#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <math.h>

//origin for graph is (63,31)
//all values for calculation need to be offset by that 

Adafruit_SSD1306 display(128,64,&Wire,-1);



#define OFFSETX 63
#define OFFSETY 31
#define TOTAL_STATES 3
#define BTN_PIN 13

int state = 0;
bool last_state = HIGH;
bool current_state = HIGH;

void drawAxes()
{
  display.drawLine(63, 0, 63, 63, SSD1306_WHITE);
  display.drawLine(0,31,127,31,SSD1306_WHITE);
}

void linear()
{
  // int par = ??? (y=nx)
  display.clearDisplay();
  drawAxes();
  display.drawLine(95,0,31,63,SSD1306_WHITE);
  display.display();

}

void quadratic()
{
  display.clearDisplay();
  drawAxes();
  float i = 0;
  
  while(i*i < 31)
  {
    display.drawPixel(OFFSETX+i,OFFSETY - i*i,SSD1306_WHITE);
    display.drawPixel(OFFSETX-i,OFFSETY - i*i,SSD1306_WHITE);
    i+=0.05;
  }
  display.display();

}

void sinusoidal();

void exponential()
{
  display.clearDisplay();
  drawAxes();
  float i = 0;

  while(i<=127)
  {
    display.drawPixel(63+i , OFFSETY - log(i), SSD1306_WHITE);
    i+=0.05;
  }
  display.display();

};


void setup() {
  
  display.begin(SSD1306_SWITCHCAPVCC,0x3C);

  pinMode(BTN_PIN, INPUT_PULLUP);

  display.clearDisplay();

  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);

  display.display();
}

void loop() {
  if (digitalRead(BTN_PIN) == LOW)
  {
    state += 1;
    while(digitalRead(BTN_PIN) == LOW){
      delay(10);
    }
    //wtf is debouncing
    delay(50);
  }

  if(state%TOTAL_STATES == 0){
    linear();
  }

  else if (state%TOTAL_STATES == 1){
    quadratic();
  }

  else if(state%TOTAL_STATES == 2){
    exponential();
  }

  
/*
  else if(state%TOTAL_STATES == 2){
    exponential();
  }
  
  else if(state%TOTAL_STATES ==3){
    sinusoidal();
  }
  */
}