#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <RTClib.h>
#include <DHT.h>

// ---------- Pin Settings ----------
#define SDA_PIN   21
#define SCL_PIN   22

#define DHT_PIN   4
#define DHT_TYPE  DHT22

#define LED_RED   25
#define LED_BLUE  26
#define BUZZER    27

// ---------- OLED ----------
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// ---------- RTC ----------
RTC_DS1307 rtc;

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

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

    // I2C
      Wire.begin(SDA_PIN, SCL_PIN);

        // LED
          pinMode(LED_RED, OUTPUT);
            pinMode(LED_BLUE, OUTPUT);

              // Buzzer
                pinMode(BUZZER, OUTPUT);

                  digitalWrite(LED_RED, LOW);
                    digitalWrite(LED_BLUE, LOW);

                      // ---------- OLED Start ----------
                        if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
                            Serial.println("OLED ERROR!");
                                while (1);
                                  }

                                    display.clearDisplay();
                                      display.setTextColor(SSD1306_WHITE);
                                        display.setTextSize(2);
                                          display.setCursor(10, 10);
                                            display.println("SYSTEM");
                                              display.setCursor(10, 35);
                                                display.println("TEST");
                                                  display.display();

                                                    // ---------- RTC Start ----------
                                                      if (!rtc.begin()) {
                                                          Serial.println("RTC ERROR!");

                                                              display.clearDisplay();
                                                                  display.setTextSize(2);
                                                                      display.setCursor(0, 20);
                                                                          display.println("RTC ERROR");
                                                                              display.display();

                                                                                  while (1);
                                                                                    }

                                                                                      // Only set RTC if it is not running
                                                                                        if (!rtc.isrunning()) {
                                                                                            rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
                                                                                              }

                                                                                                // ---------- DHT Start ----------
                                                                                                  dht.begin();

                                                                                                    // ---------- LED + Buzzer Test ----------
                                                                                                      digitalWrite(LED_RED, HIGH);
                                                                                                        digitalWrite(LED_BLUE, HIGH);

                                                                                                          tone(BUZZER, 1000);
                                                                                                            delay(500);
                                                                                                              noTone(BUZZER);

                                                                                                                delay(1000);

                                                                                                                  digitalWrite(LED_RED, LOW);
                                                                                                                    digitalWrite(LED_BLUE, LOW);

                                                                                                                      Serial.println("SYSTEM TEST STARTED");
                                                                                                                      }

                                                                                                                      void loop() {

                                                                                                                        // Read RTC
                                                                                                                          DateTime now = rtc.now();

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

                                                                                                                                  // ---------- Serial Monitor ----------
                                                                                                                                    Serial.print("Time: ");

                                                                                                                                      if (now.hour() < 10) Serial.print("0");
                                                                                                                                        Serial.print(now.hour());
                                                                                                                                          Serial.print(":");

                                                                                                                                            if (now.minute() < 10) Serial.print("0");
                                                                                                                                              Serial.print(now.minute());
                                                                                                                                                Serial.print(":");

                                                                                                                                                  if (now.second() < 10) Serial.print("0");
                                                                                                                                                    Serial.println(now.second());

                                                                                                                                                      Serial.print("Date: ");
                                                                                                                                                        Serial.print(now.day());
                                                                                                                                                          Serial.print("/");
                                                                                                                                                            Serial.print(now.month());
                                                                                                                                                              Serial.print("/");
                                                                                                                                                                Serial.println(now.year());

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

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

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

                                                                                                                                                                                // ---------- OLED ----------
                                                                                                                                                                                  display.clearDisplay();

                                                                                                                                                                                    display.setTextSize(2);
                                                                                                                                                                                      display.setCursor(0, 0);

                                                                                                                                                                                        if (now.hour() < 10) display.print("0");
                                                                                                                                                                                          display.print(now.hour());
                                                                                                                                                                                            display.print(":");

                                                                                                                                                                                              if (now.minute() < 10) display.print("0");
                                                                                                                                                                                                display.print(now.minute());
                                                                                                                                                                                                  display.print(":");

                                                                                                                                                                                                    if (now.second() < 10) display.print("0");
                                                                                                                                                                                                      display.println(now.second());

                                                                                                                                                                                                        display.setTextSize(1);

                                                                                                                                                                                                          display.setCursor(0, 25);
                                                                                                                                                                                                            display.print("Date: ");
                                                                                                                                                                                                              display.print(now.day());
                                                                                                                                                                                                                display.print("/");
                                                                                                                                                                                                                  display.print(now.month());
                                                                                                                                                                                                                    display.print("/");
                                                                                                                                                                                                                      display.println(now.year());

                                                                                                                                                                                                                        display.setCursor(0, 40);

                                                                                                                                                                                                                          if (isnan(temperature)) {
                                                                                                                                                                                                                              display.print("Temp: ERROR");
                                                                                                                                                                                                                                } else {
                                                                                                                                                                                                                                    display.print("Temp: ");
                                                                                                                                                                                                                                        display.print(temperature, 1);
                                                                                                                                                                                                                                            display.print(" C");
                                                                                                                                                                                                                                              }

                                                                                                                                                                                                                                                display.setCursor(0, 52);

                                                                                                                                                                                                                                                  if (isnan(humidity)) {
                                                                                                                                                                                                                                                      display.print("Hum: ERROR");
                                                                                                                                                                                                                                                        } else {
                                                                                                                                                                                                                                                            display.print("Hum: ");
                                                                                                                                                                                                                                                                display.print(humidity, 1);
                                                                                                                                                                                                                                                                    display.print(" %");
                                                                                                                                                                                                                                                                      }

                                                                                                                                                                                                                                                                        display.display();

                                                                                                                                                                                                                                                                          delay(2000);
                                                                                                                                                                                                                                                                          }