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

// ======== Pins ========
#define DHTPIN A0
#define DHTTYPE DHT22

#define GAS_DIGITAL_PIN 2    // DO du capteur de gaz
#define LDR_DIGITAL_PIN 3     // DO du module photoresistor
#define PIR_PIN 9             // OUT du PIR

#define LED_VERT 12
#define LED_JAUNE 11
#define LED_ROUGE 10
#define BUZZER 13

// ======== Objets ========
DHT dht(DHTPIN, DHTTYPE);
LiquidCrystal_I2C lcd(0x27, 16, 2); // si ne marche pas, essayer 0x3F

unsigned long lastChange = 0;
int page = 0;

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

  dht.begin();

  pinMode(GAS_DIGITAL_PIN, INPUT);
  pinMode(LDR_DIGITAL_PIN, INPUT);
  pinMode(PIR_PIN, INPUT);

  pinMode(LED_VERT, OUTPUT);
  pinMode(LED_JAUNE, OUTPUT);
  pinMode(LED_ROUGE, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  digitalWrite(LED_VERT, LOW);
  digitalWrite(LED_JAUNE, LOW);
  digitalWrite(LED_ROUGE, LOW);
  digitalWrite(BUZZER, LOW);

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

  lcd.setCursor(0, 0);
  lcd.print("Systeme pret");
  lcd.setCursor(0, 1);
  lcd.print("Mode digital");
  delay(2000);
  lcd.clear();
}

void loop() {
  // ======== Lecture ========
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  int gasState = digitalRead(GAS_DIGITAL_PIN);   // 0 ou 1
  int ldrState = digitalRead(LDR_DIGITAL_PIN);   // 0 ou 1
  int pirState = digitalRead(PIR_PIN);           // 0 ou 1

  // souvent modules DO:
  // LOW = détection
  // HIGH = pas de détection
  bool gazDetected = (gasState == LOW);
  bool darkDetected = (ldrState == LOW);
  bool motionDetected = (pirState == HIGH);

  if (isnan(temperature) || isnan(humidity)) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Erreur DHT22");
    lcd.setCursor(0, 1);
    lcd.print("Verifier module");
    delay(1000);
    return;
  }

  // ======== Logique ========
  String etat = "NORMAL";

  if (gazDetected) {
    etat = "DANGER GAZ";
  }
  else if (motionDetected || darkDetected || temperature > 35) {
    etat = "ALERTE";
  }
  else {
    etat = "NORMAL";
  }

  // ======== LEDs + buzzer ========
  if (etat == "NORMAL") {
    digitalWrite(LED_VERT, HIGH);
    digitalWrite(LED_JAUNE, LOW);
    digitalWrite(LED_ROUGE, LOW);
    digitalWrite(BUZZER, LOW);
  }
  else if (etat == "ALERTE") {
    digitalWrite(LED_VERT, LOW);
    digitalWrite(LED_JAUNE, HIGH);
    digitalWrite(LED_ROUGE, LOW);

    digitalWrite(BUZZER, HIGH);
    delay(100);
    digitalWrite(BUZZER, LOW);
  }
  else if (etat == "DANGER GAZ") {
    digitalWrite(LED_VERT, LOW);
    digitalWrite(LED_JAUNE, LOW);
    digitalWrite(LED_ROUGE, HIGH);

    digitalWrite(BUZZER, HIGH);
    delay(300);
    digitalWrite(BUZZER, LOW);
    delay(200);
  }

  // ======== LCD pages ========
  if (millis() - lastChange > 2000) {
    lastChange = millis();
    page++;
    if (page > 2) page = 0;
  }

  lcd.clear();

  if (page == 0) {
    lcd.setCursor(0, 0);
    lcd.print("T:");
    lcd.print(temperature, 1);
    lcd.print((char)223);
    lcd.print("C");

    lcd.setCursor(0, 1);
    lcd.print("H:");
    lcd.print(humidity, 0);
    lcd.print("% ");
    lcd.print(etat);
  }
  else if (page == 1) {
    lcd.setCursor(0, 0);
    lcd.print("Gaz:");
    lcd.print(gazDetected ? "OUI" : "NON");

    lcd.setCursor(0, 1);
    lcd.print("Mvt:");
    lcd.print(motionDetected ? "OUI" : "NON");
  }
  else if (page == 2) {
    lcd.setCursor(0, 0);
    lcd.print("Lum:");
    lcd.print(darkDetected ? "SOMBRE" : "CLAIR");

    lcd.setCursor(0, 1);
    lcd.print("Etat:");
    lcd.print(etat);
  }

  // ======== Serial ========
  Serial.print("Temp=");
  Serial.print(temperature);
  Serial.print(" Hum=");
  Serial.print(humidity);
  Serial.print(" Gaz=");
  Serial.print(gazDetected);
  Serial.print(" PIR=");
  Serial.print(motionDetected);
  Serial.print(" LDR=");
  Serial.print(darkDetected);
  Serial.print(" Etat=");
  Serial.println(etat);

  delay(500);
}