radiantwave/src/audio/audio_manager.h

#pragma once

#include "config/config_manager.h"
#include <SDL3/SDL.h>
#include <SDL3_mixer/SDL_mixer.h>
#include <mutex>
#include <string>
#include <vector>

namespace radiantwave::db {
class DatabaseManager;
}

namespace radiantwave::audio {

struct AudioDeviceItem {
    std::string raw_name;      // e.g. alsa_output.pci-0000_00_1f.3.analog-stereo
    std::string friendly_name; // e.g. "Built-In Speakers"
    SDL_AudioDeviceID id = 0;  // SDL playback device id (0 = synthetic fallback)
};

// Maps raw technical audio device strings to user-friendly labels
std::string mapToFriendlyDeviceName(const std::string& raw_name);

class AudioManager {
public:
    AudioManager();
    ~AudioManager();

    // Non-copyable
    AudioManager(const AudioManager&) = delete;
    AudioManager& operator=(const AudioManager&) = delete;

    // Initialize SDL3_mixer audio system
    bool initialize(config::ConfigManager& config);

    // Provide a database handle for user-facing display-name lookups.
    void attachDatabase(db::DatabaseManager& db);

    // Shutdown audio subsystem
    void shutdown();

    // Enumerate playback devices with friendly names
    std::vector<AudioDeviceItem> getPlaybackDevices() const;

    // Master volume control (0 - 100)
    void setVolume(int volume_0_to_100);
    int getVolume() const;

    // Master audio enable / mute toggle
    void setAudioEnabled(bool enabled);
    bool isAudioEnabled() const;

    // Audio device selection
    bool switchDevice(const std::string& raw_device_name);
    bool switchDeviceById(SDL_AudioDeviceID id);
    std::string getCurrentDevice() const;
    SDL_AudioDeviceID getCurrentDeviceId() const;

    // Handle an SDL audio device event (SDL_EVENT_AUDIO_DEVICE_ADDED / REMOVED).
    // Returns true if the active device was affected and the mixer was recreated.
    bool handleDeviceEvent(const SDL_Event& event);

    // Pure helper (no SDL audio open): find the playback device with the given
    // SDL id, returning its raw name ("" when not found / id invalid). Exposed
    // for tests; the real lookup is through getPlaybackDevices().
    static std::string resolvePlaybackDeviceName(SDL_AudioDeviceID id);

    // Builds the SDL_PropertiesID passed to MIX_PlayTrack() for tracks that
    // loop forever (MIX_PROP_PLAY_LOOPS_NUMBER = -1). Exposed for tests; no
    // mixer, track, or audio device is required. The caller owns the property
    // set and must release it with SDL_DestroyProperties().
    static SDL_PropertiesID createInfiniteLoopOptions();

    // Playback control
    bool playTrack(const std::string& wav_filename);
    void stopTrack();

    // Filename of the track currently loaded in the active slot ("" if none).
    std::string currentTrack() const;

    // Fade playback control (used by the scroller page)
    bool playTrackFadeIn(const std::string& wav_filename, float seconds);
    bool playTrackCrossfade(const std::string& wav_filename, float seconds);
    // Fades any playing track out over `seconds`. Returns false when nothing
    // was playing, so callers can skip teardown delays tied to the fade.
    bool stopTrackFadeOut(float seconds);

    // Drive in-progress fade ramps; call once per frame.
    void update(float dt);

private:
    struct TrackSlot {
        MIX_Track* track = nullptr;
        MIX_Audio* audio = nullptr;
        float fadeInDuration = 0.0f;   // >0 while ramping in (seconds)
        float fadeInElapsed = 0.0f;
        float fadeOutRemaining = 0.0f; // >0 while fading out (seconds)
    };

    float effectiveGain() const;
    bool loadTrackInto(int slotIndex, const std::string& wav_filename);
    void startFadeIn(int slotIndex, float seconds);
    std::string displayNameFor(const std::string& wav_filename) const;

    // Starts the track on the given slot with infinite looping. The track must
    // already be loaded on the slot. Calling this on a playing/stopped/fading
    // track restarts it (cancelling any in-flight stop-fade).
    bool playTrackLooping(int slotIndex);

    // Recreates the mixer on the given playback device id (0 = system default).
    // Called with mutex_ held. Preserves playback state: whichever track was
    // playing on the active slot is reloaded and resumed at full gain, an
    // in-progress fade is restarted. The replacement mixer is opened before the
    // current one is destroyed so SDL's device ids stay valid (destroy-first
    // quits the whole audio subsystem and orphans the id being opened).
    // Returns false on failure without touching the current mixer, so the
    // existing output keeps playing.
    bool recreateMixerOnDevice(SDL_AudioDeviceID targetId);

    config::ConfigManager* configManager_ = nullptr;
    db::DatabaseManager* db_ = nullptr;

    bool initialized_ = false;
    bool enabled_ = true;
    int volume_ = 80; // 0 - 100
    std::string currentDevice_ = "";
    SDL_AudioDeviceID currentDeviceId_ = SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK;
    std::string currentTrack_ = "";

    MIX_Mixer* mixer_ = nullptr;
    TrackSlot slots_[2];
    int activeSlot_ = 0;
    mutable std::mutex mutex_;
};

} // namespace radiantwave::audio