// ESP32 - Sensor Monitor → Firebase Dashboard + SIM800 SMS
// By: Muhmmad Ali

#include <WiFi.h>
#include <HTTPClient.h>
#include "DHT.h"

#define WIFI_SSID     "Wokwi-GUEST"
#define WIFI_PASSWORD ""
#define FIREBASE_URL  "https://sim800-controller-default-rtdb.firebaseio.com"
#define FIREBASE_AUTH "YUdjhcfUvLbp9s2ELz1x2wSx1iHhA1QnHAaQMzxw"
#define PHONE_NUMBER  "+923001234567"

#define DHT_PIN   4
#define DHT_TYPE  DHT22
#define PIR_PIN   26

#define TEMP_THRESHOLD   40.0
#define HUMID_THRESHOLD  80.0
#define ALERT_COOLDOWN   30000
#define FIREBASE_INTERVAL 1000  // Firebase every 1 second

DHT dht(DHT_PIN, DHT_TYPE);
HardwareSerial sim800(2);

unsigned long lastTempAlert   = 0;
unsigned long lastHumidAlert  = 0;
unsigned long lastMotionAlert = 0;
unsigned long lastFirebase    = 0;

void connectWiFi() {
  Serial.print("Connecting WiFi");
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  int tries = 0;
  while (WiFi.status() != WL_CONNECTED && tries < 20) {
    delay(300); Serial.print("."); tries++;
  }
  Serial.println(WiFi.status() == WL_CONNECTED ? "\n✅ WiFi OK" : "\n❌ Failed");
}

void initSIM800() {
  sim800.begin(9600, SERIAL_8N1, 16, 17);
  delay(500);
  sim800.println("AT");        delay(300);
  sim800.println("AT+CMGF=1"); delay(300);
  Serial.println("✅ SIM800 Ready");
}

void sendSMS(String msg) {
  sim800.println("AT+CMGS=\"" + String(PHONE_NUMBER) + "\"");
  delay(500);
  sim800.print(msg);
  sim800.write(26);
  delay(2000);
  Serial.println("✅ SMS: " + msg);
}

void sendToFirebase(float temp, float humid, bool motion) {
  if (WiFi.status() != WL_CONNECTED) { connectWiFi(); return; }
  HTTPClient http;
  http.setReuse(true); // Keep connection alive = faster!
  http.begin(String(FIREBASE_URL) + "/sensors.json?auth=" + FIREBASE_AUTH);
  http.addHeader("Content-Type", "application/json");
  String body = "{\"temperature\":" + String(temp, 1) +
                ",\"humidity\":"    + String(humid, 1) +
                ",\"motion\":"      + String(motion ? "true" : "false") +
                ",\"timestamp\":"   + String(millis()) + "}";
  int code = http.PUT(body);
  Serial.println(code == 200 ? "✅ Firebase OK" : "❌ " + String(code));
  http.end();
}

void logAlert(String sensor, String message) {
  if (WiFi.status() != WL_CONNECTED) return;
  HTTPClient http;
  http.begin(String(FIREBASE_URL) + "/sensorAlerts.json?auth=" + FIREBASE_AUTH);
  http.addHeader("Content-Type", "application/json");
  http.POST("{\"sensor\":\"" + sensor + "\",\"message\":\"" + message + "\",\"timestamp\":" + String(millis()) + "}");
  http.end();
}

void checkAlert(bool condition, unsigned long &last, String sensor, String sms) {
  if (condition && millis() - last > ALERT_COOLDOWN) {
    last = millis();
    sendSMS(sms);
    logAlert(sensor, sms);
    Serial.println("🚨 " + sensor);
  }
}

void setup() {
  Serial.begin(115200);
  Serial.println("=== Sensor Monitor ===");
  pinMode(PIR_PIN, INPUT);
  dht.begin();
  initSIM800();
  connectWiFi();
  Serial.println("✅ Ready!");
}

void loop() {
  if (WiFi.status() != WL_CONNECTED) connectWiFi();

  float temp  = dht.readTemperature();
  float humid = dht.readHumidity();
  bool  motion = digitalRead(PIR_PIN) == HIGH;

  if (isnan(temp) || isnan(humid)) { delay(200); return; }

  Serial.printf("🌡️ %.1f°C | 💧 %.1f%% | 🚶 %s\n", temp, humid, motion ? "YES" : "NO");

  // Firebase every 1 second
  if (millis() - lastFirebase >= FIREBASE_INTERVAL) {
    lastFirebase = millis();
    sendToFirebase(temp, humid, motion);
  }

  // Alerts
  checkAlert(temp > TEMP_THRESHOLD,   lastTempAlert,   "Temperature", "ALERT: High Temp! " + String(temp,1) + "C");
  checkAlert(humid > HUMID_THRESHOLD, lastHumidAlert,  "Humidity",    "ALERT: High Humidity! " + String(humid,1) + "%");
  checkAlert(motion,                  lastMotionAlert, "Motion",      "ALERT: Motion detected!");

  delay(100);
}