////////////////////////////////
//~ Track types

typedef u32 MIX_TrackFlag; enum
{
    MIX_TrackFlag_None        = 0,
    MIX_TrackFlag_Spatialize  = (1 << 0)
};

Struct(MIX_Handle)
{
    u64 gen;
    void *data;
};

Struct(MIX_TrackDesc)
{
    MIX_TrackFlag flags;
    f32 volume;         /* 0 -> 1.0+ */
    f32 speed;          /* 0 -> 1.0+ */
    b32 looping;

    /* MIX_TrackFlag_Spatialize */
    Vec2 pos;
};
#define M_TRACKDESC(...) ((MIX_TrackDesc) { \
    .flags      = 0, \
    .volume     = 1.0, \
    .speed      = 1.0, \
    .looping    = 0, \
    .pos        = VEC2(0, 0), \
    __VA_ARGS__ \
})

////////////////////////////////
//~ Mix types

/* Stereo mix of 32 bit float samples */
Struct(MIX_PcmF32)
{
    u64 count;
    f32 *samples;
};

Struct(MIX_EffectData)
{
    /* Spatialization */
    f32 spatial_volume;
    f32 spatial_pan;
};

Struct(MIX_MixData)
{
    MIX_Handle track_handle;
    b32 track_finished;

    MIX_TrackDesc desc;
    MIX_EffectData effect_data;
    SND_Sound *source;
    u64 source_pos;
};

Struct(MIX_Track){
    u64 gen;

    /* Controlled via interface */
    SND_Sound *sound;
    MIX_TrackDesc desc;

    /* Internal */
    MIX_MixData mix;

    MIX_Track *next;
    MIX_Track *prev;
};

////////////////////////////////
//~ Shared state

Struct(MIX_SharedState)
{
    P_Mutex mutex;

    /* Listener */
    Vec2 listener_pos;
    Vec2 listener_dir;

    /* Track list */
    Arena *track_arena;
    MIX_Track *track_first_playing;
    MIX_Track *track_last_playing;
    u64 track_playing_count;
    MIX_Track *track_first_free;
};

extern MIX_SharedState M_shared_state;

////////////////////////////////
//~ Startup

Struct(MIX_StartupReceipt) { i32 _; };
MIX_StartupReceipt MIX_Startup(void);

////////////////////////////////
//~ Track operations

MIX_Handle MIX_HandleFromTrack(MIX_Track *track);
MIX_Track *MIX_TrackFromHandle(MIX_Handle handle);
MIX_Track *MIX_AllocTrackLocked(P_Lock *lock, SND_Sound *sound);
void MIX_ReleaseTrackLocked(P_Lock *lock, MIX_Track *track);

////////////////////////////////
//~ Mixer state operations

MIX_Handle MIX_PlaySound(SND_Sound *sound);
MIX_Handle MIX_PlaySoundEx(SND_Sound *sound, MIX_TrackDesc desc);
MIX_TrackDesc MIX_TrackDescFromHandle(MIX_Handle handle);
void MIX_UpdateTrack(MIX_Handle handle, MIX_TrackDesc desc);
void MIX_UpdateListener(Vec2 pos, Vec2 dir);

////////////////////////////////
//~ Mixer update

i16 MIX_SampleSound(SND_Sound *sound, u64 sample_pos, b32 wrap);
MIX_PcmF32 MIX_MixAllTracks(Arena *arena, u64 frame_count);