#pragma once

#include <cmath>

#include "synth/Instruments/Instrument.hpp"

class PianoString : public Instrument {

public:

    PianoString() = default;
    PianoString(ConfigService* config, LoggerService* logger);
    ~PianoString() = default;
    
    void noteOn(float frequency, float velocity) override;
    void noteOff() override;

    bool isActive() override;

    float process(bool& scopeTrigger) override;

private:

    void recalculateConstants();

    // states
    float frequency_ = 0.0f;
    std::vector<float> stringY_current_;
    std::vector<float> stringY_previous_;
    std::vector<float> stringY_next_;
    std::vector<float> stringX_;
    bool active_ = false;

    // constants

    // string parameters
    size_t segmentCount_ = 80;
    static constexpr float rho_ = 8000.0f; // density, steel, kg/m^3
    static constexpr float radius_ = 0.001f; // meters
    static constexpr float stringTension_ = 1200.0f; // string tension, N
    static constexpr float stiffness_ = 0.0f; // stiffness coefficient
    float damping_ = 0.5f; // damping coefficient
    static constexpr float stringLength_ = 4.0f; // length of string at lowest frequency (20 hz)
    static constexpr float strikePosition_ = 0.8f; // x of impulse location
    static constexpr float impulseWidth_ = 0.1f; // x% of impulse width
    static constexpr float impulseVelocity_ = 10000.0f; // x/t of impulse magnitude
    static constexpr float samplePosition_ = 0.2f; // percentage along L of sampling for audio
    float crossSectionalArea_ = pi * std::pow(radius_, 2.0f); // string cross sectional area, assuming circular
    float mu_ = crossSectionalArea_ * rho_; // linear mass density
    float waveVelocity_ = std::sqrt(stringTension_ / mu_); // transverse wave velocity
    float L_ = 1.0f; // length of string at a given frequency
    float gain_ = 0.5f;

    // f0_ = waveVelocity_ / (2.0f * stringLength_); // fundamental frequency of a non-stiff string
    // f1_ = f0_ * std::sqrt(1.0f + stiffness_); // fundamental frequency of the stiff string

    uint32_t samplingSteps_ = 1;
    float phaseTracker_ = 0.0f;

    float dx_ = L_ / static_cast<float>(segmentCount_);
    float dt_ = 1.0f / sampleRate_;

    // derived constants
    float r1_ = waveVelocity_ * dt_/dx_;
    float r2_ = std::pow(waveVelocity_ * dt_/dx_, 2.0f);
    float s1_ = stiffness_ * dt_/std::pow(dx_, 2.0f);
    float s2_ = std::pow(stiffness_ * dt_/std::pow(dx_, 2.0f), 2.0f);
    float a1_ = 2.0f - 2.0f * damping_ * dt_;
    float a2_ = 2.0f * damping_ * dt_ - 1.0f;

    // keeping track of the string's activeness
    float rms_ = 0.0f;

};