Add Join and Play handlers, Expand Command Builder functionality

Bot/Handler/MusicPlayer/PlayCommand/PlayHandler.cs

@@ -0,0 +1,110 @@
+using Discord;
+using Discord.WebSocket;
+using Lunaris2.SlashCommand;
+using MediatR;
+using Victoria.Node;
+using Victoria.Node.EventArgs;
+using Victoria.Player;
+using Victoria.Responses.Search;
+
+namespace Lunaris2.Handler.MusicPlayer.PlayCommand;
+
+public record PlayCommand(SocketSlashCommand Message) : IRequest;
+
+public class PlayHandler : IRequestHandler<PlayCommand>
+{
+    private readonly LavaNode _lavaNode;
+    private readonly DiscordSocketClient _client;
+    
+    public PlayHandler(LavaNode lavaNode, DiscordSocketClient client)
+    {
+        _lavaNode = lavaNode;
+        _client = client;
+    }
+    
+    public async Task Handle(PlayCommand command, CancellationToken cancellationToken)
+    {
+        var context = command.Message;
+
+        await _lavaNode.EnsureConnected();
+
+        var songName = context.GetOptionValueByName(Option.Input);
+
+        if (string.IsNullOrWhiteSpace(songName)) {
+            await context.RespondAsync("Please provide search terms.");
+            return;
+        }
+
+        var player = await GetPlayer(context);
+        
+        if (player == null) 
+            return;
+
+        var searchResponse = await _lavaNode.SearchAsync(
+            Uri.IsWellFormedUriString(songName, UriKind.Absolute)
+                ? SearchType.Direct
+                : SearchType.YouTube, songName);
+        
+        if (!await HandleSearchResponse(searchResponse, player, context, songName)) 
+            return;
+
+        await PlayTrack(player);
+
+        _lavaNode.OnTrackEnd += OnTrackEnd;
+    }
+
+    private async Task OnTrackEnd(TrackEndEventArg<LavaPlayer<LavaTrack>, LavaTrack> arg)
+    {
+        var player = arg.Player;
+        if (!player.Vueue.TryDequeue(out var nextTrack))
+        {
+            await player.TextChannel.SendMessageAsync("Queue completed!");
+            return;
+        }
+
+        await player.PlayAsync(nextTrack);
+    }
+    
+    private async Task PlayTrack(LavaPlayer<LavaTrack> player)
+    {
+        if (player.PlayerState is PlayerState.Playing or PlayerState.Paused) {
+            return;
+        }
+
+        player.Vueue.TryDequeue(out var lavaTrack);
+        await player.PlayAsync(lavaTrack);
+    }
+    
+    private async Task<LavaPlayer<LavaTrack>?> GetPlayer(SocketSlashCommand context)
+    {
+        var voiceState = context.User as IVoiceState;
+
+        if (voiceState?.VoiceChannel != null)
+            return await _lavaNode.JoinAsync(voiceState.VoiceChannel, context.Channel as ITextChannel);
+        
+        await context.RespondAsync("You must be connected to a voice channel!");
+        return null;
+    }
+    
+    private async Task<bool> HandleSearchResponse(SearchResponse searchResponse, LavaPlayer<LavaTrack> player, SocketSlashCommand context, string songName)
+    {
+        if (searchResponse.Status is SearchStatus.LoadFailed or SearchStatus.NoMatches) {
+            await context.RespondAsync($"I wasn't able to find anything for `{songName}`.");
+            return false;
+        }
+
+        if (!string.IsNullOrWhiteSpace(searchResponse.Playlist.Name)) {
+            player.Vueue.Enqueue(searchResponse.Tracks);
+            
+            await context.RespondAsync($"Enqueued {searchResponse.Tracks.Count} songs.");
+        }
+        else {
+            var track = searchResponse.Tracks.FirstOrDefault()!;
+            player.Vueue.Enqueue(track);
+
+            await context.RespondAsync($"Enqueued {track?.Title}");
+        }
+
+        return true;
+    }
+}