// ============================================================
//  SMART WEATHER STATION + AUTO VENTILATION
//  Arduino UNO | Wokwi Simulation | MakeMindz Summer Course
// ============================================================

#include <DHT.h>               // Temperature & humidity sensor library
#include <Wire.h>              // I2C communication (for LCD)
#include <LiquidCrystal_I2C.h>  // LCD display control
#include <Servo.h>             // Servo motor control

// ── Pin definitions ──────────────────────────
#define DHT_PIN     7    // DHT22 data wire
#define DHT_TYPE    DHT22
#define SERVO_PIN   9    // Servo PWM signal (~pin)
#define LED_GREEN   2    // Green status LED
#define LED_YELLOW  3    // Yellow status LED
#define LED_RED     4    // Red alarm LED
#define BUZZER_PIN  5    // Buzzer
#define BTN_PIN     6    // Push button for LCD screens

// ── Library objects ──────────────────────────
DHT              dht(DHT_PIN, DHT_TYPE);
LiquidCrystal_I2C lcd(0x27, 16, 2);   // LCD at I2C address 0x27
Servo            ventServo;

// ── State variables ──────────────────────────
float tempC     = 0, humidity = 0, heatIndex = 0;
int   ventAngle = 0, screen = 0;
bool  alarmOn   = false, blinkState = false, prevBtn = HIGH;
unsigned long lastRead = 0, lastBlink = 0, lastBuzz = 0, dbBtn = 0;
void setup() {
  dht.begin();
  lcd.init();
  lcd.backlight();

  ventServo.attach(SERVO_PIN);
  ventServo.write(0);          // Start with vent fully CLOSED

  pinMode(LED_GREEN,  OUTPUT);
  pinMode(LED_YELLOW, OUTPUT);
  pinMode(LED_RED,    OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BTN_PIN, INPUT_PULLUP); // Uses internal pull-up resistor

  // Splash screen for 1.8 seconds
  lcd.setCursor(2, 0); lcd.print("WeatherStation");
  lcd.setCursor(3, 1); lcd.print("Auto Vent v1");
  delay(1800);
  lcd.clear();

  // Boot LED test — light each LED one by one
  digitalWrite(LED_GREEN,  HIGH); delay(200);
  digitalWrite(LED_YELLOW, HIGH); delay(200);
  digitalWrite(LED_RED,    HIGH); delay(200);
  digitalWrite(LED_GREEN,  LOW);
  digitalWrite(LED_YELLOW, LOW);
  digitalWrite(LED_RED,    LOW);
}
void loop() {
  unsigned long now = millis();

  // ── Read sensor every 2 seconds (non-blocking) ──
  if (now - lastRead >= 2000) {
    lastRead = now;
    float t = dht.readTemperature();
    float h = dht.readHumidity();

    if (!isnan(t) && !isnan(h)) {
      tempC = t; humidity = h;
      heatIndex = dht.computeHeatIndex(t, h, false);
    }

    // ── Smooth servo movement (5° per step) ──
    int targetAngle = tempToVent(tempC);
    if (ventAngle < targetAngle)      ventAngle = min(ventAngle + 5, targetAngle);
    else if (ventAngle > targetAngle)  ventAngle = max(ventAngle - 5, targetAngle);
    ventServo.write(ventAngle);

    // ── Update LEDs ──
    if (tempC < 28) {
      digitalWrite(LED_GREEN, HIGH); digitalWrite(LED_YELLOW, LOW); digitalWrite(LED_RED, LOW);
      alarmOn = false;
    } else if (tempC < 35) {
      digitalWrite(LED_GREEN, LOW); digitalWrite(LED_YELLOW, HIGH); digitalWrite(LED_RED, LOW);
      alarmOn = false;
    } else {
      digitalWrite(LED_GREEN, LOW); digitalWrite(LED_YELLOW, LOW);
      alarmOn = true;
    }

    // ── Refresh LCD ──
    lcd.clear();
    switch (screen) {
      case 0: showScreenTemp();    break;
      case 1: showScreenHeatIdx(); break;
      case 2: showScreenVent();    break;
    }
  }

  // ── Blink red LED every 300ms when alarm ──
  if (alarmOn && now - lastBlink >= 300) {
    lastBlink = now; blinkState = !blinkState;
    digitalWrite(LED_RED, blinkState ? HIGH : LOW);
  }

  // ── Sound buzzer every 800ms when alarm ──
  if (alarmOn && now - lastBuzz >= 800) {
    lastBuzz = now;
    tone(BUZZER_PIN, 1200, 120);   // 1200Hz for 120ms
  }

  // ── Button: cycle LCD screens with debounce ──
  bool btn = digitalRead(BTN_PIN);
  if (prevBtn == HIGH && btn == LOW && now - dbBtn > 200) {
    screen = (screen + 1) % 3;   // Cycle: 0 → 1 → 2 → 0
    dbBtn = now; lcd.clear();
  }
  prevBtn = btn;
  delay(20);
}
// Maps temperature to vent angle using proportional control
int tempToVent(float t) {
  if (t < 25.0)  return 0;                                            // Cool → CLOSED
  if (t < 30.0)  return map(t*10, 250, 300, 0,  60);  // Warm → partial
  if (t < 38.0)  return map(t*10, 300, 380, 60, 160); // Hot  → wide open
  return 170;                                                           // Critical → FULLY open
}

// Screen 0: Temperature + Humidity bar
void showScreenTemp() {
  lcd.setCursor(0, 0); lcd.print("Temp: "); lcd.print(tempC, 1); lcd.print("\xDFC");
  lcd.setCursor(0, 1); lcd.print("Hum: ");  lcd.print((int)humidity); lcd.print("%");
}

// Screen 1: Heat Index + comfort level
void showScreenHeatIdx() {
  lcd.setCursor(0, 0); lcd.print("Heat Index:");
  lcd.setCursor(0, 1);
  if      (heatIndex < 27) lcd.print("Comfort  ");
  else if (heatIndex < 32) lcd.print("Caution  ");
  else if (heatIndex < 41) lcd.print("Warning! ");
  else                     lcd.print("DANGER!! ");
  lcd.print(heatIndex, 1); lcd.print("\xDFC");
}

// Screen 2: Vent status + progress bar
void showScreenVent() {
  int pct = map(ventAngle, 0, 170, 0, 100);
  lcd.setCursor(0, 0); lcd.print("Vent: "); lcd.print(pct); lcd.print("%   ");
  lcd.setCursor(0, 1); lcd.print("[");
  for (int i = 0; i < 12; i++) lcd.print(i < pct/9 ? "#" : "-");
  lcd.print("]");
}