#include <SevenSegmentTM1637.h>

#define EPSILON 3.3f
#define PATH_LENGTH 1.0f

#define CLK 3
#define DIO 4

const uint8_t LED_PIN = 6;
const uint8_t PHOTO_PIN = 2;
const uint8_t BUTTON_PIN = 5;

int buttonState = 0;
int lastButtonState = 0;
unsigned long buttonPressTime = 0;
unsigned long buttonReleaseTime = 0;

int mode = -1;
int blank = 0;
float absorbance = 0.0;
byte sampleCount = 0;

TM1637Display display(CLK, DIO);

void showNumber(float number) {
  int digits[4];
  for (int i = 0; i < 4; i++) {
    digits[i] = int(number * 10) % 10;
    number *= 10;
  }
  int photoValue = analogRead(PHOTO_PIN);
  float absorption = EPSILON * PATH_LENGTH * photoValue / 1023;
  int absorptionInt = round(absorption * 1000);
  display.showNumberDecEx(absorptionInt, 0b00001111, 4, 0);  // Display absorption value with rotating segments
}

void uvLedOn() {
  digitalWrite(LED_PIN, HIGH);
}

void uvLedOff() {
  digitalWrite(LED_PIN, LOW);
}

void measureBlank() {
  uvLedOn();
  blank = analogRead(PHOTO_PIN);
  uvLedOff();
  display.showNumberDecEx(0, 0b01000000, 2, 0);  // Display "0000" with rotating segments
}

void calculateAbsorbance() {
  uvLedOn();
  int value = analogRead(PHOTO_PIN);
  absorbance = blank - value;
  uvLedOff();
  display.showNumberDecEx(1, 0b00010000, 2, 0);  // Display "1111" with rotating segments
}

void setup() {
  pinMode(LED_PIN, OUTPUT);
  display.setBrightness(7);
  display.begin(); // Add this line to initialize the display
  showNumber(0);
}

int pressDuration = 0;

void loop() {
  buttonState = digitalRead(BUTTON_PIN);
  
  if (pressDuration > 3 && mode != 1) {
    mode = -1;  // Set the mode to -1 for standby mode
    showNumber(0);
  }
  
  if (buttonState != lastButtonState) {
    if (buttonState == HIGH) {
      buttonPressTime = millis();
    }

    if (buttonState == LOW) {
      buttonReleaseTime = millis();
      pressDuration = (buttonReleaseTime - buttonPressTime) / 1000;

      if (pressDuration > 3) {
        mode = 0;
        showNumber(0);
      }
      else {
        mode++;
        switch (mode) {
          case -1:
            showNumber(0);
            break;
          case 0:
            showNumber(0);
            break;
          case 1:
            measureBlank();
            break;
          case 2:
            showNumber(0.1);
            sampleCount = 1;
            break;
          case 3:
            calculateAbsorbance();
            break;
          default:
            showNumber(sampleCount);
            sampleCount++;
            break;
        }
      }
      delay(100);
    }

    lastButtonState = buttonState;
  }

  if (mode == 3 || mode == 4 || mode > 4) {
    calculateAbsorbance();
    showNumber(absorbance);
  }
}