZEE_SCORE) 1 else 0) +
+            state.yahtzeeBonuses[seat] / YAHTZEE_BONUS,
+        zeros = card.boxes.count { it == 0 },
+        players = state.cards.size,
+        won = mine >= best,
+    )
+}
+
+/** A game set against the ones before it. [rank] is 1 for a new best. */
+data class YahtzeeComparison(
+    val current: YahtzeeRecord,
+    val previousGames: Int,
+    val bestBefore: Int?,
+    val averageBefore: Double?,
+    val rank: Int,
+    val gamesRanked: Int,
+    val bonusRateBefore: Double?,
+    val yahtzeesBefore: Int,
+    val winRateBefore: Double?,
+)
+
+fun compareToHistory(previous: List<YahtzeeRecord>, current: YahtzeeRecord): YahtzeeComparison =
+    YahtzeeComparison(
+        current = current,
+        previousGames = previous.size,
+        bestBefore = previous.maxOfOrNull { it.total },
+        averageBefore = previous.takeIf { it.isNotEmpty() }?.map { it.total }?.average(),
+        rank = 1 + previous.count { it.total > current.total },
+        gamesRanked = previous.size + 1,
+        bonusRateBefore = previous.takeIf { it.isNotEmpty() }?.let { p -> p.count { it.gotBonus }.toDouble() / p.size },
+        yahtzeesBefore = previous.sumOf { it.yahtzees },
+        winRateBefore = previous.takeIf { it.isNotEmpty() }?.let { p -> p.count { it.won }.toDouble() / p.size },
+    )

app/src/main/java/org/prolibertate/games/settings/YahtzeeStatsRepository.kt

@@ -0,0 +1,42 @@
+package org.prolibertate.games.settings
+
+import android.content.Context
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.edit
+import androidx.datastore.preferences.core.stringPreferencesKey
+import androidx.datastore.preferences.preferencesDataStore
+import kotlinx.coroutines.flow.first
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import org.prolibertate.games.game.yahtzee.YahtzeeComparison
+import org.prolibertate.games.game.yahtzee.YahtzeeRecord
+import org.prolibertate.games.game.yahtzee.compareToHistory
+
+private val Context.yahtzeeStatsStore: DataStore<Preferences> by preferencesDataStore(
+    name = "yahtzee_stats",
+)
+
+/** The local player's finished Yahtzee games, newest last, kept to the last [KEEP]. */
+class YahtzeeStatsRepository(private val context: Context) {
+
+    private val key = stringPreferencesKey("games")
+    private val json = Json { ignoreUnknownKeys = true }
+
+    private fun decode(stored: String?): List<YahtzeeRecord> =
+        stored?.let { runCatching { json.decodeFromString<List<YahtzeeRecord>>(it) }.getOrNull() }
+            .orEmpty()
+
+    /** Compares [record] with every earlier game, then adds it to the history. */
+    suspend fun finish(record: YahtzeeRecord): YahtzeeComparison {
+        val previous = decode(context.yahtzeeStatsStore.data.first()[key])
+        context.yahtzeeStatsStore.edit {
+            it[key] = json.encodeToString((previous + record).takeLast(KEEP))
+        }
+        return compareToHistory(previous, record)
+    }
+
+    private companion object {
+        const val KEEP = 500
+    }
+}

app/src/main/java/org/prolibertate/games/ui/AppRoot.kt

@@ -51,6 +51,7 @@ import org.prolibertate.games.net.ScorekeeperSession
 import org.prolibertate.games.score.ScorekeeperRepository
 import org.prolibertate.games.settings.Settings
 import org.prolibertate.games.settings.SettingsRepository
+import org.prolibertate.games.settings.YahtzeeStatsRepository
 import org.prolibertate.games.ui.game.LocalCardSpeed
 import org.prolibertate.games.update.UpdateChannel
 import org.prolibertate.games.update.Updater
@@ -70,6 +71,7 @@ class AppEnv(
     val peerId: String,
     /** Games in progress, kept between sessions. */
     val saves: SavedGameStore,
+    val yahtzeeStats: YahtzeeStatsRepository,
 )
 
