Woo, audio! Added a basic play command, which for now just loads a totally random video. Also added a kill command to forcefully stop a connection, might move that to debug

build.gradle

@@ -35,6 +35,7 @@ dependencies {
     testImplementation "org.junit.jupiter:junit-jupiter:5.4.2"
 
     implementation 'net.dv8tion:JDA:4.ALPHA.0_88'
+    implementation 'com.sedmelluq:lavaplayer:1.3.17'
 
     implementation "com.h2database:h2"
 

src/main/kotlin/nl/voidcorp/discord/Loader.kt

@@ -1,12 +1,15 @@
 package nl.voidcorp.discord
 
+import com.sedmelluq.discord.lavaplayer.player.DefaultAudioPlayerManager
+import com.sedmelluq.discord.lavaplayer.source.AudioSourceManagers
 import net.dv8tion.jda.api.sharding.DefaultShardManagerBuilder
 import nl.voidcorp.discord.events.CommandListener
 import nl.voidcorp.discord.events.OttoListener
-import org.springframework.stereotype.Component
+import org.springframework.stereotype.Service
 
-@Component
-class Loader(listener: CommandListener) {
+
+@Service
+class Loader(listener: CommandListener, playerManager: DefaultAudioPlayerManager) {
     init {
         val token = System.getenv("DISCORD_TOKEN") ?: throw RuntimeException("'DISCORD_TOKEN' not set!")
         val builder = DefaultShardManagerBuilder(token)
@@ -16,5 +19,6 @@ class Loader(listener: CommandListener) {
         builder.addEventListeners(OttoListener, listener)
 
         jda = builder.build()
+        AudioSourceManagers.registerRemoteSources(playerManager)
     }
 }

src/main/kotlin/nl/voidcorp/discord/command/CommandGroup.kt

@@ -3,6 +3,7 @@ package nl.voidcorp.discord.command
 enum class CommandGroup {
     GENERAL,
     FUN,
+    MUSIC,
     ROLES,
     ADMIN,
     VeRY_hIdden_CaTegoRY_LoL,

src/main/kotlin/nl/voidcorp/discord/commands/music/ForceLeave.kt

@@ -0,0 +1,17 @@
+package nl.voidcorp.discord.commands.music
+
+import nl.voidcorp.discord.command.*
+import org.springframework.stereotype.Service
+
+@Service
+class ForceLeave : Command(
+    "forceleave",
+    group = CommandGroup.MUSIC,
+    location = CommandSource.GUILD,
+    commandLevel = CommandLevel.MODERATOR
+) {
+    override fun handle(event: CommandMessage): CommandResult {
+        event.guild!!.audioManager.closeAudioConnection()
+        return CommandResult.SUCCESS
+    }
+}

src/main/kotlin/nl/voidcorp/discord/commands/music/Play.kt

@@ -0,0 +1,28 @@
+package nl.voidcorp.discord.commands.music
+
+import nl.voidcorp.discord.command.*
+import nl.voidcorp.discord.music.AudioLoadHandler
+import nl.voidcorp.discord.music.PlayerManager
+import org.springframework.stereotype.Service
+
+@Service
+class Play(val playerManager: PlayerManager) :
+    Command("play", location = CommandSource.GUILD, group = CommandGroup.MUSIC) {
+    override fun handle(event: CommandMessage): CommandResult {
+        val chan = event.member!!.voiceState!!.channel
+        if (chan == null) {
+            event.reply("Please join a voice channel to play music!")
+            return CommandResult.SUCCESS
+        }
+        val am = event.guild!!.audioManager
+
+        am.openAudioConnection(chan)
+
+        val ts = playerManager.getGuildPlayer(event.guild)
+
+        playerManager.loadItem("https://www.youtube.com/watch?v=kPgiJUeSP6Q", AudioLoadHandler(ts))
+
+
+        return CommandResult.SUCCESS
+    }
+}

