Bukkit boss bar immutable util

BukkitBossBar.kt

import org.bukkit.Bukkit
import org.bukkit.boss.BarColor
import org.bukkit.boss.BarStyle
import org.bukkit.boss.BossBar
import org.bukkit.entity.Player
import org.bukkit.event.EventHandler
import org.bukkit.event.Listener
import org.bukkit.event.player.PlayerQuitEvent
import org.bukkit.plugin.Plugin
import org.bukkit.scheduler.BukkitRunnable
import java.time.Duration
import java.time.LocalDateTime
import java.util.*

data class BossBarDisplay(
    val id: UUID,
    val title: String,
    val color: BarColor,
    val style: BarStyle,
    val progress: Double,
    val stayDuration: Duration?
) {
    fun update(x: BossBar) {
        x.title = title
        x.color = color
        x.style = style
        x.progress = progress
    }
}

data class BarPlayer(
    val id: UUID,
    val barId: UUID,
    val expireTime: LocalDateTime?
)

data class BukkitBossBar(
    val id: UUID,
    val bar: BossBar,
    val viewers: MutableMap<UUID, BarPlayer>
)

class BossBarService {
    val bukkitBars: MutableMap<UUID, BukkitBossBar> = mutableMapOf()

    fun getPlayerBars(playerId: UUID): List<Pair<BukkitBossBar, BarPlayer>> =
        bukkitBars.values.flatMap {
            val barPlayer = it.viewers[playerId]
            if (barPlayer != null) {
                listOf(it to barPlayer)
            } else emptyList()
        }
}

val bossBarService: BossBarService
    get() = Bukkit.getServicesManager().load(BossBarService::class.java)

fun registerBukkitBossBar(plugin: BattlePlugin) {
    val service = BossBarService()
    Bukkit.getServicesManager().register(BossBarService::class.java, service, plugin, ServicePriority.Normal)
    object : BukkitRunnable() {
        override fun run() {
            val nowTime = LocalDateTime.now()
            for (p in Bukkit.getOnlinePlayers()) {
                for ((bukkitBar, barPlayer) in service.getPlayerBars(p.uniqueId)) {
                    val diff = if (barPlayer.expireTime != null) {
                        Duration.between(nowTime, barPlayer.expireTime)
                    } else null
                    if (diff != null && diff.seconds <= 0) {
                        p.removeBossBar(bukkitBar.id)
                    }
                }
            }
        }
    }.runTaskTimer(plugin, 20L, 20L)
    Bukkit.getPluginManager().registerEvents(
        object : Listener {
            @EventHandler
            fun onQuit(e: PlayerQuitEvent) {
                for ((bukkitBar, _) in service.getPlayerBars(e.player.uniqueId)) {
                    bukkitBar.viewers.remove(e.player.uniqueId)
                    bukkitBar.bar.removePlayer(e.player)
                }
            }
        },
        plugin
    )
}

fun Player.showBossBar(display: BossBarDisplay) {
    val bukkitBar = bossBarService.bukkitBars.getOrPut(display.id) {
        val bar = Bukkit.createBossBar(
            display.title,
            display.color,
            display.style
        )
        BukkitBossBar(display.id, bar, mutableMapOf())
    }
    bukkitBar.viewers[uniqueId] = BarPlayer(
        uniqueId,
        display.id,
        if (display.stayDuration != null) LocalDateTime.now().plus(display.stayDuration) else null
    )
    display.update(bukkitBar.bar)
    bukkitBar.bar.addPlayer(this)
}

fun Player.removeBossBar(id: UUID) {
    val bukkitBar = bossBarService.bukkitBars[id] ?: return
    if (bukkitBar.viewers.remove(uniqueId) != null) {
        bukkitBar.bar.removePlayer(this)
    }
}