#include <Arduino.h>
#include <U8g2lib.h> // u8g2 library for drawing on OLED display - needs to be installed in Arduino IDE first
#include <Wire.h>
U8G2_SSD1306_128X64_NONAME_1_HW_I2C u8g2(U8G2_R0); // set the OLED display to 128x64px, HW IIC, no rotation, used in WOKWI

int center_x = 35; // display x center, 64px for the 128x128px display
int center_y = 40; // display y center, 64px for the 128x128px display
int speed;
int speed1;

void setup(void) { // Arduino setup
  u8g2.begin();  // begin the u8g2 library
  
  u8g2.setContrast(255); // set display contrast/brightness
}
void loop(void) { 

  u8g2.firstPage();
  do {
    speed=analogRead(A0);
    speed1=map(speed,0,1023,0,9000);
    speed=map(speed,0,1024,225,360+45*3);

    draw_background();
    draw_hand_thin(speed,30,0);
    
    u8g2.setFont(u8g2_font_ncenB14_tr);
    u8g2.setCursor(85, 45);
    u8g2.print(speed1);

    // draw the center circle to cover the center part of the hands
    u8g2.setColorIndex(0); // black color
    u8g2.drawDisc(center_x, center_y, 4);
    u8g2.setColorIndex(1); // white color
    u8g2.drawCircle(center_x, center_y, 4);
  } while ( u8g2.nextPage() );

}
void draw_background() {
  float xpos;
  float ypos;
  float xpos2;
  float ypos2;

  u8g2.setDrawColor(1); // set the drawing color to white    
  u8g2.drawCircle(center_x, center_y, 33, U8G2_DRAW_ALL); // draw fullscreen circle
  
  // draw 60 dots (pixels) around the circle, one for every minute/second
  for (int i=0; i<60; i++) { // draw 60 pixels around the circle
    xpos = round(center_x + sin(radians(i * 6)) * 35); // calculate x pos based on angle and radius
    ypos = round(center_y - cos(radians(i * 6)) * 35); // calculate y pos based on angle and radius
    
    u8g2.drawPixel(xpos,ypos); // draw white pixel on position xpos and ypos
  }
  
  for (int i=0; i<8; i++) { // draw 60 pixels around the circle
    xpos = round(center_x + sin(radians(i *45)) * 31); // calculate x pos based on angle and radius
    ypos = round(center_y - cos(radians(i *45)) * 31); // calculate y pos based on angle and radius
    
    u8g2.drawPixel(xpos,ypos); // draw white pixel on position xpos and ypos
  }
  for (int i=0; i<8; i++) { // draw 60 pixels around the circle
    xpos = round(center_x + sin(radians(i *45)) * 30); // calculate x pos based on angle and radius
    ypos = round(center_y - cos(radians(i *45)) * 30); // calculate y pos based on angle and radius
    
    u8g2.drawPixel(xpos,ypos); // draw white pixel on position xpos and ypos
  }
  for (int i=0; i<8; i++) { // draw 60 pixels around the circle
    xpos = round(center_x + sin(radians(i *45)) * 29); // calculate x pos based on angle and radius
    ypos = round(center_y - cos(radians(i *45)) * 29); // calculate y pos based on angle and radius
    
    u8g2.drawPixel(xpos,ypos); // draw white pixel on position xpos and ypos
  }
  for (int i=0; i<8; i++) { // draw 60 pixels around the circle
    xpos = round(center_x + sin(radians(i *45)) * 28); // calculate x pos based on angle and radius
    ypos = round(center_y - cos(radians(i *45)) * 28); // calculate y pos based on angle and radius
    
    u8g2.drawPixel(xpos,ypos); // draw white pixel on position xpos and ypos
  }
  u8g2.setFont(u8g2_font_5x7_mn); // set the u8g2 font
  u8g2.drawStr(10,60,"0");
  u8g2.drawStr(8,43,"1.5");
  u8g2.drawStr(18,26,"3");
  u8g2.drawStr(29,18,"4.5");
  u8g2.drawStr(50,26,"6");
  u8g2.drawStr(50,43,"7.5");
  u8g2.drawStr(50,60,"9");

  u8g2.setFont(u8g2_font_5x7_mf);
  u8g2.drawStr(22,64,"K_RPM");

  u8g2.setFont(u8g2_font_t0_11b_mr);
  u8g2.drawStr(110,64,"RPM");

  


   
}

void draw_hand_thin (int hand_angle, int hand_lenght_long, int hand_legth_short) {

  float xpos;
  float ypos;
  float xpos2;
  float ypos2;  

  // calculate starting and ending position of the second hand
  xpos = round(center_x + sin(radians(hand_angle)) * hand_lenght_long); // calculate x pos based on angle and radius
  ypos = round(center_y - cos(radians(hand_angle)) * hand_lenght_long); // calculate y pos based on angle and radius
  xpos2 = round(center_x + sin(radians(hand_angle + 180)) * hand_legth_short); // calculate x pos based on angle and radius
  ypos2 = round(center_y - cos(radians(hand_angle + 180)) * hand_legth_short); // calculate y pos based on angle and radius  

  u8g2.drawLine(xpos, ypos, xpos2, ypos2); // draw the main line
  u8g2.setDrawColor(0); // black color
  u8g2.drawDisc(xpos2, ypos2, 3); // draw small filled black circle
  u8g2.setDrawColor(1); // white color
  u8g2.drawCircle(xpos2, ypos2, 3, U8G2_DRAW_ALL); // draw small outline white circle
}