#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2); // set the LCD address to 0x27 for a 16 chars and 2 line display

const int mq7_a0 = A0;
//float ppm;
//float sensorVoltage;

const int pushButtonPin = 8;

// Calibration resistance values
float Ro = 10; // Calibrate by measuring sensor resistance in clean air
float cleanAirFactor = 9.83;

const byte contrastBlock[8] = {
  B11111,
  B11111,
  B11111,
  B11111,
  B11111,
  B11111,
  B11111,
  B00000
};

const char* co_results[] = {"No Diabetes", "Not Determined", "Diabetes Type 1", "Diabetes Type 2"};

float calibrateSensor() {
  int numReadings = 10;
  float totalVoltage = 0.0;

  for (int i = 0; i < numReadings; i++) {
    int raw_value = analogRead(mq7_a0);
    float voltage = (raw_value / 1023.0) * 5.0;
    totalVoltage += voltage;
    delay(100);
  }

  float averageVoltage = totalVoltage / numReadings;
  float baselineConcentration = averageVoltage / 0.1; // Assuming 100mV per 1 ppm CO concentration

  return baselineConcentration;
}

void displayResult(float ppm) {
  lcd.clear();
  lcd.print("CO Level: ");
  lcd.print(ppm, 1); // Display CO concentration with 1 decimal place

  int result = -1;

  if (ppm >= 3.3 && ppm < 4.7) {
    result = 2; // Diabetes Type 1
  } else if (ppm <= 5.4 && ppm >= 4.8) {
    result = 3; // Diabetes Type 2
  } else {
    result = 0; // No Diabetes
  }

  lcd.setCursor(0, 1);
  lcd.print(co_results[result]);
  delay(11000); // Display result for 11 seconds
}

void setup() {
  pinMode(mq7_a0, INPUT);
  pinMode(pushButtonPin, INPUT_PULLUP); // Set the push button pin as input with pull-up
  lcd.init();
  lcd.init();
  lcd.backlight();
  lcd.createChar(0, contrastBlock); // Create custom character for contrast control
  lcd.print("Welcome!");
  lcd.setCursor(0, 1);
  lcd.print("Press the button");
}

void loop() {
  int coLevel = analogRead(mq7_a0);
  lcd.setCursor(8, 0);
  lcd.print(" ppm:");
  lcd.print(coLevel);
  //sensorVoltage = analogRead(mq7_a0) * (5.0 / 1024.0);
  int buttonState = digitalRead(pushButtonPin);
  if (buttonState == LOW) {
    lcd.clear();
    lcd.print("Please Exhale");
    lcd.setCursor(0, 1);
    lcd.print("and Breathe Out!");
    delay(6000); // Wait for 6 seconds (Exhale time)

    lcd.clear();
    lcd.print("Detecting");
    for (int i = 0; i < 3; i++) {
      lcd.print(".");
      delay(500); // Wait for 0.5 seconds
    }

    // Calibrate the sensor for 1 second
    float baselineConcentration = calibrateSensor();

    // Read CO concentration from sensor and convert to ppm
    float ppm = map(coLevel, 0, 1023, 0, 50);

    displayResult(ppm);

    lcd.clear();
    lcd.print("Calibrating..."); // Display calibration screen
    baselineConcentration = calibrateSensor(); // Calibrate the sensor again after displaying the result
    delay(1000); // Delay to show calibration screen for 1 second

    lcd.clear();
    lcd.print("Welcome!");
    lcd.setCursor(0, 1);
    lcd.print("Press the button");
    while (digitalRead(pushButtonPin) == LOW) {
      // Wait for the button to be released before continuing
    }
  }
}

/*
void calculateCO_PPM_Log() {
  float sensorResistance = (5.0 - sensorVoltage) / sensorVoltage;
  // Take log of resistance to linearize sensor response
  sensorResistance = log(sensorResistance);
  // Apply clean air factor
  float correctedResistance = sensorResistance / cleanAirFactor;
  // Calculate PPM
  ppm = pow(10, (log(Ro) - correctedResistance));
}*/