#include <Arduino.h>
#include <U8g2lib.h>
#include <Wire.h>

U8G2_SSD1306_64X32_1F_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);


const int btn1 = 2;
const int btn2 = 3;
const int heater = 5;
const int bat = A0;
const int flow = A2;

int dutyCycle = 50;
int count = 0;
String p1,p2,p3;

void setup() {
  Serial.begin(115200);
  u8g2.begin();
  pinMode(btn1, INPUT_PULLUP);
  pinMode(btn2, INPUT_PULLUP);
  pinMode(heater, OUTPUT);
  pinMode(bat, INPUT);
  pinMode(flow, INPUT);
}

void loop() {
  // read battery voltage
  int adc = analogRead(bat);
  float voltage = adc * (5.0 / 1023.0);
  Serial.print("Battery Voltage : ");
  Serial.println(voltage);
  int vbat = map(voltage * 100, 290, 420, 0, 100);
  Serial.print("Battery Percentage : ");
  if (vbat < 0) vbat = 0;
  if (vbat > 100) vbat = 100;
  Serial.println(vbat);
  delay(100);

  // increase duty cycle
  if (!digitalRead(btn1)) {
    dutyCycle += 5;
    if (dutyCycle > 100) dutyCycle = 100;
    delay(250);
  }
  // decrese duty cycle
  if (!digitalRead(btn2)) {
    dutyCycle -= 5;
    if (dutyCycle < 0) dutyCycle = 0;
    delay(250);
  }
  Serial.print("PWM DutyCycle : ");
  Serial.println(dutyCycle);

  // calculate output voltage
  float vout = dutyCycle * 0.01 * voltage;
  Serial.print("Output Voltage : ");
  Serial.println(vout);

  // read flow sensor
  int pressure = analogRead(flow);
  Serial.print("Flow Sensor : ");
  Serial.println(pressure);

  // when flow sensor triggered
  if (pressure > 512) {
    count += 1;
    int pwm = map(dutyCycle, 0, 100, 0, 255);
    analogWrite(heater, pwm);
    delay(1000);  // ignition delay
  } else {
    analogWrite(heater, 0);
  }
  Serial.print("Trigger Count : ");
  Serial.println(count);
  Serial.println();
  
  String t1 = String(vbat) + "%";
  String t2 = String(count);
  String t3 = String(vout) + "V";

  if(p1 != t1 || p2 != t2 || p3 != t3){
    u8g2.clearBuffer();
    u8g2.setFont(u8g2_font_t0_11_tf);
    u8g2.drawStr(10, 10, t1.c_str());
    u8g2.drawStr(10, 20, t2.c_str());
    u8g2.drawStr(10, 30, t3.c_str());
    u8g2.sendBuffer();
    p1 = t1;
    p2 = t2;
    p3 = t3;
  }
}