#define BLYNK_TEMPLATE_ID "TMPL3osnHgTqu"
#define BLYNK_TEMPLATE_NAME "Harsha"
#define BLYNK_AUTH_TOKEN "Qr28QrW6cteMumkRw6Akxw2imvSSp7pz"

#include <Arduino.h>
#include <WiFi.h>
#include <BlynkSimpleEsp32.h>
#include "DHTesp.h"
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// --------------------------------------------------
// WiFi
// --------------------------------------------------

char ssid[] = "Wokwi-GUEST";
char pass[] = "";

// --------------------------------------------------
// Pin definitions
// --------------------------------------------------

const int DHT_PIN = 15;
const int BUZZER_PIN = 18;
const int GREEN_LED_PIN = 19;
const int RED_LED_PIN = 5;

// OLED pins
const int SDA_PIN = 21;
const int SCL_PIN = 22;

// --------------------------------------------------
// Safe range
// --------------------------------------------------

const float TEMP_MIN = 36.0;
const float TEMP_MAX = 38.0;

const float HUMIDITY_MIN = 50.0;
const float HUMIDITY_MAX = 60.0;

// --------------------------------------------------
// OLED
// --------------------------------------------------

#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
);

// --------------------------------------------------
// DHT22
// --------------------------------------------------

DHTesp dhtSensor;

// --------------------------------------------------
// Previous states
// --------------------------------------------------

bool previousTempOut = false;
bool previousHumidityOut = false;

// --------------------------------------------------
// Setup
// --------------------------------------------------

void setup() {

  Serial.begin(115200);

  // ------------------------------------------------
  // Pins
  // ------------------------------------------------

  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(RED_LED_PIN, OUTPUT);

  digitalWrite(BUZZER_PIN, LOW);
  digitalWrite(GREEN_LED_PIN, LOW);
  digitalWrite(RED_LED_PIN, LOW);

  // ------------------------------------------------
  // DHT22
  // ------------------------------------------------

  dhtSensor.setup(DHT_PIN, DHTesp::DHT22);

  // ------------------------------------------------
  // OLED
  // ------------------------------------------------

  Wire.begin(SDA_PIN, SCL_PIN);

  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS)) {

    Serial.println("OLED initialization failed!");

    while (true);
  }

  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  display.setTextSize(1);
  display.setCursor(20, 25);
  display.println("DHT22 SYSTEM");

  display.display();

  delay(2000);

  // ------------------------------------------------
  // Blynk connection
  // ------------------------------------------------

  Serial.println("Connecting to Blynk...");

  Blynk.begin(
    BLYNK_AUTH_TOKEN,
    ssid,
    pass
  );

  Serial.println("Blynk Connected!");
  Serial.println("System Initialized.");
}

// --------------------------------------------------
// Loop
// --------------------------------------------------

void loop() {

  // Keep Blynk connected
  Blynk.run();

  // ------------------------------------------------
  // Read DHT22
  // ------------------------------------------------

  TempAndHumidity data =
    dhtSensor.getTempAndHumidity();

  float temp = data.temperature;
  float humidity = data.humidity;

  // ------------------------------------------------
  // Sensor error
  // ------------------------------------------------

  if (isnan(temp) || isnan(humidity)) {

    Serial.println("DHT22 read error!");

    digitalWrite(GREEN_LED_PIN, LOW);
    digitalWrite(RED_LED_PIN, HIGH);

    tone(BUZZER_PIN, 1000);

    display.clearDisplay();

    display.setTextColor(SSD1306_WHITE);

    display.setTextSize(2);
    display.setCursor(15, 10);
    display.println("ERROR");

    display.setTextSize(1);
    display.setCursor(10, 40);
    display.println("DHT22 Read Failed");

    display.display();

    delay(2000);

    return;
  }

  // ------------------------------------------------
  // Send data to Blynk Datastreams (V0 & V1)
  // ------------------------------------------------

  Blynk.virtualWrite(V0, temp);
  Blynk.virtualWrite(V1, humidity);

  // ------------------------------------------------
  // Check safe ranges
  // ------------------------------------------------

  bool tempOut =
    (temp < TEMP_MIN || temp > TEMP_MAX);

  bool humidityOut =
    (humidity < HUMIDITY_MIN ||
     humidity > HUMIDITY_MAX);

  bool bothOut =
    tempOut && humidityOut;

  // ------------------------------------------------
  // LED + Buzzer
  // ------------------------------------------------

  if (!tempOut && !humidityOut) {

    // SAFE

    digitalWrite(GREEN_LED_PIN, HIGH);
    digitalWrite(RED_LED_PIN, LOW);

    noTone(BUZZER_PIN);

    Serial.println("STATUS: SAFE");

  } 
  else {

    // ALERT

    digitalWrite(GREEN_LED_PIN, LOW);
    digitalWrite(RED_LED_PIN, HIGH);

    tone(BUZZER_PIN, 1000);

    Serial.println("STATUS: ALERT");
  }

  // ------------------------------------------------
  // BLYNK EVENTS / ALERTS
  // ------------------------------------------------

  // BOTH TEMPERATURE AND HUMIDITY OUT (Triggers event: "danger")
  if (bothOut && !(previousTempOut && previousHumidityOut)) {

    Blynk.logEvent(
      "danger",
      String("TEMPERATURE + HUMIDITY DANGER! Temp: ") +
      String(temp, 1) +
      " C, Humidity: " +
      String(humidity, 1) +
      " %"
    );

    Serial.println("BLYNK: DANGER EVENT LOGGED");
  }

  // ONLY TEMPERATURE OUT (Triggers event: "temperature_warning")
  else if (tempOut && !humidityOut && !previousTempOut) {

    Blynk.logEvent(
      "temperature_warning",
      String("Temperature Warning! ") +
      String(temp, 1) +
      " C (Safe: 36-38 C)"
    );

    Serial.println("BLYNK: TEMPERATURE WARNING LOGGED");
  }

  // ONLY HUMIDITY OUT (Triggers event: "humidity_warning")
  else if (humidityOut && !tempOut && !previousHumidityOut) {

    Blynk.logEvent(
      "humidity_warning",
      String("Humidity Warning! ") +
      String(humidity, 1) +
      " % (Safe: 50-60 %)"
    );

    Serial.println("BLYNK: HUMIDITY WARNING LOGGED");
  }

  // ------------------------------------------------
  // Save current states
  // ------------------------------------------------

  previousTempOut = tempOut;
  previousHumidityOut = humidityOut;

  // ------------------------------------------------
  // Serial Monitor
  // ------------------------------------------------

  Serial.print("Temperature: ");
  Serial.print(temp, 2);
  Serial.println(" C");

  Serial.print("Humidity: ");
  Serial.print(humidity, 1);
  Serial.println(" %");

  Serial.println("------------------------------------");

  // ------------------------------------------------
  // OLED DISPLAY
  // ------------------------------------------------

  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);

  // Title
  display.setTextSize(1);
  display.setCursor(25, 0);
  display.println("DHT22 MONITOR");

  // Temperature
  display.setTextSize(2);
  display.setCursor(0, 16);

  display.print("T:");
  display.print(temp, 1);
  display.println(" C");

  // Humidity
  display.setCursor(0, 36);

  display.print("H:");
  display.print(humidity, 1);
  display.println("%");

  // Status
  display.setTextSize(1);
  display.setCursor(0, 56);

  if (!tempOut && !humidityOut) {

    display.print("STATUS: SAFE");

  } 
  else {

    display.print("STATUS: ALERT!");
  }

  display.display();

  // ------------------------------------------------
  // Reading interval
  // ------------------------------------------------

  delay(2000);
}