#include <WiFi.h>
#include "time.h"
#include <PubSubClient.h>
#include<WiFiClient.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 20, 4);

WiFiClient espclient;
PubSubClient client(espclient);
const char* broker = "test.mosquitto.org";
int port = 1883;


const char* ntpServer1 = "pool.ntp.org";
const char* time_zone = "IST-5:30";
String timestamp;

unsigned long startTime = 0; // Start time of the countdown
unsigned long countdownDuration = 0; // Countdown duration in milliseconds

const char *resetClockTopic = "sanu/resetClock";
const char *setTimerTopic = "sanu/setTimer";
const char *resetTimerTopic = "sanu/resetTimer";
const char *stopTimerTopic = "sanu/stopTimer";
const char *pauseTimerTopic = "sanu/pauseTimer";
const char *startTimerTopic = "sanu/startTimer";

bool timerRunning = false;

#define buzzer 15

unsigned int pauseInstance = 0;
unsigned int startInstance = 0;
unsigned int pauseDuration = 0;

void setup()
{
  Serial.begin(115200);
  pinMode(buzzer, OUTPUT);
  // configTzTime(time_zone, ntpServer1);
  lcd.init();
  lcd.backlight();

  //connect to WiFi

  Serial.print("Connecting to WiFi");
  WiFi.begin("Wokwi-GUEST", "", 6);
  while (WiFi.status() != WL_CONNECTED) {
    delay(100);
    Serial.print(".");
  }
  Serial.println(" Connected!");

  configTzTime(time_zone, ntpServer1);

  client.setServer(broker, port);
  if (  client.connect("timer13")) {
    Serial.println("mqtt connected");
  }
  client.setCallback(callback);

  client.subscribe(resetClockTopic);
  client.subscribe(setTimerTopic);
  client.subscribe(resetTimerTopic);
  client.subscribe(stopTimerTopic);
  client.subscribe(pauseTimerTopic);
  client.subscribe(startTimerTopic);

}

void loop()
{
  delay(1000);
  printLocalTime();
  client.loop();
  if (timerRunning) {
    updateTimer();
  }
  // client.publish("sanu/ist", timestamp.c_str());//working
  configTzTime(time_zone, ntpServer1);
}

void printLocalTime()
{
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) {
    Serial.println("No time available (yet)");
    lcd.setCursor(0, 0);
    lcd.print("Please wait...");
    return;
  }
  char printBuffer[100];
  sprintf(printBuffer, "Year %d, Month %d, Day %d, Hour %d, Min %d, Sec %d",
          timeinfo.tm_year + 1900, timeinfo.tm_mon + 1, timeinfo.tm_mday,
          timeinfo.tm_hour, timeinfo.tm_min, timeinfo.tm_sec);
  // Serial.println(printBuffer);
  strftime(printBuffer, 100, "%A, %B %d %Y %H:%M:%S", &timeinfo);
  // Serial.println(printBuffer);

  timestamp = String(timeinfo.tm_year + 1900) + "-" + String(timeinfo.tm_mon + 1) + "-" + String(timeinfo.tm_mday) + ":" + String(timeinfo.tm_hour) + "-" + String(timeinfo.tm_min) + "-" + String(timeinfo.tm_sec);
  // Serial.println(timestamp);

  // lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(String(timeinfo.tm_hour) + ":" + String(timeinfo.tm_min)+ ":" + String(timeinfo.tm_sec)  + "  " + String(timeinfo.tm_mday) + "/"  + String(timeinfo.tm_mon + 1) + "/"  + String((timeinfo.tm_year + 1900) - 2000));
}


void callback(char *topic, byte *payload, unsigned int length) {
  // Serial.println("Inside callback...");
  // Serial.print("Message arrived on topic [");
  // Serial.print(topic);
  // Serial.print("] Payload: ");

  // for (int i = 0; i < length; i++) {
  //   Serial.print((char)payload[i]);
  // }
  Serial.println();

  String message;
  for (int i = 0; i < length; i++) {
    message += (char)payload[i];
  }

  if (String(topic) == resetClockTopic) {
    if (message == "reset") {
      Serial.println("Resetting ESP32...");
      lcd.clear();
      delay(1000);
      ESP.restart();  // Perform a software reset
    }
  }
  else if (String(topic) == setTimerTopic) {
    unsigned long newDuration = message.toInt();
    if (newDuration > 0) {
      countdownDuration = newDuration;
      startTime = millis();
      timerRunning = true;
      lcd.clear();
      lcd.setCursor(0, 3);
      lcd.print("Exam Started...");
      // Serial.println("Timer set for " + String(countdownDuration) + " milliseconds");
    }
  }
  else if (String(topic) == resetTimerTopic) {

    if (message == "reset") {
      lcd.setCursor(0, 1);
      lcd.print("CD:");
      lcd.print("00");
      lcd.print(":");
      lcd.print("00");
      lcd.print(":");
      lcd.print("00");
      timerRunning = false;
      lcd.setCursor(0, 3);
      lcd.print("Timer reseted.......");
    }
  }

  else if (String(topic) == pauseTimerTopic) {
    if (message == "pause") {
      pauseInstance = 0;
      pauseDuration = 0;
      timerRunning = false;
      pauseInstance = millis();
    }
  }
  else if (String(topic) == startTimerTopic) {
    if (message == "start") {
      startInstance = 0;
      startInstance = millis();
      pauseDuration = startInstance - pauseInstance;
      timerRunning = true;      
    }
  }
}

void updateTimer() {
  unsigned long elapsedTime = millis() - startTime;
  long remainingTime = countdownDuration - elapsedTime + pauseDuration;  

  if (remainingTime <= 0) {
    // Timer expired
    timerRunning = false;
    lcd.setCursor(0, 3);
    lcd.print("Time UP.........");
    for (int i = 0; i < 5; i++) {
      digitalWrite(buzzer, HIGH);
      delay(500);
      digitalWrite(buzzer, LOW);
      delay(500);
    }
    // pauseDuration = 0;
  }
  else {
    // Display remaining time on LCD
    int seconds1 = remainingTime / 1000;
    int minutes1 = seconds1 / 60;
    int hours1 = minutes1 / 60;
    minutes1 = minutes1 % 60;
    seconds1 = seconds1 % 60;
    lcd.setCursor(0, 1);
    lcd.print("CD:");
    lcd.print(hours1);
    lcd.print(":");
    lcd.print(minutes1);
    lcd.print(":");
    if (seconds1 < 10) {
      lcd.print("0");
    }
    lcd.print(seconds1);
  }
}