#include <WiFi.h>
#include <WiFiClientSecure.h>

// ReadyMail Configuration
#define ENABLE_SMTP
#include <ReadyMail.h>

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Fonts/FreeSansBold18pt7b.h>
#include <DHT.h>

// --- Pin Definitions ---
#define I2C_SDA          21
#define I2C_SCL          22
#define FLAME_SENSOR_PIN 15
#define GAS_SENSOR_PIN   2
#define DHT_PIN          12
#define DHT_TYPE         DHT22

// --- OLED Configuration ---
#define SCREEN_WIDTH     128
#define SCREEN_HEIGHT    64
#define OLED_RESET       -1
#define OLED_ADDRESS     0x3C 

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
DHT dht(DHT_PIN, DHT_TYPE);

// --- Network & Mail Configuration ---
#define WIFI_SSID        "Wokwi-GUEST"
#define WIFI_PASSWORD    ""

#define SMTP_HOST        "smtp.gmail.com"
#define SMTP_PORT        465

#define AUTHOR_EMAIL     "[email protected]"
#define AUTHOR_PASSWORD  "viom mfli mpkm fwol"
#define RECIPIENT_EMAIL  "[email protected]"

// --- ReadyMail Objects ---
WiFiClientSecure ssl_client;
SMTPClient smtp(ssl_client);

// --- Timing Variables ---
unsigned long lastDisplayUpdate = 0;
const unsigned long displayInterval = 2000; 

unsigned long lastEmailSent = 0;
const unsigned long emailCooldown = 60000; // 60s cooldown between emails

bool displayToggle = false;

// Function Prototypes
void send_mail(float temp, float hum, int flame, int gas);
void updateDisplay(float temp, float hum, int flame, int gas);
void showSendingEmailScreen();
void showAlarmScreen(float temp, float hum, int flame, int gas);

void setup() {
  Serial.begin(115200);
  
  Wire.begin(I2C_SDA, I2C_SCL);

  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(0, 10);
  display.println(F("System Initializing..."));
  display.display();

  dht.begin();
  pinMode(FLAME_SENSOR_PIN, INPUT_PULLUP);
  pinMode(GAS_SENSOR_PIN, INPUT_PULLUP);

  // Configure Secure SSL Client
  ssl_client.setInsecure(); // Bypass server certificate verification for testing

  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.print("Connecting to Wi-Fi");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(300);
  }
  Serial.println("\nConnected with IP: " + WiFi.localIP().toString());

  display.clearDisplay();
  display.setCursor(0, 10);
  display.println(F("WiFi Connected!"));
  display.display();
  delay(1000);
}

void loop() {
  int flameValue = digitalRead(FLAME_SENSOR_PIN);
  int gasValue = digitalRead(GAS_SENSOR_PIN);
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  if (isnan(humidity) || isnan(temperature)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }

  // Active Low for Flame/Gas Digital Outputs
  bool isAlarm = (temperature > 40.0) || (flameValue == LOW) || (gasValue == LOW);

  if (isAlarm) {
    showAlarmScreen(temperature, humidity, flameValue, gasValue);

    if (millis() - lastEmailSent > emailCooldown) {
      Serial.println("Alarm condition detected! Sending email via ReadyMail...");
      showSendingEmailScreen();
      send_mail(temperature, humidity, flameValue, gasValue);
      lastEmailSent = millis();
    }
  } else {
    if (millis() - lastDisplayUpdate >= displayInterval) {
      lastDisplayUpdate = millis();
      displayToggle = !displayToggle;
      updateDisplay(temperature, humidity, flameValue, gasValue);
    }
  }
}

void showSendingEmailScreen() {
  display.clearDisplay();
  display.setFont();
  display.setTextColor(SSD1306_WHITE);
  
  display.fillRect(0, 0, 128, 16, SSD1306_WHITE);
  display.setTextColor(SSD1306_BLACK);
  display.setTextSize(1);
  display.setCursor(12, 4);
  display.print(F("CRITICAL ALARM!"));

