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

// Pin definitions
#define DHTPIN1 2
#define DHTPIN2 3
#define BUTTON_PIN 4
#define BUZZER_PIN 5

// Constants
#define DHTTYPE DHT22
#define TEMP_THRESHOLD_C 30.0
#define TEMP_THRESHOLD_F 86.0

// Create DHT objects
DHT dht1(DHTPIN1, DHTTYPE);
DHT dht2(DHTPIN2, DHTTYPE);

// LCD object: 20x4 display at I2C address 0x27
LiquidCrystal_I2C lcd(0x27, 20, 4);

// Variables
bool useFahrenheit = false;
bool lastButtonState = HIGH;
unsigned long lastDebounceTime = 0;
const unsigned long debounceDelay = 50;

void setup() {
  Serial.begin(9600);

  dht1.begin();
  dht2.begin();

  lcd.init();
  lcd.backlight();

  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);

  lcd.setCursor(0, 0);
  lcd.print("Temp Monitor Ready");
  delay(2000);
  lcd.clear();
}

void loop() {
  // --- BUTTON LOGIC (Toggle between C/F) ---
  bool reading = digitalRead(BUTTON_PIN);
  if (reading != lastButtonState) {
    lastDebounceTime = millis();
  }
  if ((millis() - lastDebounceTime) > debounceDelay) {
    if (reading == LOW && lastButtonState == HIGH) {
      useFahrenheit = !useFahrenheit;
    }
  }
  lastButtonState = reading;

  // --- READ SENSORS ---
  float temp1 = dht1.readTemperature();
  float humid1 = dht1.readHumidity();
  float temp2 = dht2.readTemperature();
  float humid2 = dht2.readHumidity();

  // Convert to Fahrenheit if needed
  float displayTemp1 = useFahrenheit ? (temp1 * 1.8 + 32) : temp1;
  float displayTemp2 = useFahrenheit ? (temp2 * 1.8 + 32) : temp2;
  float threshold = useFahrenheit ? TEMP_THRESHOLD_F : TEMP_THRESHOLD_C;

  // Calculate averages
  float avgTemp = (displayTemp1 + displayTemp2) / 2.0;
  float avgHumid = (humid1 + humid2) / 2.0;

  // --- DISPLAY ON LCD ---
  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("T1:");
  lcd.print(isnan(displayTemp1) ? "Err" : String(displayTemp1, 1));
  lcd.print(useFahrenheit ? "F " : "C ");
  lcd.print("H1:");
  lcd.print(isnan(humid1) ? "Err" : String(humid1, 1));
  lcd.print("%");

  lcd.setCursor(0, 1);
  lcd.print("T2:");
  lcd.print(isnan(displayTemp2) ? "Err" : String(displayTemp2, 1));
  lcd.print(useFahrenheit ? "F " : "C ");
  lcd.print("H2:");
  lcd.print(isnan(humid2) ? "Err" : String(humid2, 1));
  lcd.print("%");

  lcd.setCursor(0, 2);
  lcd.print("AVG T:");
  lcd.print((isnan(avgTemp) ? "Err" : String(avgTemp, 1)));
  lcd.print(useFahrenheit ? "F " : "C ");
  lcd.print("H:");
  lcd.print((isnan(avgHumid) ? "Err" : String(avgHumid, 1)));
  lcd.print("%");

  // --- BUZZER LOGIC ---
  if (!isnan(avgTemp) && avgTemp > threshold) {
    tone(BUZZER_PIN, 1000);  // sound buzzer
  } else {
    noTone(BUZZER_PIN);
  }

  delay(1000);
}