 /**

app/src/main/java/org/prolibertate/games/ui/PlayScreen.kt

@@ -594,7 +594,12 @@ fun PlayScreen(
                     )
                 }
                 StartMatch(env, controller, route)
-                YahtzeeScreen(controller = controller, localSeat = route.localSeat, onExit = onExit)
+                YahtzeeScreen(
+                    controller = controller,
+                    localSeat = route.localSeat,
+                    stats = env.yahtzeeStats,
+                    onExit = onExit,
+                )
             }
 
             GameCatalog.KLONDIKE -> {

app/src/main/java/org/prolibertate/games/ui/game/YahtzeeScreen.kt

@@ -41,6 +41,10 @@ import org.prolibertate.games.game.yahtzee.DICE_COUNT
 import org.prolibertate.games.game.yahtzee.RollDice
 import org.prolibertate.games.game.yahtzee.ScoreIn
 import org.prolibertate.games.game.yahtzee.YahtzeeCategory
+import org.prolibertate.games.game.yahtzee.YahtzeeComparison
+import org.prolibertate.games.game.yahtzee.recordOf
+import org.prolibertate.games.settings.YahtzeeStatsRepository
+import kotlin.math.roundToInt
 import org.prolibertate.games.game.yahtzee.YahtzeeMove
 import org.prolibertate.games.game.yahtzee.YahtzeeSection
 import org.prolibertate.games.game.yahtzee.YahtzeeState
@@ -66,6 +70,7 @@ private const val TITLE = "Yahtzee"
 fun YahtzeeScreen(
     controller: MatchController<YahtzeeState, YahtzeeMove>,
     localSeat: Int,
+    stats: YahtzeeStatsRepository,
     onExit: () -> Unit,
 ) {
     val state by controller.state.collectAsState()
@@ -75,6 +80,10 @@ fun YahtzeeScreen(
     val kept = remember { mutableStateListOf<Int>() }
     var confirmingEnd by remember { mutableStateOf(false) }
     var confirmingZero by remember { mutableStateOf<YahtzeeCategory?>(null) }
+    var comparison by remember { mutableStateOf<YahtzeeComparison?>(null) }
+    // Only a game seen to finish is recorded: reopening a saved game that was
+    // already over must not count it a second time.
+    var sawInProgress by remember { mutableStateOf(false) }
 
     val endGameAction: @Composable () -> Unit = {
         TextButton(onClick = { confirmingEnd = true }) { Text("End game") }
@@ -95,6 +104,15 @@ fun YahtzeeScreen(
     // refused, and the Throw button would look broken again.
     LaunchedEffect(current.turn, current.round) { kept.clear() }
 
+    LaunchedEffect(current.isOver) {
+        if (!current.isOver) {
+            sawInProgress = true
+        } else if (sawInProgress) {
+            sawInProgress = false
+            comparison = stats.finish(recordOf(current, localSeat))
+        }
+    }
+
     val yours = current.turn == localSeat && !current.isOver
     val canRoll = legal.any { it is RollDice }
     val writable = legal.filterIsInstance<ScoreIn>().map { it.category }.toSet()
@@ -162,6 +180,7 @@ fun YahtzeeScreen(
 
         abandoned?.let { LeftCardDialog(it, onExit, controller::dismissAbandoned) }
         if (confirmingEnd) EndCardDialog(onExit) { confirmingEnd = false }
+        comparison?.let { StatsDialog(it, onExit) { comparison = null } }
         confirmingZero?.let { category ->
             ZeroScoreDialog(
                 category = category,
@@ -176,6 +195,53 @@ fun YahtzeeScreen(
     }
 }
 