  display.setTextColor(SSD1306_WHITE);
  display.setCursor(10, 30);
  display.print(F("Sending Alert Email"));
  display.setCursor(20, 48);
  display.print(F("Please Wait..."));

  display.display();
}

void showAlarmScreen(float temp, float hum, int flame, int gas) {
  display.clearDisplay();
  display.setFont();
  
  display.fillRect(0, 0, 128, 16, SSD1306_WHITE);
  display.setTextColor(SSD1306_BLACK);
  display.setTextSize(1);
  display.setCursor(20, 4);
  display.print(F("** ALARM ACTIVE **"));

  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 22);
  display.printf("Temp : %.1f C %s\n", temp, (temp > 40.0) ? "[OVER]" : "");

  display.setCursor(0, 36);
  display.printf("Flame: %s\n", (flame == LOW) ? "TRIPPED!" : "OK");

  display.setCursor(0, 50);
  display.printf("Gas  : %s\n", (gas == LOW) ? "TRIPPED!" : "OK");

  display.display();
}

void updateDisplay(float temp, float hum, int flame, int gas) {
  display.clearDisplay();

  if (displayToggle) {
    display.setFont(); 
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0, 0);
    display.print(F("TEMPERATURE"));

    display.setFont(&FreeSansBold18pt7b);
    display.setCursor(5, 42);
    display.printf("%.1f", temp);
    
    display.setFont();
    display.setTextSize(1);
    display.setCursor(95, 20);
    display.print((char)247);
    display.print("C");

    display.setCursor(0, 54);
    display.printf("Humidity: %.1f%%", hum);
  } else {
    display.setFont(); 
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    
    display.setCursor(0, 0);
    display.println(F("--- SENSOR STATUS ---"));
    
    display.setCursor(0, 18);
    display.printf("Flame Sensor : %s\n", (flame == LOW) ? "ALARM!" : "OK");
    
    display.setCursor(0, 32);
    display.printf("Gas Sensor   : %s\n", (gas == LOW) ? "ALARM!" : "OK");

    display.setCursor(0, 48);
    display.printf("System Temp  : %.1f C", temp);
  }

  display.display();
}

void send_mail(float temp, float hum, int flame, int gas) {
  auto statusCallback = [](SMTPStatus status) {
    Serial.printf("[ReadyMail] %s\n", status.text.c_str());
  };

  smtp.connect(SMTP_HOST, SMTP_PORT, statusCallback);

  if (!smtp.isConnected()) {
    Serial.println("ReadyMail SMTP Connection Failed.");
    return;
  }

  smtp.authenticate(AUTHOR_EMAIL, AUTHOR_PASSWORD, readymail_auth_password);

  if (!smtp.isAuthenticated()) {
    Serial.println("ReadyMail Authentication Failed.");
    return;
  }

  SMTPMessage msg;
  msg.headers.add(rfc822_subject, "CRITICAL ALARM: Hazard Detected!");
  msg.headers.add(rfc822_from, "ESP32 Safety System <" + String(AUTHOR_EMAIL) + ">");
  msg.headers.add(rfc822_to, "Recipient <" + String(RECIPIENT_EMAIL) + ">");

  String bodyText = "CRITICAL ALARM DETECTED!\n\n";
  bodyText += "Temperature: " + String(temp, 1) + " C\n";
  bodyText += "Humidity: " + String(hum, 1) + " %\n";
  bodyText += "Flame Status: " + String((flame == LOW) ? "FIRE DETECTED" : "Normal") + "\n";
  bodyText += "Gas Status: " + String((gas == LOW) ? "GAS LEAK DETECTED" : "Normal") + "\n";

  msg.text.body(bodyText);

  if (smtp.send(msg)) {
    Serial.println("Email sent successfully via ReadyMail!");
  } else {
    Serial.println("Failed to send email via ReadyMail.");
  }
}