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

LiquidCrystal_I2C lcd(0x27, 20, 4);  // LCD 20x4, address 0x27

// Pins
const int COIN_PIN = 27;   // Pushbutton as coin slot
const int RELAY_PIN = 26;  // Relay to turn ON/OFF PC

// Config
const int SECONDS_PER_PESO = 180; // 1 peso = 3 min = 180s
const int PREPARE_SECONDS = 10;   // 10s before play starts

// Variables
volatile int credits = 0;
unsigned long totalSeconds = 0;
bool playing = false;
unsigned long lastCoinTime = 0;

void IRAM_ATTR coinInserted() {
  credits++;
  totalSeconds += SECONDS_PER_PESO;
  lastCoinTime = millis();
}

void setup() {
  Serial.begin(115200);

  pinMode(COIN_PIN, INPUT_PULLUP);
  pinMode(RELAY_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, LOW);

  attachInterrupt(digitalPinToInterrupt(COIN_PIN), coinInserted, FALLING);

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0,0); lcd.print("   PISONET V1.0");
  lcd.setCursor(0,1); lcd.print("  Insert Coins...");
  delay(2000);
  lcd.clear();
}

void loop() {
  unsigned long now = millis();

  if (!playing) {
    lcd.setCursor(0,0); lcd.print("Insert Coins     ");
    lcd.setCursor(0,1); lcd.print("Credits: ");
    lcd.print(credits);

    if (credits > 0 && (now - lastCoinTime > PREPARE_SECONDS * 1000)) {
      playing = true;
      digitalWrite(RELAY_PIN, HIGH); // turn ON load/PC
      lcd.clear();
    }
  } else {
    if (totalSeconds > 0) {
      totalSeconds--;
      showTime(totalSeconds);
      delay(1000);
    } else {
      // Time up
      digitalWrite(RELAY_PIN, LOW);
      credits = 0;
      playing = false;
      lcd.clear();
      lcd.setCursor(0,0); lcd.print("Time Finished!");
      delay(2000);
      lcd.clear();
    }
  }
}

void showTime(unsigned long sec) {
  int hours = sec / 3600;
  int mins = (sec % 3600) / 60;
  int secs = sec % 60;

  lcd.setCursor(0,0); lcd.print("Time Remaining:   ");
  lcd.setCursor(0,1);
  if (hours > 0) {
    lcd.print(hours); lcd.print("h ");
  }
  lcd.print(mins); lcd.print("m ");
  lcd.print(secs); lcd.print("s  ");
}