//  Fridge Monitoring System (ESP32 + ThingSpeak + Twilio)
//  DHT22 reads temperature & humidity
//  Push button detects fridge door status
//  Data is sent to ThingSpeak for remote monitoring
//  Twilio sends SMS alerts for critical conditions.

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

//  Wi-Fi Credentials (Replace with your Wokwi Wi-Fi)
const char* ssid = "Wokwi-GUEST";  
const char* password = "";

//  ThingSpeak Credentials
const char* THINGSPEAK_API_KEY = "D88QSHNQJZSM9SZI";  
unsigned long THINGSPEAK_CHANNEL_ID = 2838022;  

//  Twilio Credentials (for SMS Alerts)
const char* TWILIO_SID = "ACfa444b0fc581e0e3c17088d0f406c3ce";  
const char* TWILIO_AUTH_TOKEN = "5a2d7e830d8765218864167c37c78238";  
const char* TWILIO_PHONE_NUMBER = "+16402303109";  // Twilio sender number  
const char* YOUR_PHONE_NUMBER = "+916369474178";  // Your phone to receive SMS  

//  Sensor Setup
#define DHTPIN 4        
#define DHTTYPE DHT22   
DHT dht(DHTPIN, DHTTYPE);

#define DOOR_SENSOR_PIN 5   // Push button for fridge door
bool fridgeDoorOpen = false;
unsigned long doorOpenStartTime = 0;
const unsigned long DOOR_OPEN_THRESHOLD = 60000;  // 60 sec

WiFiClient client;

void setup() {
    Serial.begin(115200);
    
    //  Connect to Wi-Fi
    WiFi.begin(ssid, password);
    Serial.print("Connecting to Wi-Fi...");
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
    }
    Serial.println("\n Connected to Wi-Fi!");

    //  Initialize DHT Sensor
    dht.begin();
    
    //  Set up fridge door sensor
    pinMode(DOOR_SENSOR_PIN, INPUT_PULLUP);

    //  Initialize ThingSpeak
    ThingSpeak.begin(client);
}

void loop() {
    //  Read Temperature & Humidity
    float temperature = dht.readTemperature();
    float humidity = dht.readHumidity();
    
    if (isnan(temperature) || isnan(humidity)) {
        Serial.println(" Failed to read from DHT sensor!");
        return;
    }

    //  Check Fridge Door Status
    bool doorStatus = digitalRead(DOOR_SENSOR_PIN) == LOW;  // LOW = Open, HIGH = Closed
    if (doorStatus) {
        if (!fridgeDoorOpen) {
            fridgeDoorOpen = true;
            doorOpenStartTime = millis();
        }
    } else {
        fridgeDoorOpen = false;
    }

    //  Send Data to ThingSpeak
    sendToThingSpeak(temperature, humidity, fridgeDoorOpen);

    //  Trigger Alert if Necessary
    if (fridgeDoorOpen && (millis() - doorOpenStartTime > DOOR_OPEN_THRESHOLD)) {
        sendSMSAlert(" Fridge Door Open Too Long! Close it ASAP!");
    }
    if (temperature > 10) {
        sendSMSAlert(" Temperature Alert! Fridge is warming: " + String(temperature) + "°C");
    }
    if (humidity > 80) {
        sendSMSAlert(" Humidity Alert! Too much moisture: " + String(humidity) + "%");
    }

    delay(30000);  // Wait 30 sec before next update
}

// 📡 Send Data to ThingSpeak
void sendToThingSpeak(float temperature, float humidity, bool doorStatus) {
    if (WiFi.status() == WL_CONNECTED) {
        ThingSpeak.setField(1, temperature);
        ThingSpeak.setField(2, humidity);
        ThingSpeak.setField(3, doorStatus ? 1 : 0);

        int responseCode = ThingSpeak.writeFields(THINGSPEAK_CHANNEL_ID, THINGSPEAK_API_KEY);
        if (responseCode == 200) {
            Serial.println(" Data sent to ThingSpeak!");
        } else {
            Serial.println(" ThingSpeak Error: " + String(responseCode));
        }
    }
}

// 📲 Send SMS Alert via Twilio
void sendSMSAlert(String message) {
    if (WiFi.status() == WL_CONNECTED) {
        HTTPClient http;
        String url = "https://api.twilio.com/2010-04-01/Accounts/" + String(TWILIO_SID) + "/Messages.json";
        
        String postData = "To=" + String(YOUR_PHONE_NUMBER) +
                          "&From=" + String(TWILIO_PHONE_NUMBER) +
                          "&Body=" + message;

        http.begin(url);
        http.setAuthorization(TWILIO_SID, TWILIO_AUTH_TOKEN);
        http.addHeader("Content-Type", "application/x-www-form-urlencoded");
        
        int responseCode = http.POST(postData);
        if (responseCode > 0) {
            Serial.println(" SMS Sent: " + message);
        } else {
            Serial.println(" SMS Failed!");
        }
        http.end();
    }
}