/*************************************************
   MULTI SENSOR SYSTEM – ESP32 (OFFLINE VERSION)
   WiFi & Blynk REMOVED
   Each sensor coded in separate logical blocks
**************************************************/

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#include <ESP32Servo.h>

/* ---------- LCD I2C SETUP ---------- */
#define SDA_PIN 25
#define SCL_PIN 26
LiquidCrystal_I2C lcd(0x27, 16, 2);

/* ---------- DHT22 SENSOR ---------- */
#define DHTPIN 15
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

/* ---------- SERVO MOTOR ---------- */
Servo tempServo;
#define SERVO_PIN 5

/* ---------- ULTRASONIC SENSOR ---------- */
#define TRIG 18
#define ECHO 19
#define ULTRASONIC_LED 23

/* ---------- LDR SENSOR ---------- */
#define LDRPIN 34
#define LDR_LED 22

/* ---------- GAS SENSOR ---------- */
#define GASPIN 35
#define GAS_BUZZER 21
#define GAS_THRESHOLD 400

/* ---------- PIR SENSOR ---------- */
#define PIRPIN 32
#define PIR_RELAY 33

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

  /* ---------- LCD INITIALIZATION ---------- */
  Wire.begin(SDA_PIN, SCL_PIN);
  lcd.init();
  lcd.backlight();

  /* ---------- DHT SENSOR ---------- */
  dht.begin();

  /* ---------- SERVO SETUP ---------- */
  ESP32PWM::allocateTimer(0);
  tempServo.setPeriodHertz(50);       // Standard servo frequency
  tempServo.attach(SERVO_PIN, 500, 2400);

  /* ---------- PIN MODES ---------- */
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  pinMode(ULTRASONIC_LED, OUTPUT);

  pinMode(LDR_LED, OUTPUT);

  pinMode(GAS_BUZZER, OUTPUT);

  pinMode(PIRPIN, INPUT);
  pinMode(PIR_RELAY, OUTPUT);

  Serial.println("Multi Sensor System Started...");
}

void loop() {

  /* =================================================
     1. DHT22 SENSOR + SERVO CONTROL
     Temperature controls servo angle
  ================================================= */
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  if (!isnan(temperature)) {
    int angle = map(temperature, 20, 40, 0, 180);
    angle = constrain(angle, 0, 180);
    tempServo.write(angle);   // Rotate servo
  }

  /* =================================================
     2. ULTRASONIC SENSOR
     Object detection with LED indication
  ================================================= */
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

  long duration = pulseIn(ECHO, HIGH);
  float distance = duration * 0.034 / 2;

  if (distance < 20)
    digitalWrite(ULTRASONIC_LED, HIGH);
  else
    digitalWrite(ULTRASONIC_LED, LOW);

  /* =================================================
     3. LDR SENSOR
     Light-based LED control
  ================================================= */
  int lightValue = analogRead(LDRPIN);

  if (lightValue < 2000)
    digitalWrite(LDR_LED, HIGH);
  else
    digitalWrite(LDR_LED, LOW);

  /* =================================================
     4. GAS SENSOR
     Gas leakage alert using buzzer
  ================================================= */
  int gasValue = analogRead(GASPIN);

  if (gasValue > GAS_THRESHOLD)
    digitalWrite(GAS_BUZZER, HIGH);
  else
    digitalWrite(GAS_BUZZER, LOW);

  /* =================================================
     5. PIR SENSOR
     Motion detection using relay
  ================================================= */
  int motion = digitalRead(PIRPIN);

  if (motion == HIGH)
    digitalWrite(PIR_RELAY, HIGH);
  else
    digitalWrite(PIR_RELAY, LOW);

  /* =================================================
     6. LCD DISPLAY
     Display sensor values
  ================================================= */
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("T:");
  lcd.print(temperature, 1);
  lcd.print(" H:");
  lcd.print(humidity, 0);

  lcd.setCursor(0, 1);
  lcd.print("L:");
  lcd.print(lightValue);
  lcd.print(" D:");
  lcd.print(distance, 0);
  lcd.print("cm");

  /* =================================================
     7. SERIAL MONITOR OUTPUT
  ================================================= */
  Serial.print("Temp: "); Serial.print(temperature);
  Serial.print("C | Hum: "); Serial.print(humidity);
  Serial.print("% | Light: "); Serial.print(lightValue);
  Serial.print(" | Distance: "); Serial.print(distance);
  Serial.print("cm | Gas: "); Serial.print(gasValue);
  Serial.print(" | Motion: "); Serial.println(motion);

  delay(2000);  // Delay for stable readings
}