+@Composable
+private fun StatsDialog(c: YahtzeeComparison, onLeave: () -> Unit, onClose: () -> Unit) {
+    fun pct(v: Double?) = v?.let { "${(it * 100).roundToInt()}%" } ?: "—"
+    val headline = when {
+        c.previousGames == 0 -> "Your first recorded game."
+        c.rank == 1 -> "A new personal best!"
+        else -> "${ordinal(c.rank)} best of ${c.gamesRanked} games."
+    }
+    AlertDialog(
+        onDismissRequest = onClose,
+        title = { Text("Game over: ${c.current.total} points") },
+        text = {
+            Column(verticalArrangement = Arrangement.spacedBy(6.dp)) {
+                Text(headline, fontWeight = FontWeight.Bold)
+                StatLine("", "This game", "Before")
+                StatLine("Score", "${c.current.total}", c.averageBefore?.let { "avg ${it.roundToInt()}, best ${c.bestBefore}" } ?: "—")
+                StatLine("Upper bonus", if (c.current.gotBonus) "Yes" else "No", pct(c.bonusRateBefore))
+                StatLine("Yahtzees", "${c.current.yahtzees}", "${c.yahtzeesBefore} total")
+                StatLine("Zeroed boxes", "${c.current.zeros}", "")
+                if (c.current.players > 1) {
+                    StatLine("Result", if (c.current.won) "Won" else "Lost", "won ${pct(c.winRateBefore)}")
+                }
+                Text(
+                    "Games before this one: ${c.previousGames}",
+                    style = MaterialTheme.typography.bodySmall,
+                )
+            }
+        },
+        confirmButton = { TextButton(onClick = onLeave) { Text("Leave the game") } },
+        dismissButton = { TextButton(onClick = onClose) { Text("Look at the card") } },
+    )
+}
+
+@Composable
+private fun StatLine(label: String, now: String, before: String) {
+    Row(modifier = Modifier.fillMaxWidth()) {
+        Text(label, modifier = Modifier.weight(1.2f), fontWeight = FontWeight.Bold)
+        Text(now, modifier = Modifier.weight(1f))
+        Text(before, modifier = Modifier.weight(1.6f))
+    }
+}
+
+private fun ordinal(n: Int): String {
+    val suffix = if (n % 100 in 11..13) "th" else when (n % 10) { 1 -> "st"; 2 -> "nd"; 3 -> "rd"; else -> "th" }
+    return "$n$suffix"
+}
+
 @Composable
 private fun ZeroScoreDialog(category: YahtzeeCategory, onConfirm: () -> Unit, onCancel: () -> Unit) {
     AlertDialog(

app/src/test/java/org/prolibertate/games/game/yahtzee/YahtzeeStatsTest.kt

@@ -0,0 +1,30 @@
+package org.prolibertate.games.game.yahtzee
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+class YahtzeeStatsTest {
+    private fun game(total: Int, bonus: Boolean = false, yahtzees: Int = 0, won: Boolean = true) =
+        YahtzeeRecord(total, bonus, yahtzees, zeros = 0, players = 2, won = won)
+
+    @Test
+    fun firstGameHasNothingToCompareTo() {
+        val c = compareToHistory(emptyList(), game(200))
+        assertEquals(1, c.rank)
+        assertEquals(0, c.previousGames)
+        assertNull(c.bestBefore)
+        assertNull(c.averageBefore)
+    }
+
+    @Test
+    fun ranksAgainstPreviousGames() {
+        val history = listOf(game(150, bonus = true, yahtzees = 1), game(250), game(200, won = false))
+        val c = compareToHistory(history, game(220))
+        assertEquals(2, c.rank)
+        assertEquals(4, c.gamesRanked)
+        assertEquals(250, c.bestBefore)
+        assertEquals(200.0, c.averageBefore!!, 0.001)
+        assertEquals(1, c.yahtzeesBefore)
+    }
+}