/*
 *  Erik Hansen
 *  April 2, 2023
 *  Lab 6 Project
 */

// include the library code:
#include <LiquidCrystal.h>

// Declaration
LiquidCrystal lcd(12, 11, 10, 9, 8, 7); // LCD Pins (7-10 = Data 4-7, 11-12 = Enable/Read)

// Values/Variables
unsigned long displaySec = 59; // Seconds
unsigned long displayMin = 0; // Minutes
unsigned long prevMillis = 0;
unsigned long currMillis = 0;
unsigned long elapsedMillis = 0;

void setup() {
  // Set up LCD (rows/columns)
  lcd.begin(16, 2);
  digitalWrite(LED_BUILTIN, LOW); // turn off the LED
}


void loop() {
  // Countdown display
  currMillis = millis();
  elapsedMillis = currMillis - prevMillis;

  // Countdown
  if (elapsedMillis >= 1000) {
    prevMillis = currMillis;
    displaySec--;

    // Check when 0 seconds remain
    if (displaySec == 0) {
      displaySec = 59;

      // Check if 0 minutes remain
      if (displayMin == 0) {
        displayMin = 2;
        displaySec = 59;
      }
      displayMin--;
    }

    // Check if the countdown has reached 0:00
    if (displayMin == 0 && displaySec == 0) {
      digitalWrite(LED_BUILTIN, HIGH);
      while (true) {} // Enter an infinite loop
    }
      
      // LCD print
      // Countdown in millis (Line 1)
      lcd.setCursor(0, 0);
      lcd.print((displayMin * 60 + displaySec) * 1000);

      // Countdown in seconds (Line 2)
      lcd.setCursor(0, 1);
      lcd.print(displayMin);
      lcd.print(":");
      if (displaySec < 10) {
        lcd.print("0"); // add a leading zero if necessary
      }
      lcd.print(displaySec);
  }
}