tbd-station-14/Content.Client/Audio/BackgroundAudioSystem.cs

using Content.Client.GameTicking.Managers;
using Content.Client.Lobby;
using Content.Shared.CCVar;
using JetBrains.Annotations;
using Robust.Client;
using Robust.Client.State;
using Robust.Shared.Audio;
using Robust.Shared.Configuration;
using Robust.Shared.Player;

namespace Content.Client.Audio;

[UsedImplicitly]
public sealed class BackgroundAudioSystem : EntitySystem
{
    [Dependency] private readonly SharedAudioSystem _audio = default!;
    [Dependency] private readonly IBaseClient _client = default!;
    [Dependency] private readonly IConfigurationManager _configManager = default!;
    [Dependency] private readonly ClientGameTicker _gameTicker = default!;
    [Dependency] private readonly IStateManager _stateManager = default!;

    private readonly AudioParams _lobbyParams = new(-5f, 1, "Master", 0, 0, 0, true, 0f);

    private IPlayingAudioStream? _lobbyStream;

    public override void Initialize()
    {
        base.Initialize();

        _configManager.OnValueChanged(CCVars.LobbyMusicEnabled, LobbyMusicCVarChanged);
        _configManager.OnValueChanged(CCVars.LobbyMusicVolume, LobbyMusicVolumeCVarChanged);

        _stateManager.OnStateChanged += StateManagerOnStateChanged;

        _client.PlayerLeaveServer += OnLeave;

        _gameTicker.LobbySongUpdated += LobbySongUpdated;
    }

    public override void Shutdown()
    {
        base.Shutdown();

        _configManager.UnsubValueChanged(CCVars.LobbyMusicEnabled, LobbyMusicCVarChanged);
        _configManager.UnsubValueChanged(CCVars.LobbyMusicVolume, LobbyMusicVolumeCVarChanged);

        _stateManager.OnStateChanged -= StateManagerOnStateChanged;

        _client.PlayerLeaveServer -= OnLeave;

        _gameTicker.LobbySongUpdated -= LobbySongUpdated;

        EndLobbyMusic();
    }

    private void StateManagerOnStateChanged(StateChangedEventArgs args)
    {
        switch (args.NewState)
        {
            case LobbyState:
                StartLobbyMusic();
                break;
            default:
                EndLobbyMusic();
                break;
        }
    }

    private void OnLeave(object? sender, PlayerEventArgs args)
    {
        EndLobbyMusic();
    }

    private void LobbyMusicVolumeCVarChanged(float volume)
    {
        if (_stateManager.CurrentState is LobbyState)
        {
            RestartLobbyMusic();
        }
    }

    private void LobbyMusicCVarChanged(bool musicEnabled)
    {
        if (!musicEnabled)
        {
            EndLobbyMusic();
        }
        else if (_stateManager.CurrentState is LobbyState)
        {
            StartLobbyMusic();
        }
        else
        {
            EndLobbyMusic();
        }
    }

    private void LobbySongUpdated()
    {
        RestartLobbyMusic();
    }

    public void RestartLobbyMusic()
    {
        EndLobbyMusic();
        StartLobbyMusic();
    }

    public void StartLobbyMusic()
    {
        if (_lobbyStream != null || !_configManager.GetCVar(CCVars.LobbyMusicEnabled))
            return;

        var file = _gameTicker.LobbySong;
        if (file == null) // We have not received the lobby song yet.
        {
            return;
        }

        _lobbyStream = _audio.PlayGlobal(file, Filter.Local(), false,
            _lobbyParams.WithVolume(_lobbyParams.Volume + _configManager.GetCVar(CCVars.LobbyMusicVolume)));
    }

    private void EndLobbyMusic()
    {
        _lobbyStream?.Stop();
        _lobbyStream = null;
    }
}