src/main/kotlin/nl/voidcorp/discord/music/AudioLoadHandler.kt

@@ -0,0 +1,30 @@
+package nl.voidcorp.discord.music
+
+import com.sedmelluq.discord.lavaplayer.player.AudioLoadResultHandler
+import com.sedmelluq.discord.lavaplayer.tools.FriendlyException
+import com.sedmelluq.discord.lavaplayer.track.AudioPlaylist
+import com.sedmelluq.discord.lavaplayer.track.AudioTrack
+import nl.voidcorp.discord.logger
+
+
+class AudioLoadHandler(private val trackScheduler: TrackScheduler) : AudioLoadResultHandler {
+
+    override fun loadFailed(exception: FriendlyException) {
+        throw exception
+    }
+
+    override fun trackLoaded(track: AudioTrack) {
+        logger.info("loaded track ${track.identifier}")
+        trackScheduler.queue(track)
+    }
+
+    override fun noMatches() {
+
+    }
+
+    override fun playlistLoaded(playlist: AudioPlaylist) {
+        for (t in playlist.tracks) {
+            trackScheduler.queue(t)
+        }
+    }
+}

src/main/kotlin/nl/voidcorp/discord/music/AudioPlayerSendHandler.kt

@@ -0,0 +1,22 @@
+package nl.voidcorp.discord.music
+
+import com.sedmelluq.discord.lavaplayer.player.AudioPlayer
+import com.sedmelluq.discord.lavaplayer.track.playback.AudioFrame
+import net.dv8tion.jda.api.audio.AudioSendHandler
+import java.nio.ByteBuffer
+
+
+class AudioPlayerSendHandler(private val audioPlayer: AudioPlayer) : AudioSendHandler {
+    private var lastFrame: AudioFrame? = null
+
+    override fun canProvide(): Boolean {
+        lastFrame = audioPlayer.provide()
+        return lastFrame != null
+    }
+
+    override fun provide20MsAudio() = ByteBuffer.wrap(lastFrame!!.data)
+
+    override fun isOpus(): Boolean {
+        return true
+    }
+}

src/main/kotlin/nl/voidcorp/discord/music/PlayerManager.kt

@@ -0,0 +1,22 @@
+package nl.voidcorp.discord.music
+
+import com.sedmelluq.discord.lavaplayer.player.DefaultAudioPlayerManager
+import net.dv8tion.jda.api.entities.Guild
+import org.springframework.stereotype.Service
+
+@Service
+class PlayerManager : DefaultAudioPlayerManager() {
+    val guildPlayMap = mutableMapOf<Long, TrackScheduler>()
+    fun getGuildPlayer(guild: Guild): TrackScheduler {
+        return if (guildPlayMap.containsKey(guild.idLong)) {
+            guildPlayMap[guild.idLong] ?: error("oof?")
+        } else {
+            val player = createPlayer()
+            val ts = TrackScheduler(player)
+            player.addListener(ts)
+            guild.audioManager.sendingHandler = AudioPlayerSendHandler(player)
+            guildPlayMap[guild.idLong] = ts
+            ts
+        }
+    }
+}

src/main/kotlin/nl/voidcorp/discord/music/TrackScheduler.kt

@@ -0,0 +1,25 @@
+package nl.voidcorp.discord.music
+
+import com.sedmelluq.discord.lavaplayer.player.AudioPlayer
+import com.sedmelluq.discord.lavaplayer.player.event.AudioEventAdapter
+import com.sedmelluq.discord.lavaplayer.track.AudioTrack
+import com.sedmelluq.discord.lavaplayer.track.AudioTrackEndReason
+import java.util.*
+
+class TrackScheduler(private val player: AudioPlayer) : AudioEventAdapter() {
+    private val queue = ArrayDeque<AudioTrack>()
+    fun queue(track: AudioTrack) {
+        if (!player.startTrack(track, true)) {
+            queue.addLast(track)
+        }
+
+    }
+
+    fun pop() = queue.pop()
+
+    override fun onTrackEnd(player: AudioPlayer, track: AudioTrack, endReason: AudioTrackEndReason) {
+        if (endReason.mayStartNext && queue.isNotEmpty()) {
+            player.startTrack(pop(), true)
+        }
+    }
+}