#include <Arduino.h>
#include <Wire.h>
#include <DHT.h>
#include <Adafruit_BMP085.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// ---------------- PIN CONNECTIONS ----------------
#define DHT_PIN       4
#define DHT_TYPE      DHT22

#define SDA_PIN       21
#define SCL_PIN       22

#define GREEN_LED     25
#define RED_LED       26
#define BUZZER        23
#define TEST_BUTTON   5

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

DHT dht(DHT_PIN, DHT_TYPE);
Adafruit_BMP085 bmp;
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// ---------------- VARIABLES ----------------
float temperature;
float humidity;
float pressure;

bool bmpOK = false;
bool dhtOK = false;
bool fault = false;

unsigned long lastRead = 0;

// ------------------------------------------------
// SETUP
// ------------------------------------------------
void setup() {

  Serial.begin(115200);

  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  pinMode(TEST_BUTTON, INPUT_PULLUP);

  Wire.begin(SDA_PIN, SCL_PIN);

  dht.begin();

  // Start BMP180
  bmpOK = bmp.begin();

  // Start OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS)) {
    Serial.println("OLED not found!");
  }

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

  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("AI WEATHER STATION");
  display.println();
  display.println("Starting...");
  display.display();

  delay(2000);
}

// ------------------------------------------------
// LOOP
// ------------------------------------------------
void loop() {

  if (millis() - lastRead >= 2000) {

    lastRead = millis();

    // Read DHT22
    temperature = dht.readTemperature();
    humidity = dht.readHumidity();

    // Read BMP180
    if (bmpOK) {
      pressure = bmp.readPressure() / 100.0;
    }

    // Check sensors
    dhtOK = !isnan(temperature) && !isnan(humidity);

    fault = false;

    // ---------------- SENSOR FAULT DETECTION ----------------

    // DHT sensor failure
    if (!dhtOK) {
      fault = true;
      Serial.println("FAULT: DHT22 sensor failure");
    }

    // BMP180 failure
    if (!bmpOK) {
      fault = true;
      Serial.println("FAULT: BMP180 sensor failure");
    }

    // Temperature abnormality
    if (dhtOK) {
      if (temperature < -40 || temperature > 80) {
        fault = true;
        Serial.println("FAULT: Abnormal temperature");
      }
    }

    // Humidity abnormality
    if (dhtOK) {
      if (humidity < 0 || humidity > 100) {
        fault = true;
        Serial.println("FAULT: Abnormal humidity");
      }
    }

    // Pressure abnormality
    if (bmpOK) {
      if (pressure < 300 || pressure > 1100) {
        fault = true;
        Serial.println("FAULT: Abnormal pressure");
      }
    }

    // Pushbutton = simulated sensor fault
    if (digitalRead(TEST_BUTTON) == LOW) {
      fault = true;
      Serial.println("FAULT TEST: Pushbutton activated");
    }

    // ---------------- OUTPUT ----------------

    if (fault) {

      digitalWrite(GREEN_LED, LOW);
      digitalWrite(RED_LED, HIGH);

      tone(BUZZER, 1000);

      showFault();

    } else {

      digitalWrite(GREEN_LED, HIGH);
      digitalWrite(RED_LED, LOW);

      noTone(BUZZER);

      showWeather();
    }
  }
}

// ------------------------------------------------
// NORMAL WEATHER DISPLAY
// ------------------------------------------------
void showWeather() {

  display.clearDisplay();

  display.setTextSize(1);
  display.setCursor(0, 0);

  display.println("AI SMART WEATHER");
  display.println("----------------");

  display.print("Temp : ");
  display.print(temperature, 1);
  display.println(" C");

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

  display.print("Press: ");
  display.print(pressure, 1);
  display.println(" hPa");

  display.println();
  display.println("STATUS: NORMAL");

  display.display();

  // Serial monitor
  Serial.println("-------------------------");
  Serial.println("WEATHER DATA");

  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" C");

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

  Serial.print("Pressure: ");
  Serial.print(pressure);
  Serial.println(" hPa");

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

// ------------------------------------------------
// FAULT DISPLAY
// ------------------------------------------------
void showFault() {

  display.clearDisplay();

  display.setTextSize(1);
  display.setCursor(0, 0);

  display.println("AI SMART WEATHER");
  display.println("----------------");

  display.println("!! SENSOR FAULT !!");

  if (!dhtOK) {
    display.println("DHT22: ERROR");
  }

  if (!bmpOK) {
    display.println("BMP180: ERROR");
  }

  if (digitalRead(TEST_BUTTON) == LOW) {
    display.println("TEST: FAULT");
  }

  display.println();
  display.println("CHECK SENSOR");

  display.display();
}