/*
  Forum: https://forum.arduino.cc/t/countdown-timer/1440331
  Wokwi: https://wokwi.com/projects/461542314286743553

  Based on
  https://github.com/untr0py/SevSeg/tree/master/examples/SevSeg_Counter

  ec2021
  2026/04/17

  Starts to count down from 2 minutes (120 seconds) when green button pressed
  During countdown mode the red button can be pressed at any time to reset the counter
  The counter value is converted into minutes and seconds for display
  The decimal point is (mis-)used to indicate where minutes are displayed to the right and seconds to the left
  A minimum countdown value of - 10 minutes = -600 sec has been defined to take care of the displayable numbers
  If this minimum values has been reached or at any lower number the display will show "--.--"

*/

#include "SevSeg.h"

class BtnClass {
  private:
    byte pin;
    byte state;
    byte lastState;
    unsigned long lastChange;
  public:
    init(byte p) {
      pin = p;
      pinMode(pin, INPUT_PULLUP);
    };
    boolean pressed() {
      byte actState = digitalRead(pin);
      if (actState != lastState) {
        lastChange = millis();
        lastState = actState;
      };
      if (actState != state && millis() - lastChange > 30) {  // Fixed debounce time 30 ms
        state = actState;
        return !state;
      }
      return false;
    };
};

constexpr byte numOfDigits = 4;
constexpr byte digitPins[] = {2, 3, 4, 5};
constexpr byte segmentPins[] = {6, 7, 8, 9, 10, 11, 12, 13};
constexpr bool resistorsOnSegments = false; // 'false' means resistors are on digit pins
constexpr byte hardwareConfig = COMMON_ANODE; // See README.md at GitHub (link see above)for options
constexpr bool updateWithDelays = false; // Default 'false' is Recommended
constexpr bool leadingZeros = true; // Use 'true' if you'd like to keep the leading zeros
constexpr bool disableDecPoint = false; // Use 'true' if your decimal point doesn't exist or isn't connected

constexpr byte startPin {A1};
constexpr byte resetPin  {A0};
constexpr int startCount {120};  // 2 minutes in seconds = 120
constexpr int  minCount {- 600}; // in seconds = - (10 minutes ) = - 600
constexpr unsigned long countDownInterval {1000}; // in ms, can be changed for test purposes (e.g. to 500 ms or 200 ms ...)


enum class MODE {IDLE, COUNTDOWN, RESET};
MODE mode = MODE::IDLE;

SevSeg sevseg;

BtnClass startBtn;
BtnClass resetBtn;

unsigned long lastChange = 0;
int combinedTime = 200;
int counter;

void setup() {
  sevseg.begin(hardwareConfig, numOfDigits, digitPins, segmentPins, resistorsOnSegments,
               updateWithDelays, leadingZeros, disableDecPoint);
  sevseg.setBrightness(90);
  startBtn.init(startPin);
  resetBtn.init(resetPin);
  resetCounter();
}

void loop() {
  countDownMachine();
  sevseg.refreshDisplay(); // Must run repeatedly
}

void countDownMachine() {
  switch (mode) {
    case MODE::IDLE:
      if (startBtn.pressed()) {
        mode = MODE::COUNTDOWN;
        lastChange = millis(); // the first second starts with the
      }
      break;
    case MODE::COUNTDOWN:
      countDown();
      // The btnClass makes sure that you have to release a button before a next
      // pressed() event can become true
      // Therefore you can use the startBtn here also to reset the counter
      // To do this uncomment the following line
      //if (startBtn.pressed()) {
      // and comment this line:
      if (resetBtn.pressed()) {
        mode = MODE::RESET;
      }
      break;
    case MODE::RESET:
      resetCounter();
      mode = MODE::IDLE;
      break;
  }
}

void resetCounter() {
  counter = startCount;
  setTimer();
  mode = MODE::IDLE;
}

void countDown() {
  if (millis() - lastChange >= countDownInterval && counter > minCount) {
    lastChange = millis();
    counter--;
  }
  setTimer();
}

void setTimer() {
  int minutes = counter / 60;
  int seconds = counter - minutes * 60;
  int combinedTime = minutes * 100 + seconds;
  sevseg.setNumber(combinedTime, 2);
}