matris/Synth.hpp

#pragma once
#include <SDL2/SDL.h>
#include <mutex>
#include <vector>

enum class WaveType {
    SINE,
    SQUARE,
    TRIANGLE,
    NOISE
};

enum class ChordType {
    AM,
    E7,
    DM,
    F,
    G,
    C
};

struct Envelope {
    float attackTime = 0.005f;  // seconds
    float decayTime = 0.05f;    // seconds
    float sustainLevel = 0.7f;  // 0.0 to 1.0
    float releaseTime = 0.12f;  // seconds
};

struct Voice {
    bool active = false;
    WaveType wave = WaveType::SQUARE;
    float frequency = 0.0f;
    float phase = 0.0f;
    float volume = 0.12f;
    float pan = 0.5f;           // 0.0 (left) to 1.0 (right)

    // Envelope tracking
    Envelope adsr;
    float age = 0.0f;           // duration active (seconds)
    float releaseAge = 0.0f;    // duration in release phase (seconds)
    bool releasing = false;

    // Frequency sweeps (for sound effects)
    float startFreq = 0.0f;
    float targetFreq = 0.0f;
    float sweepDuration = 0.0f;
    float sweepAge = 0.0f;
    
    // Vibrato
    float vibratoFreq = 0.0f;   // LFO speed (Hz)
    float vibratoDepth = 0.0f;  // pitch variation depth
};

enum class SFXType {
    MOVE,
    ROTATE,
    LAND,
    LINE_CLEAR,
    TETRIS_CLEAR,
    LEVEL_UP,
    GAME_OVER
};

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

    bool init();
    void playBGM(bool play);
    void triggerSFX(SFXType type);
    void stopAllSFX();
    
    // Thread-safe copy of visualizer buffer for the GPU renderer
    std::vector<float> getVisualizerBuffer();

    // SDL Audio Callback
    void audioCallback(Uint8* stream, int len);

private:
    static void audioCallbackWrapper(void* userdata, Uint8* stream, int len);

    SDL_AudioDeviceID mAudioDevice = 0;
    bool mBGMEnabled = false;

    std::mutex mMutex;

    // 8 Dedicated voices:
    // Voice 0: BGM Lead (Square)
    // Voice 1: BGM Harmony / Echo (Pulse)
    // Voice 2: BGM Bass (Triangle)
    // Voice 3: BGM Drums / Noise (Noise/Triangle)
    // Voice 4, 5, 6, 7: Dedicated SFX voices
    static constexpr int NUM_VOICES = 8;
    Voice mVoices[NUM_VOICES];

    // Sequencer state
    int mBPM = 138;
    float mSecsPerTick = 0.0f; // Seconds per eighth note tick
    float mTickTimer = 0.0f;
    int mCurrentTick = 0;
    
    // Pattern-based Sequencer
    static constexpr int NUM_PATTERNS = 6;
    uint8_t mPatternLead[NUM_PATTERNS][64];
    uint8_t mPatternBass[NUM_PATTERNS][64];
    ChordType mPatternChords[NUM_PATTERNS][8]; // 8 bars per pattern

    // Dynamic Playlist (4 patterns per cycle)
    int mPlaylist[4];
    void shufflePlaylist();

    // Visualizer Oscilloscope Ring Buffer
    static constexpr int VIS_BUFFER_SIZE = 512;
    float mVisBuffer[VIS_BUFFER_SIZE];
    int mVisWritePos = 0;

    void initSequencer();
    void updateSequencer(float dt);
    void updateVoice(Voice& voice, float dt);
    float generateSample(Voice& voice);
    
    // Helper to start BGM notes
    void triggerMusicNote(int voiceIdx, uint8_t midiNote, WaveType wave, float duration, float pan = 0.5f, float volume = 0.1f);
};