sharp-chat/SharpChat/Commands/WhoCommand.cs

using SharpChat.Packet;
using System.Linq;

namespace SharpChat.Commands {
    public class WhoCommand : IChatCommand {
        public bool IsMatch(ChatCommandContext ctx) {
            return ctx.NameEquals("who");
        }

        public void Dispatch(ChatCommandContext ctx) {
            string? channelName = ctx.Args.FirstOrDefault();

            if(string.IsNullOrEmpty(channelName)) {
                ctx.Chat.SendTo(ctx.User, new WhoServerResponsePacket(
                    ctx.Chat.Users.Select(u => u.LegacyName).ToArray(),
                    ctx.User.LegacyName
                ));
                return;
            }

            ChatChannel? channel = ctx.Chat.Channels.FirstOrDefault(c => c.NameEquals(channelName));

            if(channel == null) {
                ctx.Chat.SendTo(ctx.User, new ChannelNotFoundErrorPacket(channelName));
                return;
            }

            if(channel.Rank > ctx.User.Rank || (channel.HasPassword && !ctx.User.Permissions.HasFlag(ChatUserPermissions.JoinAnyChannel))) {
                ctx.Chat.SendTo(ctx.User, new WhoChannelNotFoundErrorPacket(channelName));
                return;
            }

            ctx.Chat.SendTo(ctx.User, new WhoChannelResponsePacket(
                channel.Name,
                ctx.Chat.GetChannelUsers(channel).Select(user => user.LegacyName).ToArray(),
                ctx.User.LegacyName
            ));
        }
    }
}