/*
** Odin 2 Synthesizer Plugin
** Copyright (C) 2020 TheWaveWarden
**
** Odin 2 is free software: you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation, either version 3 of the License, or
** (at your option) any later version.
**
** Odin 2 is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
*/

// The code for this filter is based on the diagrams and implementations in Will Pirkles book
// "Designing Software Synthesizer Plug-Ins in C++". Find out more on https://willpirkle.com

#pragma once

#include "../../GlobalIncludes.h"
#include "Filter.h"

class VAOnePoleFilter : public Filter {
public:
	VAOnePoleFilter();
	virtual ~VAOnePoleFilter();

	void setFeedback(double fb) {
		m_feedback = fb;
	}

	double getFeedbackOutput() {
		return m_beta * (m_z_1 + m_feedback * m_delta);
	}

	void reset() {
		m_z_1      = 0;
		m_feedback = 0;
	}

	void update();

	double doFilter(double xn);

	inline void setLP() {
		m_is_lowpass = true;
	}

	inline void setHP() {
		m_is_lowpass = false;
	}

	//these are public for easy access
	double m_alpha; // Feed Forward coeff
	double m_beta;
	double m_gamma;    // Pre-Gain
	double m_delta;    // FB_IN Coeff
	double m_epsilon;  // FB_OUT scalar
	double m_a_0;      // input gain
	double m_feedback; // our own feedback coeff from S
protected:

	bool m_is_lowpass = true; //else highpass
	double m_z_1;             // our z-1 storage location
};
