public abstract class SQLiteOpenHelper implements AutoCloseable {
        :
    public SQLiteOpenHelper(@Nullable Context context, @Nullable String name,
            @Nullable CursorFactory factory, int version) {
        this(context, name, factory, version, null);
    }
	    :
}

data class Player(
    val id: Int = -1,
    val name: String = "XXXXXXXX",
    val score: Int = 0
)

class GameDb(context: Context, version: Int = DB_VERSION)
    : SQLiteOpenHelper(context, DB_NAME, null, version) {

    companion object {
        const val DB_NAME = "Game.db"
        const val DB_VERSION = 1
    }

    val tableName = "player"

    //
    // Table Parameter
    //
    val idField = "id"
    val nameField = "name"
    val scoreField = "score"
    val columns = arrayOf(idField, nameField, scoreField)
    val idIndex = columns.indexOf(idField)
    val nameIndex = columns.indexOf(nameField)
    val scoreIndex = columns.indexOf(scoreField)

    //
    // SQL Command
    //
    private val createTable = """
        CREATE TABLE ${tableName} (
            id    INTEGER PRIMARY KEY AUTOINCREMENT,
            name  TEXT    NOT NULL,
            score INTEGER NOT NULL
        )
    """.trimIndent()
    private val dropTable = "DROP TABLE IF EXISTS ${tableName}"

    //
    // Lifecycle operation
    //
    override fun onCreate(db: SQLiteDatabase?) {
        db?.execSQL(createTable)
    }
    override fun onUpgrade(db: SQLiteDatabase?, oldVer: Int, newVer: Int) {
        db?.execSQL(dropTable)
        onCreate(db)
    }

    //
    // Helper function (PlayerDbのインスタンス内に限定)
    //
    fun Cursor.toPlayerList(): List<Player> {
        val _list = ArrayList<Player>(count)
        try {
            if(moveToFirst()) {
                do {
                    val _id = getInt(idIndex)
                    val _name = getString(nameIndex)
                    val _score = getInt(scoreIndex)
                    _list.add(Player(_id, _name, _score))
                } while(moveToNext())
            }
        }
        finally { close() }     // closeは必須
        return _list
    }
}

fun GameDb.insert(player: Player) {        // プレーヤーの追加登録
    val values = ContentValues().apply {
        put(nameField, player.name)
        put(scoreField, player.score)
    }
    writableDatabase.insert(tableName, null, values)
}

fun GameDb.fetchTop10(): List<Player> {    // スコアトップ10の検索
    return writableDatabase.query(
        tableName,              // テーブル名
        columns,                // 取得対象のカラムリスト
        null,                   // 検索の条件
        null,                   // 検索の値
        null,                   // グループ化関連
        null,                   // 　　〃
        "${scoreField} DESC",   // ソート対象のカラム(降順)
        "10"                    // 取得する行数
    ).toPlayerList()
}

class MainActivity : ComponentActivity() {

    private lateinit var gameDb: GameDb
    private lateinit var playerFlow: MutableStateFlow<List<Player>>

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        setContent {
            GamebTheme {
                Scaffold(
                    modifier = Modifier.fillMaxSize(),
                    floatingActionButton = {
                        FloatingActionButton(
                            onClick = {
                                gameDb.insert(randomPlayer())
                                playerFlow.value = gameDb.fetchTop10()
                            },
                            modifier = Modifier.padding(15.dp)
                        ) { Icon(Icons.Default.Add, contentDescription = "Add") }
                    }
                ) { innerPadding ->
                    Box(
                        modifier = Modifier.padding(innerPadding).fillMaxSize(),
                        contentAlignment = Alignment.Center
                    ) {
                        RankingPanel(playerFlow.asStateFlow())
                    }
                }
            }
        }

        gameDb = (application as MyApplication).gameDb
        playerFlow = MutableStateFlow<List<Player>>(playerDb.fetchTop10())
    }
}

@Composable
fun RankingPanel(playerFlow: StateFlow<List<Player>>) {
    val _players = playerFlow.collectAsState().value
    LazyColumn {
        items(items = _players, key = { it.id }) {
            Text(
                text = "%-8s  %06d".format(it.name, it.score),
                fontSize = 20.sp,
                fontFamily = FontFamily.Monospace,
                fontWeight = FontWeight.Bold
            )
        }
    }
}