/**
 * ESP32 Firebase Sensor Monitoring System
 * 
 * This script collects data from DHT sensor (temperature and humidity)
 * and a photoresistor (light intensity), then uploads it to Firebase
 * Realtime Database.
 * 
 * Libraries required:
 * - WiFiManager by tzapu (https://github.com/tzapu/WiFiManager)
 * - Firebase-ESP32 by mobizt (https://github.com/mobizt/Firebase-ESP32)
 * - DHT sensor library by Adafruit
 */

#include <WiFiManager.h>         // WiFiManager library for easy network configuration
#include <FirebaseESP32.h>       // Firebase ESP32 client library
#include <DHT.h>                 // DHT sensor library
#include <addons/TokenHelper.h>  // Firebase token generation helper
#include <addons/RTDBHelper.h>   // Firebase RTDB helper

// Firebase credentials - Get these from Firebase Console
#define API_KEY "AIzaSyAJpYEXlwTjMOIAueqqDiti49PKRnsXAns"                                             // Project settings -> General -> Your apps -> Web API Key
#define DATABASE_URL "https://projectstrata-57a90-default-rtdb.asia-southeast1.firebasedatabase.app"  // e.g. "https://your-project-id-default-rtdb.firebasedatabase.app/"

// User Email and Password for Firebase Authentication
// Create this user in Firebase Console -> Authentication -> Users
#define USER_EMAIL "device@projectstrata.com"
#define USER_PASSWORD "projectstrata"

// Sensor and button pin definitions
#define DHT_PIN 15        // Digital pin connected to the DHT sensor
#define LDR_PIN 34        // Analog pin connected to the LDR (photoresistor)
#define RESET_BTN_PIN 23  // Digital pin for WiFi reset button
#define DHT_TYPE DHT11    // DHT sensor type (DHT11, DHT22, etc.)

// Data upload interval (milliseconds)
#define UPLOAD_INTERVAL 5000
#define BUTTON_HOLD_TIME 5000

// Firebase objects
FirebaseData fbdo;
FirebaseAuth auth;
FirebaseConfig config;

// DHT sensor
DHT dht(DHT_PIN, DHT_TYPE);

// Global variables
unsigned long lastUploadTime = 0;
unsigned long buttonPressTime = 0;
String deviceId;
bool signupOK = false;
bool resetButtonPressed = false;

bool checkResetButton() {
  if (digitalRead(RESET_BTN_PIN) == LOW) {
    if (!resetButtonPressed) {
      resetButtonPressed = true;
      buttonPressTime = millis();
      // Serial.println("Hold to reset WiFi");
    }

    if (resetButtonPressed && (millis() - buttonPressTime >= BUTTON_HOLD_TIME)) {
      return true;
    }
  } else {
    if (resetButtonPressed) {
      resetButtonPressed = false;
    }
  }
  return false;
}

void setupWiFi() {
  WiFiManager wifiManager;

  if (checkResetButton()) {
    // Serial.println("Resetting WiFi settings");
    wifiManager.resetSettings();
  }

  String apName = "ProjectSTRATA - WiFiSetter";

  wifiManager.setConfigPortalTimeout(180);

  if (!wifiManager.autoConnect(apName.c_str())) {
    Serial.println("Failed to connect");
    ESP.restart();
  }

  // Serial.print("Connected: ");
  Serial.println(WiFi.localIP());

  deviceId = String((uint32_t)ESP.getEfuseMac(), HEX);
}

void setupFirebase() {
  config.api_key = API_KEY;
  config.database_url = DATABASE_URL;

  auth.user.email = USER_EMAIL;
  auth.user.password = USER_PASSWORD;

  config.token_status_callback = tokenStatusCallback;

  Firebase.begin(&config, &auth);

  if (Firebase.signUp(&config, &auth, USER_EMAIL, USER_PASSWORD)) {
    // Serial.println("Firebase sign up OK");
    signupOK = true;
  } else {
    Serial.printf("Sign up failed: %s\n", config.signer.signupError.message.c_str());
  }

  Firebase.reconnectWiFi(true);
}

bool readSensorData(float &temperature, float &humidity, int &light) {
  // Read temperature
  temperature = dht.readTemperature();
  if (isnan(temperature)) {
    return false;
  }

  // Read humidity
  humidity = dht.readHumidity();
  if (isnan(humidity)) {
    return false;
  }

  // Read light
  light = analogRead(LDR_PIN);

  Serial.printf("Temp: %.1f°C, Humidity: %.1f%%, Light: %d\n",
                temperature, humidity, light);

  return true;
}

void uploadToFirebase() {
  if (!signupOK || !Firebase.ready()) {
    // Serial.println("Firebase not ready");
    return;
  }

  float temperature, humidity;
  int lightIntensity;

  if (!readSensorData(temperature, humidity, lightIntensity)) {
    return;
  }

  unsigned long timestamp = millis();

  // Create JSON with minimal memory footprint
  FirebaseJson json;
  json.add("id", deviceId);
  json.add("ts", timestamp);
  json.add("temp", temperature);
  json.add("hum", humidity);
  json.add("light", lightIntensity);

  // Path to save data
  String path = "/sensor_data/" + deviceId + "/" + String(timestamp);

  if (Firebase.setJSON(fbdo, path, json)) {
    Serial.println("Data uploaded OK");
  } else {
    Serial.println("Upload failed: " + fbdo.errorReason());
  }

  // Update latest data with minimal path length
  if (Firebase.setJSON(fbdo, "/latest/" + deviceId, json)) {
    Serial.println("Latest data updated");
  }
}

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

  dht.begin();

  pinMode(LDR_PIN, INPUT);
  pinMode(RESET_BTN_PIN, INPUT_PULLUP);

  setupWiFi();
  setupFirebase();
}

void loop() {
  // Check for WiFi reset
  if (checkResetButton()) {
    // Serial.println("WiFi reset requested");
    WiFiManager wifiManager;
    wifiManager.resetSettings();
    ESP.restart();
  }

  // Upload data at interval
  if (millis() - lastUploadTime >= UPLOAD_INTERVAL) {
    uploadToFirebase();
    lastUploadTime = millis();
  }

  delay(100);
}